postgresql/contrib/tsearch2/dict_thesaurus.c

/* $PostgreSQL: pgsql/contrib/tsearch2/dict_thesaurus.c,v 1.5 2006/06/06 16:25:55 teodor Exp $ */

/*
 * thesaurus
 * Teodor Sigaev <teodor@sigaev.ru>
 */
#include "postgres.h"
#include "executor/spi.h"

#include <ctype.h>

#include "dict.h"
#include "common.h"
#include "ts_locale.h"

/*
 * Temporay we use TSLexeme.flags for inner use...
 */
#define	DT_USEASIS		0x1000

typedef struct LexemeInfo {
	uint16	idsubst; /* entry's number in DictThesaurus->subst */
	uint16	posinsubst; /* pos info in entry */
	uint16	tnvariant;  /* total num lexemes in one variant */
	struct LexemeInfo *nextentry;
	struct LexemeInfo *nextvariant;
} LexemeInfo;

typedef struct {
	char 		*lexeme;
	LexemeInfo	*entries;
} TheLexeme; 

typedef struct {
	uint16	lastlexeme; /* number lexemes to substitute */
	uint16	reslen;
	TSLexeme	*res;   /* prepared substituted result */ 
} TheSubstitute;

typedef struct
{
	/* subdictionary to normalize lexemes */	
	DictInfo	subdict;

	/* Array to search lexeme by exact match */
	TheLexeme	*wrds;
	int			nwrds;
	int			ntwrds;

	/* Storage of substituted result, n-th element is for
	   n-th expression */
	TheSubstitute	*subst;
	int				nsubst;
}	DictThesaurus;

PG_FUNCTION_INFO_V1(thesaurus_init);
Datum		thesaurus_init(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(thesaurus_lexize);
Datum		thesaurus_lexize(PG_FUNCTION_ARGS);

static void
freeDictThesaurus(DictThesaurus * d)
{
	free(d);
}

static void
newLexeme( DictThesaurus *d, char *b, char *e, uint16 idsubst, uint16 posinsubst ) {
	TheLexeme	*ptr;

	if ( d->nwrds >= d->ntwrds ) {
		if ( d->ntwrds == 0 ) {
			d->ntwrds = 16;
			d->wrds = (TheLexeme*)malloc(sizeof(TheLexeme) * d->ntwrds);
		} else {
			d->ntwrds *= 2;
			d->wrds = (TheLexeme*)realloc(d->wrds, sizeof(TheLexeme) * d->ntwrds);
		}
		if (!d->wrds)
			elog(ERROR,"Out of memory");
	}

	ptr = d->wrds + d->nwrds;
	d->nwrds++;

	if  ( (ptr->lexeme = malloc(e-b+1)) == NULL )
		elog(ERROR,"Out of memory");

	memcpy(ptr->lexeme, b, e-b);
	ptr->lexeme[e-b] = '\0';

	if  ( (ptr->entries = (LexemeInfo*)malloc( sizeof(LexemeInfo) ))==NULL )
		elog(ERROR,"Out of memory");

	ptr->entries->nextentry=NULL;
	ptr->entries->idsubst = idsubst;
	ptr->entries->posinsubst = posinsubst;
}

static void
addWrd( DictThesaurus *d, char *b, char *e, uint16 idsubst, uint16 nwrd, uint16 posinsubst, bool useasis ) {
	static	int nres=0;
	static  int ntres = 0;
	TheSubstitute	*ptr;

	if ( nwrd == 0 ) {
		nres = ntres = 0;

		if ( idsubst <= d->nsubst ) {
			if ( d->nsubst == 0 ) {
				d->nsubst = 16;
				d->subst = (TheSubstitute*)malloc(sizeof(TheSubstitute) * d->nsubst);
			} else {
				d->nsubst *= 2;
				d->subst = (TheSubstitute*)realloc(d->subst, sizeof(TheSubstitute) * d->nsubst);
			}
			if (!d->subst)
				elog(ERROR,"Out of memory");
		}
	}

	ptr = d->subst + idsubst;

	ptr->lastlexeme = posinsubst-1;

