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Modify fts3 to support a more complex expression syntax that allows parenthesis. The new syntax is not entirely backwards compatible, so is disabled by default. Use -DSQLITE_ENABLE_FTS3_PARENTHESIS to enable it. (CVS 6034)
FossilOrigin-Name: 7389b9ecb80294569845c40a23e0c832d07f7a45
This commit is contained in:
danielk1977
864
ext/fts3/fts3_expr.c
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864
ext/fts3/fts3_expr.c
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@ -0,0 +1,864 @@
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/*
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** 2008 Nov 28
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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******************************************************************************
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**
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** This module contains code that implements a parser for fts3 query strings
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** (the right-hand argument to the MATCH operator). Because the supported
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** syntax is relatively simple, the whole tokenizer/parser system is
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** hand-coded. The public interface to this module is declared in source
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** code file "fts3_expr.h".
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*/
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/*
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** By default, this module parses the legacy syntax that has been
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** traditionally used by fts3. Or, if SQLITE_ENABLE_FTS3_PARENTHESIS
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** is defined, then it uses the new syntax. The differences between
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** the new and the old syntaxes are:
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**
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** a) The new syntax supports parenthesis. The old does not.
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**
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** b) The new syntax supports the AND and NOT operators. The old does not.
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**
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** c) The old syntax supports the "-" token qualifier. This is not
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** supported by the new syntax (it is replaced by the NOT operator).
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**
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** d) When using the old syntax, the OR operator has a greater precedence
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** than an implicit AND. When using the new, both implicity and explicit
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** AND operators have a higher precedence than OR.
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**
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** If compiled with SQLITE_TEST defined, then this module exports the
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** symbol "int sqlite3_fts3_enable_parentheses". Setting this variable
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** to zero causes the module to use the old syntax. If it is set to
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** non-zero the new syntax is activated. This is so both syntaxes can
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** be tested using a single build of testfixture.
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*/
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#ifdef SQLITE_TEST
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int sqlite3_fts3_enable_parentheses = 0;
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#else
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# ifdef SQLITE_ENABLE_FTS3_PARENTHESIS
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# define sqlite3_fts3_enable_parentheses 1
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# else
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# define sqlite3_fts3_enable_parentheses 0
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# endif
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#endif
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/*
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** Default span for NEAR operators.
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*/
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#define SQLITE_FTS3_DEFAULT_NEAR_PARAM 10
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#include "fts3_expr.h"
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#include "sqlite3.h"
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#include <ctype.h>
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#include <string.h>
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#include <assert.h>
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typedef struct ParseContext ParseContext;
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struct ParseContext {
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sqlite3_tokenizer *pTokenizer; /* Tokenizer module */
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const char **azCol; /* Array of column names for fts3 table */
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int nCol; /* Number of entries in azCol[] */
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int iDefaultCol; /* Default column to query */
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sqlite3_context *pCtx; /* Write error message here */
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int nNest; /* Number of nested brackets */
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};
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/*
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** This function is equivalent to the standard isspace() function.
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**
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** The standard isspace() can be awkward to use safely, because although it
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** is defined to accept an argument of type int, its behaviour when passed
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** an integer that falls outside of the range of the unsigned char type
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** is undefined (and sometimes, "undefined" means segfault). This wrapper
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** is defined to accept an argument of type char, and always returns 0 for
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** any values that fall outside of the range of the unsigned char type (i.e.
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** negative values).
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*/
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static int safe_isspace(char c){
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return (c&0x80)==0 ? isspace(c) : 0;
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}
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/*
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** Extract the next token from buffer z (length n) using the tokenizer
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** and other information (column names etc.) in pParse. Create an Fts3Expr
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** structure of type FTSQUERY_PHRASE containing a phrase consisting of this
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** single token and set *ppExpr to point to it. If the end of the buffer is
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** reached before a token is found, set *ppExpr to zero. It is the
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** responsibility of the caller to eventually deallocate the allocated
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** Fts3Expr structure (if any) by passing it to sqlite3_free().
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**
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** Return SQLITE_OK if successful, or SQLITE_NOMEM if a memory allocation
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** fails.
