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c3ccc9ee58
Allow for the possibility that folding a string to lower case makes it longer (due to replacing a character with a longer multibyte character). This doesn't change the number of trigrams that will be extracted, but it does affect the required size of an intermediate buffer in generate_trgm(). Per bug #8821 from Ufuk Kayserilioglu. Also install some checks that the input string length is not so large as to cause overflow in the calculations of palloc request sizes. Back-patch to all supported versions.
736 lines
14 KiB
C
736 lines
14 KiB
C
/*
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* contrib/pg_trgm/trgm_op.c
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*/
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#include "postgres.h"
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#include <ctype.h>
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#include "trgm.h"
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#include "catalog/pg_type.h"
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#include "tsearch/ts_locale.h"
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#include "utils/memutils.h"
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PG_MODULE_MAGIC;
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float4 trgm_limit = 0.3f;
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PG_FUNCTION_INFO_V1(set_limit);
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Datum set_limit(PG_FUNCTION_ARGS);
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PG_FUNCTION_INFO_V1(show_limit);
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Datum show_limit(PG_FUNCTION_ARGS);
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PG_FUNCTION_INFO_V1(show_trgm);
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Datum show_trgm(PG_FUNCTION_ARGS);
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PG_FUNCTION_INFO_V1(similarity);
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Datum similarity(PG_FUNCTION_ARGS);
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PG_FUNCTION_INFO_V1(similarity_dist);
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Datum similarity_dist(PG_FUNCTION_ARGS);
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PG_FUNCTION_INFO_V1(similarity_op);
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Datum similarity_op(PG_FUNCTION_ARGS);
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Datum
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set_limit(PG_FUNCTION_ARGS)
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{
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float4 nlimit = PG_GETARG_FLOAT4(0);
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if (nlimit < 0 || nlimit > 1.0)
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elog(ERROR, "wrong limit, should be between 0 and 1");
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trgm_limit = nlimit;
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PG_RETURN_FLOAT4(trgm_limit);
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}
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Datum
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show_limit(PG_FUNCTION_ARGS)
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{
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PG_RETURN_FLOAT4(trgm_limit);
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}
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static int
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comp_trgm(const void *a, const void *b)
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{
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return CMPTRGM(a, b);
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}
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static int
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unique_array(trgm *a, int len)
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{
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trgm *curend,
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*tmp;
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curend = tmp = a;
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while (tmp - a < len)
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if (CMPTRGM(tmp, curend))
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{
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curend++;
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CPTRGM(curend, tmp);
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tmp++;
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}
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else
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tmp++;
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return curend + 1 - a;
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}
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/*
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* Finds first word in string, returns pointer to the word,
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* endword points to the character after word
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*/
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static char *
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find_word(char *str, int lenstr, char **endword, int *charlen)
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{
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char *beginword = str;
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while (beginword - str < lenstr && !ISWORDCHR(beginword))
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beginword += pg_mblen(beginword);
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if (beginword - str >= lenstr)
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return NULL;
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*endword = beginword;
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*charlen = 0;
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while (*endword - str < lenstr && ISWORDCHR(*endword))
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{
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*endword += pg_mblen(*endword);
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(*charlen)++;
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}
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return beginword;
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}
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/*
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* Reduce a trigram (three possibly multi-byte characters) to a trgm,
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* which is always exactly three bytes. If we have three single-byte
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* characters, we just use them as-is; otherwise we form a hash value.
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*/
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void
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compact_trigram(trgm *tptr, char *str, int bytelen)
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{
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if (bytelen == 3)
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{
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CPTRGM(tptr, str);
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}
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else
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{
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pg_crc32 crc;
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INIT_CRC32(crc);
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COMP_CRC32(crc, str, bytelen);
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FIN_CRC32(crc);
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/*
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* use only 3 upper bytes from crc, hope, it's good enough hashing
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*/
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CPTRGM(tptr, &crc);
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}
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}
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/*
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* Adds trigrams from words (already padded).