	if ( nres+1 >= ntres ) {
		if ( ntres == 0 ) {
			ntres = 2;
			ptr->res = (TSLexeme*)malloc( sizeof(TSLexeme) * ntres );
		} else {
			ntres *= 2;
			ptr->res = (TSLexeme*)realloc( ptr->res, sizeof(TSLexeme) * ntres );
		}

		if ( !ptr->res ) 
				elog(ERROR,"Out of memory");
	}

	if ( (ptr->res[ nres ].lexeme = malloc(e-b+1))==0 ) 
		elog(ERROR,"Out of memory");
	memcpy(ptr->res[ nres ].lexeme, b, e-b);
	ptr->res[ nres ].lexeme[e-b] = '\0';

	ptr->res[ nres ].nvariant = nwrd;
	if ( useasis )
		ptr->res[ nres ].flags = DT_USEASIS;
	else
		ptr->res[ nres ].flags = 0;

	ptr->res[ ++nres ].lexeme = NULL;
}

#define TR_WAITLEX	1
#define TR_INLEX	2
#define	TR_WAITSUBS	3
#define TR_INSUBS	4

static void
thesaurusRead( char *filename, DictThesaurus *d ) {
	FILE *fh;
	char str[BUFSIZ];
	int lineno=0;
	uint16	idsubst = 0;
	bool	useasis=false;

	fh = fopen(to_absfilename(filename), "r");
	if (!fh)
		elog(ERROR,"Thesaurus: can't open '%s' file", filename);

	while( fgets(str, sizeof(str), fh)) {
		char *ptr = str;
		int state = TR_WAITLEX;
		char	*beginwrd = NULL;
		uint16	posinsubst=0;
		uint16	nwrd=0;

		lineno++;

		/* is it comment ? */
		while( t_isspace(ptr) )
			ptr += pg_mblen(ptr);
		if ( t_iseq(str, '#') || *str=='\0' || t_iseq(str, '\n') || t_iseq(str, '\r') )
			continue;

		pg_verifymbstr(ptr, strlen(ptr), false);
		while(*ptr) {
			if ( state == TR_WAITLEX ) {
				if ( t_iseq(ptr, ':' ) ) {
					if ( posinsubst == 0 ) {
						fclose(fh);
						elog(ERROR, "Thesaurus: Unexpected delimiter at %d line", lineno);
					}
					state = TR_WAITSUBS;
				} else if ( !t_isspace(ptr) ) {
					beginwrd = ptr;
					state = TR_INLEX;
				}
			} else if ( state == TR_INLEX ) {
				if ( t_iseq(ptr, ':') ) {
					newLexeme( d, beginwrd, ptr, idsubst, posinsubst++ );
					state = TR_WAITSUBS;
				} else if ( t_isspace(ptr) ) {
					newLexeme( d, beginwrd, ptr, idsubst, posinsubst++ );
					state = TR_WAITLEX;
				}
			} else if ( state == TR_WAITSUBS ) {
				if ( t_iseq(ptr, '*') ) {
					useasis = true;
					state = TR_INSUBS;
					beginwrd = ptr + pg_mblen(ptr);
				} else if ( t_iseq(ptr, '\\') ) {
					useasis = false;
					state = TR_INSUBS;
					beginwrd = ptr + pg_mblen(ptr);
				} else if ( !t_isspace(ptr) ) { 
					useasis = false;
					beginwrd = ptr;
					state = TR_INSUBS;
				}
			} else if ( state == TR_INSUBS ) {
				if ( t_isspace(ptr) ) { 
					if ( ptr == beginwrd )
						elog(ERROR, "Thesaurus: Unexpected end of line or lexeme at %d line", lineno);
					addWrd( d, beginwrd, ptr, idsubst, nwrd++, posinsubst, useasis );
					state = TR_WAITSUBS;
				}
			} else
				elog(ERROR,"Thesaurus: Unknown state: %d", state);
				
			ptr += pg_mblen(ptr);
		}

		if ( state == TR_INSUBS ) {
			if ( ptr == beginwrd )
				elog(ERROR, "Thesaurus: Unexpected end of line or lexeme at %d line", lineno);
			addWrd( d, beginwrd, ptr, idsubst, nwrd++, posinsubst, useasis );
		}

		idsubst++;

		if ( !(nwrd && posinsubst) ) {
			fclose(fh);
			elog(ERROR, "Thesaurus: Unexpected end of line at %d line", lineno);
		}
			