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*/
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static int getNextToken(
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ParseContext *pParse, /* fts3 query parse context */
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int iCol, /* Value for Fts3Phrase.iColumn */
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const char *z, int n, /* Input string */
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Fts3Expr **ppExpr, /* OUT: expression */
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int *pnConsumed /* OUT: Number of bytes consumed */
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){
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sqlite3_tokenizer *pTokenizer = pParse->pTokenizer;
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sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
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int rc;
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sqlite3_tokenizer_cursor *pCursor;
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Fts3Expr *pRet = 0;
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int nConsumed = 0;
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rc = pModule->xOpen(pTokenizer, z, n, &pCursor);
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if( rc==SQLITE_OK ){
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const char *zToken;
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int nToken, iStart, iEnd, iPosition;
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int nByte; /* total space to allocate */
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pCursor->pTokenizer = pTokenizer;
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rc = pModule->xNext(pCursor, &zToken, &nToken, &iStart, &iEnd, &iPosition);
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if( rc==SQLITE_OK ){
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nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase) + nToken;
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pRet = (Fts3Expr *)sqlite3_malloc(nByte);
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if( !pRet ){
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rc = SQLITE_NOMEM;
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}else{
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memset(pRet, 0, nByte);
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pRet->eType = FTSQUERY_PHRASE;
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pRet->pPhrase = (Fts3Phrase *)&pRet[1];
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pRet->pPhrase->nToken = 1;
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pRet->pPhrase->iColumn = iCol;
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pRet->pPhrase->aToken[0].n = nToken;
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pRet->pPhrase->aToken[0].z = (char *)&pRet->pPhrase[1];
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memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);
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if( iEnd<n && z[iEnd]=='*' ){
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pRet->pPhrase->aToken[0].isPrefix = 1;
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iEnd++;
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}
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if( !sqlite3_fts3_enable_parentheses && iStart>0 && z[iStart-1]=='-' ){
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pRet->pPhrase->isNot = 1;
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}
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}
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}
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nConsumed = iEnd;
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pModule->xClose(pCursor);
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}
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*pnConsumed = nConsumed;
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*ppExpr = pRet;
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return rc;
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}
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void realloc_or_free(void **ppOrig, int nNew){
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void *pRet = sqlite3_realloc(*ppOrig, nNew);
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if( !pRet ){
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sqlite3_free(*ppOrig);
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}
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*ppOrig = pRet;
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}
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/*
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** Buffer zInput, length nInput, contains the contents of a quoted string
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** that appeared as part of an fts3 query expression. Neither quote character
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** is included in the buffer. This function attempts to tokenize the entire
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** input buffer and create an Fts3Expr structure of type FTSQUERY_PHRASE
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** containing the results.
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**
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** If successful, SQLITE_OK is returned and *ppExpr set to point at the
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** allocated Fts3Expr structure. Otherwise, either SQLITE_NOMEM (out of memory
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** error) or SQLITE_ERROR (tokenization error) is returned and *ppExpr set
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** to 0.
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*/
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static int getNextString(
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ParseContext *pParse, /* fts3 query parse context */
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const char *zInput, int nInput, /* Input string */
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Fts3Expr **ppExpr /* OUT: expression */
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){
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sqlite3_tokenizer *pTokenizer = pParse->pTokenizer;
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sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
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int rc;
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Fts3Expr *p = 0;
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sqlite3_tokenizer_cursor *pCursor = 0;
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char *zTemp = 0;
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int nTemp = 0;
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rc = pModule->xOpen(pTokenizer, zInput, nInput, &pCursor);
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if( rc==SQLITE_OK ){
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int ii;
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pCursor->pTokenizer = pTokenizer;
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for(ii=0; rc==SQLITE_OK; ii++){
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const char *zToken;
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int nToken, iBegin, iEnd, iPos;
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rc = pModule->xNext(pCursor, &zToken, &nToken, &iBegin, &iEnd, &iPos);
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if( rc==SQLITE_OK ){
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int nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
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realloc_or_free((void **)&p, nByte+ii*sizeof(struct PhraseToken));
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realloc_or_free((void **)&zTemp, nTemp + nToken);
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if( !p || !zTemp ){
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goto no_mem;
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}
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if( ii==0 ){
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memset(p, 0, nByte);
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p->pPhrase = (Fts3Phrase *)&p[1];
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p->eType = FTSQUERY_PHRASE;
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p->pPhrase->iColumn = pParse->iDefaultCol;
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}
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p->pPhrase = (Fts3Phrase *)&p[1];
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p->pPhrase->nToken = ii+1;
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p->pPhrase->aToken[ii].n = nToken;
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memcpy(&zTemp[nTemp], zToken, nToken);
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nTemp += nToken;
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if( iEnd<nInput && zInput[iEnd]=='*' ){
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p->pPhrase->aToken[ii].isPrefix = 1;
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}else{
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p->pPhrase->aToken[ii].isPrefix = 0;
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}
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}
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}
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pModule->xClose(pCursor);
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pCursor = 0;
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}
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if( rc==SQLITE_DONE ){
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int jj;
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char *zNew;
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int nNew = 0;
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int nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
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nByte += (p->pPhrase->nToken-1) * sizeof(struct PhraseToken);
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realloc_or_free((void **)&p, nByte + nTemp);
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if( !p ){
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goto no_mem;
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}
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p->pPhrase = (Fts3Phrase *)&p[1];
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zNew = &(((char *)p)[nByte]);
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memcpy(zNew, zTemp, nTemp);
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for(jj=0; jj<p->pPhrase->nToken; jj++){
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p->pPhrase->aToken[jj].z = &zNew[nNew];
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nNew += p->pPhrase->aToken[jj].n;
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}
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sqlite3_free(zTemp);
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rc = SQLITE_OK;
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}
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*ppExpr = p;
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return rc;
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no_mem:
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if( pCursor ){
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pModule->xClose(pCursor);
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}
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sqlite3_free(zTemp);
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sqlite3_free(p);
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*ppExpr = 0;
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return SQLITE_NOMEM;
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}
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/*
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** Function getNextNode(), which is called by fts3ExprParse(), may itself
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** call fts3ExprParse(). So this forward declaration is required.
