enum.c

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/*-------------------------------------------------------------------------
 *
 * enum.c
 *    I/O functions, operators, aggregates etc for enum types
 *
 * Copyright (c) 2006-2013, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/enum.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "catalog/indexing.h"
#include "catalog/pg_enum.h"
#include "libpq/pqformat.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/typcache.h"


static Oid  enum_endpoint(Oid enumtypoid, ScanDirection direction);
static ArrayType *enum_range_internal(Oid enumtypoid, Oid lower, Oid upper);


/* Basic I/O support */

Datum
enum_in(PG_FUNCTION_ARGS)
{
    char       *name = PG_GETARG_CSTRING(0);
    Oid         enumtypoid = PG_GETARG_OID(1);
    Oid         enumoid;
    HeapTuple   tup;

    /* must check length to prevent Assert failure within SearchSysCache */
    if (strlen(name) >= NAMEDATALEN)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input value for enum %s: \"%s\"",
                        format_type_be(enumtypoid),
                        name)));

    tup = SearchSysCache2(ENUMTYPOIDNAME,
                          ObjectIdGetDatum(enumtypoid),
                          CStringGetDatum(name));
    if (!HeapTupleIsValid(tup))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input value for enum %s: \"%s\"",
                        format_type_be(enumtypoid),
                        name)));

    /*
     * This comes from pg_enum.oid and stores system oids in user tables. This
     * oid must be preserved by binary upgrades.
     */
    enumoid = HeapTupleGetOid(tup);

    ReleaseSysCache(tup);

    PG_RETURN_OID(enumoid);
}

Datum
enum_out(PG_FUNCTION_ARGS)
{
    Oid         enumval = PG_GETARG_OID(0);
    char       *result;
    HeapTuple   tup;
    Form_pg_enum en;

    tup = SearchSysCache1(ENUMOID, ObjectIdGetDatum(enumval));
    if (!HeapTupleIsValid(tup))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("invalid internal value for enum: %u",
                        enumval)));
    en = (Form_pg_enum) GETSTRUCT(tup);

    result = pstrdup(NameStr(en->enumlabel));

    ReleaseSysCache(tup);

    PG_RETURN_CSTRING(result);
}

/* Binary I/O support */
Datum
enum_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
    Oid         enumtypoid = PG_GETARG_OID(1);
    Oid         enumoid;
    HeapTuple   tup;
    char       *name;
    int         nbytes;

    name = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);

    /* must check length to prevent Assert failure within SearchSysCache */
    if (strlen(name) >= NAMEDATALEN)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input value for enum %s: \"%s\"",
                        format_type_be(enumtypoid),
                        name)));

    tup = SearchSysCache2(ENUMTYPOIDNAME,
                          ObjectIdGetDatum(enumtypoid),
                          CStringGetDatum(name));
    if (!HeapTupleIsValid(tup))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input value for enum %s: \"%s\"",
                        format_type_be(enumtypoid),
                        name)));

    enumoid = HeapTupleGetOid(tup);

    ReleaseSysCache(tup);

    pfree(name);

    PG_RETURN_OID(enumoid);
}

Datum
enum_send(PG_FUNCTION_ARGS)
{
    Oid         enumval = PG_GETARG_OID(0);
    StringInfoData buf;
    HeapTuple   tup;
    Form_pg_enum en;

    tup = SearchSysCache1(ENUMOID, ObjectIdGetDatum(enumval));
    if (!HeapTupleIsValid(tup))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                 errmsg("invalid internal value for enum: %u",
                        enumval)));
    en = (Form_pg_enum) GETSTRUCT(tup);

    pq_begintypsend(&buf);
    pq_sendtext(&buf, NameStr(en->enumlabel), strlen(NameStr(en->enumlabel)));

    ReleaseSysCache(tup);

    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}

/* Comparison functions and related */

/*
 * enum_cmp_internal is the common engine for all the visible comparison
 * functions, except for enum_eq and enum_ne which can just check for OID
 * equality directly.
 */
static int
enum_cmp_internal(Oid arg1, Oid arg2, FunctionCallInfo fcinfo)
{
    TypeCacheEntry *tcache;

    /* Equal OIDs are equal no matter what */
    if (arg1 == arg2)
        return 0;

    /* Fast path: even-numbered Oids are known to compare correctly */
    if ((arg1 & 1) == 0 && (arg2 & 1) == 0)
    {
        if (arg1 < arg2)
            return -1;
        else
            return 1;
    }