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*/
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static trgm *
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make_trigrams(trgm *tptr, char *str, int bytelen, int charlen)
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{
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char *ptr = str;
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if (charlen < 3)
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return tptr;
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if (bytelen > charlen)
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{
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/* Find multibyte character boundaries and apply compact_trigram */
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int lenfirst = pg_mblen(str),
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lenmiddle = pg_mblen(str + lenfirst),
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lenlast = pg_mblen(str + lenfirst + lenmiddle);
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while ((ptr - str) + lenfirst + lenmiddle + lenlast <= bytelen)
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{
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compact_trigram(tptr, ptr, lenfirst + lenmiddle + lenlast);
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ptr += lenfirst;
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tptr++;
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lenfirst = lenmiddle;
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lenmiddle = lenlast;
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lenlast = pg_mblen(ptr + lenfirst + lenmiddle);
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}
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}
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else
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{
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/* Fast path when there are no multibyte characters */
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Assert(bytelen == charlen);
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while (ptr - str < bytelen - 2 /* number of trigrams = strlen - 2 */ )
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{
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CPTRGM(tptr, ptr);
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ptr++;
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tptr++;
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}
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}
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return tptr;
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}
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TRGM *
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generate_trgm(char *str, int slen)
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{
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TRGM *trg;
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char *buf;
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trgm *tptr;
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int len,
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charlen,
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bytelen;
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char *bword,
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*eword;
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/*
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* Guard against possible overflow in the palloc requests below. (We
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* don't worry about the additive constants, since palloc can detect
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* requests that are a little above MaxAllocSize --- we just need to
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* prevent integer overflow in the multiplications.)
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*/
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if ((Size) (slen / 2) >= (MaxAllocSize / (sizeof(trgm) * 3)) ||
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(Size) slen >= (MaxAllocSize / pg_database_encoding_max_length()))
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ereport(ERROR,
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(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
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errmsg("out of memory")));
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trg = (TRGM *) palloc(TRGMHDRSIZE + sizeof(trgm) * (slen / 2 + 1) *3);
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trg->flag = ARRKEY;
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SET_VARSIZE(trg, TRGMHDRSIZE);
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if (slen + LPADDING + RPADDING < 3 || slen == 0)
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return trg;
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tptr = GETARR(trg);
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/* Allocate a buffer for case-folded, blank-padded words */
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buf = (char *) palloc(slen * pg_database_encoding_max_length() + 4);
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if (LPADDING > 0)
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{
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*buf = ' ';
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if (LPADDING > 1)
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*(buf + 1) = ' ';
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}
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eword = str;
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while ((bword = find_word(eword, slen - (eword - str), &eword, &charlen)) != NULL)
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{
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#ifdef IGNORECASE
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bword = lowerstr_with_len(bword, eword - bword);
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bytelen = strlen(bword);
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#else
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bytelen = eword - bword;
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#endif
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memcpy(buf + LPADDING, bword, bytelen);
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#ifdef IGNORECASE
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pfree(bword);
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#endif
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buf[LPADDING + bytelen] = ' ';
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buf[LPADDING + bytelen + 1] = ' ';
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/*
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* count trigrams
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*/
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tptr = make_trigrams(tptr, buf, bytelen + LPADDING + RPADDING,
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charlen + LPADDING + RPADDING);
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}
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pfree(buf);
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if ((len = tptr - GETARR(trg)) == 0)
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return trg;
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/*
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* Make trigrams unique.
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*/
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if (len > 1)
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{
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qsort((void *) GETARR(trg), len, sizeof(trgm), comp_trgm);
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len = unique_array(GETARR(trg), len);
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}
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SET_VARSIZE(trg, CALCGTSIZE(ARRKEY, len));
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return trg;
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}
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/*
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* Extract the next non-wildcard part of a search string, ie, a word bounded
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* by '_' or '%' meta-characters, non-word characters or string end.
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*
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* str: source string, of length lenstr bytes (need not be null-terminated)
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* buf: where to return the substring (must be long enough)
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* *bytelen: receives byte length of the found substring
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* *charlen: receives character length of the found substring
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*
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* Returns pointer to end+1 of the found substring in the source string.
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* Returns NULL if no word found (in which case buf, bytelen, charlen not set)
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*
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* If the found word is bounded by non-word characters or string boundaries
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* then this function will include corresponding padding spaces into buf.
