trgm - Trigram matching for PostgreSQL

--------------------------------------

	The pg_trgm contrib module provides functions and index classes
	for determining the similarity of text based on trigram
	matching.

1 files changed, 88 insertions, 0 deletions

diff --git a/contrib/pg_trgm/trgm.h b/contrib/pg_trgm/trgm.h
new file mode 100644
index 00000000000..a56edca1297
--- /dev/null
+++ b/contrib/pg_trgm/trgm.h
@@ -0,0 +1,88 @@
+#ifndef __TRGM_H__
+#define __TRGM_H__
+
+#include "postgres.h"
+
+#include "access/gist.h"
+#include "access/itup.h"
+#include "utils/elog.h"
+#include "utils/palloc.h"
+#include "utils/builtins.h"
+#include "storage/bufpage.h"
+
+/* options */
+#define LPADDING        2
+#define RPADDING        1
+#define KEEPONLYALNUM
+#define IGNORECASE  
+#define DIVUNION
+
+
+typedef char trgm[3];
+
+#define CMPCHAR(a,b) ( ((a)==(b)) ? 0 : ( ((a)<(b)) ? -1 : 1 ) )
+#define CMPPCHAR(a,b,i)  CMPCHAR( *(((char*)(a))+i), *(((char*)(b))+i) ) 
+#define CMPTRGM(a,b) ( CMPPCHAR(a,b,0) ? CMPPCHAR(a,b,0) : ( CMPPCHAR(a,b,1) ? CMPPCHAR(a,b,1) : CMPPCHAR(a,b,2) ) )
+
+#define CPTRGM(a,b) do {		      	\
+	*(((char*)(a))+0) = *(((char*)(b))+0);	\
+	*(((char*)(a))+1) = *(((char*)(b))+1);	\
+	*(((char*)(a))+2) = *(((char*)(b))+2);	\
+} while(0);
+
+
+typedef struct {
+	int4	len;
+	uint8	flag;
+	char	data[1];
+} TRGM;
+
+#define TRGMHRDSIZE       (sizeof(int4)+sizeof(uint8))
+
+/* gist */
+#define BITBYTE 8
+#define SIGLENINT  3               /* >122 => key will toast, so very slow!!! */
+#define SIGLEN  ( sizeof(int)*SIGLENINT )
+
+#define SIGLENBIT (SIGLEN*BITBYTE - 1) /* see makesign */ 
+
+typedef char BITVEC[SIGLEN];
+typedef char *BITVECP;
+
+#define LOOPBYTE(a) \
+                for(i=0;i<SIGLEN;i++) {\
+                                a;\
+                }
+
+#define LOOPBIT(a) \
+                for(i=0;i<SIGLENBIT;i++) {\
+                                a;\
+                }
+
+#define GETBYTE(x,i) ( *( (BITVECP)(x) + (int)( (i) / BITBYTE ) ) )
+#define GETBITBYTE(x,i) ( ((char)(x)) >> i & 0x01 )
+#define CLRBIT(x,i)   GETBYTE(x,i) &= ~( 0x01 << ( (i) % BITBYTE ) )
+#define SETBIT(x,i)   GETBYTE(x,i) |=  ( 0x01 << ( (i) % BITBYTE ) )
+#define GETBIT(x,i) ( (GETBYTE(x,i) >> ( (i) % BITBYTE )) & 0x01 )
+
+#define HASHVAL(val) (((unsigned int)(val)) % SIGLENBIT)
+#define HASH(sign, val) SETBIT((sign), HASHVAL(val))
+
+#define ARRKEY          0x01
+#define SIGNKEY         0x02
+#define ALLISTRUE       0x04
+   
+#define ISARRKEY(x) ( ((TRGM*)x)->flag & ARRKEY )
+#define ISSIGNKEY(x)    ( ((TRGM*)x)->flag & SIGNKEY )
+#define ISALLTRUE(x)    ( ((TRGM*)x)->flag & ALLISTRUE )
+
+#define CALCGTSIZE(flag, len) ( TRGMHRDSIZE + ( ( (flag) & ARRKEY ) ? ((len)*sizeof(trgm)) : (((flag) & ALLISTRUE) ? 0 : SIGLEN) ) )
+#define GETSIGN(x)      ( (BITVECP)( (char*)x+TRGMHRDSIZE ) )
+#define GETARR(x)       ( (trgm*)( (char*)x+TRGMHRDSIZE ) )
+#define ARRNELEM(x) ( ( ((TRGM*)x)->len - TRGMHRDSIZE )/sizeof(trgm) )
+
+extern float4 trgm_limit;
+TRGM* generate_trgm(char *str, int slen);
+float4 cnt_sml(TRGM *trg1, TRGM *trg2);
+
+#endif