    /* Locate the typcache entry for the enum type */
    tcache = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
    if (tcache == NULL)
    {
        HeapTuple   enum_tup;
        Form_pg_enum en;
        Oid         typeoid;

        /* Get the OID of the enum type containing arg1 */
        enum_tup = SearchSysCache1(ENUMOID, ObjectIdGetDatum(arg1));
        if (!HeapTupleIsValid(enum_tup))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
                     errmsg("invalid internal value for enum: %u",
                            arg1)));
        en = (Form_pg_enum) GETSTRUCT(enum_tup);
        typeoid = en->enumtypid;
        ReleaseSysCache(enum_tup);
        /* Now locate and remember the typcache entry */
        tcache = lookup_type_cache(typeoid, 0);
        fcinfo->flinfo->fn_extra = (void *) tcache;
    }

    /* The remaining comparison logic is in typcache.c */
    return compare_values_of_enum(tcache, arg1, arg2);
}

Datum
enum_lt(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    PG_RETURN_BOOL(enum_cmp_internal(a, b, fcinfo) < 0);
}

Datum
enum_le(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    PG_RETURN_BOOL(enum_cmp_internal(a, b, fcinfo) <= 0);
}

Datum
enum_eq(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    PG_RETURN_BOOL(a == b);
}

Datum
enum_ne(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    PG_RETURN_BOOL(a != b);
}

Datum
enum_ge(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    PG_RETURN_BOOL(enum_cmp_internal(a, b, fcinfo) >= 0);
}

Datum
enum_gt(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    PG_RETURN_BOOL(enum_cmp_internal(a, b, fcinfo) > 0);
}

Datum
enum_smaller(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    PG_RETURN_OID(enum_cmp_internal(a, b, fcinfo) < 0 ? a : b);
}

Datum
enum_larger(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    PG_RETURN_OID(enum_cmp_internal(a, b, fcinfo) > 0 ? a : b);
}

Datum
enum_cmp(PG_FUNCTION_ARGS)
{
    Oid         a = PG_GETARG_OID(0);
    Oid         b = PG_GETARG_OID(1);

    if (a == b)
        PG_RETURN_INT32(0);
    else if (enum_cmp_internal(a, b, fcinfo) > 0)
        PG_RETURN_INT32(1);
    else
        PG_RETURN_INT32(-1);
}

/* Enum programming support functions */

/*
 * enum_endpoint: common code for enum_first/enum_last
 */
static Oid
enum_endpoint(Oid enumtypoid, ScanDirection direction)
{
    Relation    enum_rel;
    Relation    enum_idx;
    SysScanDesc enum_scan;
    HeapTuple   enum_tuple;
    ScanKeyData skey;
    Oid         minmax;

    /*
     * Find the first/last enum member using pg_enum_typid_sortorder_index.
     * Note we must not use the syscache, and must use an MVCC snapshot here.
     * See comments for RenumberEnumType in catalog/pg_enum.c for more info.
     */
    ScanKeyInit(&skey,
                Anum_pg_enum_enumtypid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(enumtypoid));

    enum_rel = heap_open(EnumRelationId, AccessShareLock);
    enum_idx = index_open(EnumTypIdSortOrderIndexId, AccessShareLock);
    enum_scan = systable_beginscan_ordered(enum_rel, enum_idx,
                                           GetTransactionSnapshot(),
                                           1, &skey);

    enum_tuple = systable_getnext_ordered(enum_scan, direction);
    if (HeapTupleIsValid(enum_tuple))
        minmax = HeapTupleGetOid(enum_tuple);
    else
        minmax = InvalidOid;

    systable_endscan_ordered(enum_scan);
    index_close(enum_idx, AccessShareLock);
    heap_close(enum_rel, AccessShareLock);

    return minmax;
}

Datum
enum_first(PG_FUNCTION_ARGS)
{
    Oid         enumtypoid;
    Oid         min;

    /*
     * We rely on being able to get the specific enum type from the calling
     * expression tree.  Notice that the actual value of the argument isn't
     * examined at all; in particular it might be NULL.
     */
    enumtypoid = get_fn_expr_argtype(fcinfo->flinfo, 0);
    if (enumtypoid == InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("could not determine actual enum type")));

    /* Get the OID using the index */
    min = enum_endpoint(enumtypoid, ForwardScanDirection);

    if (!OidIsValid(min))
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("enum %s contains no values",
                        format_type_be(enumtypoid))));