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*/
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static const char *
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get_wildcard_part(const char *str, int lenstr,
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char *buf, int *bytelen, int *charlen)
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{
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const char *beginword = str;
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const char *endword;
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char *s = buf;
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bool in_leading_wildcard_meta = false;
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bool in_trailing_wildcard_meta = false;
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bool in_escape = false;
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int clen;
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/*
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* Find the first word character, remembering whether preceding character
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* was wildcard meta-character. Note that the in_escape state persists
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* from this loop to the next one, since we may exit at a word character
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* that is in_escape.
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*/
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while (beginword - str < lenstr)
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{
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if (in_escape)
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{
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if (ISWORDCHR(beginword))
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break;
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in_escape = false;
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in_leading_wildcard_meta = false;
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}
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else
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{
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if (ISESCAPECHAR(beginword))
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in_escape = true;
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else if (ISWILDCARDCHAR(beginword))
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in_leading_wildcard_meta = true;
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else if (ISWORDCHR(beginword))
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break;
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else
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in_leading_wildcard_meta = false;
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}
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beginword += pg_mblen(beginword);
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}
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/*
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* Handle string end.
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*/
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if (beginword - str >= lenstr)
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return NULL;
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/*
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* Add left padding spaces if preceding character wasn't wildcard
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* meta-character.
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*/
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*charlen = 0;
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if (!in_leading_wildcard_meta)
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{
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if (LPADDING > 0)
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{
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*s++ = ' ';
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(*charlen)++;
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if (LPADDING > 1)
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{
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*s++ = ' ';
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(*charlen)++;
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}
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}
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}
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/*
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* Copy data into buf until wildcard meta-character, non-word character or
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* string boundary. Strip escapes during copy.
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*/
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endword = beginword;
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while (endword - str < lenstr)
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{
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clen = pg_mblen(endword);
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if (in_escape)
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{
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if (ISWORDCHR(endword))
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{
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memcpy(s, endword, clen);
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(*charlen)++;
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s += clen;
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}
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else
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{
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/*
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* Back up endword to the escape character when stopping at an
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* escaped char, so that subsequent get_wildcard_part will
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* restart from the escape character. We assume here that
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* escape chars are single-byte.
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*/
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endword--;
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break;
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}
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in_escape = false;
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}
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else
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{
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if (ISESCAPECHAR(endword))
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in_escape = true;
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else if (ISWILDCARDCHAR(endword))
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{
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in_trailing_wildcard_meta = true;
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break;
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}
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else if (ISWORDCHR(endword))
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{
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memcpy(s, endword, clen);
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(*charlen)++;
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s += clen;
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}
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else
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break;
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}
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endword += clen;
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}
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/*
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* Add right padding spaces if next character isn't wildcard
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* meta-character.
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*/
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if (!in_trailing_wildcard_meta)
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{
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if (RPADDING > 0)
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{
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*s++ = ' ';
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(*charlen)++;
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if (RPADDING > 1)
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{
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*s++ = ' ';
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(*charlen)++;
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}
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}
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}
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*bytelen = s - buf;
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return endword;
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}
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/*
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* Generates trigrams for wildcard search string.
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*
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* Returns array of trigrams that must occur in any string that matches the
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* wildcard string. For example, given pattern "a%bcd%" the trigrams
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* " a", "bcd" would be extracted.
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*/
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TRGM *
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generate_wildcard_trgm(const char *str, int slen)
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{
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TRGM *trg;
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char *buf,
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*buf2;
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trgm *tptr;
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int len,
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charlen,
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bytelen;
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const char *eword;
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/*
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* Guard against possible overflow in the palloc requests below. (We
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* don't worry about the additive constants, since palloc can detect
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|
* requests that are a little above MaxAllocSize --- we just need to
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* prevent integer overflow in the multiplications.)
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*/
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if ((Size) (slen / 2) >= (MaxAllocSize / (sizeof(trgm) * 3)) ||
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(Size) slen >= (MaxAllocSize / pg_database_encoding_max_length()))
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ereport(ERROR,
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(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
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errmsg("out of memory")));
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trg = (TRGM *) palloc(TRGMHDRSIZE + sizeof(trgm) * (slen / 2 + 1) *3);
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trg->flag = ARRKEY;
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SET_VARSIZE(trg, TRGMHDRSIZE);
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if (slen + LPADDING + RPADDING < 3 || slen == 0)
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return trg;
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tptr = GETARR(trg);
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/* Allocate a buffer for blank-padded, but not yet case-folded, words */
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buf = palloc(sizeof(char) * (slen + 4));
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/*
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* Extract trigrams from each substring extracted by get_wildcard_part.