	}

	d->nsubst = idsubst;

	fclose(fh);
}

static TheLexeme*
addCompiledLexeme(TheLexeme   *newwrds, int *nnw, int *tnm, TSLexeme *lexeme, LexemeInfo* src, uint16 tnvariant) {

	if ( *nnw >= *tnm ) {
		*tnm *= 2;
		newwrds = (TheLexeme*)realloc( newwrds, sizeof(TheLexeme) * *tnm);
		if (!newwrds)
			elog(ERROR,"Out of memory");
	}

	newwrds[ *nnw ].entries = (LexemeInfo*)malloc( sizeof(LexemeInfo) );
	if (!newwrds[ *nnw ].entries)
		elog(ERROR,"Out of memory");

	if ( lexeme && lexeme->lexeme ) {
		newwrds[ *nnw ].lexeme = strdup( lexeme->lexeme );
		if ( !newwrds[ *nnw ].lexeme )
			elog(ERROR,"Out of memory");

		newwrds[ *nnw ].entries->tnvariant = tnvariant;
	} else {
		newwrds[ *nnw ].lexeme = NULL;
		newwrds[ *nnw ].entries->tnvariant = 1;
	}

	newwrds[ *nnw ].entries->idsubst = src->idsubst;
	newwrds[ *nnw ].entries->posinsubst = src->posinsubst;

	newwrds[ *nnw ].entries->nextentry = NULL;

	(*nnw)++;
	return newwrds;
}

static int
cmpLexemeInfo(LexemeInfo *a, LexemeInfo *b) {
	if ( a==NULL || b==NULL )
		return 0;

	if ( a->idsubst == b->idsubst ) {
		if ( a->posinsubst == b->posinsubst ) {
			if ( a->tnvariant == b->tnvariant ) 
					return 0;

			return ( a->tnvariant > b->tnvariant ) ? 1 : -1;
		}

		return ( a->posinsubst > b->posinsubst ) ? 1 : -1;
	}

	return ( a->idsubst > b->idsubst ) ? 1 : -1;
}

static int
cmpLexeme(TheLexeme *a, TheLexeme* b) {
	if ( a->lexeme == NULL ) {
		if ( b->lexeme == NULL )
			return 0;
		else
			return 1;
	} else if ( b->lexeme == NULL )
		return -1;

	return strcmp( a->lexeme, b->lexeme );
}

static int
cmpLexemeQ(const void *a, const void *b) {
	return cmpLexeme( (TheLexeme*)a, (TheLexeme*)b ); 
}

static int cmpTheLexeme(const void *a, const void *b) {
	TheLexeme *la  = (TheLexeme*)a;
	TheLexeme *lb  = (TheLexeme*)b;
	int res;

	if ( (res=cmpLexeme(la, lb)) != 0 )
		return res;

	return -cmpLexemeInfo(la->entries, lb->entries);
}

static void
compileTheLexeme(DictThesaurus *d) {
	int			i,nnw=0, tnm=16;
	TheLexeme	*newwrds = (TheLexeme*)malloc(sizeof(TheLexeme)*tnm), *ptrwrds;

	if (!newwrds) 
		elog(ERROR,"Out of memory");

	for(i=0;i<d->nwrds;i++) {
		TSLexeme *ptr;

		ptr = (TSLexeme*) DatumGetPointer( 
				FunctionCall4(
					&(d->subdict.lexize_info),
					PointerGetDatum(d->subdict.dictionary),
					PointerGetDatum(d->wrds[i].lexeme),
					Int32GetDatum(strlen(d->wrds[i].lexeme)),
					PointerGetDatum(NULL)
				)
			);

		if ( !(ptr && ptr->lexeme) ) {
			if ( !ptr )
				elog(ERROR,"Thesaurus: word-sample '%s' isn't recognized by subdictionary (rule %d)", 
						d->wrds[i].lexeme, d->wrds[i].entries->idsubst+1	);
			else
				elog(NOTICE,"Thesaurus: word-sample '%s' is recognized as stop-word, assign any stop-word (rule %d)", 
					d->wrds[i].lexeme,  d->wrds[i].entries->idsubst+1);

			newwrds = addCompiledLexeme( newwrds, &nnw, &tnm, NULL, d->wrds[i].entries, 0);
		} else {
			while( ptr->lexeme ) {
				TSLexeme	*remptr = ptr+1;
				int tnvar = 1;
				int	curvar = ptr->nvariant;

