diff options
Diffstat (limited to 'ext/fts1/fts1_tokenizer1.c')
| -rw-r--r-- | ext/fts1/fts1_tokenizer1.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/ext/fts1/fts1_tokenizer1.c b/ext/fts1/fts1_tokenizer1.c new file mode 100644 index 0000000..f58fba8 --- /dev/null +++ b/ext/fts1/fts1_tokenizer1.c @@ -0,0 +1,221 @@ +/* +** The author disclaims copyright to this source code. +** +************************************************************************* +** Implementation of the "simple" full-text-search tokenizer. +*/ + +/* +** The code in this file is only compiled if: +** +** * The FTS1 module is being built as an extension +** (in which case SQLITE_CORE is not defined), or +** +** * The FTS1 module is being built into the core of +** SQLite (in which case SQLITE_ENABLE_FTS1 is defined). +*/ +#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) + + +#include <assert.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <ctype.h> + +#include "fts1_tokenizer.h" + +typedef struct simple_tokenizer { + sqlite3_tokenizer base; + char delim[128]; /* flag ASCII 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 */ + int iOffset; /* current position in pInput */ + int iToken; /* index of next token to be returned */ + char *pToken; /* storage for current token */ + int nTokenAllocated; /* space allocated to zToken buffer */ +} simple_tokenizer_cursor; + + +/* Forward declaration */ +static const sqlite3_tokenizer_module simpleTokenizerModule; + +static int isDelim(simple_tokenizer *t, unsigned char c){ + return c<0x80 && t->delim[c]; +} + +/* +** Create a new tokenizer instance. +*/ +static int simpleCreate( + int argc, const char * const *argv, + sqlite3_tokenizer **ppTokenizer +){ + simple_tokenizer *t; + + t = (simple_tokenizer *) calloc(sizeof(*t), 1); + if( t==NULL ) return SQLITE_NOMEM; + + /* 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 ){ + int i, n = strlen(argv[1]); + for(i=0; i<n; i++){ + unsigned char ch = argv[1][i]; + /* We explicitly don't support UTF-8 delimiters for now. */ + if( ch>=0x80 ){ + free(t); + return SQLITE_ERROR; + } + t->delim[ch] = 1; + } + } else { + /* Mark non-alphanumeric ASCII characters as delimiters */ + int i; + for(i=1; i<0x80; i++){ + t->delim[i] = !isalnum(i); + } + } + + *ppTokenizer = &t->base; + return SQLITE_OK; +} + +/* +** Destroy a tokenizer +*/ +static int simpleDestroy(sqlite3_tokenizer *pTokenizer){ + free(pTokenizer); + return SQLITE_OK; +} + +/* +** Prepare to begin tokenizing a particular string. The input +** string to be tokenized is pInput[0..nBytes-1]. A cursor +** used to incrementally tokenize this string is returned in +** *ppCursor. +*/ +static int simpleOpen( + sqlite3_tokenizer *pTokenizer, /* The tokenizer */ + const char *pInput, int nBytes, /* String to be tokenized */ + sqlite3_tokenizer_cursor **ppCursor /* OUT: Tokenization cursor */ +){ + simple_tokenizer_cursor *c; + + c = (simple_tokenizer_cursor *) malloc(sizeof(*c)); + if( c==NULL ) return SQLITE_NOMEM; + + c->pInput = pInput; + if( pInput==0 ){ + c->nBytes = 0; + }else if( nBytes<0 ){ + c->nBytes = (int)strlen(pInput); + }else{ + c->nBytes = nBytes; + } + c->iOffset = 0; /* start tokenizing at the beginning */ + c->iToken = 0; + c->pToken = NULL; /* no space allocated, yet. */ + c->nTokenAllocated = 0; + + *ppCursor = &c->base; + return SQLITE_OK; +} + +/* +** Close a tokenization cursor previously opened by a call to +** simpleOpen() above. +*/ +static int simpleClose(sqlite3_tokenizer_cursor *pCursor){ + simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; + free(c->pToken); + free(c); + return SQLITE_OK; +} + +/* +** Extract the next token from a tokenization cursor. The cursor must +** have been opened by a prior call to simpleOpen(). +*/ +static int simpleNext( + sqlite3_tokenizer_cursor *pCursor, /* Cursor returned by simpleOpen */ + const char **ppToken, /* OUT: *ppToken is the token text */ + int *pnBytes, /* OUT: Number of bytes in token */ + int *piStartOffset, /* OUT: Starting offset of token */ + int *piEndOffset, /* OUT: Ending offset of token */ + int *piPosition /* OUT: Position integer of token */ +){ + simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; + simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer; + unsigned char *p = (unsigned char *)c->pInput; + + while( c->iOffset<c->nBytes ){ + int iStartOffset; + + /* Scan past delimiter characters */ + while( c->iOffset<c->nBytes && isDelim(t, p[c->iOffset]) ){ + c->iOffset++; + } + + /* Count non-delimiter characters. */ + iStartOffset = c->iOffset; + while( c->iOffset<c->nBytes && !isDelim(t, p[c->iOffset]) ){ + c->iOffset++; + } + + if( c->iOffset>iStartOffset ){ + int i, n = c->iOffset-iStartOffset; + if( n>c->nTokenAllocated ){ + c->nTokenAllocated = n+20; + c->pToken = realloc(c->pToken, c->nTokenAllocated); + if( c->pToken==NULL ) return SQLITE_NOMEM; + } + for(i=0; i<n; i++){ + /* TODO(shess) This needs expansion to handle UTF-8 + ** case-insensitivity. + */ + unsigned char ch = p[iStartOffset+i]; + c->pToken[i] = ch<0x80 ? tolower(ch) : ch; + } + *ppToken = c->pToken; + *pnBytes = n; + *piStartOffset = iStartOffset; + *piEndOffset = c->iOffset; + *piPosition = c->iToken++; + + return SQLITE_OK; + } + } + return SQLITE_DONE; +} + +/* +** The set of routines that implement the simple tokenizer +*/ +static const sqlite3_tokenizer_module simpleTokenizerModule = { + 0, + simpleCreate, + simpleDestroy, + simpleOpen, + simpleClose, + simpleNext, +}; + +/* +** Allocate a new simple tokenizer. Return a pointer to the new +** tokenizer in *ppModule +*/ +void sqlite3Fts1SimpleTokenizerModule( + sqlite3_tokenizer_module const**ppModule +){ + *ppModule = &simpleTokenizerModule; +} + +#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) */ |