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This works by extracting trigrams from the given regular expression, in generally the same spirit as the previously-existing support for LIKE searches, though of course the details are far more complicated. Currently, only GIN indexes are supported. We might be able to make it work with GiST indexes later. The implementation includes adding API functions to backend/regex/ to provide a view of the search NFA created from a regular expression. These functions are meant to be generic enough to be supportable in a standalone version of the regex library, should that ever happen. Alexander Korotkov, reviewed by Heikki Linnakangas and Tom Lane
121 lines
4.0 KiB
C
121 lines
4.0 KiB
C
/*
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* contrib/pg_trgm/trgm.h
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*/
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#ifndef __TRGM_H__
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#define __TRGM_H__
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#include "access/gist.h"
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#include "access/itup.h"
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#include "storage/bufpage.h"
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/*
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* Options ... but note that trgm_regexp.c effectively assumes these values
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* of LPADDING and RPADDING.
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*/
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#define LPADDING 2
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#define RPADDING 1
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#define KEEPONLYALNUM
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/*
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* Caution: IGNORECASE macro means that trigrams are case-insensitive.
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* If this macro is disabled, the ~* and ~~* operators must be removed from
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* the operator classes, because we can't handle case-insensitive wildcard
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* search with case-sensitive trigrams. Failure to do this will result in
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* "cannot handle ~*(~~*) with case-sensitive trigrams" errors.
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*/
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#define IGNORECASE
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#define DIVUNION
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/* operator strategy numbers */
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#define SimilarityStrategyNumber 1
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#define DistanceStrategyNumber 2
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#define LikeStrategyNumber 3
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#define ILikeStrategyNumber 4
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#define RegExpStrategyNumber 5
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#define RegExpICaseStrategyNumber 6
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typedef char trgm[3];
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#define CMPCHAR(a,b) ( ((a)==(b)) ? 0 : ( ((a)<(b)) ? -1 : 1 ) )
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#define CMPPCHAR(a,b,i) CMPCHAR( *(((const char*)(a))+i), *(((const char*)(b))+i) )
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#define CMPTRGM(a,b) ( CMPPCHAR(a,b,0) ? CMPPCHAR(a,b,0) : ( CMPPCHAR(a,b,1) ? CMPPCHAR(a,b,1) : CMPPCHAR(a,b,2) ) )
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#define CPTRGM(a,b) do { \
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*(((char*)(a))+0) = *(((char*)(b))+0); \
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*(((char*)(a))+1) = *(((char*)(b))+1); \
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*(((char*)(a))+2) = *(((char*)(b))+2); \
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} while(0);
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#ifdef KEEPONLYALNUM
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#define ISWORDCHR(c) (t_isalpha(c) || t_isdigit(c))
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#define ISPRINTABLECHAR(a) ( isascii( *(unsigned char*)(a) ) && (isalnum( *(unsigned char*)(a) ) || *(unsigned char*)(a)==' ') )
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#else
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#define ISWORDCHR(c) (!t_isspace(c))
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#define ISPRINTABLECHAR(a) ( isascii( *(unsigned char*)(a) ) && isprint( *(unsigned char*)(a) ) )
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#endif
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#define ISPRINTABLETRGM(t) ( ISPRINTABLECHAR( ((char*)(t)) ) && ISPRINTABLECHAR( ((char*)(t))+1 ) && ISPRINTABLECHAR( ((char*)(t))+2 ) )
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#define ISESCAPECHAR(x) (*(x) == '\\') /* Wildcard escape character */
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#define ISWILDCARDCHAR(x) (*(x) == '_' || *(x) == '%') /* Wildcard
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* meta-character */
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typedef struct
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{
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int32 vl_len_; /* varlena header (do not touch directly!) */
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uint8 flag;
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char data[1];
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} TRGM;
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#define TRGMHDRSIZE (VARHDRSZ + sizeof(uint8))
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/* gist */
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#define BITBYTE 8
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#define SIGLENINT 3 /* >122 => key will toast, so very slow!!! */
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#define SIGLEN ( sizeof(int)*SIGLENINT )
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#define SIGLENBIT (SIGLEN*BITBYTE - 1) /* see makesign */
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typedef char BITVEC[SIGLEN];
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typedef char *BITVECP;
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#define LOOPBYTE \
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for(i=0;i<SIGLEN;i++)
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#define GETBYTE(x,i) ( *( (BITVECP)(x) + (int)( (i) / BITBYTE ) ) )
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#define GETBITBYTE(x,i) ( (((char)(x)) >> (i)) & 0x01 )
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#define CLRBIT(x,i) GETBYTE(x,i) &= ~( 0x01 << ( (i) % BITBYTE ) )
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#define SETBIT(x,i) GETBYTE(x,i) |= ( 0x01 << ( (i) % BITBYTE ) )
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#define GETBIT(x,i) ( (GETBYTE(x,i) >> ( (i) % BITBYTE )) & 0x01 )
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#define HASHVAL(val) (((unsigned int)(val)) % SIGLENBIT)
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#define HASH(sign, val) SETBIT((sign), HASHVAL(val))
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#define ARRKEY 0x01
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#define SIGNKEY 0x02
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#define ALLISTRUE 0x04
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#define ISARRKEY(x) ( ((TRGM*)x)->flag & ARRKEY )
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#define ISSIGNKEY(x) ( ((TRGM*)x)->flag & SIGNKEY )
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#define ISALLTRUE(x) ( ((TRGM*)x)->flag & ALLISTRUE )
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#define CALCGTSIZE(flag, len) ( TRGMHDRSIZE + ( ( (flag) & ARRKEY ) ? ((len)*sizeof(trgm)) : (((flag) & ALLISTRUE) ? 0 : SIGLEN) ) )
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#define GETSIGN(x) ( (BITVECP)( (char*)x+TRGMHDRSIZE ) )
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#define GETARR(x) ( (trgm*)( (char*)x+TRGMHDRSIZE ) )
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#define ARRNELEM(x) ( ( VARSIZE(x) - TRGMHDRSIZE )/sizeof(trgm) )
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typedef struct TrgmPackedGraph TrgmPackedGraph;
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extern float4 trgm_limit;
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extern uint32 trgm2int(trgm *ptr);
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extern void compact_trigram(trgm *tptr, char *str, int bytelen);
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extern TRGM *generate_trgm(char *str, int slen);
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extern TRGM *generate_wildcard_trgm(const char *str, int slen);
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extern float4 cnt_sml(TRGM *trg1, TRGM *trg2);
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extern bool trgm_contained_by(TRGM *trg1, TRGM *trg2);
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extern TRGM *createTrgmNFA(text *text_re, TrgmPackedGraph **graph,
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Oid collation);
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extern bool trigramsMatchGraph(TrgmPackedGraph *graph, bool *check);
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#endif /* __TRGM_H__ */
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