dict_simple.c

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/*-------------------------------------------------------------------------
 *
 * dict_simple.c
 *      Simple dictionary: just lowercase and check for stopword
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *    src/backend/tsearch/dict_simple.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "commands/defrem.h"
#include "tsearch/ts_locale.h"
#include "tsearch/ts_utils.h"


typedef struct
{
    StopList    stoplist;
    bool        accept;
} DictSimple;


Datum
dsimple_init(PG_FUNCTION_ARGS)
{
    List       *dictoptions = (List *) PG_GETARG_POINTER(0);
    DictSimple *d = (DictSimple *) palloc0(sizeof(DictSimple));
    bool        stoploaded = false,
                acceptloaded = false;
    ListCell   *l;

    d->accept = true;           /* default */

    foreach(l, dictoptions)
    {
        DefElem    *defel = (DefElem *) lfirst(l);

        if (pg_strcasecmp("StopWords", defel->defname) == 0)
        {
            if (stoploaded)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                         errmsg("multiple StopWords parameters")));
            readstoplist(defGetString(defel), &d->stoplist, lowerstr);
            stoploaded = true;
        }
        else if (pg_strcasecmp("Accept", defel->defname) == 0)
        {
            if (acceptloaded)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                         errmsg("multiple Accept parameters")));
            d->accept = defGetBoolean(defel);
            acceptloaded = true;
        }
        else
        {
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                   errmsg("unrecognized simple dictionary parameter: \"%s\"",
                          defel->defname)));
        }
    }

    PG_RETURN_POINTER(d);
}

Datum
dsimple_lexize(PG_FUNCTION_ARGS)
{
    DictSimple *d = (DictSimple *) PG_GETARG_POINTER(0);
    char       *in = (char *) PG_GETARG_POINTER(1);
    int32       len = PG_GETARG_INT32(2);
    char       *txt;
    TSLexeme   *res;

    txt = lowerstr_with_len(in, len);

    if (*txt == '\0' || searchstoplist(&(d->stoplist), txt))
    {
        /* reject as stopword */
        pfree(txt);
        res = palloc0(sizeof(TSLexeme) * 2);
        PG_RETURN_POINTER(res);
    }
    else if (d->accept)
    {
        /* accept */
        res = palloc0(sizeof(TSLexeme) * 2);
        res[0].lexeme = txt;
        PG_RETURN_POINTER(res);
    }
    else
    {
        /* report as unrecognized */
        pfree(txt);
        PG_RETURN_POINTER(NULL);
    }
}