				/* compute n words in one variant */
				while( remptr->lexeme ) {
					if ( remptr->nvariant != (remptr-1)->nvariant )
						break;
					tnvar++;
					remptr++;
				}

				remptr = ptr;
				while( remptr->lexeme && remptr->nvariant == curvar ) {
					newwrds = addCompiledLexeme( newwrds, &nnw, &tnm, remptr, d->wrds[i].entries, tnvar); 
					remptr++;
				}

				ptr = remptr;
			}
		}

		free( d->wrds[i].lexeme );
		free( d->wrds[i].entries );
	}

	free( d->wrds );
	d->wrds = newwrds;
	d->nwrds = nnw;
	d->ntwrds = tnm;

	if ( d->nwrds > 1 ) {
		qsort( d->wrds, d->nwrds, sizeof(TheLexeme), cmpTheLexeme ); 

		/* uniq */
		newwrds = d->wrds;
		ptrwrds = d->wrds + 1;
		while( ptrwrds - d->wrds < d->nwrds ) {
			if ( cmpLexeme( ptrwrds, newwrds ) == 0 ) {
				if ( cmpLexemeInfo(ptrwrds->entries, newwrds->entries) ) {
					ptrwrds->entries->nextentry = newwrds->entries;
					newwrds->entries = ptrwrds->entries;
				} else
					free( ptrwrds->entries );

				if ( ptrwrds->lexeme )
					free( ptrwrds->lexeme );
			} else {
				newwrds++;
				*newwrds = *ptrwrds;
			}

			ptrwrds++;
		}

		d->nwrds = newwrds - d->wrds + 1;
		d->wrds = (TheLexeme*)realloc( d->wrds, sizeof(TheLexeme) * d->nwrds );
	}
}

static void
compileTheSubstitute(DictThesaurus *d) {
	int i;

	for(i=0;i<d->nsubst;i++) {
		TSLexeme	*rem = d->subst[i].res, *outptr, *inptr;
		int			n=2;

		outptr = d->subst[i].res = (TSLexeme*)malloc( sizeof(TSLexeme) * n );
		if ( d->subst[i].res == NULL )
			elog(ERROR,"Out of Memory");
		outptr->lexeme = NULL;
		inptr = rem;

		while( inptr && inptr->lexeme ) { 
			TSLexeme	*lexized, tmplex[2];

			if ( inptr->flags & DT_USEASIS ) { /* do not lexize */
				tmplex[0] = *inptr;
				tmplex[0].flags = 0; 
				tmplex[1].lexeme = NULL;
				lexized = tmplex; 
			} else {
				lexized = (TSLexeme*) DatumGetPointer( 
					FunctionCall4(
						&(d->subdict.lexize_info),
						PointerGetDatum(d->subdict.dictionary),
						PointerGetDatum(inptr->lexeme),
						Int32GetDatum(strlen(inptr->lexeme)),
						PointerGetDatum(NULL)
					)
				);
			}

			if ( lexized && lexized->lexeme ) {
				int toset = (lexized->lexeme && outptr != d->subst[i].res ) ? (outptr - d->subst[i].res)  : -1;

				while( lexized->lexeme ) {
					if ( outptr - d->subst[i].res + 1 >= n ) {
						int diff = outptr - d->subst[i].res;
						n *= 2;
						d->subst[i].res = (TSLexeme*)realloc( d->subst[i].res, sizeof(TSLexeme) * n );
						if ( d->subst[i].res == NULL )
							elog(ERROR,"Out of Memory");
						outptr = d->subst[i].res + diff;
					}

