/* ** 2006 Oct 10 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ****************************************************************************** ** ** Implementation of the "simple" full-text-search tokenizer. */ /* ** The code in this file is only compiled if: ** ** * The FTS3 module is being built as an extension ** (in which case SQLITE_CORE is not defined), or ** ** * The FTS3 module is being built into the core of ** SQLite (in which case SQLITE_ENABLE_FTS3 is defined). */ #include "fts3Int.h" #if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) #include <assert.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include "fts3_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; static int simpleDelim(simple_tokenizer *t, unsigned char c){ return c<0x80 && t->delim[c]; } static int fts3_isalnum(int x){ return (x>='0' && x<='9') || (x>='A' && x<='Z') || (x>='a' && x<='z'); } /* ** Create a new tokenizer instance. */ static int simpleCreate( int argc, const char * const *argv, sqlite3_tokenizer **ppTokenizer ){ simple_tokenizer *t; t = (simple_tokenizer *) sqlite3_malloc(sizeof(*t)); if( t==NULL ) return SQLITE_NOMEM; memset(t, 0, sizeof(*t)); /* 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 = (int)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 ){ sqlite3_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] = !fts3_isalnum(i) ? -1 : 0; } } *ppTokenizer = &t->base; return SQLITE_OK; } /* ** Destroy a tokenizer */ static int simpleDestroy(sqlite3_tokenizer *pTokenizer){ sqlite3_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; UNUSED_PARAMETER(pTokenizer); c = (simple_tokenizer_cursor *) sqlite3_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; sqlite3_free(c->pToken); sqlite3_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 && simpleDelim(t, p[c->iOffset]) ){ c->iOffset++; } /* Count non-delimiter characters. */ iStartOffset = c->iOffset; while( c->iOffset<c->nBytes && !simpleDelim(t, p[c->iOffset]) ){ c->iOffset++; } if( c->iOffset>iStartOffset ){ int i, n = c->iOffset-iStartOffset; if( n>c->nTokenAllocated ){ char *pNew; c->nTokenAllocated = n+20; pNew = sqlite3_realloc(c->pToken, c->nTokenAllocated); if( !pNew ) return SQLITE_NOMEM; c->pToken = pNew; } 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] = (char)((ch>='A' && ch<='Z') ? ch-'A'+'a' : 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, 0, }; /* ** Allocate a new simple tokenizer. Return a pointer to the new ** tokenizer in *ppModule */ void sqlite3Fts3SimpleTokenizerModule( sqlite3_tokenizer_module const**ppModule ){ *ppModule = &simpleTokenizerModule; } #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */