arrayfuncs.c

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/*-------------------------------------------------------------------------
 *
 * arrayfuncs.c
 *    Support functions for arrays.
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/arrayfuncs.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <ctype.h>

#include "access/htup_details.h"
#include "funcapi.h"
#include "libpq/pqformat.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/typcache.h"


/*
 * GUC parameter
 */
bool        Array_nulls = true;

/*
 * Local definitions
 */
#define ASSGN    "="

typedef enum
{
    ARRAY_NO_LEVEL,
    ARRAY_LEVEL_STARTED,
    ARRAY_ELEM_STARTED,
    ARRAY_ELEM_COMPLETED,
    ARRAY_QUOTED_ELEM_STARTED,
    ARRAY_QUOTED_ELEM_COMPLETED,
    ARRAY_ELEM_DELIMITED,
    ARRAY_LEVEL_COMPLETED,
    ARRAY_LEVEL_DELIMITED
} ArrayParseState;

/* Working state for array_iterate() */
typedef struct ArrayIteratorData
{
    /* basic info about the array, set up during array_create_iterator() */
    ArrayType  *arr;            /* array we're iterating through */
    bits8      *nullbitmap;     /* its null bitmap, if any */
    int         nitems;         /* total number of elements in array */
    int16       typlen;         /* element type's length */
    bool        typbyval;       /* element type's byval property */
    char        typalign;       /* element type's align property */

    /* information about the requested slice size */
    int         slice_ndim;     /* slice dimension, or 0 if not slicing */
    int         slice_len;      /* number of elements per slice */
    int        *slice_dims;     /* slice dims array */
    int        *slice_lbound;   /* slice lbound array */
    Datum      *slice_values;   /* workspace of length slice_len */
    bool       *slice_nulls;    /* workspace of length slice_len */

    /* current position information, updated on each iteration */
    char       *data_ptr;       /* our current position in the array */
    int         current_item;   /* the item # we're at in the array */
}   ArrayIteratorData;

static bool array_isspace(char ch);
static int  ArrayCount(const char *str, int *dim, char typdelim);
static void ReadArrayStr(char *arrayStr, const char *origStr,
             int nitems, int ndim, int *dim,
             FmgrInfo *inputproc, Oid typioparam, int32 typmod,
             char typdelim,
             int typlen, bool typbyval, char typalign,
             Datum *values, bool *nulls,
             bool *hasnulls, int32 *nbytes);
static void ReadArrayBinary(StringInfo buf, int nitems,
                FmgrInfo *receiveproc, Oid typioparam, int32 typmod,
                int typlen, bool typbyval, char typalign,
                Datum *values, bool *nulls,
                bool *hasnulls, int32 *nbytes);
static void CopyArrayEls(ArrayType *array,
             Datum *values, bool *nulls, int nitems,
             int typlen, bool typbyval, char typalign,
             bool freedata);
static bool array_get_isnull(const bits8 *nullbitmap, int offset);
static void array_set_isnull(bits8 *nullbitmap, int offset, bool isNull);
static Datum ArrayCast(char *value, bool byval, int len);
static int ArrayCastAndSet(Datum src,
                int typlen, bool typbyval, char typalign,
                char *dest);
static char *array_seek(char *ptr, int offset, bits8 *nullbitmap, int nitems,
           int typlen, bool typbyval, char typalign);
static int array_nelems_size(char *ptr, int offset, bits8 *nullbitmap,
                  int nitems, int typlen, bool typbyval, char typalign);
static int array_copy(char *destptr, int nitems,
           char *srcptr, int offset, bits8 *nullbitmap,
           int typlen, bool typbyval, char typalign);
static int array_slice_size(char *arraydataptr, bits8 *arraynullsptr,
                 int ndim, int *dim, int *lb,
                 int *st, int *endp,
                 int typlen, bool typbyval, char typalign);
static void array_extract_slice(ArrayType *newarray,
                    int ndim, int *dim, int *lb,
                    char *arraydataptr, bits8 *arraynullsptr,
                    int *st, int *endp,
                    int typlen, bool typbyval, char typalign);
static void array_insert_slice(ArrayType *destArray, ArrayType *origArray,
                   ArrayType *srcArray,
                   int ndim, int *dim, int *lb,
                   int *st, int *endp,
                   int typlen, bool typbyval, char typalign);
static int  array_cmp(FunctionCallInfo fcinfo);
static ArrayType *create_array_envelope(int ndims, int *dimv, int *lbv, int nbytes,
                      Oid elmtype, int dataoffset);
static ArrayType *array_fill_internal(ArrayType *dims, ArrayType *lbs,
                    Datum value, bool isnull, Oid elmtype,
                    FunctionCallInfo fcinfo);
static ArrayType *array_replace_internal(ArrayType *array,
                       Datum search, bool search_isnull,
                       Datum replace, bool replace_isnull,
                       bool remove, Oid collation,
                       FunctionCallInfo fcinfo);


/*
 * array_in :
 *        converts an array from the external format in "string" to
 *        its internal format.
 *
 * return value :
 *        the internal representation of the input array
 */
Datum
array_in(PG_FUNCTION_ARGS)
{
    char       *string = PG_GETARG_CSTRING(0);  /* external form */
    Oid         element_type = PG_GETARG_OID(1);        /* type of an array
                                                         * element */
    int32       typmod = PG_GETARG_INT32(2);    /* typmod for array elements */
    int         typlen;
    bool        typbyval;
    char        typalign;
    char        typdelim;
    Oid         typioparam;
    char       *string_save,
               *p;
    int         i,
                nitems;
    Datum      *dataPtr;
    bool       *nullsPtr;
    bool        hasnulls;
    int32       nbytes;
    int32       dataoffset;
    ArrayType  *retval;
    int         ndim,
                dim[MAXDIM],
                lBound[MAXDIM];
    ArrayMetaState *my_extra;

    /*
     * We arrange to look up info about element type, including its input
     * conversion proc, only once per series of calls, assuming the element
     * type doesn't change underneath us.
     */
    my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
    if (my_extra == NULL)
    {
        fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                                                      sizeof(ArrayMetaState));
        my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
        my_extra->element_type = ~element_type;
    }

    if (my_extra->element_type != element_type)
    {
        /*
         * Get info about element type, including its input conversion proc
         */
        get_type_io_data(element_type, IOFunc_input,
                         &my_extra->typlen, &my_extra->typbyval,
                         &my_extra->typalign, &my_extra->typdelim,
                         &my_extra->typioparam, &my_extra->typiofunc);
        fmgr_info_cxt(my_extra->typiofunc, &my_extra->proc,
                      fcinfo->flinfo->fn_mcxt);
        my_extra->element_type = element_type;
    }
    typlen = my_extra->typlen;
    typbyval = my_extra->typbyval;
    typalign = my_extra->typalign;
    typdelim = my_extra->typdelim;
    typioparam = my_extra->typioparam;

    /* Make a modifiable copy of the input */
    string_save = pstrdup(string);

    /*
     * If the input string starts with dimension info, read and use that.
     * Otherwise, we require the input to be in curly-brace style, and we
     * prescan the input to determine dimensions.
     *
     * Dimension info takes the form of one or more [n] or [m:n] items. The
     * outer loop iterates once per dimension item.
     */
    p = string_save;
    ndim = 0;
    for (;;)
    {
        char       *q;
        int         ub;

        /*
         * Note: we currently allow whitespace between, but not within,
         * dimension items.
         */
        while (array_isspace(*p))
            p++;
        if (*p != '[')
            break;              /* no more dimension items */
        p++;
        if (ndim >= MAXDIM)
            ereport(ERROR,
                    (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                     errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
                            ndim + 1, MAXDIM)));

        for (q = p; isdigit((unsigned char) *q) || (*q == '-') || (*q == '+'); q++);
        if (q == p)             /* no digits? */
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("missing dimension value")));

        if (*q == ':')
        {
            /* [m:n] format */
            *q = '\0';
            lBound[ndim] = atoi(p);
            p = q + 1;
            for (q = p; isdigit((unsigned char) *q) || (*q == '-') || (*q == '+'); q++);
            if (q == p)         /* no digits? */
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                         errmsg("missing dimension value")));
        }
        else
        {
            /* [n] format */
            lBound[ndim] = 1;
        }
        if (*q != ']')
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("missing \"]\" in array dimensions")));

        *q = '\0';
        ub = atoi(p);
        p = q + 1;
        if (ub < lBound[ndim])
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("upper bound cannot be less than lower bound")));

        dim[ndim] = ub - lBound[ndim] + 1;
        ndim++;
    }

    if (ndim == 0)
    {
        /* No array dimensions, so intuit dimensions from brace structure */
        if (*p != '{')
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("array value must start with \"{\" or dimension information")));
        ndim = ArrayCount(p, dim, typdelim);
        for (i = 0; i < ndim; i++)
            lBound[i] = 1;
    }
    else
    {
        int         ndim_braces,
                    dim_braces[MAXDIM];

        /* If array dimensions are given, expect '=' operator */
        if (strncmp(p, ASSGN, strlen(ASSGN)) != 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("missing assignment operator")));
        p += strlen(ASSGN);
        while (array_isspace(*p))
            p++;

        /*
         * intuit dimensions from brace structure -- it better match what we
         * were given
         */
        if (*p != '{')
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("array value must start with \"{\" or dimension information")));
        ndim_braces = ArrayCount(p, dim_braces, typdelim);
        if (ndim_braces != ndim)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                errmsg("array dimensions incompatible with array literal")));
        for (i = 0; i < ndim; ++i)
        {
            if (dim[i] != dim_braces[i])
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                errmsg("array dimensions incompatible with array literal")));
        }
    }

#ifdef ARRAYDEBUG
    printf("array_in- ndim %d (", ndim);
    for (i = 0; i < ndim; i++)
    {
        printf(" %d", dim[i]);
    };
    printf(") for %s\n", string);
#endif

    /* This checks for overflow of the array dimensions */
    nitems = ArrayGetNItems(ndim, dim);
    /* Empty array? */
    if (nitems == 0)
        PG_RETURN_ARRAYTYPE_P(construct_empty_array(element_type));

    dataPtr = (Datum *) palloc(nitems * sizeof(Datum));
    nullsPtr = (bool *) palloc(nitems * sizeof(bool));
    ReadArrayStr(p, string,
                 nitems, ndim, dim,
                 &my_extra->proc, typioparam, typmod,
                 typdelim,
                 typlen, typbyval, typalign,
                 dataPtr, nullsPtr,
                 &hasnulls, &nbytes);
    if (hasnulls)
    {
        dataoffset = ARR_OVERHEAD_WITHNULLS(ndim, nitems);
        nbytes += dataoffset;
    }
    else
    {
        dataoffset = 0;         /* marker for no null bitmap */
        nbytes += ARR_OVERHEAD_NONULLS(ndim);
    }
    retval = (ArrayType *) palloc0(nbytes);
    SET_VARSIZE(retval, nbytes);
    retval->ndim = ndim;
    retval->dataoffset = dataoffset;

    /*
     * This comes from the array's pg_type.typelem (which points to the base
     * data type's pg_type.oid) and stores system oids in user tables. This
     * oid must be preserved by binary upgrades.
     */
    retval->elemtype = element_type;
    memcpy(ARR_DIMS(retval), dim, ndim * sizeof(int));
    memcpy(ARR_LBOUND(retval), lBound, ndim * sizeof(int));

    CopyArrayEls(retval,
                 dataPtr, nullsPtr, nitems,
                 typlen, typbyval, typalign,
                 true);

    pfree(dataPtr);
    pfree(nullsPtr);
    pfree(string_save);

    PG_RETURN_ARRAYTYPE_P(retval);
}

/*
 * array_isspace() --- a non-locale-dependent isspace()
 *
 * We used to use isspace() for parsing array values, but that has
 * undesirable results: an array value might be silently interpreted
 * differently depending on the locale setting.  Now we just hard-wire
 * the traditional ASCII definition of isspace().
 */
static bool
array_isspace(char ch)
{
    if (ch == ' ' ||
        ch == '\t' ||
        ch == '\n' ||
        ch == '\r' ||
        ch == '\v' ||
        ch == '\f')
        return true;
    return false;
}

/*
 * ArrayCount
 *   Determines the dimensions for an array string.
 *
 * Returns number of dimensions as function result.  The axis lengths are
 * returned in dim[], which must be of size MAXDIM.
 */
static int
ArrayCount(const char *str, int *dim, char typdelim)
{
    int         nest_level = 0,
                i;
    int         ndim = 1,
                temp[MAXDIM],
                nelems[MAXDIM],
                nelems_last[MAXDIM];
    bool        in_quotes = false;
    bool        eoArray = false;
    bool        empty_array = true;
    const char *ptr;
    ArrayParseState parse_state = ARRAY_NO_LEVEL;

    for (i = 0; i < MAXDIM; ++i)
    {
        temp[i] = dim[i] = 0;
        nelems_last[i] = nelems[i] = 1;
    }

    ptr = str;
    while (!eoArray)
    {
        bool        itemdone = false;

        while (!itemdone)
        {
            if (parse_state == ARRAY_ELEM_STARTED ||
                parse_state == ARRAY_QUOTED_ELEM_STARTED)
                empty_array = false;

            switch (*ptr)
            {
                case '\0':
                    /* Signal a premature end of the string */
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                             errmsg("malformed array literal: \"%s\"", str)));
                    break;
                case '\\':

                    /*
                     * An escape must be after a level start, after an element
                     * start, or after an element delimiter. In any case we
                     * now must be past an element start.
                     */
                    if (parse_state != ARRAY_LEVEL_STARTED &&
                        parse_state != ARRAY_ELEM_STARTED &&
                        parse_state != ARRAY_QUOTED_ELEM_STARTED &&
                        parse_state != ARRAY_ELEM_DELIMITED)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                            errmsg("malformed array literal: \"%s\"", str)));
                    if (parse_state != ARRAY_QUOTED_ELEM_STARTED)
                        parse_state = ARRAY_ELEM_STARTED;
                    /* skip the escaped character */
                    if (*(ptr + 1))
                        ptr++;
                    else
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                            errmsg("malformed array literal: \"%s\"", str)));
                    break;
                case '\"':

                    /*
                     * A quote must be after a level start, after a quoted
                     * element start, or after an element delimiter. In any
                     * case we now must be past an element start.
                     */
                    if (parse_state != ARRAY_LEVEL_STARTED &&
                        parse_state != ARRAY_QUOTED_ELEM_STARTED &&
                        parse_state != ARRAY_ELEM_DELIMITED)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                            errmsg("malformed array literal: \"%s\"", str)));
                    in_quotes = !in_quotes;
                    if (in_quotes)
                        parse_state = ARRAY_QUOTED_ELEM_STARTED;
                    else
                        parse_state = ARRAY_QUOTED_ELEM_COMPLETED;
                    break;
                case '{':
                    if (!in_quotes)
                    {
                        /*
                         * A left brace can occur if no nesting has occurred
                         * yet, after a level start, or after a level
                         * delimiter.
                         */
                        if (parse_state != ARRAY_NO_LEVEL &&
                            parse_state != ARRAY_LEVEL_STARTED &&
                            parse_state != ARRAY_LEVEL_DELIMITED)
                            ereport(ERROR,
                               (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                            errmsg("malformed array literal: \"%s\"", str)));
                        parse_state = ARRAY_LEVEL_STARTED;
                        if (nest_level >= MAXDIM)
                            ereport(ERROR,
                                    (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                                     errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
                                            nest_level + 1, MAXDIM)));
                        temp[nest_level] = 0;
                        nest_level++;
                        if (ndim < nest_level)
                            ndim = nest_level;
                    }
                    break;
                case '}':
                    if (!in_quotes)
                    {
                        /*
                         * A right brace can occur after an element start, an
                         * element completion, a quoted element completion, or
                         * a level completion.
                         */
                        if (parse_state != ARRAY_ELEM_STARTED &&
                            parse_state != ARRAY_ELEM_COMPLETED &&
                            parse_state != ARRAY_QUOTED_ELEM_COMPLETED &&
                            parse_state != ARRAY_LEVEL_COMPLETED &&
                            !(nest_level == 1 && parse_state == ARRAY_LEVEL_STARTED))
                            ereport(ERROR,
                               (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                            errmsg("malformed array literal: \"%s\"", str)));
                        parse_state = ARRAY_LEVEL_COMPLETED;
                        if (nest_level == 0)
                            ereport(ERROR,
                               (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                            errmsg("malformed array literal: \"%s\"", str)));
                        nest_level--;

                        if ((nelems_last[nest_level] != 1) &&
                            (nelems[nest_level] != nelems_last[nest_level]))
                            ereport(ERROR,
                               (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                errmsg("multidimensional arrays must have "
                                       "array expressions with matching "
                                       "dimensions")));
                        nelems_last[nest_level] = nelems[nest_level];
                        nelems[nest_level] = 1;
                        if (nest_level == 0)
                            eoArray = itemdone = true;
                        else
                        {
                            /*
                             * We don't set itemdone here; see comments in
                             * ReadArrayStr
                             */
                            temp[nest_level - 1]++;
                        }
                    }
                    break;
                default:
                    if (!in_quotes)
                    {
                        if (*ptr == typdelim)
                        {
                            /*
                             * Delimiters can occur after an element start, an
                             * element completion, a quoted element
                             * completion, or a level completion.
                             */
                            if (parse_state != ARRAY_ELEM_STARTED &&
                                parse_state != ARRAY_ELEM_COMPLETED &&
                                parse_state != ARRAY_QUOTED_ELEM_COMPLETED &&
                                parse_state != ARRAY_LEVEL_COMPLETED)
                                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                 errmsg("malformed array literal: \"%s\"", str)));
                            if (parse_state == ARRAY_LEVEL_COMPLETED)
                                parse_state = ARRAY_LEVEL_DELIMITED;
                            else
                                parse_state = ARRAY_ELEM_DELIMITED;
                            itemdone = true;
                            nelems[nest_level - 1]++;
                        }
                        else if (!array_isspace(*ptr))
                        {
                            /*
                             * Other non-space characters must be after a
                             * level start, after an element start, or after
                             * an element delimiter. In any case we now must
                             * be past an element start.
                             */
                            if (parse_state != ARRAY_LEVEL_STARTED &&
                                parse_state != ARRAY_ELEM_STARTED &&
                                parse_state != ARRAY_ELEM_DELIMITED)
                                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                 errmsg("malformed array literal: \"%s\"", str)));
                            parse_state = ARRAY_ELEM_STARTED;
                        }
                    }
                    break;
            }
            if (!itemdone)
                ptr++;
        }
        temp[ndim - 1]++;
        ptr++;
    }

    /* only whitespace is allowed after the closing brace */
    while (*ptr)
    {
        if (!array_isspace(*ptr++))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("malformed array literal: \"%s\"", str)));
    }

    /* special case for an empty array */
    if (empty_array)
        return 0;

    for (i = 0; i < ndim; ++i)
        dim[i] = temp[i];

    return ndim;
}

/*
 * ReadArrayStr :
 *   parses the array string pointed to by "arrayStr" and converts the values
 *   to internal format.  Unspecified elements are initialized to nulls.
 *   The array dimensions must already have been determined.
 *
 * Inputs:
 *  arrayStr: the string to parse.
 *            CAUTION: the contents of "arrayStr" will be modified!
 *  origStr: the unmodified input string, used only in error messages.
 *  nitems: total number of array elements, as already determined.
 *  ndim: number of array dimensions
 *  dim[]: array axis lengths
 *  inputproc: type-specific input procedure for element datatype.
 *  typioparam, typmod: auxiliary values to pass to inputproc.
 *  typdelim: the value delimiter (type-specific).
 *  typlen, typbyval, typalign: storage parameters of element datatype.
 *
 * Outputs:
 *  values[]: filled with converted data values.
 *  nulls[]: filled with is-null markers.
 *  *hasnulls: set TRUE iff there are any null elements.
 *  *nbytes: set to total size of data area needed (including alignment
 *      padding but not including array header overhead).
 *
 * Note that values[] and nulls[] are allocated by the caller, and must have
 * nitems elements.
 */
static void
ReadArrayStr(char *arrayStr,
             const char *origStr,
             int nitems,
             int ndim,
             int *dim,
             FmgrInfo *inputproc,
             Oid typioparam,
             int32 typmod,
             char typdelim,
             int typlen,
             bool typbyval,
             char typalign,
             Datum *values,
             bool *nulls,
             bool *hasnulls,
             int32 *nbytes)
{
    int         i,
                nest_level = 0;
    char       *srcptr;
    bool        in_quotes = false;
    bool        eoArray = false;
    bool        hasnull;
    int32       totbytes;
    int         indx[MAXDIM],
                prod[MAXDIM];

    mda_get_prod(ndim, dim, prod);
    MemSet(indx, 0, sizeof(indx));

    /* Initialize is-null markers to true */
    memset(nulls, true, nitems * sizeof(bool));

    /*
     * We have to remove " and \ characters to create a clean item value to
     * pass to the datatype input routine.  We overwrite each item value
     * in-place within arrayStr to do this.  srcptr is the current scan point,
     * and dstptr is where we are copying to.
     *
     * We also want to suppress leading and trailing unquoted whitespace. We
     * use the leadingspace flag to suppress leading space.  Trailing space is
     * tracked by using dstendptr to point to the last significant output
     * character.
     *
     * The error checking in this routine is mostly pro-forma, since we expect
     * that ArrayCount() already validated the string.
     */
    srcptr = arrayStr;
    while (!eoArray)
    {
        bool        itemdone = false;
        bool        leadingspace = true;
        bool        hasquoting = false;
        char       *itemstart;
        char       *dstptr;
        char       *dstendptr;

        i = -1;
        itemstart = dstptr = dstendptr = srcptr;

        while (!itemdone)
        {
            switch (*srcptr)
            {
                case '\0':
                    /* Signal a premature end of the string */
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                             errmsg("malformed array literal: \"%s\"",
                                    origStr)));
                    break;
                case '\\':
                    /* Skip backslash, copy next character as-is. */
                    srcptr++;
                    if (*srcptr == '\0')
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                 errmsg("malformed array literal: \"%s\"",
                                        origStr)));
                    *dstptr++ = *srcptr++;
                    /* Treat the escaped character as non-whitespace */
                    leadingspace = false;
                    dstendptr = dstptr;
                    hasquoting = true;  /* can't be a NULL marker */
                    break;
                case '\"':
                    in_quotes = !in_quotes;
                    if (in_quotes)
                        leadingspace = false;
                    else
                    {
                        /*
                         * Advance dstendptr when we exit in_quotes; this
                         * saves having to do it in all the other in_quotes
                         * cases.
                         */
                        dstendptr = dstptr;
                    }
                    hasquoting = true;  /* can't be a NULL marker */
                    srcptr++;
                    break;
                case '{':
                    if (!in_quotes)
                    {
                        if (nest_level >= ndim)
                            ereport(ERROR,
                               (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                errmsg("malformed array literal: \"%s\"",
                                       origStr)));
                        nest_level++;
                        indx[nest_level - 1] = 0;
                        srcptr++;
                    }
                    else
                        *dstptr++ = *srcptr++;
                    break;
                case '}':
                    if (!in_quotes)
                    {
                        if (nest_level == 0)
                            ereport(ERROR,
                               (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                                errmsg("malformed array literal: \"%s\"",
                                       origStr)));
                        if (i == -1)
                            i = ArrayGetOffset0(ndim, indx, prod);
                        indx[nest_level - 1] = 0;
                        nest_level--;
                        if (nest_level == 0)
                            eoArray = itemdone = true;
                        else
                            indx[nest_level - 1]++;
                        srcptr++;
                    }
                    else
                        *dstptr++ = *srcptr++;
                    break;
                default:
                    if (in_quotes)
                        *dstptr++ = *srcptr++;
                    else if (*srcptr == typdelim)
                    {
                        if (i == -1)
                            i = ArrayGetOffset0(ndim, indx, prod);
                        itemdone = true;
                        indx[ndim - 1]++;
                        srcptr++;
                    }
                    else if (array_isspace(*srcptr))
                    {
                        /*
                         * If leading space, drop it immediately.  Else, copy
                         * but don't advance dstendptr.
                         */
                        if (leadingspace)
                            srcptr++;
                        else
                            *dstptr++ = *srcptr++;
                    }
                    else
                    {
                        *dstptr++ = *srcptr++;
                        leadingspace = false;
                        dstendptr = dstptr;
                    }
                    break;
            }
        }

        Assert(dstptr < srcptr);
        *dstendptr = '\0';

        if (i < 0 || i >= nitems)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                     errmsg("malformed array literal: \"%s\"",
                            origStr)));

        if (Array_nulls && !hasquoting &&
            pg_strcasecmp(itemstart, "NULL") == 0)
        {
            /* it's a NULL item */
            values[i] = InputFunctionCall(inputproc, NULL,
                                          typioparam, typmod);
            nulls[i] = true;
        }
        else
        {
            values[i] = InputFunctionCall(inputproc, itemstart,
                                          typioparam, typmod);
            nulls[i] = false;
        }
    }

    /*
     * Check for nulls, compute total data space needed
     */
    hasnull = false;
    totbytes = 0;
    for (i = 0; i < nitems; i++)
    {
        if (nulls[i])
            hasnull = true;
        else
        {
            /* let's just make sure data is not toasted */
            if (typlen == -1)
                values[i] = PointerGetDatum(PG_DETOAST_DATUM(values[i]));
            totbytes = att_addlength_datum(totbytes, typlen, values[i]);
            totbytes = att_align_nominal(totbytes, typalign);
            /* check for overflow of total request */
            if (!AllocSizeIsValid(totbytes))
                ereport(ERROR,
                        (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                         errmsg("array size exceeds the maximum allowed (%d)",
                                (int) MaxAllocSize)));
        }
    }
    *hasnulls = hasnull;
    *nbytes = totbytes;
}


/*
 * Copy data into an array object from a temporary array of Datums.
 *
 * array: array object (with header fields already filled in)
 * values: array of Datums to be copied
 * nulls: array of is-null flags (can be NULL if no nulls)
 * nitems: number of Datums to be copied
 * typbyval, typlen, typalign: info about element datatype
 * freedata: if TRUE and element type is pass-by-ref, pfree data values
 * referenced by Datums after copying them.
 *
 * If the input data is of varlena type, the caller must have ensured that
 * the values are not toasted.  (Doing it here doesn't work since the
 * caller has already allocated space for the array...)
 */
static void
CopyArrayEls(ArrayType *array,
             Datum *values,
             bool *nulls,
             int nitems,
             int typlen,
             bool typbyval,
             char typalign,
             bool freedata)
{
    char       *p = ARR_DATA_PTR(array);
    bits8      *bitmap = ARR_NULLBITMAP(array);
    int         bitval = 0;
    int         bitmask = 1;
    int         i;

    if (typbyval)
        freedata = false;

    for (i = 0; i < nitems; i++)
    {
        if (nulls && nulls[i])
        {
            if (!bitmap)        /* shouldn't happen */
                elog(ERROR, "null array element where not supported");
            /* bitmap bit stays 0 */
        }
        else
        {
            bitval |= bitmask;
            p += ArrayCastAndSet(values[i], typlen, typbyval, typalign, p);
            if (freedata)
                pfree(DatumGetPointer(values[i]));
        }
        if (bitmap)
        {
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                *bitmap++ = bitval;
                bitval = 0;
                bitmask = 1;
            }
        }
    }

    if (bitmap && bitmask != 1)
        *bitmap = bitval;
}

/*
 * array_out :
 *         takes the internal representation of an array and returns a string
 *        containing the array in its external format.
 */
Datum
array_out(PG_FUNCTION_ARGS)
{
    ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
    Oid         element_type = ARR_ELEMTYPE(v);
    int         typlen;
    bool        typbyval;
    char        typalign;
    char        typdelim;
    char       *p,
               *tmp,
               *retval,
              **values,
                dims_str[(MAXDIM * 33) + 2];

    /*
     * 33 per dim since we assume 15 digits per number + ':' +'[]'
     *
     * +2 allows for assignment operator + trailing null
     */
    bits8      *bitmap;
    int         bitmask;
    bool       *needquotes,
                needdims = false;
    int         nitems,
                overall_length,
                i,
                j,
                k,
                indx[MAXDIM];
    int         ndim,
               *dims,
               *lb;
    ArrayMetaState *my_extra;

    /*
     * We arrange to look up info about element type, including its output
     * conversion proc, only once per series of calls, assuming the element
     * type doesn't change underneath us.
     */
    my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
    if (my_extra == NULL)
    {
        fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                                                      sizeof(ArrayMetaState));
        my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
        my_extra->element_type = ~element_type;
    }

    if (my_extra->element_type != element_type)
    {
        /*
         * Get info about element type, including its output conversion proc
         */
        get_type_io_data(element_type, IOFunc_output,
                         &my_extra->typlen, &my_extra->typbyval,
                         &my_extra->typalign, &my_extra->typdelim,
                         &my_extra->typioparam, &my_extra->typiofunc);
        fmgr_info_cxt(my_extra->typiofunc, &my_extra->proc,
                      fcinfo->flinfo->fn_mcxt);
        my_extra->element_type = element_type;
    }
    typlen = my_extra->typlen;
    typbyval = my_extra->typbyval;
    typalign = my_extra->typalign;
    typdelim = my_extra->typdelim;

    ndim = ARR_NDIM(v);
    dims = ARR_DIMS(v);
    lb = ARR_LBOUND(v);
    nitems = ArrayGetNItems(ndim, dims);

    if (nitems == 0)
    {
        retval = pstrdup("{}");
        PG_RETURN_CSTRING(retval);
    }

    /*
     * we will need to add explicit dimensions if any dimension has a lower
     * bound other than one
     */
    for (i = 0; i < ndim; i++)
    {
        if (lb[i] != 1)
        {
            needdims = true;
            break;
        }
    }

    /*
     * Convert all values to string form, count total space needed (including
     * any overhead such as escaping backslashes), and detect whether each
     * item needs double quotes.
     */
    values = (char **) palloc(nitems * sizeof(char *));
    needquotes = (bool *) palloc(nitems * sizeof(bool));
    overall_length = 1;         /* don't forget to count \0 at end. */

    p = ARR_DATA_PTR(v);
    bitmap = ARR_NULLBITMAP(v);
    bitmask = 1;

    for (i = 0; i < nitems; i++)
    {
        bool        needquote;

        /* Get source element, checking for NULL */
        if (bitmap && (*bitmap & bitmask) == 0)
        {
            values[i] = pstrdup("NULL");
            overall_length += 4;
            needquote = false;
        }
        else
        {
            Datum       itemvalue;

            itemvalue = fetch_att(p, typbyval, typlen);
            values[i] = OutputFunctionCall(&my_extra->proc, itemvalue);
            p = att_addlength_pointer(p, typlen, p);
            p = (char *) att_align_nominal(p, typalign);

            /* count data plus backslashes; detect chars needing quotes */
            if (values[i][0] == '\0')
                needquote = true;       /* force quotes for empty string */
            else if (pg_strcasecmp(values[i], "NULL") == 0)
                needquote = true;       /* force quotes for literal NULL */
            else
                needquote = false;

            for (tmp = values[i]; *tmp != '\0'; tmp++)
            {
                char        ch = *tmp;

                overall_length += 1;
                if (ch == '"' || ch == '\\')
                {
                    needquote = true;
                    overall_length += 1;
                }
                else if (ch == '{' || ch == '}' || ch == typdelim ||
                         array_isspace(ch))
                    needquote = true;
            }
        }

        needquotes[i] = needquote;

        /* Count the pair of double quotes, if needed */
        if (needquote)
            overall_length += 2;
        /* and the comma */
        overall_length += 1;

        /* advance bitmap pointer if any */
        if (bitmap)
        {
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                bitmap++;
                bitmask = 1;
            }
        }
    }

    /*
     * count total number of curly braces in output string
     */
    for (i = j = 0, k = 1; i < ndim; i++)
        k *= dims[i], j += k;

    dims_str[0] = '\0';

    /* add explicit dimensions if required */
    if (needdims)
    {
        char       *ptr = dims_str;

        for (i = 0; i < ndim; i++)
        {
            sprintf(ptr, "[%d:%d]", lb[i], lb[i] + dims[i] - 1);
            ptr += strlen(ptr);
        }
        *ptr++ = *ASSGN;
        *ptr = '\0';
    }

    retval = (char *) palloc(strlen(dims_str) + overall_length + 2 * j);
    p = retval;

#define APPENDSTR(str)  (strcpy(p, (str)), p += strlen(p))
#define APPENDCHAR(ch)  (*p++ = (ch), *p = '\0')

    if (needdims)
        APPENDSTR(dims_str);
    APPENDCHAR('{');
    for (i = 0; i < ndim; i++)
        indx[i] = 0;
    j = 0;
    k = 0;
    do
    {
        for (i = j; i < ndim - 1; i++)
            APPENDCHAR('{');

        if (needquotes[k])
        {
            APPENDCHAR('"');
            for (tmp = values[k]; *tmp; tmp++)
            {
                char        ch = *tmp;

                if (ch == '"' || ch == '\\')
                    *p++ = '\\';
                *p++ = ch;
            }
            *p = '\0';
            APPENDCHAR('"');
        }
        else
            APPENDSTR(values[k]);
        pfree(values[k++]);

        for (i = ndim - 1; i >= 0; i--)
        {
            indx[i] = (indx[i] + 1) % dims[i];
            if (indx[i])
            {
                APPENDCHAR(typdelim);
                break;
            }
            else
                APPENDCHAR('}');
        }
        j = i;
    } while (j != -1);

#undef APPENDSTR
#undef APPENDCHAR

    pfree(values);
    pfree(needquotes);

    PG_RETURN_CSTRING(retval);
}

/*
 * array_recv :
 *        converts an array from the external binary format to
 *        its internal format.
 *
 * return value :
 *        the internal representation of the input array
 */
Datum
array_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
    Oid         spec_element_type = PG_GETARG_OID(1);   /* type of an array
                                                         * element */
    int32       typmod = PG_GETARG_INT32(2);    /* typmod for array elements */
    Oid         element_type;
    int         typlen;
    bool        typbyval;
    char        typalign;
    Oid         typioparam;
    int         i,
                nitems;
    Datum      *dataPtr;
    bool       *nullsPtr;
    bool        hasnulls;
    int32       nbytes;
    int32       dataoffset;
    ArrayType  *retval;
    int         ndim,
                flags,
                dim[MAXDIM],
                lBound[MAXDIM];
    ArrayMetaState *my_extra;

    /* Get the array header information */
    ndim = pq_getmsgint(buf, 4);
    if (ndim < 0)               /* we do allow zero-dimension arrays */
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("invalid number of dimensions: %d", ndim)));
    if (ndim > MAXDIM)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
                        ndim, MAXDIM)));

    flags = pq_getmsgint(buf, 4);
    if (flags != 0 && flags != 1)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("invalid array flags")));

    element_type = pq_getmsgint(buf, sizeof(Oid));
    if (element_type != spec_element_type)
    {
        /* XXX Can we allow taking the input element type in any cases? */
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("wrong element type")));
    }

    for (i = 0; i < ndim; i++)
    {
        dim[i] = pq_getmsgint(buf, 4);
        lBound[i] = pq_getmsgint(buf, 4);

        /*
         * Check overflow of upper bound. (ArrayNItems() below checks that
         * dim[i] >= 0)
         */
        if (dim[i] != 0)
        {
            int         ub = lBound[i] + dim[i] - 1;

            if (lBound[i] > ub)
                ereport(ERROR,
                        (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
                         errmsg("integer out of range")));
        }
    }

    /* This checks for overflow of array dimensions */
    nitems = ArrayGetNItems(ndim, dim);

    /*
     * We arrange to look up info about element type, including its receive
     * conversion proc, only once per series of calls, assuming the element
     * type doesn't change underneath us.
     */
    my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
    if (my_extra == NULL)
    {
        fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                                                      sizeof(ArrayMetaState));
        my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
        my_extra->element_type = ~element_type;
    }

    if (my_extra->element_type != element_type)
    {
        /* Get info about element type, including its receive proc */
        get_type_io_data(element_type, IOFunc_receive,
                         &my_extra->typlen, &my_extra->typbyval,
                         &my_extra->typalign, &my_extra->typdelim,
                         &my_extra->typioparam, &my_extra->typiofunc);
        if (!OidIsValid(my_extra->typiofunc))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_FUNCTION),
                     errmsg("no binary input function available for type %s",
                            format_type_be(element_type))));
        fmgr_info_cxt(my_extra->typiofunc, &my_extra->proc,
                      fcinfo->flinfo->fn_mcxt);
        my_extra->element_type = element_type;
    }

    if (nitems == 0)
    {
        /* Return empty array ... but not till we've validated element_type */
        PG_RETURN_ARRAYTYPE_P(construct_empty_array(element_type));
    }

    typlen = my_extra->typlen;
    typbyval = my_extra->typbyval;
    typalign = my_extra->typalign;
    typioparam = my_extra->typioparam;

    dataPtr = (Datum *) palloc(nitems * sizeof(Datum));
    nullsPtr = (bool *) palloc(nitems * sizeof(bool));
    ReadArrayBinary(buf, nitems,
                    &my_extra->proc, typioparam, typmod,
                    typlen, typbyval, typalign,
                    dataPtr, nullsPtr,
                    &hasnulls, &nbytes);
    if (hasnulls)
    {
        dataoffset = ARR_OVERHEAD_WITHNULLS(ndim, nitems);
        nbytes += dataoffset;
    }
    else
    {
        dataoffset = 0;         /* marker for no null bitmap */
        nbytes += ARR_OVERHEAD_NONULLS(ndim);
    }
    retval = (ArrayType *) palloc0(nbytes);
    SET_VARSIZE(retval, nbytes);
    retval->ndim = ndim;
    retval->dataoffset = dataoffset;
    retval->elemtype = element_type;
    memcpy(ARR_DIMS(retval), dim, ndim * sizeof(int));
    memcpy(ARR_LBOUND(retval), lBound, ndim * sizeof(int));

    CopyArrayEls(retval,
                 dataPtr, nullsPtr, nitems,
                 typlen, typbyval, typalign,
                 true);

    pfree(dataPtr);
    pfree(nullsPtr);

    PG_RETURN_ARRAYTYPE_P(retval);
}

/*
 * ReadArrayBinary:
 *   collect the data elements of an array being read in binary style.
 *
 * Inputs:
 *  buf: the data buffer to read from.
 *  nitems: total number of array elements (already read).
 *  receiveproc: type-specific receive procedure for element datatype.
 *  typioparam, typmod: auxiliary values to pass to receiveproc.
 *  typlen, typbyval, typalign: storage parameters of element datatype.
 *
 * Outputs:
 *  values[]: filled with converted data values.
 *  nulls[]: filled with is-null markers.
 *  *hasnulls: set TRUE iff there are any null elements.
 *  *nbytes: set to total size of data area needed (including alignment
 *      padding but not including array header overhead).
 *
 * Note that values[] and nulls[] are allocated by the caller, and must have
 * nitems elements.
 */
static void
ReadArrayBinary(StringInfo buf,
                int nitems,
                FmgrInfo *receiveproc,
                Oid typioparam,
                int32 typmod,
                int typlen,
                bool typbyval,
                char typalign,
                Datum *values,
                bool *nulls,
                bool *hasnulls,
                int32 *nbytes)
{
    int         i;
    bool        hasnull;
    int32       totbytes;

    for (i = 0; i < nitems; i++)
    {
        int         itemlen;
        StringInfoData elem_buf;
        char        csave;

        /* Get and check the item length */
        itemlen = pq_getmsgint(buf, 4);
        if (itemlen < -1 || itemlen > (buf->len - buf->cursor))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                     errmsg("insufficient data left in message")));

        if (itemlen == -1)
        {
            /* -1 length means NULL */
            values[i] = ReceiveFunctionCall(receiveproc, NULL,
                                            typioparam, typmod);
            nulls[i] = true;
            continue;
        }

        /*
         * Rather than copying data around, we just set up a phony StringInfo
         * pointing to the correct portion of the input buffer. We assume we
         * can scribble on the input buffer so as to maintain the convention
         * that StringInfos have a trailing null.
         */
        elem_buf.data = &buf->data[buf->cursor];
        elem_buf.maxlen = itemlen + 1;
        elem_buf.len = itemlen;
        elem_buf.cursor = 0;

        buf->cursor += itemlen;

        csave = buf->data[buf->cursor];
        buf->data[buf->cursor] = '\0';

        /* Now call the element's receiveproc */
        values[i] = ReceiveFunctionCall(receiveproc, &elem_buf,
                                        typioparam, typmod);
        nulls[i] = false;

        /* Trouble if it didn't eat the whole buffer */
        if (elem_buf.cursor != itemlen)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                     errmsg("improper binary format in array element %d",
                            i + 1)));

        buf->data[buf->cursor] = csave;
    }

    /*
     * Check for nulls, compute total data space needed
     */
    hasnull = false;
    totbytes = 0;
    for (i = 0; i < nitems; i++)
    {
        if (nulls[i])
            hasnull = true;
        else
        {
            /* let's just make sure data is not toasted */
            if (typlen == -1)
                values[i] = PointerGetDatum(PG_DETOAST_DATUM(values[i]));
            totbytes = att_addlength_datum(totbytes, typlen, values[i]);
            totbytes = att_align_nominal(totbytes, typalign);
            /* check for overflow of total request */
            if (!AllocSizeIsValid(totbytes))
                ereport(ERROR,
                        (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                         errmsg("array size exceeds the maximum allowed (%d)",
                                (int) MaxAllocSize)));
        }
    }
    *hasnulls = hasnull;
    *nbytes = totbytes;
}


/*
 * array_send :
 *        takes the internal representation of an array and returns a bytea
 *        containing the array in its external binary format.
 */
Datum
array_send(PG_FUNCTION_ARGS)
{
    ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
    Oid         element_type = ARR_ELEMTYPE(v);
    int         typlen;
    bool        typbyval;
    char        typalign;
    char       *p;
    bits8      *bitmap;
    int         bitmask;
    int         nitems,
                i;
    int         ndim,
               *dim;
    StringInfoData buf;
    ArrayMetaState *my_extra;

    /*
     * We arrange to look up info about element type, including its send
     * conversion proc, only once per series of calls, assuming the element
     * type doesn't change underneath us.
     */
    my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
    if (my_extra == NULL)
    {
        fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                                                      sizeof(ArrayMetaState));
        my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
        my_extra->element_type = ~element_type;
    }

    if (my_extra->element_type != element_type)
    {
        /* Get info about element type, including its send proc */
        get_type_io_data(element_type, IOFunc_send,
                         &my_extra->typlen, &my_extra->typbyval,
                         &my_extra->typalign, &my_extra->typdelim,
                         &my_extra->typioparam, &my_extra->typiofunc);
        if (!OidIsValid(my_extra->typiofunc))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_FUNCTION),
                     errmsg("no binary output function available for type %s",
                            format_type_be(element_type))));
        fmgr_info_cxt(my_extra->typiofunc, &my_extra->proc,
                      fcinfo->flinfo->fn_mcxt);
        my_extra->element_type = element_type;
    }
    typlen = my_extra->typlen;
    typbyval = my_extra->typbyval;
    typalign = my_extra->typalign;

    ndim = ARR_NDIM(v);
    dim = ARR_DIMS(v);
    nitems = ArrayGetNItems(ndim, dim);

    pq_begintypsend(&buf);

    /* Send the array header information */
    pq_sendint(&buf, ndim, 4);
    pq_sendint(&buf, ARR_HASNULL(v) ? 1 : 0, 4);
    pq_sendint(&buf, element_type, sizeof(Oid));
    for (i = 0; i < ndim; i++)
    {
        pq_sendint(&buf, ARR_DIMS(v)[i], 4);
        pq_sendint(&buf, ARR_LBOUND(v)[i], 4);
    }

    /* Send the array elements using the element's own sendproc */
    p = ARR_DATA_PTR(v);
    bitmap = ARR_NULLBITMAP(v);
    bitmask = 1;

    for (i = 0; i < nitems; i++)
    {
        /* Get source element, checking for NULL */
        if (bitmap && (*bitmap & bitmask) == 0)
        {
            /* -1 length means a NULL */
            pq_sendint(&buf, -1, 4);
        }
        else
        {
            Datum       itemvalue;
            bytea      *outputbytes;

            itemvalue = fetch_att(p, typbyval, typlen);
            outputbytes = SendFunctionCall(&my_extra->proc, itemvalue);
            pq_sendint(&buf, VARSIZE(outputbytes) - VARHDRSZ, 4);
            pq_sendbytes(&buf, VARDATA(outputbytes),
                         VARSIZE(outputbytes) - VARHDRSZ);
            pfree(outputbytes);

            p = att_addlength_pointer(p, typlen, p);
            p = (char *) att_align_nominal(p, typalign);
        }

        /* advance bitmap pointer if any */
        if (bitmap)
        {
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                bitmap++;
                bitmask = 1;
            }
        }
    }

    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/*
 * array_ndims :
 *        returns the number of dimensions of the array pointed to by "v"
 */
Datum
array_ndims(PG_FUNCTION_ARGS)
{
    ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);

    /* Sanity check: does it look like an array at all? */
    if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
        PG_RETURN_NULL();

    PG_RETURN_INT32(ARR_NDIM(v));
}

/*
 * array_dims :
 *        returns the dimensions of the array pointed to by "v", as a "text"
 */
Datum
array_dims(PG_FUNCTION_ARGS)
{
    ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
    char       *p;
    int         i;
    int        *dimv,
               *lb;

    /*
     * 33 since we assume 15 digits per number + ':' +'[]'
     *
     * +1 for trailing null
     */
    char        buf[MAXDIM * 33 + 1];

    /* Sanity check: does it look like an array at all? */
    if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
        PG_RETURN_NULL();

    dimv = ARR_DIMS(v);
    lb = ARR_LBOUND(v);

    p = buf;
    for (i = 0; i < ARR_NDIM(v); i++)
    {
        sprintf(p, "[%d:%d]", lb[i], dimv[i] + lb[i] - 1);
        p += strlen(p);
    }

    PG_RETURN_TEXT_P(cstring_to_text(buf));
}

/*
 * array_lower :
 *      returns the lower dimension, of the DIM requested, for
 *      the array pointed to by "v", as an int4
 */
Datum
array_lower(PG_FUNCTION_ARGS)
{
    ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
    int         reqdim = PG_GETARG_INT32(1);
    int        *lb;
    int         result;

    /* Sanity check: does it look like an array at all? */
    if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
        PG_RETURN_NULL();

    /* Sanity check: was the requested dim valid */
    if (reqdim <= 0 || reqdim > ARR_NDIM(v))
        PG_RETURN_NULL();

    lb = ARR_LBOUND(v);
    result = lb[reqdim - 1];

    PG_RETURN_INT32(result);
}

/*
 * array_upper :
 *      returns the upper dimension, of the DIM requested, for
 *      the array pointed to by "v", as an int4
 */
Datum
array_upper(PG_FUNCTION_ARGS)
{
    ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
    int         reqdim = PG_GETARG_INT32(1);
    int        *dimv,
               *lb;
    int         result;

    /* Sanity check: does it look like an array at all? */
    if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
        PG_RETURN_NULL();

    /* Sanity check: was the requested dim valid */
    if (reqdim <= 0 || reqdim > ARR_NDIM(v))
        PG_RETURN_NULL();

    lb = ARR_LBOUND(v);
    dimv = ARR_DIMS(v);

    result = dimv[reqdim - 1] + lb[reqdim - 1] - 1;

    PG_RETURN_INT32(result);
}

/*
 * array_length :
 *      returns the length, of the dimension requested, for
 *      the array pointed to by "v", as an int4
 */
Datum
array_length(PG_FUNCTION_ARGS)
{
    ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
    int         reqdim = PG_GETARG_INT32(1);
    int        *dimv;
    int         result;

    /* Sanity check: does it look like an array at all? */
    if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
        PG_RETURN_NULL();

    /* Sanity check: was the requested dim valid */
    if (reqdim <= 0 || reqdim > ARR_NDIM(v))
        PG_RETURN_NULL();

    dimv = ARR_DIMS(v);

    result = dimv[reqdim - 1];

    PG_RETURN_INT32(result);
}

/*
 * array_ref :
 *    This routine takes an array pointer and a subscript array and returns
 *    the referenced item as a Datum.  Note that for a pass-by-reference
 *    datatype, the returned Datum is a pointer into the array object.
 *
 * This handles both ordinary varlena arrays and fixed-length arrays.
 *
 * Inputs:
 *  array: the array object (mustn't be NULL)
 *  nSubscripts: number of subscripts supplied
 *  indx[]: the subscript values
 *  arraytyplen: pg_type.typlen for the array type
 *  elmlen: pg_type.typlen for the array's element type
 *  elmbyval: pg_type.typbyval for the array's element type
 *  elmalign: pg_type.typalign for the array's element type
 *
 * Outputs:
 *  The return value is the element Datum.
 *  *isNull is set to indicate whether the element is NULL.
 */
Datum
array_ref(ArrayType *array,
          int nSubscripts,
          int *indx,
          int arraytyplen,
          int elmlen,
          bool elmbyval,
          char elmalign,
          bool *isNull)
{
    int         i,
                ndim,
               *dim,
               *lb,
                offset,
                fixedDim[1],
                fixedLb[1];
    char       *arraydataptr,
               *retptr;
    bits8      *arraynullsptr;

    if (arraytyplen > 0)
    {
        /*
         * fixed-length arrays -- these are assumed to be 1-d, 0-based
         */
        ndim = 1;
        fixedDim[0] = arraytyplen / elmlen;
        fixedLb[0] = 0;
        dim = fixedDim;
        lb = fixedLb;
        arraydataptr = (char *) array;
        arraynullsptr = NULL;
    }
    else
    {
        /* detoast input array if necessary */
        array = DatumGetArrayTypeP(PointerGetDatum(array));

        ndim = ARR_NDIM(array);
        dim = ARR_DIMS(array);
        lb = ARR_LBOUND(array);
        arraydataptr = ARR_DATA_PTR(array);
        arraynullsptr = ARR_NULLBITMAP(array);
    }

    /*
     * Return NULL for invalid subscript
     */
    if (ndim != nSubscripts || ndim <= 0 || ndim > MAXDIM)
    {
        *isNull = true;
        return (Datum) 0;
    }
    for (i = 0; i < ndim; i++)
    {
        if (indx[i] < lb[i] || indx[i] >= (dim[i] + lb[i]))
        {
            *isNull = true;
            return (Datum) 0;
        }
    }

    /*
     * Calculate the element number
     */
    offset = ArrayGetOffset(nSubscripts, dim, lb, indx);

    /*
     * Check for NULL array element
     */
    if (array_get_isnull(arraynullsptr, offset))
    {
        *isNull = true;
        return (Datum) 0;
    }

    /*
     * OK, get the element
     */
    *isNull = false;
    retptr = array_seek(arraydataptr, 0, arraynullsptr, offset,
                        elmlen, elmbyval, elmalign);
    return ArrayCast(retptr, elmbyval, elmlen);
}

/*
 * array_get_slice :
 *         This routine takes an array and a range of indices (upperIndex and
 *         lowerIndx), creates a new array structure for the referred elements
 *         and returns a pointer to it.
 *
 * This handles both ordinary varlena arrays and fixed-length arrays.
 *
 * Inputs:
 *  array: the array object (mustn't be NULL)
 *  nSubscripts: number of subscripts supplied (must be same for upper/lower)
 *  upperIndx[]: the upper subscript values
 *  lowerIndx[]: the lower subscript values
 *  arraytyplen: pg_type.typlen for the array type
 *  elmlen: pg_type.typlen for the array's element type
 *  elmbyval: pg_type.typbyval for the array's element type
 *  elmalign: pg_type.typalign for the array's element type
 *
 * Outputs:
 *  The return value is the new array Datum (it's never NULL)
 *
 * NOTE: we assume it is OK to scribble on the provided subscript arrays
 * lowerIndx[] and upperIndx[].  These are generally just temporaries.
 */
ArrayType *
array_get_slice(ArrayType *array,
                int nSubscripts,
                int *upperIndx,
                int *lowerIndx,
                int arraytyplen,
                int elmlen,
                bool elmbyval,
                char elmalign)
{
    ArrayType  *newarray;
    int         i,
                ndim,
               *dim,
               *lb,
               *newlb;
    int         fixedDim[1],
                fixedLb[1];
    Oid         elemtype;
    char       *arraydataptr;
    bits8      *arraynullsptr;
    int32       dataoffset;
    int         bytes,
                span[MAXDIM];

    if (arraytyplen > 0)
    {
        /*
         * fixed-length arrays -- currently, cannot slice these because parser
         * labels output as being of the fixed-length array type! Code below
         * shows how we could support it if the parser were changed to label
         * output as a suitable varlena array type.
         */
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("slices of fixed-length arrays not implemented")));

        /*
         * fixed-length arrays -- these are assumed to be 1-d, 0-based
         *
         * XXX where would we get the correct ELEMTYPE from?
         */
        ndim = 1;
        fixedDim[0] = arraytyplen / elmlen;
        fixedLb[0] = 0;
        dim = fixedDim;
        lb = fixedLb;
        elemtype = InvalidOid;  /* XXX */
        arraydataptr = (char *) array;
        arraynullsptr = NULL;
    }
    else
    {
        /* detoast input array if necessary */
        array = DatumGetArrayTypeP(PointerGetDatum(array));

        ndim = ARR_NDIM(array);
        dim = ARR_DIMS(array);
        lb = ARR_LBOUND(array);
        elemtype = ARR_ELEMTYPE(array);
        arraydataptr = ARR_DATA_PTR(array);
        arraynullsptr = ARR_NULLBITMAP(array);
    }

    /*
     * Check provided subscripts.  A slice exceeding the current array limits
     * is silently truncated to the array limits.  If we end up with an empty
     * slice, return an empty array.
     */
    if (ndim < nSubscripts || ndim <= 0 || ndim > MAXDIM)
        return construct_empty_array(elemtype);

    for (i = 0; i < nSubscripts; i++)
    {
        if (lowerIndx[i] < lb[i])
            lowerIndx[i] = lb[i];
        if (upperIndx[i] >= (dim[i] + lb[i]))
            upperIndx[i] = dim[i] + lb[i] - 1;
        if (lowerIndx[i] > upperIndx[i])
            return construct_empty_array(elemtype);
    }
    /* fill any missing subscript positions with full array range */
    for (; i < ndim; i++)
    {
        lowerIndx[i] = lb[i];
        upperIndx[i] = dim[i] + lb[i] - 1;
        if (lowerIndx[i] > upperIndx[i])
            return construct_empty_array(elemtype);
    }

    mda_get_range(ndim, span, lowerIndx, upperIndx);

    bytes = array_slice_size(arraydataptr, arraynullsptr,
                             ndim, dim, lb,
                             lowerIndx, upperIndx,
                             elmlen, elmbyval, elmalign);

    /*
     * Currently, we put a null bitmap in the result if the source has one;
     * could be smarter ...
     */
    if (arraynullsptr)
    {
        dataoffset = ARR_OVERHEAD_WITHNULLS(ndim, ArrayGetNItems(ndim, span));
        bytes += dataoffset;
    }
    else
    {
        dataoffset = 0;         /* marker for no null bitmap */
        bytes += ARR_OVERHEAD_NONULLS(ndim);
    }

    newarray = (ArrayType *) palloc0(bytes);
    SET_VARSIZE(newarray, bytes);
    newarray->ndim = ndim;
    newarray->dataoffset = dataoffset;
    newarray->elemtype = elemtype;
    memcpy(ARR_DIMS(newarray), span, ndim * sizeof(int));

    /*
     * Lower bounds of the new array are set to 1.  Formerly (before 7.3) we
     * copied the given lowerIndx values ... but that seems confusing.
     */
    newlb = ARR_LBOUND(newarray);
    for (i = 0; i < ndim; i++)
        newlb[i] = 1;

    array_extract_slice(newarray,
                        ndim, dim, lb,
                        arraydataptr, arraynullsptr,
                        lowerIndx, upperIndx,
                        elmlen, elmbyval, elmalign);

    return newarray;
}

/*
 * array_set :
 *        This routine sets the value of an array element (specified by
 *        a subscript array) to a new value specified by "dataValue".
 *
 * This handles both ordinary varlena arrays and fixed-length arrays.
 *
 * Inputs:
 *  array: the initial array object (mustn't be NULL)
 *  nSubscripts: number of subscripts supplied
 *  indx[]: the subscript values
 *  dataValue: the datum to be inserted at the given position
 *  isNull: whether dataValue is NULL
 *  arraytyplen: pg_type.typlen for the array type
 *  elmlen: pg_type.typlen for the array's element type
 *  elmbyval: pg_type.typbyval for the array's element type
 *  elmalign: pg_type.typalign for the array's element type
 *
 * Result:
 *        A new array is returned, just like the old except for the one
 *        modified entry.  The original array object is not changed.
 *
 * For one-dimensional arrays only, we allow the array to be extended
 * by assigning to a position outside the existing subscript range; any
 * positions between the existing elements and the new one are set to NULLs.
 * (XXX TODO: allow a corresponding behavior for multidimensional arrays)
 *
 * NOTE: For assignments, we throw an error for invalid subscripts etc,
 * rather than returning a NULL as the fetch operations do.
 */
ArrayType *
array_set(ArrayType *array,
          int nSubscripts,
          int *indx,
          Datum dataValue,
          bool isNull,
          int arraytyplen,
          int elmlen,
          bool elmbyval,
          char elmalign)
{
    ArrayType  *newarray;
    int         i,
                ndim,
                dim[MAXDIM],
                lb[MAXDIM],
                offset;
    char       *elt_ptr;
    bool        newhasnulls;
    bits8      *oldnullbitmap;
    int         oldnitems,
                newnitems,
                olddatasize,
                newsize,
                olditemlen,
                newitemlen,
                overheadlen,
                oldoverheadlen,
                addedbefore,
                addedafter,
                lenbefore,
                lenafter;

    if (arraytyplen > 0)
    {
        /*
         * fixed-length arrays -- these are assumed to be 1-d, 0-based. We
         * cannot extend them, either.
         */
        if (nSubscripts != 1)
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("wrong number of array subscripts")));

        if (indx[0] < 0 || indx[0] * elmlen >= arraytyplen)
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("array subscript out of range")));

        if (isNull)
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("cannot assign null value to an element of a fixed-length array")));

        newarray = (ArrayType *) palloc(arraytyplen);
        memcpy(newarray, array, arraytyplen);
        elt_ptr = (char *) newarray + indx[0] * elmlen;
        ArrayCastAndSet(dataValue, elmlen, elmbyval, elmalign, elt_ptr);
        return newarray;
    }

    if (nSubscripts <= 0 || nSubscripts > MAXDIM)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("wrong number of array subscripts")));

    /* make sure item to be inserted is not toasted */
    if (elmlen == -1 && !isNull)
        dataValue = PointerGetDatum(PG_DETOAST_DATUM(dataValue));

    /* detoast input array if necessary */
    array = DatumGetArrayTypeP(PointerGetDatum(array));

    ndim = ARR_NDIM(array);

    /*
     * if number of dims is zero, i.e. an empty array, create an array with
     * nSubscripts dimensions, and set the lower bounds to the supplied
     * subscripts
     */
    if (ndim == 0)
    {
        Oid         elmtype = ARR_ELEMTYPE(array);

        for (i = 0; i < nSubscripts; i++)
        {
            dim[i] = 1;
            lb[i] = indx[i];
        }

        return construct_md_array(&dataValue, &isNull, nSubscripts,
                                  dim, lb, elmtype,
                                  elmlen, elmbyval, elmalign);
    }

    if (ndim != nSubscripts)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("wrong number of array subscripts")));

    /* copy dim/lb since we may modify them */
    memcpy(dim, ARR_DIMS(array), ndim * sizeof(int));
    memcpy(lb, ARR_LBOUND(array), ndim * sizeof(int));

    newhasnulls = (ARR_HASNULL(array) || isNull);
    addedbefore = addedafter = 0;

    /*
     * Check subscripts
     */
    if (ndim == 1)
    {
        if (indx[0] < lb[0])
        {
            addedbefore = lb[0] - indx[0];
            dim[0] += addedbefore;
            lb[0] = indx[0];
            if (addedbefore > 1)
                newhasnulls = true;     /* will insert nulls */
        }
        if (indx[0] >= (dim[0] + lb[0]))
        {
            addedafter = indx[0] - (dim[0] + lb[0]) + 1;
            dim[0] += addedafter;
            if (addedafter > 1)
                newhasnulls = true;     /* will insert nulls */
        }
    }
    else
    {
        /*
         * XXX currently we do not support extending multi-dimensional arrays
         * during assignment
         */
        for (i = 0; i < ndim; i++)
        {
            if (indx[i] < lb[i] ||
                indx[i] >= (dim[i] + lb[i]))
                ereport(ERROR,
                        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                         errmsg("array subscript out of range")));
        }
    }

    /*
     * Compute sizes of items and areas to copy
     */
    newnitems = ArrayGetNItems(ndim, dim);
    if (newhasnulls)
        overheadlen = ARR_OVERHEAD_WITHNULLS(ndim, newnitems);
    else
        overheadlen = ARR_OVERHEAD_NONULLS(ndim);
    oldnitems = ArrayGetNItems(ndim, ARR_DIMS(array));
    oldnullbitmap = ARR_NULLBITMAP(array);
    oldoverheadlen = ARR_DATA_OFFSET(array);
    olddatasize = ARR_SIZE(array) - oldoverheadlen;
    if (addedbefore)
    {
        offset = 0;
        lenbefore = 0;
        olditemlen = 0;
        lenafter = olddatasize;
    }
    else if (addedafter)
    {
        offset = oldnitems;
        lenbefore = olddatasize;
        olditemlen = 0;
        lenafter = 0;
    }
    else
    {
        offset = ArrayGetOffset(nSubscripts, dim, lb, indx);
        elt_ptr = array_seek(ARR_DATA_PTR(array), 0, oldnullbitmap, offset,
                             elmlen, elmbyval, elmalign);
        lenbefore = (int) (elt_ptr - ARR_DATA_PTR(array));
        if (array_get_isnull(oldnullbitmap, offset))
            olditemlen = 0;
        else
        {
            olditemlen = att_addlength_pointer(0, elmlen, elt_ptr);
            olditemlen = att_align_nominal(olditemlen, elmalign);
        }
        lenafter = (int) (olddatasize - lenbefore - olditemlen);
    }

    if (isNull)
        newitemlen = 0;
    else
    {
        newitemlen = att_addlength_datum(0, elmlen, dataValue);
        newitemlen = att_align_nominal(newitemlen, elmalign);
    }

    newsize = overheadlen + lenbefore + newitemlen + lenafter;

    /*
     * OK, create the new array and fill in header/dimensions
     */
    newarray = (ArrayType *) palloc0(newsize);
    SET_VARSIZE(newarray, newsize);
    newarray->ndim = ndim;
    newarray->dataoffset = newhasnulls ? overheadlen : 0;
    newarray->elemtype = ARR_ELEMTYPE(array);
    memcpy(ARR_DIMS(newarray), dim, ndim * sizeof(int));
    memcpy(ARR_LBOUND(newarray), lb, ndim * sizeof(int));

    /*
     * Fill in data
     */
    memcpy((char *) newarray + overheadlen,
           (char *) array + oldoverheadlen,
           lenbefore);
    if (!isNull)
        ArrayCastAndSet(dataValue, elmlen, elmbyval, elmalign,
                        (char *) newarray + overheadlen + lenbefore);
    memcpy((char *) newarray + overheadlen + lenbefore + newitemlen,
           (char *) array + oldoverheadlen + lenbefore + olditemlen,
           lenafter);

    /*
     * Fill in nulls bitmap if needed
     *
     * Note: it's possible we just replaced the last NULL with a non-NULL, and
     * could get rid of the bitmap.  Seems not worth testing for though.
     */
    if (newhasnulls)
    {
        bits8      *newnullbitmap = ARR_NULLBITMAP(newarray);

        /* Zero the bitmap to take care of marking inserted positions null */
        MemSet(newnullbitmap, 0, (newnitems + 7) / 8);
        /* Fix the inserted value */
        if (addedafter)
            array_set_isnull(newnullbitmap, newnitems - 1, isNull);
        else
            array_set_isnull(newnullbitmap, offset, isNull);
        /* Fix the copied range(s) */
        if (addedbefore)
            array_bitmap_copy(newnullbitmap, addedbefore,
                              oldnullbitmap, 0,
                              oldnitems);
        else
        {
            array_bitmap_copy(newnullbitmap, 0,
                              oldnullbitmap, 0,
                              offset);
            if (addedafter == 0)
                array_bitmap_copy(newnullbitmap, offset + 1,
                                  oldnullbitmap, offset + 1,
                                  oldnitems - offset - 1);
        }
    }

    return newarray;
}

/*
 * array_set_slice :
 *        This routine sets the value of a range of array locations (specified
 *        by upper and lower subscript values) to new values passed as
 *        another array.
 *
 * This handles both ordinary varlena arrays and fixed-length arrays.
 *
 * Inputs:
 *  array: the initial array object (mustn't be NULL)
 *  nSubscripts: number of subscripts supplied (must be same for upper/lower)
 *  upperIndx[]: the upper subscript values
 *  lowerIndx[]: the lower subscript values
 *  srcArray: the source for the inserted values
 *  isNull: indicates whether srcArray is NULL
 *  arraytyplen: pg_type.typlen for the array type
 *  elmlen: pg_type.typlen for the array's element type
 *  elmbyval: pg_type.typbyval for the array's element type
 *  elmalign: pg_type.typalign for the array's element type
 *
 * Result:
 *        A new array is returned, just like the old except for the
 *        modified range.  The original array object is not changed.
 *
 * For one-dimensional arrays only, we allow the array to be extended
 * by assigning to positions outside the existing subscript range; any
 * positions between the existing elements and the new ones are set to NULLs.
 * (XXX TODO: allow a corresponding behavior for multidimensional arrays)
 *
 * NOTE: we assume it is OK to scribble on the provided index arrays
 * lowerIndx[] and upperIndx[].  These are generally just temporaries.
 *
 * NOTE: For assignments, we throw an error for silly subscripts etc,
 * rather than returning a NULL or empty array as the fetch operations do.
 */
ArrayType *
array_set_slice(ArrayType *array,
                int nSubscripts,
                int *upperIndx,
                int *lowerIndx,
                ArrayType *srcArray,
                bool isNull,
                int arraytyplen,
                int elmlen,
                bool elmbyval,
                char elmalign)
{
    ArrayType  *newarray;
    int         i,
                ndim,
                dim[MAXDIM],
                lb[MAXDIM],
                span[MAXDIM];
    bool        newhasnulls;
    int         nitems,
                nsrcitems,
                olddatasize,
                newsize,
                olditemsize,
                newitemsize,
                overheadlen,
                oldoverheadlen,
                addedbefore,
                addedafter,
                lenbefore,
                lenafter,
                itemsbefore,
                itemsafter,
                nolditems;

    /* Currently, assignment from a NULL source array is a no-op */
    if (isNull)
        return array;

    if (arraytyplen > 0)
    {
        /*
         * fixed-length arrays -- not got round to doing this...
         */
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
        errmsg("updates on slices of fixed-length arrays not implemented")));
    }

    /* detoast arrays if necessary */
    array = DatumGetArrayTypeP(PointerGetDatum(array));
    srcArray = DatumGetArrayTypeP(PointerGetDatum(srcArray));

    /* note: we assume srcArray contains no toasted elements */

    ndim = ARR_NDIM(array);

    /*
     * if number of dims is zero, i.e. an empty array, create an array with
     * nSubscripts dimensions, and set the upper and lower bounds to the
     * supplied subscripts
     */
    if (ndim == 0)
    {
        Datum      *dvalues;
        bool       *dnulls;
        int         nelems;
        Oid         elmtype = ARR_ELEMTYPE(array);

        deconstruct_array(srcArray, elmtype, elmlen, elmbyval, elmalign,
                          &dvalues, &dnulls, &nelems);

        for (i = 0; i < nSubscripts; i++)
        {
            dim[i] = 1 + upperIndx[i] - lowerIndx[i];
            lb[i] = lowerIndx[i];
        }

        /* complain if too few source items; we ignore extras, however */
        if (nelems < ArrayGetNItems(nSubscripts, dim))
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("source array too small")));

        return construct_md_array(dvalues, dnulls, nSubscripts,
                                  dim, lb, elmtype,
                                  elmlen, elmbyval, elmalign);
    }

    if (ndim < nSubscripts || ndim <= 0 || ndim > MAXDIM)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("wrong number of array subscripts")));

    /* copy dim/lb since we may modify them */
    memcpy(dim, ARR_DIMS(array), ndim * sizeof(int));
    memcpy(lb, ARR_LBOUND(array), ndim * sizeof(int));

    newhasnulls = (ARR_HASNULL(array) || ARR_HASNULL(srcArray));
    addedbefore = addedafter = 0;

    /*
     * Check subscripts
     */
    if (ndim == 1)
    {
        Assert(nSubscripts == 1);
        if (lowerIndx[0] > upperIndx[0])
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("upper bound cannot be less than lower bound")));
        if (lowerIndx[0] < lb[0])
        {
            if (upperIndx[0] < lb[0] - 1)
                newhasnulls = true;     /* will insert nulls */
            addedbefore = lb[0] - lowerIndx[0];
            dim[0] += addedbefore;
            lb[0] = lowerIndx[0];
        }
        if (upperIndx[0] >= (dim[0] + lb[0]))
        {
            if (lowerIndx[0] > (dim[0] + lb[0]))
                newhasnulls = true;     /* will insert nulls */
            addedafter = upperIndx[0] - (dim[0] + lb[0]) + 1;
            dim[0] += addedafter;
        }
    }
    else
    {
        /*
         * XXX currently we do not support extending multi-dimensional arrays
         * during assignment
         */
        for (i = 0; i < nSubscripts; i++)
        {
            if (lowerIndx[i] > upperIndx[i])
                ereport(ERROR,
                        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("upper bound cannot be less than lower bound")));
            if (lowerIndx[i] < lb[i] ||
                upperIndx[i] >= (dim[i] + lb[i]))
                ereport(ERROR,
                        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                         errmsg("array subscript out of range")));
        }
        /* fill any missing subscript positions with full array range */
        for (; i < ndim; i++)
        {
            lowerIndx[i] = lb[i];
            upperIndx[i] = dim[i] + lb[i] - 1;
            if (lowerIndx[i] > upperIndx[i])
                ereport(ERROR,
                        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("upper bound cannot be less than lower bound")));
        }
    }

    /* Do this mainly to check for overflow */
    nitems = ArrayGetNItems(ndim, dim);

    /*
     * Make sure source array has enough entries.  Note we ignore the shape of
     * the source array and just read entries serially.
     */
    mda_get_range(ndim, span, lowerIndx, upperIndx);
    nsrcitems = ArrayGetNItems(ndim, span);
    if (nsrcitems > ArrayGetNItems(ARR_NDIM(srcArray), ARR_DIMS(srcArray)))
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("source array too small")));

    /*
     * Compute space occupied by new entries, space occupied by replaced
     * entries, and required space for new array.
     */
    if (newhasnulls)
        overheadlen = ARR_OVERHEAD_WITHNULLS(ndim, nitems);
    else
        overheadlen = ARR_OVERHEAD_NONULLS(ndim);
    newitemsize = array_nelems_size(ARR_DATA_PTR(srcArray), 0,
                                    ARR_NULLBITMAP(srcArray), nsrcitems,
                                    elmlen, elmbyval, elmalign);
    oldoverheadlen = ARR_DATA_OFFSET(array);
    olddatasize = ARR_SIZE(array) - oldoverheadlen;
    if (ndim > 1)
    {
        /*
         * here we do not need to cope with extension of the array; it would
         * be a lot more complicated if we had to do so...
         */
        olditemsize = array_slice_size(ARR_DATA_PTR(array),
                                       ARR_NULLBITMAP(array),
                                       ndim, dim, lb,
                                       lowerIndx, upperIndx,
                                       elmlen, elmbyval, elmalign);
        lenbefore = lenafter = 0;       /* keep compiler quiet */
        itemsbefore = itemsafter = nolditems = 0;
    }
    else
    {
        /*
         * here we must allow for possibility of slice larger than orig array
         * and/or not adjacent to orig array subscripts
         */
        int         oldlb = ARR_LBOUND(array)[0];
        int         oldub = oldlb + ARR_DIMS(array)[0] - 1;
        int         slicelb = Max(oldlb, lowerIndx[0]);
        int         sliceub = Min(oldub, upperIndx[0]);
        char       *oldarraydata = ARR_DATA_PTR(array);
        bits8      *oldarraybitmap = ARR_NULLBITMAP(array);

        /* count/size of old array entries that will go before the slice */
        itemsbefore = Min(slicelb, oldub + 1) - oldlb;
        lenbefore = array_nelems_size(oldarraydata, 0, oldarraybitmap,
                                      itemsbefore,
                                      elmlen, elmbyval, elmalign);
        /* count/size of old array entries that will be replaced by slice */
        if (slicelb > sliceub)
        {
            nolditems = 0;
            olditemsize = 0;
        }
        else
        {
            nolditems = sliceub - slicelb + 1;
            olditemsize = array_nelems_size(oldarraydata + lenbefore,
                                            itemsbefore, oldarraybitmap,
                                            nolditems,
                                            elmlen, elmbyval, elmalign);
        }
        /* count/size of old array entries that will go after the slice */
        itemsafter = oldub + 1 - Max(sliceub + 1, oldlb);
        lenafter = olddatasize - lenbefore - olditemsize;
    }

    newsize = overheadlen + olddatasize - olditemsize + newitemsize;

    newarray = (ArrayType *) palloc0(newsize);
    SET_VARSIZE(newarray, newsize);
    newarray->ndim = ndim;
    newarray->dataoffset = newhasnulls ? overheadlen : 0;
    newarray->elemtype = ARR_ELEMTYPE(array);
    memcpy(ARR_DIMS(newarray), dim, ndim * sizeof(int));
    memcpy(ARR_LBOUND(newarray), lb, ndim * sizeof(int));

    if (ndim > 1)
    {
        /*
         * here we do not need to cope with extension of the array; it would
         * be a lot more complicated if we had to do so...
         */
        array_insert_slice(newarray, array, srcArray,
                           ndim, dim, lb,
                           lowerIndx, upperIndx,
                           elmlen, elmbyval, elmalign);
    }
    else
    {
        /* fill in data */
        memcpy((char *) newarray + overheadlen,
               (char *) array + oldoverheadlen,
               lenbefore);
        memcpy((char *) newarray + overheadlen + lenbefore,
               ARR_DATA_PTR(srcArray),
               newitemsize);
        memcpy((char *) newarray + overheadlen + lenbefore + newitemsize,
               (char *) array + oldoverheadlen + lenbefore + olditemsize,
               lenafter);
        /* fill in nulls bitmap if needed */
        if (newhasnulls)
        {
            bits8      *newnullbitmap = ARR_NULLBITMAP(newarray);
            bits8      *oldnullbitmap = ARR_NULLBITMAP(array);

            /* Zero the bitmap to handle marking inserted positions null */
            MemSet(newnullbitmap, 0, (nitems + 7) / 8);
            array_bitmap_copy(newnullbitmap, addedbefore,
                              oldnullbitmap, 0,
                              itemsbefore);
            array_bitmap_copy(newnullbitmap, lowerIndx[0] - lb[0],
                              ARR_NULLBITMAP(srcArray), 0,
                              nsrcitems);
            array_bitmap_copy(newnullbitmap, addedbefore + itemsbefore + nolditems,
                              oldnullbitmap, itemsbefore + nolditems,
                              itemsafter);
        }
    }

    return newarray;
}

/*
 * array_map()
 *
 * Map an array through an arbitrary function.  Return a new array with
 * same dimensions and each source element transformed by fn().  Each
 * source element is passed as the first argument to fn(); additional
 * arguments to be passed to fn() can be specified by the caller.
 * The output array can have a different element type than the input.
 *
 * Parameters are:
 * * fcinfo: a function-call data structure pre-constructed by the caller
 *   to be ready to call the desired function, with everything except the
 *   first argument position filled in.  In particular, flinfo identifies
 *   the function fn(), and if nargs > 1 then argument positions after the
 *   first must be preset to the additional values to be passed.  The
 *   first argument position initially holds the input array value.
 * * inpType: OID of element type of input array.  This must be the same as,
 *   or binary-compatible with, the first argument type of fn().
 * * retType: OID of element type of output array.  This must be the same as,
 *   or binary-compatible with, the result type of fn().
 * * amstate: workspace for array_map.  Must be zeroed by caller before
 *   first call, and not touched after that.
 *
 * It is legitimate to pass a freshly-zeroed ArrayMapState on each call,
 * but better performance can be had if the state can be preserved across
 * a series of calls.
 *
 * NB: caller must assure that input array is not NULL.  NULL elements in
 * the array are OK however.
 */
Datum
array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
          ArrayMapState *amstate)
{
    ArrayType  *v;
    ArrayType  *result;
    Datum      *values;
    bool       *nulls;
    Datum       elt;
    int        *dim;
    int         ndim;
    int         nitems;
    int         i;
    int32       nbytes = 0;
    int32       dataoffset;
    bool        hasnulls;
    int         inp_typlen;
    bool        inp_typbyval;
    char        inp_typalign;
    int         typlen;
    bool        typbyval;
    char        typalign;
    char       *s;
    bits8      *bitmap;
    int         bitmask;
    ArrayMetaState *inp_extra;
    ArrayMetaState *ret_extra;

    /* Get input array */
    if (fcinfo->nargs < 1)
        elog(ERROR, "invalid nargs: %d", fcinfo->nargs);
    if (PG_ARGISNULL(0))
        elog(ERROR, "null input array");
    v = PG_GETARG_ARRAYTYPE_P(0);

    Assert(ARR_ELEMTYPE(v) == inpType);

    ndim = ARR_NDIM(v);
    dim = ARR_DIMS(v);
    nitems = ArrayGetNItems(ndim, dim);

    /* Check for empty array */
    if (nitems <= 0)
    {
        /* Return empty array */
        PG_RETURN_ARRAYTYPE_P(construct_empty_array(retType));
    }

    /*
     * We arrange to look up info about input and return element types only
     * once per series of calls, assuming the element type doesn't change
     * underneath us.
     */
    inp_extra = &amstate->inp_extra;
    ret_extra = &amstate->ret_extra;

    if (inp_extra->element_type != inpType)
    {
        get_typlenbyvalalign(inpType,
                             &inp_extra->typlen,
                             &inp_extra->typbyval,
                             &inp_extra->typalign);
        inp_extra->element_type = inpType;
    }
    inp_typlen = inp_extra->typlen;
    inp_typbyval = inp_extra->typbyval;
    inp_typalign = inp_extra->typalign;

    if (ret_extra->element_type != retType)
    {
        get_typlenbyvalalign(retType,
                             &ret_extra->typlen,
                             &ret_extra->typbyval,
                             &ret_extra->typalign);
        ret_extra->element_type = retType;
    }
    typlen = ret_extra->typlen;
    typbyval = ret_extra->typbyval;
    typalign = ret_extra->typalign;

    /* Allocate temporary arrays for new values */
    values = (Datum *) palloc(nitems * sizeof(Datum));
    nulls = (bool *) palloc(nitems * sizeof(bool));

    /* Loop over source data */
    s = ARR_DATA_PTR(v);
    bitmap = ARR_NULLBITMAP(v);
    bitmask = 1;
    hasnulls = false;

    for (i = 0; i < nitems; i++)
    {
        bool        callit = true;

        /* Get source element, checking for NULL */
        if (bitmap && (*bitmap & bitmask) == 0)
        {
            fcinfo->argnull[0] = true;
        }
        else
        {
            elt = fetch_att(s, inp_typbyval, inp_typlen);
            s = att_addlength_datum(s, inp_typlen, elt);
            s = (char *) att_align_nominal(s, inp_typalign);
            fcinfo->arg[0] = elt;
            fcinfo->argnull[0] = false;
        }

        /*
         * Apply the given function to source elt and extra args.
         */
        if (fcinfo->flinfo->fn_strict)
        {
            int         j;

            for (j = 0; j < fcinfo->nargs; j++)
            {
                if (fcinfo->argnull[j])
                {
                    callit = false;
                    break;
                }
            }
        }

        if (callit)
        {
            fcinfo->isnull = false;
            values[i] = FunctionCallInvoke(fcinfo);
        }
        else
            fcinfo->isnull = true;

        nulls[i] = fcinfo->isnull;
        if (fcinfo->isnull)
            hasnulls = true;
        else
        {
            /* Ensure data is not toasted */
            if (typlen == -1)
                values[i] = PointerGetDatum(PG_DETOAST_DATUM(values[i]));
            /* Update total result size */
            nbytes = att_addlength_datum(nbytes, typlen, values[i]);
            nbytes = att_align_nominal(nbytes, typalign);
            /* check for overflow of total request */
            if (!AllocSizeIsValid(nbytes))
                ereport(ERROR,
                        (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                         errmsg("array size exceeds the maximum allowed (%d)",
                                (int) MaxAllocSize)));
        }

        /* advance bitmap pointer if any */
        if (bitmap)
        {
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                bitmap++;
                bitmask = 1;
            }
        }
    }

    /* Allocate and initialize the result array */
    if (hasnulls)
    {
        dataoffset = ARR_OVERHEAD_WITHNULLS(ndim, nitems);
        nbytes += dataoffset;
    }
    else
    {
        dataoffset = 0;         /* marker for no null bitmap */
        nbytes += ARR_OVERHEAD_NONULLS(ndim);
    }
    result = (ArrayType *) palloc0(nbytes);
    SET_VARSIZE(result, nbytes);
    result->ndim = ndim;
    result->dataoffset = dataoffset;
    result->elemtype = retType;
    memcpy(ARR_DIMS(result), ARR_DIMS(v), 2 * ndim * sizeof(int));

    /*
     * Note: do not risk trying to pfree the results of the called function
     */
    CopyArrayEls(result,
                 values, nulls, nitems,
                 typlen, typbyval, typalign,
                 false);

    pfree(values);
    pfree(nulls);

    PG_RETURN_ARRAYTYPE_P(result);
}

/*
 * construct_array  --- simple method for constructing an array object
 *
 * elems: array of Datum items to become the array contents
 *        (NULL element values are not supported).
 * nelems: number of items
 * elmtype, elmlen, elmbyval, elmalign: info for the datatype of the items
 *
 * A palloc'd 1-D array object is constructed and returned.  Note that
 * elem values will be copied into the object even if pass-by-ref type.
 *
 * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
 * from the system catalogs, given the elmtype.  However, the caller is
 * in a better position to cache this info across multiple uses, or even
 * to hard-wire values if the element type is hard-wired.
 */
ArrayType *
construct_array(Datum *elems, int nelems,
                Oid elmtype,
                int elmlen, bool elmbyval, char elmalign)
{
    int         dims[1];
    int         lbs[1];

    dims[0] = nelems;
    lbs[0] = 1;

    return construct_md_array(elems, NULL, 1, dims, lbs,
                              elmtype, elmlen, elmbyval, elmalign);
}

/*
 * construct_md_array   --- simple method for constructing an array object
 *                          with arbitrary dimensions and possible NULLs
 *
 * elems: array of Datum items to become the array contents
 * nulls: array of is-null flags (can be NULL if no nulls)
 * ndims: number of dimensions
 * dims: integer array with size of each dimension
 * lbs: integer array with lower bound of each dimension
 * elmtype, elmlen, elmbyval, elmalign: info for the datatype of the items
 *
 * A palloc'd ndims-D array object is constructed and returned.  Note that
 * elem values will be copied into the object even if pass-by-ref type.
 *
 * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
 * from the system catalogs, given the elmtype.  However, the caller is
 * in a better position to cache this info across multiple uses, or even
 * to hard-wire values if the element type is hard-wired.
 */
ArrayType *
construct_md_array(Datum *elems,
                   bool *nulls,
                   int ndims,
                   int *dims,
                   int *lbs,
                   Oid elmtype, int elmlen, bool elmbyval, char elmalign)
{
    ArrayType  *result;
    bool        hasnulls;
    int32       nbytes;
    int32       dataoffset;
    int         i;
    int         nelems;

    if (ndims < 0)              /* we do allow zero-dimension arrays */
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid number of dimensions: %d", ndims)));
    if (ndims > MAXDIM)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
                        ndims, MAXDIM)));

    /* fast track for empty array */
    if (ndims == 0)
        return construct_empty_array(elmtype);

    nelems = ArrayGetNItems(ndims, dims);

    /* compute required space */
    nbytes = 0;
    hasnulls = false;
    for (i = 0; i < nelems; i++)
    {
        if (nulls && nulls[i])
        {
            hasnulls = true;
            continue;
        }
        /* make sure data is not toasted */
        if (elmlen == -1)
            elems[i] = PointerGetDatum(PG_DETOAST_DATUM(elems[i]));
        nbytes = att_addlength_datum(nbytes, elmlen, elems[i]);
        nbytes = att_align_nominal(nbytes, elmalign);
        /* check for overflow of total request */
        if (!AllocSizeIsValid(nbytes))
            ereport(ERROR,
                    (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                     errmsg("array size exceeds the maximum allowed (%d)",
                            (int) MaxAllocSize)));
    }

    /* Allocate and initialize result array */
    if (hasnulls)
    {
        dataoffset = ARR_OVERHEAD_WITHNULLS(ndims, nelems);
        nbytes += dataoffset;
    }
    else
    {
        dataoffset = 0;         /* marker for no null bitmap */
        nbytes += ARR_OVERHEAD_NONULLS(ndims);
    }
    result = (ArrayType *) palloc0(nbytes);
    SET_VARSIZE(result, nbytes);
    result->ndim = ndims;
    result->dataoffset = dataoffset;
    result->elemtype = elmtype;
    memcpy(ARR_DIMS(result), dims, ndims * sizeof(int));
    memcpy(ARR_LBOUND(result), lbs, ndims * sizeof(int));

    CopyArrayEls(result,
                 elems, nulls, nelems,
                 elmlen, elmbyval, elmalign,
                 false);

    return result;
}

/*
 * construct_empty_array    --- make a zero-dimensional array of given type
 */
ArrayType *
construct_empty_array(Oid elmtype)
{
    ArrayType  *result;

    result = (ArrayType *) palloc0(sizeof(ArrayType));
    SET_VARSIZE(result, sizeof(ArrayType));
    result->ndim = 0;
    result->dataoffset = 0;
    result->elemtype = elmtype;
    return result;
}

/*
 * deconstruct_array  --- simple method for extracting data from an array
 *
 * array: array object to examine (must not be NULL)
 * elmtype, elmlen, elmbyval, elmalign: info for the datatype of the items
 * elemsp: return value, set to point to palloc'd array of Datum values
 * nullsp: return value, set to point to palloc'd array of isnull markers
 * nelemsp: return value, set to number of extracted values
 *
 * The caller may pass nullsp == NULL if it does not support NULLs in the
 * array.  Note that this produces a very uninformative error message,
 * so do it only in cases where a NULL is really not expected.
 *
 * If array elements are pass-by-ref data type, the returned Datums will
 * be pointers into the array object.
 *
 * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
 * from the system catalogs, given the elmtype.  However, in most current
 * uses the type is hard-wired into the caller and so we can save a lookup
 * cycle by hard-wiring the type info as well.
 */
void
deconstruct_array(ArrayType *array,
                  Oid elmtype,
                  int elmlen, bool elmbyval, char elmalign,
                  Datum **elemsp, bool **nullsp, int *nelemsp)
{
    Datum      *elems;
    bool       *nulls;
    int         nelems;
    char       *p;
    bits8      *bitmap;
    int         bitmask;
    int         i;

    Assert(ARR_ELEMTYPE(array) == elmtype);

    nelems = ArrayGetNItems(ARR_NDIM(array), ARR_DIMS(array));
    *elemsp = elems = (Datum *) palloc(nelems * sizeof(Datum));
    if (nullsp)
        *nullsp = nulls = (bool *) palloc0(nelems * sizeof(bool));
    else
        nulls = NULL;
    *nelemsp = nelems;

    p = ARR_DATA_PTR(array);
    bitmap = ARR_NULLBITMAP(array);
    bitmask = 1;

    for (i = 0; i < nelems; i++)
    {
        /* Get source element, checking for NULL */
        if (bitmap && (*bitmap & bitmask) == 0)
        {
            elems[i] = (Datum) 0;
            if (nulls)
                nulls[i] = true;
            else
                ereport(ERROR,
                        (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                  errmsg("null array element not allowed in this context")));
        }
        else
        {
            elems[i] = fetch_att(p, elmbyval, elmlen);
            p = att_addlength_pointer(p, elmlen, p);
            p = (char *) att_align_nominal(p, elmalign);
        }

        /* advance bitmap pointer if any */
        if (bitmap)
        {
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                bitmap++;
                bitmask = 1;
            }
        }
    }
}

/*
 * array_contains_nulls --- detect whether an array has any null elements
 *
 * This gives an accurate answer, whereas testing ARR_HASNULL only tells
 * if the array *might* contain a null.
 */
bool
array_contains_nulls(ArrayType *array)
{
    int         nelems;
    bits8      *bitmap;
    int         bitmask;

    /* Easy answer if there's no null bitmap */
    if (!ARR_HASNULL(array))
        return false;

    nelems = ArrayGetNItems(ARR_NDIM(array), ARR_DIMS(array));

    bitmap = ARR_NULLBITMAP(array);

    /* check whole bytes of the bitmap byte-at-a-time */
    while (nelems >= 8)
    {
        if (*bitmap != 0xFF)
            return true;
        bitmap++;
        nelems -= 8;
    }

    /* check last partial byte */
    bitmask = 1;
    while (nelems > 0)
    {
        if ((*bitmap & bitmask) == 0)
            return true;
        bitmask <<= 1;
        nelems--;
    }

    return false;
}


/*
 * array_eq :
 *        compares two arrays for equality
 * result :
 *        returns true if the arrays are equal, false otherwise.
 *
 * Note: we do not use array_cmp here, since equality may be meaningful in
 * datatypes that don't have a total ordering (and hence no btree support).
 */
Datum
array_eq(PG_FUNCTION_ARGS)
{
    ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
    Oid         collation = PG_GET_COLLATION();
    int         ndims1 = ARR_NDIM(array1);
    int         ndims2 = ARR_NDIM(array2);
    int        *dims1 = ARR_DIMS(array1);
    int        *dims2 = ARR_DIMS(array2);
    Oid         element_type = ARR_ELEMTYPE(array1);
    bool        result = true;
    int         nitems;
    TypeCacheEntry *typentry;
    int         typlen;
    bool        typbyval;
    char        typalign;
    char       *ptr1;
    char       *ptr2;
    bits8      *bitmap1;
    bits8      *bitmap2;
    int         bitmask;
    int         i;
    FunctionCallInfoData locfcinfo;

    if (element_type != ARR_ELEMTYPE(array2))
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("cannot compare arrays of different element types")));

    /* fast path if the arrays do not have the same dimensionality */
    if (ndims1 != ndims2 ||
        memcmp(dims1, dims2, 2 * ndims1 * sizeof(int)) != 0)
        result = false;
    else
    {
        /*
         * We arrange to look up the equality function only once per series of
         * calls, assuming the element type doesn't change underneath us.  The
         * typcache is used so that we have no memory leakage when being used
         * as an index support function.
         */
        typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
        if (typentry == NULL ||
            typentry->type_id != element_type)
        {
            typentry = lookup_type_cache(element_type,
                                         TYPECACHE_EQ_OPR_FINFO);
            if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
                ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_FUNCTION),
                errmsg("could not identify an equality operator for type %s",
                       format_type_be(element_type))));
            fcinfo->flinfo->fn_extra = (void *) typentry;
        }
        typlen = typentry->typlen;
        typbyval = typentry->typbyval;
        typalign = typentry->typalign;

        /*
         * apply the operator to each pair of array elements.
         */
        InitFunctionCallInfoData(locfcinfo, &typentry->eq_opr_finfo, 2,
                                 collation, NULL, NULL);

        /* Loop over source data */
        nitems = ArrayGetNItems(ndims1, dims1);
        ptr1 = ARR_DATA_PTR(array1);
        ptr2 = ARR_DATA_PTR(array2);
        bitmap1 = ARR_NULLBITMAP(array1);
        bitmap2 = ARR_NULLBITMAP(array2);
        bitmask = 1;            /* use same bitmask for both arrays */

        for (i = 0; i < nitems; i++)
        {
            Datum       elt1;
            Datum       elt2;
            bool        isnull1;
            bool        isnull2;
            bool        oprresult;

            /* Get elements, checking for NULL */
            if (bitmap1 && (*bitmap1 & bitmask) == 0)
            {
                isnull1 = true;
                elt1 = (Datum) 0;
            }
            else
            {
                isnull1 = false;
                elt1 = fetch_att(ptr1, typbyval, typlen);
                ptr1 = att_addlength_pointer(ptr1, typlen, ptr1);
                ptr1 = (char *) att_align_nominal(ptr1, typalign);
            }

            if (bitmap2 && (*bitmap2 & bitmask) == 0)
            {
                isnull2 = true;
                elt2 = (Datum) 0;
            }
            else
            {
                isnull2 = false;
                elt2 = fetch_att(ptr2, typbyval, typlen);
                ptr2 = att_addlength_pointer(ptr2, typlen, ptr2);
                ptr2 = (char *) att_align_nominal(ptr2, typalign);
            }

            /* advance bitmap pointers if any */
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                if (bitmap1)
                    bitmap1++;
                if (bitmap2)
                    bitmap2++;
                bitmask = 1;
            }

            /*
             * We consider two NULLs equal; NULL and not-NULL are unequal.
             */
            if (isnull1 && isnull2)
                continue;
            if (isnull1 || isnull2)
            {
                result = false;
                break;
            }

            /*
             * Apply the operator to the element pair
             */
            locfcinfo.arg[0] = elt1;
            locfcinfo.arg[1] = elt2;
            locfcinfo.argnull[0] = false;
            locfcinfo.argnull[1] = false;
            locfcinfo.isnull = false;
            oprresult = DatumGetBool(FunctionCallInvoke(&locfcinfo));
            if (!oprresult)
            {
                result = false;
                break;
            }
        }
    }

    /* Avoid leaking memory when handed toasted input. */
    PG_FREE_IF_COPY(array1, 0);
    PG_FREE_IF_COPY(array2, 1);

    PG_RETURN_BOOL(result);
}


/*-----------------------------------------------------------------------------
 * array-array bool operators:
 *      Given two arrays, iterate comparison operators
 *      over the array. Uses logic similar to text comparison
 *      functions, except element-by-element instead of
 *      character-by-character.
 *----------------------------------------------------------------------------
 */

Datum
array_ne(PG_FUNCTION_ARGS)
{
    PG_RETURN_BOOL(!DatumGetBool(array_eq(fcinfo)));
}

Datum
array_lt(PG_FUNCTION_ARGS)
{
    PG_RETURN_BOOL(array_cmp(fcinfo) < 0);
}

Datum
array_gt(PG_FUNCTION_ARGS)
{
    PG_RETURN_BOOL(array_cmp(fcinfo) > 0);
}

Datum
array_le(PG_FUNCTION_ARGS)
{
    PG_RETURN_BOOL(array_cmp(fcinfo) <= 0);
}

Datum
array_ge(PG_FUNCTION_ARGS)
{
    PG_RETURN_BOOL(array_cmp(fcinfo) >= 0);
}

Datum
btarraycmp(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT32(array_cmp(fcinfo));
}

/*
 * array_cmp()
 * Internal comparison function for arrays.
 *
 * Returns -1, 0 or 1
 */
static int
array_cmp(FunctionCallInfo fcinfo)
{
    ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
    Oid         collation = PG_GET_COLLATION();
    int         ndims1 = ARR_NDIM(array1);
    int         ndims2 = ARR_NDIM(array2);
    int        *dims1 = ARR_DIMS(array1);
    int        *dims2 = ARR_DIMS(array2);
    int         nitems1 = ArrayGetNItems(ndims1, dims1);
    int         nitems2 = ArrayGetNItems(ndims2, dims2);
    Oid         element_type = ARR_ELEMTYPE(array1);
    int         result = 0;
    TypeCacheEntry *typentry;
    int         typlen;
    bool        typbyval;
    char        typalign;
    int         min_nitems;
    char       *ptr1;
    char       *ptr2;
    bits8      *bitmap1;
    bits8      *bitmap2;
    int         bitmask;
    int         i;
    FunctionCallInfoData locfcinfo;

    if (element_type != ARR_ELEMTYPE(array2))
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("cannot compare arrays of different element types")));

    /*
     * We arrange to look up the comparison function only once per series of
     * calls, assuming the element type doesn't change underneath us. The
     * typcache is used so that we have no memory leakage when being used as
     * an index support function.
     */
    typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
    if (typentry == NULL ||
        typentry->type_id != element_type)
    {
        typentry = lookup_type_cache(element_type,
                                     TYPECACHE_CMP_PROC_FINFO);
        if (!OidIsValid(typentry->cmp_proc_finfo.fn_oid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_FUNCTION),
               errmsg("could not identify a comparison function for type %s",
                      format_type_be(element_type))));
        fcinfo->flinfo->fn_extra = (void *) typentry;
    }
    typlen = typentry->typlen;
    typbyval = typentry->typbyval;
    typalign = typentry->typalign;

    /*
     * apply the operator to each pair of array elements.
     */
    InitFunctionCallInfoData(locfcinfo, &typentry->cmp_proc_finfo, 2,
                             collation, NULL, NULL);

    /* Loop over source data */
    min_nitems = Min(nitems1, nitems2);
    ptr1 = ARR_DATA_PTR(array1);
    ptr2 = ARR_DATA_PTR(array2);
    bitmap1 = ARR_NULLBITMAP(array1);
    bitmap2 = ARR_NULLBITMAP(array2);
    bitmask = 1;                /* use same bitmask for both arrays */

    for (i = 0; i < min_nitems; i++)
    {
        Datum       elt1;
        Datum       elt2;
        bool        isnull1;
        bool        isnull2;
        int32       cmpresult;

        /* Get elements, checking for NULL */
        if (bitmap1 && (*bitmap1 & bitmask) == 0)
        {
            isnull1 = true;
            elt1 = (Datum) 0;
        }
        else
        {
            isnull1 = false;
            elt1 = fetch_att(ptr1, typbyval, typlen);
            ptr1 = att_addlength_pointer(ptr1, typlen, ptr1);
            ptr1 = (char *) att_align_nominal(ptr1, typalign);
        }

        if (bitmap2 && (*bitmap2 & bitmask) == 0)
        {
            isnull2 = true;
            elt2 = (Datum) 0;
        }
        else
        {
            isnull2 = false;
            elt2 = fetch_att(ptr2, typbyval, typlen);
            ptr2 = att_addlength_pointer(ptr2, typlen, ptr2);
            ptr2 = (char *) att_align_nominal(ptr2, typalign);
        }

        /* advance bitmap pointers if any */
        bitmask <<= 1;
        if (bitmask == 0x100)
        {
            if (bitmap1)
                bitmap1++;
            if (bitmap2)
                bitmap2++;
            bitmask = 1;
        }

        /*
         * We consider two NULLs equal; NULL > not-NULL.
         */
        if (isnull1 && isnull2)
            continue;
        if (isnull1)
        {
            /* arg1 is greater than arg2 */
            result = 1;
            break;
        }
        if (isnull2)
        {
            /* arg1 is less than arg2 */
            result = -1;
            break;
        }

        /* Compare the pair of elements */
        locfcinfo.arg[0] = elt1;
        locfcinfo.arg[1] = elt2;
        locfcinfo.argnull[0] = false;
        locfcinfo.argnull[1] = false;
        locfcinfo.isnull = false;
        cmpresult = DatumGetInt32(FunctionCallInvoke(&locfcinfo));

        if (cmpresult == 0)
            continue;           /* equal */

        if (cmpresult < 0)
        {
            /* arg1 is less than arg2 */
            result = -1;
            break;
        }
        else
        {
            /* arg1 is greater than arg2 */
            result = 1;
            break;
        }
    }

    /*
     * If arrays contain same data (up to end of shorter one), apply
     * additional rules to sort by dimensionality.  The relative significance
     * of the different bits of information is historical; mainly we just care
     * that we don't say "equal" for arrays of different dimensionality.
     */
    if (result == 0)
    {
        if (nitems1 != nitems2)
            result = (nitems1 < nitems2) ? -1 : 1;
        else if (ndims1 != ndims2)
            result = (ndims1 < ndims2) ? -1 : 1;
        else
        {
            /* this relies on LB array immediately following DIMS array */
            for (i = 0; i < ndims1 * 2; i++)
            {
                if (dims1[i] != dims2[i])
                {
                    result = (dims1[i] < dims2[i]) ? -1 : 1;
                    break;
                }
            }
        }
    }

    /* Avoid leaking memory when handed toasted input. */
    PG_FREE_IF_COPY(array1, 0);
    PG_FREE_IF_COPY(array2, 1);

    return result;
}


/*-----------------------------------------------------------------------------
 * array hashing
 *      Hash the elements and combine the results.
 *----------------------------------------------------------------------------
 */

Datum
hash_array(PG_FUNCTION_ARGS)
{
    ArrayType  *array = PG_GETARG_ARRAYTYPE_P(0);
    int         ndims = ARR_NDIM(array);
    int        *dims = ARR_DIMS(array);
    Oid         element_type = ARR_ELEMTYPE(array);
    uint32      result = 1;
    int         nitems;
    TypeCacheEntry *typentry;
    int         typlen;
    bool        typbyval;
    char        typalign;
    char       *ptr;
    bits8      *bitmap;
    int         bitmask;
    int         i;
    FunctionCallInfoData locfcinfo;

    /*
     * We arrange to look up the hash function only once per series of calls,
     * assuming the element type doesn't change underneath us.  The typcache
     * is used so that we have no memory leakage when being used as an index
     * support function.
     */
    typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
    if (typentry == NULL ||
        typentry->type_id != element_type)
    {
        typentry = lookup_type_cache(element_type,
                                     TYPECACHE_HASH_PROC_FINFO);
        if (!OidIsValid(typentry->hash_proc_finfo.fn_oid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_FUNCTION),
                     errmsg("could not identify a hash function for type %s",
                            format_type_be(element_type))));
        fcinfo->flinfo->fn_extra = (void *) typentry;
    }
    typlen = typentry->typlen;
    typbyval = typentry->typbyval;
    typalign = typentry->typalign;

    /*
     * apply the hash function to each array element.
     */
    InitFunctionCallInfoData(locfcinfo, &typentry->hash_proc_finfo, 1,
                             InvalidOid, NULL, NULL);

    /* Loop over source data */
    nitems = ArrayGetNItems(ndims, dims);
    ptr = ARR_DATA_PTR(array);
    bitmap = ARR_NULLBITMAP(array);
    bitmask = 1;

    for (i = 0; i < nitems; i++)
    {
        uint32      elthash;

        /* Get element, checking for NULL */
        if (bitmap && (*bitmap & bitmask) == 0)
        {
            /* Treat nulls as having hashvalue 0 */
            elthash = 0;
        }
        else
        {
            Datum       elt;

            elt = fetch_att(ptr, typbyval, typlen);
            ptr = att_addlength_pointer(ptr, typlen, ptr);
            ptr = (char *) att_align_nominal(ptr, typalign);

            /* Apply the hash function */
            locfcinfo.arg[0] = elt;
            locfcinfo.argnull[0] = false;
            locfcinfo.isnull = false;
            elthash = DatumGetUInt32(FunctionCallInvoke(&locfcinfo));
        }

        /* advance bitmap pointer if any */
        if (bitmap)
        {
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                bitmap++;
                bitmask = 1;
            }
        }

        /*
         * Combine hash values of successive elements by multiplying the
         * current value by 31 and adding on the new element's hash value.
         *
         * The result is a sum in which each element's hash value is
         * multiplied by a different power of 31. This is modulo 2^32
         * arithmetic, and the powers of 31 modulo 2^32 form a cyclic group of
         * order 2^27. So for arrays of up to 2^27 elements, each element's
         * hash value is multiplied by a different (odd) number, resulting in
         * a good mixing of all the elements' hash values.
         */
        result = (result << 5) - result + elthash;
    }

    /* Avoid leaking memory when handed toasted input. */
    PG_FREE_IF_COPY(array, 0);

    PG_RETURN_UINT32(result);
}


/*-----------------------------------------------------------------------------
 * array overlap/containment comparisons
 *      These use the same methods of comparing array elements as array_eq.
 *      We consider only the elements of the arrays, ignoring dimensionality.
 *----------------------------------------------------------------------------
 */

/*
 * array_contain_compare :
 *        compares two arrays for overlap/containment
 *
 * When matchall is true, return true if all members of array1 are in array2.
 * When matchall is false, return true if any members of array1 are in array2.
 */
static bool
array_contain_compare(ArrayType *array1, ArrayType *array2, Oid collation,
                      bool matchall, void **fn_extra)
{
    bool        result = matchall;
    Oid         element_type = ARR_ELEMTYPE(array1);
    TypeCacheEntry *typentry;
    int         nelems1;
    Datum      *values2;
    bool       *nulls2;
    int         nelems2;
    int         typlen;
    bool        typbyval;
    char        typalign;
    char       *ptr1;
    bits8      *bitmap1;
    int         bitmask;
    int         i;
    int         j;
    FunctionCallInfoData locfcinfo;

    if (element_type != ARR_ELEMTYPE(array2))
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("cannot compare arrays of different element types")));

    /*
     * We arrange to look up the equality function only once per series of
     * calls, assuming the element type doesn't change underneath us.  The
     * typcache is used so that we have no memory leakage when being used as
     * an index support function.
     */
    typentry = (TypeCacheEntry *) *fn_extra;
    if (typentry == NULL ||
        typentry->type_id != element_type)
    {
        typentry = lookup_type_cache(element_type,
                                     TYPECACHE_EQ_OPR_FINFO);
        if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_FUNCTION),
                errmsg("could not identify an equality operator for type %s",
                       format_type_be(element_type))));
        *fn_extra = (void *) typentry;
    }
    typlen = typentry->typlen;
    typbyval = typentry->typbyval;
    typalign = typentry->typalign;

    /*
     * Since we probably will need to scan array2 multiple times, it's
     * worthwhile to use deconstruct_array on it.  We scan array1 the hard way
     * however, since we very likely won't need to look at all of it.
     */
    deconstruct_array(array2, element_type, typlen, typbyval, typalign,
                      &values2, &nulls2, &nelems2);

    /*
     * Apply the comparison operator to each pair of array elements.
     */
    InitFunctionCallInfoData(locfcinfo, &typentry->eq_opr_finfo, 2,
                             collation, NULL, NULL);

    /* Loop over source data */
    nelems1 = ArrayGetNItems(ARR_NDIM(array1), ARR_DIMS(array1));
    ptr1 = ARR_DATA_PTR(array1);
    bitmap1 = ARR_NULLBITMAP(array1);
    bitmask = 1;

    for (i = 0; i < nelems1; i++)
    {
        Datum       elt1;
        bool        isnull1;

        /* Get element, checking for NULL */
        if (bitmap1 && (*bitmap1 & bitmask) == 0)
        {
            isnull1 = true;
            elt1 = (Datum) 0;
        }
        else
        {
            isnull1 = false;
            elt1 = fetch_att(ptr1, typbyval, typlen);
            ptr1 = att_addlength_pointer(ptr1, typlen, ptr1);
            ptr1 = (char *) att_align_nominal(ptr1, typalign);
        }

        /* advance bitmap pointer if any */
        bitmask <<= 1;
        if (bitmask == 0x100)
        {
            if (bitmap1)
                bitmap1++;
            bitmask = 1;
        }

        /*
         * We assume that the comparison operator is strict, so a NULL can't
         * match anything.  XXX this diverges from the "NULL=NULL" behavior of
         * array_eq, should we act like that?
         */
        if (isnull1)
        {
            if (matchall)
            {
                result = false;
                break;
            }
            continue;
        }

        for (j = 0; j < nelems2; j++)
        {
            Datum       elt2 = values2[j];
            bool        isnull2 = nulls2[j];
            bool        oprresult;

            if (isnull2)
                continue;       /* can't match */

            /*
             * Apply the operator to the element pair
             */
            locfcinfo.arg[0] = elt1;
            locfcinfo.arg[1] = elt2;
            locfcinfo.argnull[0] = false;
            locfcinfo.argnull[1] = false;
            locfcinfo.isnull = false;
            oprresult = DatumGetBool(FunctionCallInvoke(&locfcinfo));
            if (oprresult)
                break;
        }

        if (j < nelems2)
        {
            /* found a match for elt1 */
            if (!matchall)
            {
                result = true;
                break;
            }
        }
        else
        {
            /* no match for elt1 */
            if (matchall)
            {
                result = false;
                break;
            }
        }
    }

    pfree(values2);
    pfree(nulls2);

    return result;
}

Datum
arrayoverlap(PG_FUNCTION_ARGS)
{
    ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
    Oid         collation = PG_GET_COLLATION();
    bool        result;

    result = array_contain_compare(array1, array2, collation, false,
                                   &fcinfo->flinfo->fn_extra);

    /* Avoid leaking memory when handed toasted input. */
    PG_FREE_IF_COPY(array1, 0);
    PG_FREE_IF_COPY(array2, 1);

    PG_RETURN_BOOL(result);
}

Datum
arraycontains(PG_FUNCTION_ARGS)
{
    ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
    Oid         collation = PG_GET_COLLATION();
    bool        result;

    result = array_contain_compare(array2, array1, collation, true,
                                   &fcinfo->flinfo->fn_extra);

    /* Avoid leaking memory when handed toasted input. */
    PG_FREE_IF_COPY(array1, 0);
    PG_FREE_IF_COPY(array2, 1);

    PG_RETURN_BOOL(result);
}

Datum
arraycontained(PG_FUNCTION_ARGS)
{
    ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
    ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
    Oid         collation = PG_GET_COLLATION();
    bool        result;

    result = array_contain_compare(array1, array2, collation, true,
                                   &fcinfo->flinfo->fn_extra);

    /* Avoid leaking memory when handed toasted input. */
    PG_FREE_IF_COPY(array1, 0);
    PG_FREE_IF_COPY(array2, 1);

    PG_RETURN_BOOL(result);
}


/*-----------------------------------------------------------------------------
 * Array iteration functions
 *      These functions are used to iterate efficiently through arrays
 *-----------------------------------------------------------------------------
 */

/*
 * array_create_iterator --- set up to iterate through an array
 *
 * If slice_ndim is zero, we will iterate element-by-element; the returned
 * datums are of the array's element type.
 *
 * If slice_ndim is 1..ARR_NDIM(arr), we will iterate by slices: the
 * returned datums are of the same array type as 'arr', but of size
 * equal to the rightmost N dimensions of 'arr'.
 *
 * The passed-in array must remain valid for the lifetime of the iterator.
 */
ArrayIterator
array_create_iterator(ArrayType *arr, int slice_ndim)
{
    ArrayIterator iterator = palloc0(sizeof(ArrayIteratorData));

    /*
     * Sanity-check inputs --- caller should have got this right already
     */
    Assert(PointerIsValid(arr));
    if (slice_ndim < 0 || slice_ndim > ARR_NDIM(arr))
        elog(ERROR, "invalid arguments to array_create_iterator");

    /*
     * Remember basic info about the array and its element type
     */
    iterator->arr = arr;
    iterator->nullbitmap = ARR_NULLBITMAP(arr);
    iterator->nitems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
    get_typlenbyvalalign(ARR_ELEMTYPE(arr),
                         &iterator->typlen,
                         &iterator->typbyval,
                         &iterator->typalign);

    /*
     * Remember the slicing parameters.
     */
    iterator->slice_ndim = slice_ndim;

    if (slice_ndim > 0)
    {
        /*
         * Get pointers into the array's dims and lbound arrays to represent
         * the dims/lbound arrays of a slice.  These are the same as the
         * rightmost N dimensions of the array.
         */
        iterator->slice_dims = ARR_DIMS(arr) + ARR_NDIM(arr) - slice_ndim;
        iterator->slice_lbound = ARR_LBOUND(arr) + ARR_NDIM(arr) - slice_ndim;

        /*
         * Compute number of elements in a slice.
         */
        iterator->slice_len = ArrayGetNItems(slice_ndim,
                                             iterator->slice_dims);

        /*
         * Create workspace for building sub-arrays.
         */
        iterator->slice_values = (Datum *)
            palloc(iterator->slice_len * sizeof(Datum));
        iterator->slice_nulls = (bool *)
            palloc(iterator->slice_len * sizeof(bool));
    }

    /*
     * Initialize our data pointer and linear element number.  These will
     * advance through the array during array_iterate().
     */
    iterator->data_ptr = ARR_DATA_PTR(arr);
    iterator->current_item = 0;

    return iterator;
}

/*
 * Iterate through the array referenced by 'iterator'.
 *
 * As long as there is another element (or slice), return it into
 * *value / *isnull, and return true.  Return false when no more data.
 */
bool
array_iterate(ArrayIterator iterator, Datum *value, bool *isnull)
{
    /* Done if we have reached the end of the array */
    if (iterator->current_item >= iterator->nitems)
        return false;

    if (iterator->slice_ndim == 0)
    {
        /*
         * Scalar case: return one element.
         */
        if (array_get_isnull(iterator->nullbitmap, iterator->current_item++))
        {
            *isnull = true;
            *value = (Datum) 0;
        }
        else
        {
            /* non-NULL, so fetch the individual Datum to return */
            char       *p = iterator->data_ptr;

            *isnull = false;
            *value = fetch_att(p, iterator->typbyval, iterator->typlen);

            /* Move our data pointer forward to the next element */
            p = att_addlength_pointer(p, iterator->typlen, p);
            p = (char *) att_align_nominal(p, iterator->typalign);
            iterator->data_ptr = p;
        }
    }
    else
    {
        /*
         * Slice case: build and return an array of the requested size.
         */
        ArrayType  *result;
        Datum      *values = iterator->slice_values;
        bool       *nulls = iterator->slice_nulls;
        char       *p = iterator->data_ptr;
        int         i;

        for (i = 0; i < iterator->slice_len; i++)
        {
            if (array_get_isnull(iterator->nullbitmap,
                                 iterator->current_item++))
            {
                nulls[i] = true;
                values[i] = (Datum) 0;
            }
            else
            {
                nulls[i] = false;
                values[i] = fetch_att(p, iterator->typbyval, iterator->typlen);

                /* Move our data pointer forward to the next element */
                p = att_addlength_pointer(p, iterator->typlen, p);
                p = (char *) att_align_nominal(p, iterator->typalign);
            }
        }

        iterator->data_ptr = p;

        result = construct_md_array(values,
                                    nulls,
                                    iterator->slice_ndim,
                                    iterator->slice_dims,
                                    iterator->slice_lbound,
                                    ARR_ELEMTYPE(iterator->arr),
                                    iterator->typlen,
                                    iterator->typbyval,
                                    iterator->typalign);

        *isnull = false;
        *value = PointerGetDatum(result);
    }

    return true;
}

/*
 * Release an ArrayIterator data structure
 */
void
array_free_iterator(ArrayIterator iterator)
{
    if (iterator->slice_ndim > 0)
    {
        pfree(iterator->slice_values);
        pfree(iterator->slice_nulls);
    }
    pfree(iterator);
}


/***************************************************************************/
/******************|          Support  Routines           |*****************/
/***************************************************************************/

/*
 * Check whether a specific array element is NULL
 *
 * nullbitmap: pointer to array's null bitmap (NULL if none)
 * offset: 0-based linear element number of array element
 */
static bool
array_get_isnull(const bits8 *nullbitmap, int offset)
{
    if (nullbitmap == NULL)
        return false;           /* assume not null */
    if (nullbitmap[offset / 8] & (1 << (offset % 8)))
        return false;           /* not null */
    return true;
}

/*
 * Set a specific array element's null-bitmap entry
 *
 * nullbitmap: pointer to array's null bitmap (mustn't be NULL)
 * offset: 0-based linear element number of array element
 * isNull: null status to set
 */
static void
array_set_isnull(bits8 *nullbitmap, int offset, bool isNull)
{
    int         bitmask;

    nullbitmap += offset / 8;
    bitmask = 1 << (offset % 8);
    if (isNull)
        *nullbitmap &= ~bitmask;
    else
        *nullbitmap |= bitmask;
}