					*outptr = *lexized;
					if ( (outptr->lexeme = strdup(lexized->lexeme)) == NULL )
						elog(ERROR,"Out of Memory");

					outptr++;
					lexized++;
				}

				if ( toset > 0)
					d->subst[i].res[toset].flags |= TSL_ADDPOS;
			} else if ( lexized ) {
				elog(NOTICE,"Thesaurus: word '%s' in substition is a stop-word, ignored (rule %d)", inptr->lexeme, i+1);
			} else {
				elog(ERROR,"Thesaurus: word '%s' in substition isn't recognized (rule %d)", inptr->lexeme, i+1);
			}

			if ( inptr->lexeme )
				free( inptr->lexeme );
			inptr++;
		}

		if ( outptr == d->subst[i].res )
			elog(ERROR,"Thesaurus: all words in subsitution are stop word (rule %d)", i+1);

		d->subst[i].reslen = outptr - d->subst[i].res;

		free(rem);
	}
}

Datum
thesaurus_init(PG_FUNCTION_ARGS)
{
	DictThesaurus *d;
	Map		   *cfg,
			   *pcfg;
	text	   *in, *subdictname=NULL;
	bool 		fileloaded = false;

	if (PG_ARGISNULL(0) || PG_GETARG_POINTER(0) == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_CONFIG_FILE_ERROR),
				 errmsg("Thesaurus confguration error")));

	d = (DictThesaurus *) malloc(sizeof(DictThesaurus));
	if (!d)
		ereport(ERROR,
				(errcode(ERRCODE_OUT_OF_MEMORY),
				 errmsg("out of memory")));
	memset(d, 0, sizeof(DictThesaurus));

	in = PG_GETARG_TEXT_P(0);
	parse_cfgdict(in, &cfg);
	PG_FREE_IF_COPY(in, 0);
	pcfg = cfg;
	while (pcfg->key)
	{
		if (pg_strcasecmp("DictFile", pcfg->key) == 0)
		{
			if (fileloaded)
			{
				freeDictThesaurus(d);
				ereport(ERROR,
						(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
						 errmsg("Thesaurus file is already loaded")));
			}
			fileloaded = true;
			thesaurusRead( pcfg->value, d );
		}
		else if (pg_strcasecmp("Dictionary", pcfg->key) == 0)
		{
			if (subdictname)
			{
				freeDictThesaurus(d);
				ereport(ERROR,
						(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
						 errmsg("Thesaurus: SubDictionary is already defined")));
			}
			subdictname = char2text( pcfg->value );
		}
		else
		{
			freeDictThesaurus(d);
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("unrecognized option: %s => %s",
							pcfg->key, pcfg->value)));
		}
		pfree(pcfg->key);
		pfree(pcfg->value);
		pcfg++;
	}
	pfree(cfg);

	if (!fileloaded)
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("Thesaurus file  isn't defined")));

	if ( subdictname ) {
		DictInfo	*subdictptr;
		/* 
		 * we already in SPI, but name2id_dict()/finddict()
		 * invoke SPI_connect()
		 */
		SPI_push(); 

		subdictptr = finddict( name2id_dict( subdictname ) );

		SPI_pop();

		d->subdict = *subdictptr;
	} else 
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("Thesaurus: SubDictionary isn't defined")));

	compileTheLexeme( d );
	compileTheSubstitute(d);

	PG_RETURN_POINTER(d);
}

static LexemeInfo*
findTheLexeme(DictThesaurus *d, char * lexeme) {
	TheLexeme key = { lexeme, NULL }, *res;

	if ( d->nwrds == 0 )
		return NULL;

	res = bsearch(&key, d->wrds, d->nwrds, sizeof(TheLexeme), cmpLexemeQ);

	if ( res == NULL )
		return NULL;
	return res->entries;
}

static bool
matchIdSubst(LexemeInfo *stored, uint16 idsubst) {
	bool res = true;

	if (stored) {
		res = false;

		for(; stored; stored=stored->nextvariant) 
			if ( stored->idsubst == idsubst ) {
				res = true;
				break;
			}
	}

	return res;
}

static LexemeInfo*
findVariant( LexemeInfo *in, LexemeInfo *stored, uint16 curpos, LexemeInfo **newin, int newn) {
	for(;;) {
		int i;
		LexemeInfo *ptr = newin[0];

		for(i=0; i<newn; i++) {
			while(newin[i] && newin[i]->idsubst < ptr->idsubst) 
				newin[i] = newin[i]->nextentry;

			if ( newin[i] == NULL )
				return in;

			if ( newin[i]->idsubst > ptr->idsubst ) {
				ptr = newin[i];
				i=-1;
				continue;
			}

