diff options
Diffstat (limited to 'ext/fts1/simple_tokenizer.c')
| -rw-r--r-- | ext/fts1/simple_tokenizer.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/ext/fts1/simple_tokenizer.c b/ext/fts1/simple_tokenizer.c new file mode 100644 index 0000000..0ddc705 --- /dev/null +++ b/ext/fts1/simple_tokenizer.c @@ -0,0 +1,174 @@ +/* +** The author disclaims copyright to this source code. +** +************************************************************************* +** Implementation of the "simple" full-text-search tokenizer. +*/ + +#include <assert.h> +#if !defined(__APPLE__) +#include <malloc.h> +#else +#include <stdlib.h> +#endif +#include <stdio.h> +#include <string.h> +#include <ctype.h> + +#include "tokenizer.h" + +/* Duplicate a string; the caller must free() the returned string. + * (We don't use strdup() since it's not part of the standard C library and + * may not be available everywhere.) */ +/* TODO(shess) Copied from fulltext.c, consider util.c for such +** things. */ +static char *string_dup(const char *s){ + char *str = malloc(strlen(s) + 1); + strcpy(str, s); + return str; +} + +typedef struct simple_tokenizer { + sqlite3_tokenizer base; + const char *zDelim; /* token delimiters */ +} simple_tokenizer; + +typedef struct simple_tokenizer_cursor { + sqlite3_tokenizer_cursor base; + const char *pInput; /* input we are tokenizing */ + int nBytes; /* size of the input */ + const char *pCurrent; /* current position in pInput */ + int iToken; /* index of next token to be returned */ + char *zToken; /* storage for current token */ + int nTokenBytes; /* actual size of current token */ + int nTokenAllocated; /* space allocated to zToken buffer */ +} simple_tokenizer_cursor; + +static sqlite3_tokenizer_module simpleTokenizerModule;/* forward declaration */ + +static int simpleCreate( + int argc, const char **argv, + sqlite3_tokenizer **ppTokenizer +){ + simple_tokenizer *t; + + t = (simple_tokenizer *) malloc(sizeof(simple_tokenizer)); + /* TODO(shess) Delimiters need to remain the same from run to run, + ** else we need to reindex. One solution would be a meta-table to + ** track such information in the database, then we'd only want this + ** information on the initial create. + */ + if( argc>1 ){ + t->zDelim = string_dup(argv[1]); + } else { + /* Build a string excluding alphanumeric ASCII characters */ + char zDelim[0x80]; /* nul-terminated, so nul not a member */ + int i, j; + for(i=1, j=0; i<0x80; i++){ + if( !isalnum(i) ){ + zDelim[j++] = i; + } + } + zDelim[j++] = '\0'; + assert( j<=sizeof(zDelim) ); + t->zDelim = string_dup(zDelim); + } + + *ppTokenizer = &t->base; + return SQLITE_OK; +} + +static int simpleDestroy(sqlite3_tokenizer *pTokenizer){ + simple_tokenizer *t = (simple_tokenizer *) pTokenizer; + + free((void *) t->zDelim); + free(t); + + return SQLITE_OK; +} + +static int simpleOpen( + sqlite3_tokenizer *pTokenizer, + const char *pInput, int nBytes, + sqlite3_tokenizer_cursor **ppCursor +){ + simple_tokenizer_cursor *c; + + c = (simple_tokenizer_cursor *) malloc(sizeof(simple_tokenizer_cursor)); + c->pInput = pInput; + c->nBytes = nBytes<0 ? (int) strlen(pInput) : nBytes; + c->pCurrent = c->pInput; /* start tokenizing at the beginning */ + c->iToken = 0; + c->zToken = NULL; /* no space allocated, yet. */ + c->nTokenBytes = 0; + c->nTokenAllocated = 0; + + *ppCursor = &c->base; + return SQLITE_OK; +} + +static int simpleClose(sqlite3_tokenizer_cursor *pCursor){ + simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; + + if( NULL!=c->zToken ){ + free(c->zToken); + } + free(c); + + return SQLITE_OK; +} + +static int simpleNext( + sqlite3_tokenizer_cursor *pCursor, + const char **ppToken, int *pnBytes, + int *piStartOffset, int *piEndOffset, int *piPosition +){ + simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; + simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer; + int ii; + + while( c->pCurrent-c->pInput<c->nBytes ){ + int n = (int) strcspn(c->pCurrent, t->zDelim); + if( n>0 ){ + if( n+1>c->nTokenAllocated ){ + c->zToken = realloc(c->zToken, n+1); + } + for(ii=0; ii<n; ii++){ + /* TODO(shess) This needs expansion to handle UTF-8 + ** case-insensitivity. + */ + char ch = c->pCurrent[ii]; + c->zToken[ii] = (unsigned char)ch<0x80 ? tolower((unsigned char)ch):ch; + } + c->zToken[n] = '\0'; + *ppToken = c->zToken; + *pnBytes = n; + *piStartOffset = (int) (c->pCurrent-c->pInput); + *piEndOffset = *piStartOffset+n; + *piPosition = c->iToken++; + c->pCurrent += n + 1; + + return SQLITE_OK; + } + c->pCurrent += n + 1; + /* TODO(shess) could strspn() to skip delimiters en masse. Needs + ** to happen in two places, though, which is annoying. + */ + } + return SQLITE_DONE; +} + +static sqlite3_tokenizer_module simpleTokenizerModule = { + 0, + simpleCreate, + simpleDestroy, + simpleOpen, + simpleClose, + simpleNext, +}; + +void get_simple_tokenizer_module( + sqlite3_tokenizer_module **ppModule +){ + *ppModule = &simpleTokenizerModule; +} |