    PG_RETURN_OID(min);
}

Datum
enum_last(PG_FUNCTION_ARGS)
{
    Oid         enumtypoid;
    Oid         max;

    /*
     * We rely on being able to get the specific enum type from the calling
     * expression tree.  Notice that the actual value of the argument isn't
     * examined at all; in particular it might be NULL.
     */
    enumtypoid = get_fn_expr_argtype(fcinfo->flinfo, 0);
    if (enumtypoid == InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("could not determine actual enum type")));

    /* Get the OID using the index */
    max = enum_endpoint(enumtypoid, BackwardScanDirection);

    if (!OidIsValid(max))
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("enum %s contains no values",
                        format_type_be(enumtypoid))));

    PG_RETURN_OID(max);
}

/* 2-argument variant of enum_range */
Datum
enum_range_bounds(PG_FUNCTION_ARGS)
{
    Oid         lower;
    Oid         upper;
    Oid         enumtypoid;

    if (PG_ARGISNULL(0))
        lower = InvalidOid;
    else
        lower = PG_GETARG_OID(0);
    if (PG_ARGISNULL(1))
        upper = InvalidOid;
    else
        upper = PG_GETARG_OID(1);

    /*
     * We rely on being able to get the specific enum type from the calling
     * expression tree.  The generic type mechanism should have ensured that
     * both are of the same type.
     */
    enumtypoid = get_fn_expr_argtype(fcinfo->flinfo, 0);
    if (enumtypoid == InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("could not determine actual enum type")));

    PG_RETURN_ARRAYTYPE_P(enum_range_internal(enumtypoid, lower, upper));
}

/* 1-argument variant of enum_range */
Datum
enum_range_all(PG_FUNCTION_ARGS)
{
    Oid         enumtypoid;

    /*
     * We rely on being able to get the specific enum type from the calling
     * expression tree.  Notice that the actual value of the argument isn't
     * examined at all; in particular it might be NULL.
     */
    enumtypoid = get_fn_expr_argtype(fcinfo->flinfo, 0);
    if (enumtypoid == InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("could not determine actual enum type")));

    PG_RETURN_ARRAYTYPE_P(enum_range_internal(enumtypoid,
                                              InvalidOid, InvalidOid));
}

static ArrayType *
enum_range_internal(Oid enumtypoid, Oid lower, Oid upper)
{
    ArrayType  *result;
    Relation    enum_rel;
    Relation    enum_idx;
    SysScanDesc enum_scan;
    HeapTuple   enum_tuple;
    ScanKeyData skey;
    Datum      *elems;
    int         max,
                cnt;
    bool        left_found;

    /*
     * Scan the enum members in order using pg_enum_typid_sortorder_index.
     * Note we must not use the syscache, and must use an MVCC snapshot here.
     * See comments for RenumberEnumType in catalog/pg_enum.c for more info.
     */
    ScanKeyInit(&skey,
                Anum_pg_enum_enumtypid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(enumtypoid));

    enum_rel = heap_open(EnumRelationId, AccessShareLock);
    enum_idx = index_open(EnumTypIdSortOrderIndexId, AccessShareLock);
    enum_scan = systable_beginscan_ordered(enum_rel, enum_idx,
                                           GetTransactionSnapshot(),
                                           1, &skey);

    max = 64;
    elems = (Datum *) palloc(max * sizeof(Datum));
    cnt = 0;
    left_found = !OidIsValid(lower);

    while (HeapTupleIsValid(enum_tuple = systable_getnext_ordered(enum_scan, ForwardScanDirection)))
    {
        Oid         enum_oid = HeapTupleGetOid(enum_tuple);

        if (!left_found && lower == enum_oid)
            left_found = true;

        if (left_found)
        {
            if (cnt >= max)
            {
                max *= 2;
                elems = (Datum *) repalloc(elems, max * sizeof(Datum));
            }

            elems[cnt++] = ObjectIdGetDatum(enum_oid);
        }

        if (OidIsValid(upper) && upper == enum_oid)
            break;
    }

    systable_endscan_ordered(enum_scan);
    index_close(enum_idx, AccessShareLock);
    heap_close(enum_rel, AccessShareLock);

    /* and build the result array */
    /* note this hardwires some details about the representation of Oid */
    result = construct_array(elems, cnt, enumtypoid, sizeof(Oid), true, 'i');

    pfree(elems);

    return result;
}