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*/
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eword = str;
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while ((eword = get_wildcard_part(eword, slen - (eword - str),
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buf, &bytelen, &charlen)) != NULL)
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{
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#ifdef IGNORECASE
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buf2 = lowerstr_with_len(buf, bytelen);
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bytelen = strlen(buf2);
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#else
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buf2 = buf;
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#endif
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/*
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* count trigrams
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*/
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tptr = make_trigrams(tptr, buf2, bytelen, charlen);
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#ifdef IGNORECASE
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pfree(buf2);
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#endif
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}
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pfree(buf);
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if ((len = tptr - GETARR(trg)) == 0)
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return trg;
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/*
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* Make trigrams unique.
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*/
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if (len > 1)
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{
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qsort((void *) GETARR(trg), len, sizeof(trgm), comp_trgm);
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len = unique_array(GETARR(trg), len);
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}
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SET_VARSIZE(trg, CALCGTSIZE(ARRKEY, len));
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return trg;
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}
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uint32
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trgm2int(trgm *ptr)
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{
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uint32 val = 0;
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val |= *(((unsigned char *) ptr));
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val <<= 8;
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val |= *(((unsigned char *) ptr) + 1);
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val <<= 8;
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val |= *(((unsigned char *) ptr) + 2);
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return val;
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}
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Datum
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show_trgm(PG_FUNCTION_ARGS)
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{
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text *in = PG_GETARG_TEXT_P(0);
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TRGM *trg;
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Datum *d;
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ArrayType *a;
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trgm *ptr;
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int i;
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trg = generate_trgm(VARDATA(in), VARSIZE(in) - VARHDRSZ);
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d = (Datum *) palloc(sizeof(Datum) * (1 + ARRNELEM(trg)));
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for (i = 0, ptr = GETARR(trg); i < ARRNELEM(trg); i++, ptr++)
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{
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text *item = (text *) palloc(VARHDRSZ + Max(12, pg_database_encoding_max_length() * 3));
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|
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if (pg_database_encoding_max_length() > 1 && !ISPRINTABLETRGM(ptr))
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{
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snprintf(VARDATA(item), 12, "0x%06x", trgm2int(ptr));
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SET_VARSIZE(item, VARHDRSZ + strlen(VARDATA(item)));
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}
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else
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{
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SET_VARSIZE(item, VARHDRSZ + 3);
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CPTRGM(VARDATA(item), ptr);
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}
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d[i] = PointerGetDatum(item);
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}
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|
|
a = construct_array(
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d,
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ARRNELEM(trg),
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TEXTOID,
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-1,
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false,
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'i'
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);
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for (i = 0; i < ARRNELEM(trg); i++)
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pfree(DatumGetPointer(d[i]));
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pfree(d);
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pfree(trg);
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PG_FREE_IF_COPY(in, 0);
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|
|
PG_RETURN_POINTER(a);
|
|
}
|
|
|
|
float4
|
|
cnt_sml(TRGM *trg1, TRGM *trg2)
|
|
{
|
|
trgm *ptr1,
|
|
*ptr2;
|
|
int count = 0;
|
|
int len1,
|
|
len2;
|
|
|
|
ptr1 = GETARR(trg1);
|
|
ptr2 = GETARR(trg2);
|
|
|
|
len1 = ARRNELEM(trg1);
|
|
len2 = ARRNELEM(trg2);
|
|
|
|
/* explicit test is needed to avoid 0/0 division when both lengths are 0 */
|
|
if (len1 <= 0 || len2 <= 0)
|
|
return (float4) 0.0;
|
|
|
|
while (ptr1 - GETARR(trg1) < len1 && ptr2 - GETARR(trg2) < len2)
|
|
{
|
|
int res = CMPTRGM(ptr1, ptr2);
|
|
|
|
if (res < 0)
|
|
ptr1++;
|
|
else if (res > 0)
|
|
ptr2++;
|
|
else
|
|
{
|
|
ptr1++;
|
|
ptr2++;
|
|
count++;
|
|
}
|
|
}
|
|
|
|
#ifdef DIVUNION
|
|
return ((float4) count) / ((float4) (len1 + len2 - count));
|
|
#else
|
|
return ((float4) count) / ((float4) ((len1 > len2) ? len1 : len2));
|
|
#endif
|
|
|
|
}
|
|
|
|
/*
|
|
* Returns whether trg2 contains all trigrams in trg1.