/*
 * Fetch array element at pointer, converted correctly to a Datum
 *
 * Caller must have handled case of NULL element
 */
static Datum
ArrayCast(char *value, bool byval, int len)
{
    return fetch_att(value, byval, len);
}

/*
 * Copy datum to *dest and return total space used (including align padding)
 *
 * Caller must have handled case of NULL element
 */
static int
ArrayCastAndSet(Datum src,
                int typlen,
                bool typbyval,
                char typalign,
                char *dest)
{
    int         inc;

    if (typlen > 0)
    {
        if (typbyval)
            store_att_byval(dest, src, typlen);
        else
            memmove(dest, DatumGetPointer(src), typlen);
        inc = att_align_nominal(typlen, typalign);
    }
    else
    {
        Assert(!typbyval);
        inc = att_addlength_datum(0, typlen, src);
        memmove(dest, DatumGetPointer(src), inc);
        inc = att_align_nominal(inc, typalign);
    }

    return inc;
}

/*
 * Advance ptr over nitems array elements
 *
 * ptr: starting location in array
 * offset: 0-based linear element number of first element (the one at *ptr)
 * nullbitmap: start of array's null bitmap, or NULL if none
 * nitems: number of array elements to advance over (>= 0)
 * typlen, typbyval, typalign: storage parameters of array element datatype
 *
 * It is caller's responsibility to ensure that nitems is within range
 */
static char *
array_seek(char *ptr, int offset, bits8 *nullbitmap, int nitems,
           int typlen, bool typbyval, char typalign)
{
    int         bitmask;
    int         i;

    /* easy if fixed-size elements and no NULLs */
    if (typlen > 0 && !nullbitmap)
        return ptr + nitems * ((Size) att_align_nominal(typlen, typalign));

    /* seems worth having separate loops for NULL and no-NULLs cases */
    if (nullbitmap)
    {
        nullbitmap += offset / 8;
        bitmask = 1 << (offset % 8);

        for (i = 0; i < nitems; i++)
        {
            if (*nullbitmap & bitmask)
            {
                ptr = att_addlength_pointer(ptr, typlen, ptr);
                ptr = (char *) att_align_nominal(ptr, typalign);
            }
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                nullbitmap++;
                bitmask = 1;
            }
        }
    }
    else
    {
        for (i = 0; i < nitems; i++)
        {
            ptr = att_addlength_pointer(ptr, typlen, ptr);
            ptr = (char *) att_align_nominal(ptr, typalign);
        }
    }
    return ptr;
}

/*
 * Compute total size of the nitems array elements starting at *ptr
 *
 * Parameters same as for array_seek
 */
static int
array_nelems_size(char *ptr, int offset, bits8 *nullbitmap, int nitems,
                  int typlen, bool typbyval, char typalign)
{
    return array_seek(ptr, offset, nullbitmap, nitems,
                      typlen, typbyval, typalign) - ptr;
}

/*
 * Copy nitems array elements from srcptr to destptr
 *
 * destptr: starting destination location (must be enough room!)
 * nitems: number of array elements to copy (>= 0)
 * srcptr: starting location in source array
 * offset: 0-based linear element number of first element (the one at *srcptr)
 * nullbitmap: start of source array's null bitmap, or NULL if none
 * typlen, typbyval, typalign: storage parameters of array element datatype
 *
 * Returns number of bytes copied
 *
 * NB: this does not take care of setting up the destination's null bitmap!
 */
static int
array_copy(char *destptr, int nitems,
           char *srcptr, int offset, bits8 *nullbitmap,
           int typlen, bool typbyval, char typalign)
{
    int         numbytes;

    numbytes = array_nelems_size(srcptr, offset, nullbitmap, nitems,
                                 typlen, typbyval, typalign);
    memcpy(destptr, srcptr, numbytes);
    return numbytes;
}

/*
 * Copy nitems null-bitmap bits from source to destination
 *
 * destbitmap: start of destination array's null bitmap (mustn't be NULL)
 * destoffset: 0-based linear element number of first dest element
 * srcbitmap: start of source array's null bitmap, or NULL if none
 * srcoffset: 0-based linear element number of first source element
 * nitems: number of bits to copy (>= 0)
 *
 * If srcbitmap is NULL then we assume the source is all-non-NULL and
 * fill 1's into the destination bitmap.  Note that only the specified
 * bits in the destination map are changed, not any before or after.
 *
 * Note: this could certainly be optimized using standard bitblt methods.
 * However, it's not clear that the typical Postgres array has enough elements
 * to make it worth worrying too much.  For the moment, KISS.
 */
void
array_bitmap_copy(bits8 *destbitmap, int destoffset,
                  const bits8 *srcbitmap, int srcoffset,
                  int nitems)
{
    int         destbitmask,
                destbitval,
                srcbitmask,
                srcbitval;

    Assert(destbitmap);
    if (nitems <= 0)
        return;                 /* don't risk fetch off end of memory */
    destbitmap += destoffset / 8;
    destbitmask = 1 << (destoffset % 8);
    destbitval = *destbitmap;
    if (srcbitmap)
    {
        srcbitmap += srcoffset / 8;
        srcbitmask = 1 << (srcoffset % 8);
        srcbitval = *srcbitmap;
        while (nitems-- > 0)
        {
            if (srcbitval & srcbitmask)
                destbitval |= destbitmask;
            else
                destbitval &= ~destbitmask;
            destbitmask <<= 1;
            if (destbitmask == 0x100)
            {
                *destbitmap++ = destbitval;
                destbitmask = 1;
                if (nitems > 0)
                    destbitval = *destbitmap;
            }
            srcbitmask <<= 1;
            if (srcbitmask == 0x100)
            {
                srcbitmap++;
                srcbitmask = 1;
                if (nitems > 0)
                    srcbitval = *srcbitmap;
            }
        }
        if (destbitmask != 1)
            *destbitmap = destbitval;
    }
    else
    {
        while (nitems-- > 0)
        {
            destbitval |= destbitmask;
            destbitmask <<= 1;
            if (destbitmask == 0x100)
            {
                *destbitmap++ = destbitval;
                destbitmask = 1;
                if (nitems > 0)
                    destbitval = *destbitmap;
            }
        }
        if (destbitmask != 1)
            *destbitmap = destbitval;
    }
}

/*
 * Compute space needed for a slice of an array
 *
 * We assume the caller has verified that the slice coordinates are valid.
 */
static int
array_slice_size(char *arraydataptr, bits8 *arraynullsptr,
                 int ndim, int *dim, int *lb,
                 int *st, int *endp,
                 int typlen, bool typbyval, char typalign)
{
    int         src_offset,
                span[MAXDIM],
                prod[MAXDIM],
                dist[MAXDIM],
                indx[MAXDIM];
    char       *ptr;
    int         i,
                j,
                inc;
    int         count = 0;

    mda_get_range(ndim, span, st, endp);

    /* Pretty easy for fixed element length without nulls ... */
    if (typlen > 0 && !arraynullsptr)
        return ArrayGetNItems(ndim, span) * att_align_nominal(typlen, typalign);

    /* Else gotta do it the hard way */
    src_offset = ArrayGetOffset(ndim, dim, lb, st);
    ptr = array_seek(arraydataptr, 0, arraynullsptr, src_offset,
                     typlen, typbyval, typalign);
    mda_get_prod(ndim, dim, prod);
    mda_get_offset_values(ndim, dist, prod, span);
    for (i = 0; i < ndim; i++)
        indx[i] = 0;
    j = ndim - 1;
    do
    {
        if (dist[j])
        {
            ptr = array_seek(ptr, src_offset, arraynullsptr, dist[j],
                             typlen, typbyval, typalign);
            src_offset += dist[j];
        }
        if (!array_get_isnull(arraynullsptr, src_offset))
        {
            inc = att_addlength_pointer(0, typlen, ptr);
            inc = att_align_nominal(inc, typalign);
            ptr += inc;
            count += inc;
        }
        src_offset++;
    } while ((j = mda_next_tuple(ndim, indx, span)) != -1);
    return count;
}

/*
 * Extract a slice of an array into consecutive elements in the destination
 * array.
 *
 * We assume the caller has verified that the slice coordinates are valid,
 * allocated enough storage for the result, and initialized the header
 * of the new array.
 */
static void
array_extract_slice(ArrayType *newarray,
                    int ndim,
                    int *dim,
                    int *lb,
                    char *arraydataptr,
                    bits8 *arraynullsptr,
                    int *st,
                    int *endp,
                    int typlen,
                    bool typbyval,
                    char typalign)
{
    char       *destdataptr = ARR_DATA_PTR(newarray);
    bits8      *destnullsptr = ARR_NULLBITMAP(newarray);
    char       *srcdataptr;
    int         src_offset,
                dest_offset,
                prod[MAXDIM],
                span[MAXDIM],
                dist[MAXDIM],
                indx[MAXDIM];
    int         i,
                j,
                inc;

    src_offset = ArrayGetOffset(ndim, dim, lb, st);
    srcdataptr = array_seek(arraydataptr, 0, arraynullsptr, src_offset,
                            typlen, typbyval, typalign);
    mda_get_prod(ndim, dim, prod);
    mda_get_range(ndim, span, st, endp);
    mda_get_offset_values(ndim, dist, prod, span);
    for (i = 0; i < ndim; i++)
        indx[i] = 0;
    dest_offset = 0;
    j = ndim - 1;
    do
    {
        if (dist[j])
        {
            /* skip unwanted elements */
            srcdataptr = array_seek(srcdataptr, src_offset, arraynullsptr,
                                    dist[j],
                                    typlen, typbyval, typalign);
            src_offset += dist[j];
        }
        inc = array_copy(destdataptr, 1,
                         srcdataptr, src_offset, arraynullsptr,
                         typlen, typbyval, typalign);
        if (destnullsptr)
            array_bitmap_copy(destnullsptr, dest_offset,
                              arraynullsptr, src_offset,
                              1);
        destdataptr += inc;
        srcdataptr += inc;
        src_offset++;
        dest_offset++;
    } while ((j = mda_next_tuple(ndim, indx, span)) != -1);
}

/*
 * Insert a slice into an array.
 *
 * ndim/dim[]/lb[] are dimensions of the original array.  A new array with
 * those same dimensions is to be constructed.  destArray must already
 * have been allocated and its header initialized.
 *
 * st[]/endp[] identify the slice to be replaced.  Elements within the slice
 * volume are taken from consecutive elements of the srcArray; elements
 * outside it are copied from origArray.
 *
 * We assume the caller has verified that the slice coordinates are valid.
 */
static void
array_insert_slice(ArrayType *destArray,
                   ArrayType *origArray,
                   ArrayType *srcArray,
                   int ndim,
                   int *dim,
                   int *lb,
                   int *st,
                   int *endp,
                   int typlen,
                   bool typbyval,
                   char typalign)
{
    char       *destPtr = ARR_DATA_PTR(destArray);
    char       *origPtr = ARR_DATA_PTR(origArray);
    char       *srcPtr = ARR_DATA_PTR(srcArray);
    bits8      *destBitmap = ARR_NULLBITMAP(destArray);
    bits8      *origBitmap = ARR_NULLBITMAP(origArray);
    bits8      *srcBitmap = ARR_NULLBITMAP(srcArray);
    int         orignitems = ArrayGetNItems(ARR_NDIM(origArray),
                                            ARR_DIMS(origArray));
    int         dest_offset,
                orig_offset,
                src_offset,
                prod[MAXDIM],
                span[MAXDIM],
                dist[MAXDIM],
                indx[MAXDIM];
    int         i,
                j,
                inc;

    dest_offset = ArrayGetOffset(ndim, dim, lb, st);
    /* copy items before the slice start */
    inc = array_copy(destPtr, dest_offset,
                     origPtr, 0, origBitmap,
                     typlen, typbyval, typalign);
    destPtr += inc;
    origPtr += inc;
    if (destBitmap)
        array_bitmap_copy(destBitmap, 0, origBitmap, 0, dest_offset);
    orig_offset = dest_offset;
    mda_get_prod(ndim, dim, prod);
    mda_get_range(ndim, span, st, endp);
    mda_get_offset_values(ndim, dist, prod, span);
    for (i = 0; i < ndim; i++)
        indx[i] = 0;
    src_offset = 0;
    j = ndim - 1;
    do
    {
        /* Copy/advance over elements between here and next part of slice */
        if (dist[j])
        {
            inc = array_copy(destPtr, dist[j],
                             origPtr, orig_offset, origBitmap,
                             typlen, typbyval, typalign);
            destPtr += inc;
            origPtr += inc;
            if (destBitmap)
                array_bitmap_copy(destBitmap, dest_offset,
                                  origBitmap, orig_offset,
                                  dist[j]);
            dest_offset += dist[j];
            orig_offset += dist[j];
        }
        /* Copy new element at this slice position */
        inc = array_copy(destPtr, 1,
                         srcPtr, src_offset, srcBitmap,
                         typlen, typbyval, typalign);
        if (destBitmap)
            array_bitmap_copy(destBitmap, dest_offset,
                              srcBitmap, src_offset,
                              1);
        destPtr += inc;
        srcPtr += inc;
        dest_offset++;
        src_offset++;
        /* Advance over old element at this slice position */
        origPtr = array_seek(origPtr, orig_offset, origBitmap, 1,
                             typlen, typbyval, typalign);
        orig_offset++;
    } while ((j = mda_next_tuple(ndim, indx, span)) != -1);

    /* don't miss any data at the end */
    array_copy(destPtr, orignitems - orig_offset,
               origPtr, orig_offset, origBitmap,
               typlen, typbyval, typalign);
    if (destBitmap)
        array_bitmap_copy(destBitmap, dest_offset,
                          origBitmap, orig_offset,
                          orignitems - orig_offset);
}

/*
 * accumArrayResult - accumulate one (more) Datum for an array result
 *
 *  astate is working state (NULL on first call)
 *  rcontext is where to keep working state
 */
ArrayBuildState *
accumArrayResult(ArrayBuildState *astate,
                 Datum dvalue, bool disnull,
                 Oid element_type,
                 MemoryContext rcontext)
{
    MemoryContext arr_context,
                oldcontext;

    if (astate == NULL)
    {
        /* First time through --- initialize */

        /* Make a temporary context to hold all the junk */
        arr_context = AllocSetContextCreate(rcontext,
                                            "accumArrayResult",
                                            ALLOCSET_DEFAULT_MINSIZE,
                                            ALLOCSET_DEFAULT_INITSIZE,
                                            ALLOCSET_DEFAULT_MAXSIZE);
        oldcontext = MemoryContextSwitchTo(arr_context);
        astate = (ArrayBuildState *) palloc(sizeof(ArrayBuildState));
        astate->mcontext = arr_context;
        astate->alen = 64;      /* arbitrary starting array size */
        astate->dvalues = (Datum *) palloc(astate->alen * sizeof(Datum));
        astate->dnulls = (bool *) palloc(astate->alen * sizeof(bool));
        astate->nelems = 0;
        astate->element_type = element_type;
        get_typlenbyvalalign(element_type,
                             &astate->typlen,
                             &astate->typbyval,
                             &astate->typalign);
    }
    else
    {
        oldcontext = MemoryContextSwitchTo(astate->mcontext);
        Assert(astate->element_type == element_type);
        /* enlarge dvalues[]/dnulls[] if needed */
        if (astate->nelems >= astate->alen)
        {
            astate->alen *= 2;
            astate->dvalues = (Datum *)
                repalloc(astate->dvalues, astate->alen * sizeof(Datum));
            astate->dnulls = (bool *)
                repalloc(astate->dnulls, astate->alen * sizeof(bool));
        }
    }

    /*
     * Ensure pass-by-ref stuff is copied into mcontext; and detoast it too if
     * it's varlena.  (You might think that detoasting is not needed here
     * because construct_md_array can detoast the array elements later.
     * However, we must not let construct_md_array modify the ArrayBuildState
     * because that would mean array_agg_finalfn damages its input, which is
     * verboten.  Also, this way frequently saves one copying step.)
     */
    if (!disnull && !astate->typbyval)
    {
        if (astate->typlen == -1)
            dvalue = PointerGetDatum(PG_DETOAST_DATUM_COPY(dvalue));
        else
            dvalue = datumCopy(dvalue, astate->typbyval, astate->typlen);
    }

    astate->dvalues[astate->nelems] = dvalue;
    astate->dnulls[astate->nelems] = disnull;
    astate->nelems++;

    MemoryContextSwitchTo(oldcontext);

    return astate;
}

/*
 * makeArrayResult - produce 1-D final result of accumArrayResult
 *
 *  astate is working state (not NULL)
 *  rcontext is where to construct result
 */
Datum
makeArrayResult(ArrayBuildState *astate,
                MemoryContext rcontext)
{
    int         dims[1];
    int         lbs[1];

    dims[0] = astate->nelems;
    lbs[0] = 1;

    return makeMdArrayResult(astate, 1, dims, lbs, rcontext, true);
}

/*
 * makeMdArrayResult - produce multi-D final result of accumArrayResult
 *
 * beware: no check that specified dimensions match the number of values
 * accumulated.
 *
 *  astate is working state (not NULL)
 *  rcontext is where to construct result
 *  release is true if okay to release working state
 */
Datum
makeMdArrayResult(ArrayBuildState *astate,
                  int ndims,
                  int *dims,
                  int *lbs,
                  MemoryContext rcontext,
                  bool release)
{
    ArrayType  *result;
    MemoryContext oldcontext;

    /* Build the final array result in rcontext */
    oldcontext = MemoryContextSwitchTo(rcontext);

    result = construct_md_array(astate->dvalues,
                                astate->dnulls,
                                ndims,
                                dims,
                                lbs,
                                astate->element_type,
                                astate->typlen,
                                astate->typbyval,
                                astate->typalign);

    MemoryContextSwitchTo(oldcontext);

    /* Clean up all the junk */
    if (release)
        MemoryContextDelete(astate->mcontext);

    return PointerGetDatum(result);
}

Datum
array_larger(PG_FUNCTION_ARGS)
{
    ArrayType  *v1,
               *v2,
               *result;

    v1 = PG_GETARG_ARRAYTYPE_P(0);
    v2 = PG_GETARG_ARRAYTYPE_P(1);

    result = ((array_cmp(fcinfo) > 0) ? v1 : v2);

    PG_RETURN_ARRAYTYPE_P(result);
}

Datum
array_smaller(PG_FUNCTION_ARGS)
{
    ArrayType  *v1,
               *v2,
               *result;

    v1 = PG_GETARG_ARRAYTYPE_P(0);
    v2 = PG_GETARG_ARRAYTYPE_P(1);

    result = ((array_cmp(fcinfo) < 0) ? v1 : v2);

    PG_RETURN_ARRAYTYPE_P(result);
}


typedef struct generate_subscripts_fctx
{
    int32       lower;
    int32       upper;
    bool        reverse;
} generate_subscripts_fctx;

/*
 * generate_subscripts(array anyarray, dim int [, reverse bool])
 *      Returns all subscripts of the array for any dimension
 */
Datum
generate_subscripts(PG_FUNCTION_ARGS)
{
    FuncCallContext *funcctx;
    MemoryContext oldcontext;
    generate_subscripts_fctx *fctx;

    /* stuff done only on the first call of the function */
    if (SRF_IS_FIRSTCALL())
    {
        ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
        int         reqdim = PG_GETARG_INT32(1);
        int        *lb,
                   *dimv;

        /* create a function context for cross-call persistence */
        funcctx = SRF_FIRSTCALL_INIT();

        /* Sanity check: does it look like an array at all? */
        if (ARR_NDIM(v) <= 0 || ARR_NDIM(v) > MAXDIM)
            SRF_RETURN_DONE(funcctx);