			while(newin[i]->idsubst == ptr->idsubst) {
				if ( newin[i]->posinsubst == curpos && newin[i]->tnvariant == newn ) {
					ptr = newin[i];
					break;
				}

				newin[i] = newin[i]->nextentry;
				if ( newin[i] == NULL )
					return in;
			}

			if ( newin[i]->idsubst != ptr->idsubst ) {
				ptr = newin[i];
				i=-1;
				continue;
			}
		}

		if ( i==newn && matchIdSubst(stored, ptr->idsubst) && (in==NULL || !matchIdSubst(in, ptr->idsubst)) ) { /* found */

			ptr->nextvariant = in;
			in = ptr;
		}

		/* step forward */
		for(i=0; i<newn; i++)
			newin[i] = newin[i]->nextentry;
	}

	return NULL;
}

static TSLexeme*
copyTSLexeme( TheSubstitute *ts ) {
	TSLexeme	*res;
	uint16 i;

	res = (TSLexeme*)palloc( sizeof(TSLexeme) * (ts->reslen+1) );
	for(i=0;i<ts->reslen;i++) {	
		res[i] = ts->res[i];
		res[i].lexeme = pstrdup( ts->res[i].lexeme );
	}

	res[ts->reslen].lexeme = NULL;

	return res;
}

static TSLexeme*
checkMatch(DictThesaurus *d, LexemeInfo *info, uint16 curpos, bool *moreres) {
	*moreres = false;
	while(info) {
		Assert( info->idsubst < d->nsubst );
		if ( info->nextvariant )
			*moreres = true;
		if ( d->subst[ info->idsubst ].lastlexeme == curpos ) 
			return copyTSLexeme( d->subst + info->idsubst );
		info = info->nextvariant;
	}

	return NULL;
}

Datum
thesaurus_lexize(PG_FUNCTION_ARGS)
{
	DictThesaurus *d = (DictThesaurus *) PG_GETARG_POINTER(0);
	DictSubState	*dstate = (DictSubState*)PG_GETARG_POINTER(3);
	TSLexeme	*res=NULL;
	LexemeInfo *stored, *info = NULL;
	uint16	curpos = 0;
	bool	moreres = false;

	if ( dstate == NULL || PG_NARGS() < 4 )
		elog(ERROR,"Forbidden call of thesaurus or nested call");

	if ( dstate->isend ) 
		PG_RETURN_POINTER(NULL);
	stored = (LexemeInfo*) dstate->private;

	if (stored) 
		curpos = stored->posinsubst+1;

	res =(TSLexeme*) DatumGetPointer (
		FunctionCall4(
			&(d->subdict.lexize_info),
			PointerGetDatum(d->subdict.dictionary),
			PG_GETARG_DATUM(1),
			PG_GETARG_INT32(2),
			PointerGetDatum(NULL)
		)
	);

	if ( res && res->lexeme ) {
		TSLexeme	*ptr = res , *basevar;

		while( ptr->lexeme ) {
			uint16		nv = ptr->nvariant;
			uint16		i,nlex = 0;
			LexemeInfo	**infos;

			basevar = ptr;
			while( ptr->lexeme && nv == ptr->nvariant ) {
				nlex++;
				ptr++;
			}

			infos = (LexemeInfo**)palloc(sizeof(LexemeInfo*)*nlex);
			for(i=0;i<nlex;i++) 
				if ( (infos[i] = findTheLexeme(d, basevar[i].lexeme)) == NULL ) 
					break;

			if ( i<nlex ) { 
				/* no chance to find */
				pfree( infos );
				continue;
			}

			info = findVariant( info, stored, curpos, infos, nlex);
		}
	} else if ( res ) { /* stop-word */
		LexemeInfo	*infos = findTheLexeme(d, NULL);
		info = findVariant( NULL, stored, curpos, &infos, 1);
	} else {
		info = NULL; /* word isn't recognized */
	}

	dstate->private = (void*)info;

	if ( !info ) {
		dstate->getnext = false;
		PG_RETURN_POINTER(NULL);
	}
			
	if ( (res=checkMatch(d, info, curpos,&moreres)) != NULL ) {
		dstate->getnext = moreres;
		PG_RETURN_POINTER(res);
	}

	dstate->getnext = true;

	PG_RETURN_POINTER(NULL);	
}