|
|
* This relies on the trigram arrays being sorted.
|
|
*/
|
|
bool
|
|
trgm_contained_by(TRGM *trg1, TRGM *trg2)
|
|
{
|
|
trgm *ptr1,
|
|
*ptr2;
|
|
int len1,
|
|
len2;
|
|
|
|
ptr1 = GETARR(trg1);
|
|
ptr2 = GETARR(trg2);
|
|
|
|
len1 = ARRNELEM(trg1);
|
|
len2 = ARRNELEM(trg2);
|
|
|
|
while (ptr1 - GETARR(trg1) < len1 && ptr2 - GETARR(trg2) < len2)
|
|
{
|
|
int res = CMPTRGM(ptr1, ptr2);
|
|
|
|
if (res < 0)
|
|
return false;
|
|
else if (res > 0)
|
|
ptr2++;
|
|
else
|
|
{
|
|
ptr1++;
|
|
ptr2++;
|
|
}
|
|
}
|
|
if (ptr1 - GETARR(trg1) < len1)
|
|
return false;
|
|
else
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Return a palloc'd boolean array showing, for each trigram in "query",
|
|
* whether it is present in the trigram array "key".
|
|
* This relies on the "key" array being sorted, but "query" need not be.
|
|
*/
|
|
bool *
|
|
trgm_presence_map(TRGM *query, TRGM *key)
|
|
{
|
|
bool *result;
|
|
trgm *ptrq = GETARR(query),
|
|
*ptrk = GETARR(key);
|
|
int lenq = ARRNELEM(query),
|
|
lenk = ARRNELEM(key),
|
|
i;
|
|
|
|
result = (bool *) palloc0(lenq * sizeof(bool));
|
|
|
|
/* for each query trigram, do a binary search in the key array */
|
|
for (i = 0; i < lenq; i++)
|
|
{
|
|
int lo = 0;
|
|
int hi = lenk;
|
|
|
|
while (lo < hi)
|
|
{
|
|
int mid = (lo + hi) / 2;
|
|
int res = CMPTRGM(ptrq, ptrk + mid);
|
|
|
|
if (res < 0)
|
|
hi = mid;
|
|
else if (res > 0)
|
|
lo = mid + 1;
|
|
else
|
|
{
|
|
result[i] = true;
|
|
break;
|
|
}
|
|
}
|
|
ptrq++;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
Datum
|
|
similarity(PG_FUNCTION_ARGS)
|
|
{
|
|
text *in1 = PG_GETARG_TEXT_P(0);
|
|
text *in2 = PG_GETARG_TEXT_P(1);
|
|
TRGM *trg1,
|
|
*trg2;
|
|
float4 res;
|
|
|
|
trg1 = generate_trgm(VARDATA(in1), VARSIZE(in1) - VARHDRSZ);
|
|
trg2 = generate_trgm(VARDATA(in2), VARSIZE(in2) - VARHDRSZ);
|
|
|
|
res = cnt_sml(trg1, trg2);
|
|
|
|
pfree(trg1);
|
|
pfree(trg2);
|
|
PG_FREE_IF_COPY(in1, 0);
|
|
PG_FREE_IF_COPY(in2, 1);
|
|
|
|
PG_RETURN_FLOAT4(res);
|
|
}
|
|
|
|
Datum
|
|
similarity_dist(PG_FUNCTION_ARGS)
|
|
{
|
|
float4 res = DatumGetFloat4(DirectFunctionCall2(similarity,
|
|
PG_GETARG_DATUM(0),
|
|
PG_GETARG_DATUM(1)));
|
|
|
|
PG_RETURN_FLOAT4(1.0 - res);
|
|
}
|
|
|
|
Datum
|
|
similarity_op(PG_FUNCTION_ARGS)
|
|
{
|
|
float4 res = DatumGetFloat4(DirectFunctionCall2(similarity,
|
|
PG_GETARG_DATUM(0),
|
|
PG_GETARG_DATUM(1)));
|
|
|
|
PG_RETURN_BOOL(res >= trgm_limit);
|
|
}
|