        /* Sanity check: was the requested dim valid */
        if (reqdim <= 0 || reqdim > ARR_NDIM(v))
            SRF_RETURN_DONE(funcctx);

        /*
         * switch to memory context appropriate for multiple function calls
         */
        oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
        fctx = (generate_subscripts_fctx *) palloc(sizeof(generate_subscripts_fctx));

        lb = ARR_LBOUND(v);
        dimv = ARR_DIMS(v);

        fctx->lower = lb[reqdim - 1];
        fctx->upper = dimv[reqdim - 1] + lb[reqdim - 1] - 1;
        fctx->reverse = (PG_NARGS() < 3) ? false : PG_GETARG_BOOL(2);

        funcctx->user_fctx = fctx;

        MemoryContextSwitchTo(oldcontext);
    }

    funcctx = SRF_PERCALL_SETUP();

    fctx = funcctx->user_fctx;

    if (fctx->lower <= fctx->upper)
    {
        if (!fctx->reverse)
            SRF_RETURN_NEXT(funcctx, Int32GetDatum(fctx->lower++));
        else
            SRF_RETURN_NEXT(funcctx, Int32GetDatum(fctx->upper--));
    }
    else
        /* done when there are no more elements left */
        SRF_RETURN_DONE(funcctx);
}

/*
 * generate_subscripts_nodir
 *      Implements the 2-argument version of generate_subscripts
 */
Datum
generate_subscripts_nodir(PG_FUNCTION_ARGS)
{
    /* just call the other one -- it can handle both cases */
    return generate_subscripts(fcinfo);
}

/*
 * array_fill_with_lower_bounds
 *      Create and fill array with defined lower bounds.
 */
Datum
array_fill_with_lower_bounds(PG_FUNCTION_ARGS)
{
    ArrayType  *dims;
    ArrayType  *lbs;
    ArrayType  *result;
    Oid         elmtype;
    Datum       value;
    bool        isnull;

    if (PG_ARGISNULL(1) || PG_ARGISNULL(2))
        ereport(ERROR,
                (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
               errmsg("dimension array or low bound array cannot be null")));

    dims = PG_GETARG_ARRAYTYPE_P(1);
    lbs = PG_GETARG_ARRAYTYPE_P(2);

    if (!PG_ARGISNULL(0))
    {
        value = PG_GETARG_DATUM(0);
        isnull = false;
    }
    else
    {
        value = 0;
        isnull = true;
    }

    elmtype = get_fn_expr_argtype(fcinfo->flinfo, 0);
    if (!OidIsValid(elmtype))
        elog(ERROR, "could not determine data type of input");

    result = array_fill_internal(dims, lbs, value, isnull, elmtype, fcinfo);
    PG_RETURN_ARRAYTYPE_P(result);
}

/*
 * array_fill
 *      Create and fill array with default lower bounds.
 */
Datum
array_fill(PG_FUNCTION_ARGS)
{
    ArrayType  *dims;
    ArrayType  *result;
    Oid         elmtype;
    Datum       value;
    bool        isnull;

    if (PG_ARGISNULL(1))
        ereport(ERROR,
                (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
               errmsg("dimension array or low bound array cannot be null")));

    dims = PG_GETARG_ARRAYTYPE_P(1);

    if (!PG_ARGISNULL(0))
    {
        value = PG_GETARG_DATUM(0);
        isnull = false;
    }
    else
    {
        value = 0;
        isnull = true;
    }

    elmtype = get_fn_expr_argtype(fcinfo->flinfo, 0);
    if (!OidIsValid(elmtype))
        elog(ERROR, "could not determine data type of input");

    result = array_fill_internal(dims, NULL, value, isnull, elmtype, fcinfo);
    PG_RETURN_ARRAYTYPE_P(result);
}

static ArrayType *
create_array_envelope(int ndims, int *dimv, int *lbsv, int nbytes,
                      Oid elmtype, int dataoffset)
{
    ArrayType  *result;

    result = (ArrayType *) palloc0(nbytes);
    SET_VARSIZE(result, nbytes);
    result->ndim = ndims;
    result->dataoffset = dataoffset;
    result->elemtype = elmtype;
    memcpy(ARR_DIMS(result), dimv, ndims * sizeof(int));
    memcpy(ARR_LBOUND(result), lbsv, ndims * sizeof(int));

    return result;
}

static ArrayType *
array_fill_internal(ArrayType *dims, ArrayType *lbs,
                    Datum value, bool isnull, Oid elmtype,
                    FunctionCallInfo fcinfo)
{
    ArrayType  *result;
    int        *dimv;
    int        *lbsv;
    int         ndims;
    int         nitems;
    int         deflbs[MAXDIM];
    int16       elmlen;
    bool        elmbyval;
    char        elmalign;
    ArrayMetaState *my_extra;

    /*
     * Params checks
     */
    if (ARR_NDIM(dims) != 1)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("wrong number of array subscripts"),
                 errdetail("Dimension array must be one dimensional.")));

    if (ARR_LBOUND(dims)[0] != 1)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("wrong range of array subscripts"),
                 errdetail("Lower bound of dimension array must be one.")));

    if (array_contains_nulls(dims))
        ereport(ERROR,
                (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                 errmsg("dimension values cannot be null")));

    dimv = (int *) ARR_DATA_PTR(dims);
    ndims = ARR_DIMS(dims)[0];

    if (ndims < 0)              /* we do allow zero-dimension arrays */
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid number of dimensions: %d", ndims)));
    if (ndims > MAXDIM)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
                        ndims, MAXDIM)));

    if (lbs != NULL)
    {
        if (ARR_NDIM(lbs) != 1)
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("wrong number of array subscripts"),
                     errdetail("Dimension array must be one dimensional.")));

        if (ARR_LBOUND(lbs)[0] != 1)
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("wrong range of array subscripts"),
                  errdetail("Lower bound of dimension array must be one.")));

        if (array_contains_nulls(lbs))
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("dimension values cannot be null")));

        if (ARR_DIMS(lbs)[0] != ndims)
            ereport(ERROR,
                    (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                     errmsg("wrong number of array subscripts"),
                     errdetail("Low bound array has different size than dimensions array.")));

        lbsv = (int *) ARR_DATA_PTR(lbs);
    }
    else
    {
        int         i;

        for (i = 0; i < MAXDIM; i++)
            deflbs[i] = 1;

        lbsv = deflbs;
    }

    /* fast track for empty array */
    if (ndims == 0)
        return construct_empty_array(elmtype);

    nitems = ArrayGetNItems(ndims, dimv);

    /*
     * We arrange to look up info about element type only once per series of
     * calls, assuming the element type doesn't change underneath us.
     */
    my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
    if (my_extra == NULL)
    {
        fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                                                      sizeof(ArrayMetaState));
        my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
        my_extra->element_type = InvalidOid;
    }

    if (my_extra->element_type != elmtype)
    {
        /* Get info about element type */
        get_typlenbyvalalign(elmtype,
                             &my_extra->typlen,
                             &my_extra->typbyval,
                             &my_extra->typalign);
        my_extra->element_type = elmtype;
    }

    elmlen = my_extra->typlen;
    elmbyval = my_extra->typbyval;
    elmalign = my_extra->typalign;

    /* compute required space */
    if (!isnull)
    {
        int         i;
        char       *p;
        int         nbytes;
        int         totbytes;

        /* make sure data is not toasted */
        if (elmlen == -1)
            value = PointerGetDatum(PG_DETOAST_DATUM(value));

        nbytes = att_addlength_datum(0, elmlen, value);
        nbytes = att_align_nominal(nbytes, elmalign);
        Assert(nbytes > 0);

        totbytes = nbytes * nitems;

        /* check for overflow of multiplication or total request */
        if (totbytes / nbytes != nitems ||
            !AllocSizeIsValid(totbytes))
            ereport(ERROR,
                    (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                     errmsg("array size exceeds the maximum allowed (%d)",
                            (int) MaxAllocSize)));

        /*
         * This addition can't overflow, but it might cause us to go past
         * MaxAllocSize.  We leave it to palloc to complain in that case.
         */
        totbytes += ARR_OVERHEAD_NONULLS(ndims);

        result = create_array_envelope(ndims, dimv, lbsv, totbytes,
                                       elmtype, 0);

        p = ARR_DATA_PTR(result);
        for (i = 0; i < nitems; i++)
            p += ArrayCastAndSet(value, elmlen, elmbyval, elmalign, p);
    }
    else
    {
        int         nbytes;
        int         dataoffset;

        dataoffset = ARR_OVERHEAD_WITHNULLS(ndims, nitems);
        nbytes = dataoffset;

        result = create_array_envelope(ndims, dimv, lbsv, nbytes,
                                       elmtype, dataoffset);

        /* create_array_envelope already zeroed the bitmap, so we're done */
    }

    return result;
}


/*
 * UNNEST
 */
Datum
array_unnest(PG_FUNCTION_ARGS)
{
    typedef struct
    {
        ArrayType  *arr;
        int         nextelem;
        int         numelems;
        char       *elemdataptr;    /* this moves with nextelem */
        bits8      *arraynullsptr;      /* this does not */
        int16       elmlen;
        bool        elmbyval;
        char        elmalign;
    } array_unnest_fctx;

    FuncCallContext *funcctx;
    array_unnest_fctx *fctx;
    MemoryContext oldcontext;

    /* stuff done only on the first call of the function */
    if (SRF_IS_FIRSTCALL())
    {
        ArrayType  *arr;

        /* create a function context for cross-call persistence */
        funcctx = SRF_FIRSTCALL_INIT();

        /*
         * switch to memory context appropriate for multiple function calls
         */
        oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

        /*
         * Get the array value and detoast if needed.  We can't do this
         * earlier because if we have to detoast, we want the detoasted copy
         * to be in multi_call_memory_ctx, so it will go away when we're done
         * and not before.  (If no detoast happens, we assume the originally
         * passed array will stick around till then.)
         */
        arr = PG_GETARG_ARRAYTYPE_P(0);

        /* allocate memory for user context */
        fctx = (array_unnest_fctx *) palloc(sizeof(array_unnest_fctx));

        /* initialize state */
        fctx->arr = arr;
        fctx->nextelem = 0;
        fctx->numelems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));

        fctx->elemdataptr = ARR_DATA_PTR(arr);
        fctx->arraynullsptr = ARR_NULLBITMAP(arr);

        get_typlenbyvalalign(ARR_ELEMTYPE(arr),
                             &fctx->elmlen,
                             &fctx->elmbyval,
                             &fctx->elmalign);

        funcctx->user_fctx = fctx;
        MemoryContextSwitchTo(oldcontext);
    }

    /* stuff done on every call of the function */
    funcctx = SRF_PERCALL_SETUP();
    fctx = funcctx->user_fctx;

    if (fctx->nextelem < fctx->numelems)
    {
        int         offset = fctx->nextelem++;
        Datum       elem;

        /*
         * Check for NULL array element
         */
        if (array_get_isnull(fctx->arraynullsptr, offset))
        {
            fcinfo->isnull = true;
            elem = (Datum) 0;
            /* elemdataptr does not move */
        }
        else
        {
            /*
             * OK, get the element
             */
            char       *ptr = fctx->elemdataptr;

            fcinfo->isnull = false;
            elem = ArrayCast(ptr, fctx->elmbyval, fctx->elmlen);

            /*
             * Advance elemdataptr over it
             */
            ptr = att_addlength_pointer(ptr, fctx->elmlen, ptr);
            ptr = (char *) att_align_nominal(ptr, fctx->elmalign);
            fctx->elemdataptr = ptr;
        }

        SRF_RETURN_NEXT(funcctx, elem);
    }
    else
    {
        /* do when there is no more left */
        SRF_RETURN_DONE(funcctx);
    }
}


/*
 * array_replace/array_remove support
 *
 * Find all array entries matching (not distinct from) search/search_isnull,
 * and delete them if remove is true, else replace them with
 * replace/replace_isnull.  Comparisons are done using the specified
 * collation.  fcinfo is passed only for caching purposes.
 */
static ArrayType *
array_replace_internal(ArrayType *array,
                       Datum search, bool search_isnull,
                       Datum replace, bool replace_isnull,
                       bool remove, Oid collation,
                       FunctionCallInfo fcinfo)
{
    ArrayType  *result;
    Oid         element_type;
    Datum      *values;
    bool       *nulls;
    int        *dim;
    int         ndim;
    int         nitems,
                nresult;
    int         i;
    int32       nbytes = 0;
    int32       dataoffset;
    bool        hasnulls;
    int         typlen;
    bool        typbyval;
    char        typalign;
    char       *arraydataptr;
    bits8      *bitmap;
    int         bitmask;
    bool        changed = false;
    TypeCacheEntry *typentry;
    FunctionCallInfoData locfcinfo;

    element_type = ARR_ELEMTYPE(array);
    ndim = ARR_NDIM(array);
    dim = ARR_DIMS(array);
    nitems = ArrayGetNItems(ndim, dim);

    /* Return input array unmodified if it is empty */
    if (nitems <= 0)
        return array;

    /*
     * We can't remove elements from multi-dimensional arrays, since the
     * result might not be rectangular.
     */
    if (remove && ndim > 1)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("removing elements from multidimensional arrays is not supported")));

    /*
     * We arrange to look up the equality function only once per series of
     * calls, assuming the element type doesn't change underneath us.
     */
    typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
    if (typentry == NULL ||
        typentry->type_id != element_type)
    {
        typentry = lookup_type_cache(element_type,
                                     TYPECACHE_EQ_OPR_FINFO);
        if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_FUNCTION),
                     errmsg("could not identify an equality operator for type %s",
                            format_type_be(element_type))));
        fcinfo->flinfo->fn_extra = (void *) typentry;
    }
    typlen = typentry->typlen;
    typbyval = typentry->typbyval;
    typalign = typentry->typalign;

    /*
     * Detoast values if they are toasted.  The replacement value must be
     * detoasted for insertion into the result array, while detoasting the
     * search value only once saves cycles.
     */
    if (typlen == -1)
    {
        if (!search_isnull)
            search = PointerGetDatum(PG_DETOAST_DATUM(search));
        if (!replace_isnull)
            replace = PointerGetDatum(PG_DETOAST_DATUM(replace));
    }

    /* Prepare to apply the comparison operator */
    InitFunctionCallInfoData(locfcinfo, &typentry->eq_opr_finfo, 2,
                             collation, NULL, NULL);

    /* Allocate temporary arrays for new values */
    values = (Datum *) palloc(nitems * sizeof(Datum));
    nulls = (bool *) palloc(nitems * sizeof(bool));

    /* Loop over source data */
    arraydataptr = ARR_DATA_PTR(array);
    bitmap = ARR_NULLBITMAP(array);
    bitmask = 1;
    hasnulls = false;
    nresult = 0;

    for (i = 0; i < nitems; i++)
    {
        Datum       elt;
        bool        isNull;
        bool        oprresult;
        bool        skip = false;

        /* Get source element, checking for NULL */
        if (bitmap && (*bitmap & bitmask) == 0)
        {
            isNull = true;
            /* If searching for NULL, we have a match */
            if (search_isnull)
            {
                if (remove)
                {
                    skip = true;
                    changed = true;
                }
                else if (!replace_isnull)
                {
                    values[nresult] = replace;
                    isNull = false;
                    changed = true;
                }
            }
        }
        else
        {
            isNull = false;
            elt = fetch_att(arraydataptr, typbyval, typlen);
            arraydataptr = att_addlength_datum(arraydataptr, typlen, elt);
            arraydataptr = (char *) att_align_nominal(arraydataptr, typalign);

            if (search_isnull)
            {
                /* no match possible, keep element */
                values[nresult] = elt;
            }
            else
            {
                /*
                 * Apply the operator to the element pair
                 */
                locfcinfo.arg[0] = elt;
                locfcinfo.arg[1] = search;
                locfcinfo.argnull[0] = false;
                locfcinfo.argnull[1] = false;
                locfcinfo.isnull = false;
                oprresult = DatumGetBool(FunctionCallInvoke(&locfcinfo));
                if (!oprresult)
                {
                    /* no match, keep element */
                    values[nresult] = elt;
                }
                else
                {
                    /* match, so replace or delete */
                    changed = true;
                    if (remove)
                        skip = true;
                    else
                    {
                        values[nresult] = replace;
                        isNull = replace_isnull;
                    }
                }
            }
        }

        if (!skip)
        {
            nulls[nresult] = isNull;
            if (isNull)
                hasnulls = true;
            else
            {
                /* Update total result size */
                nbytes = att_addlength_datum(nbytes, typlen, values[nresult]);
                nbytes = att_align_nominal(nbytes, typalign);
                /* check for overflow of total request */
                if (!AllocSizeIsValid(nbytes))
                    ereport(ERROR,
                            (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                             errmsg("array size exceeds the maximum allowed (%d)",
                                    (int) MaxAllocSize)));
            }
            nresult++;
        }

        /* advance bitmap pointer if any */
        if (bitmap)
        {
            bitmask <<= 1;
            if (bitmask == 0x100)
            {
                bitmap++;
                bitmask = 1;
            }
        }
    }

    /*
     * If not changed just return the original array
     */
    if (!changed)
    {
        pfree(values);
        pfree(nulls);
        return array;
    }

    /* Allocate and initialize the result array */
    if (hasnulls)
    {
        dataoffset = ARR_OVERHEAD_WITHNULLS(ndim, nresult);
        nbytes += dataoffset;
    }
    else
    {
        dataoffset = 0;         /* marker for no null bitmap */
        nbytes += ARR_OVERHEAD_NONULLS(ndim);
    }
    result = (ArrayType *) palloc0(nbytes);
    SET_VARSIZE(result, nbytes);
    result->ndim = ndim;
    result->dataoffset = dataoffset;
    result->elemtype = element_type;
    memcpy(ARR_DIMS(result), ARR_DIMS(array), 2 * ndim * sizeof(int));

    if (remove)
    {
        /* Adjust the result length */
        ARR_DIMS(result)[0] = nresult;
    }

    /* Insert data into result array */
    CopyArrayEls(result,
                 values, nulls, nresult,
                 typlen, typbyval, typalign,
                 false);

    pfree(values);
    pfree(nulls);

    return result;
}

/*
 * Remove any occurrences of an element from an array
 *
 * If used on a multi-dimensional array this will raise an error.
 */
Datum
array_remove(PG_FUNCTION_ARGS)
{
    ArrayType  *array;
    Datum       search = PG_GETARG_DATUM(1);
    bool        search_isnull = PG_ARGISNULL(1);

    if (PG_ARGISNULL(0))
        PG_RETURN_NULL();
    array = PG_GETARG_ARRAYTYPE_P(0);

    array = array_replace_internal(array,
                                   search, search_isnull,
                                   (Datum) 0, true,
                                   true, PG_GET_COLLATION(),
                                   fcinfo);
    PG_RETURN_ARRAYTYPE_P(array);
}

/*
 * Replace any occurrences of an element in an array
 */
Datum
array_replace(PG_FUNCTION_ARGS)
{
    ArrayType  *array;
    Datum       search = PG_GETARG_DATUM(1);
    bool        search_isnull = PG_ARGISNULL(1);
    Datum       replace = PG_GETARG_DATUM(2);
    bool        replace_isnull = PG_ARGISNULL(2);

    if (PG_ARGISNULL(0))
        PG_RETURN_NULL();
    array = PG_GETARG_ARRAYTYPE_P(0);

    array = array_replace_internal(array,
                                   search, search_isnull,
                                   replace, replace_isnull,
                                   false, PG_GET_COLLATION(),
                                   fcinfo);
    PG_RETURN_ARRAYTYPE_P(array);
}