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*/
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static int fts3ExprParse(ParseContext *, const char *, int, Fts3Expr **, int *);
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/*
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** The output variable *ppExpr is populated with an allocated Fts3Expr
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** structure, or set to 0 if the end of the input buffer is reached.
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**
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** Returns an SQLite error code. SQLITE_OK if everything works, SQLITE_NOMEM
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** if a malloc failure occurs, or SQLITE_ERROR if a parse error is encountered.
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** If SQLITE_ERROR is returned, pContext is populated with an error message.
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*/
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static int getNextNode(
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ParseContext *pParse, /* fts3 query parse context */
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const char *z, int n, /* Input string */
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Fts3Expr **ppExpr, /* OUT: expression */
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int *pnConsumed /* OUT: Number of bytes consumed */
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){
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struct Fts3Keyword {
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char *z;
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int n;
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int eType;
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} aKeyword[] = {
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{ "OR" , 2, FTSQUERY_OR },
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{ "AND", 3, FTSQUERY_AND },
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{ "NOT", 3, FTSQUERY_NOT },
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{ "NEAR", 4, FTSQUERY_NEAR }
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};
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int ii;
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int iCol;
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int iColLen;
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int rc;
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Fts3Expr *pRet = 0;
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const char *zInput = z;
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int nInput = n;
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/* Skip over any whitespace before checking for a keyword, an open or
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** close bracket, or a quoted string.
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*/
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while( nInput>0 && safe_isspace(*zInput) ){
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nInput--;
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zInput++;
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}
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/* See if we are dealing with a keyword. */
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for(ii=0; ii<sizeof(aKeyword)/sizeof(struct Fts3Keyword); ii++){
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struct Fts3Keyword *pKey = &aKeyword[ii];
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if( (0==sqlite3_fts3_enable_parentheses)
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&& (pKey->eType==FTSQUERY_AND || pKey->eType==FTSQUERY_NOT)
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){
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continue;
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}
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if( nInput>=pKey->n && 0==memcmp(zInput, pKey->z, pKey->n) ){
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int nNear = SQLITE_FTS3_DEFAULT_NEAR_PARAM;
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int nKey = pKey->n;
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char cNext;
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/* If this is a "NEAR" keyword, check for an explicit nearness. */
|
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if( pKey->eType==FTSQUERY_NEAR ){
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assert( nKey==4 );
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if( zInput[4]=='/' && zInput[5]>='0' && zInput[5]<='9' ){
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nNear = 0;
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for(nKey=5; zInput[nKey]>='0' && zInput[nKey]<='9'; nKey++){
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nNear = nNear * 10 + (zInput[nKey] - '0');
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}
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}
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}
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/* At this point this is probably a keyword. But for that to be true,
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** the next byte must contain either whitespace, an open or close
|
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** bracket, a quote character, or EOF.
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*/
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cNext = zInput[nKey];
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if( safe_isspace(cNext)
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|| cNext=='"' || cNext=='(' || cNext==')' || cNext==0
|
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){
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pRet = (Fts3Expr *)sqlite3_malloc(sizeof(Fts3Expr));
|
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memset(pRet, 0, sizeof(Fts3Expr));
|
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pRet->eType = pKey->eType;
|
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pRet->nNear = nNear;
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*ppExpr = pRet;
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*pnConsumed = (zInput - z) + nKey;
|
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return SQLITE_OK;
|
||||
}
|
||||
|
||||
/* Turns out that wasn't a keyword after all. This happens if the
|
||||
** user has supplied a token such as "ORacle". Continue.
|
||||
*/
|
||||
}
|
||||
}
|
||||
|
||||
/* Check for an open bracket. */
|
||||
if( sqlite3_fts3_enable_parentheses ){
|
||||
if( *zInput=='(' ){
|
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int nConsumed;
|
||||
int rc;
|
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pParse->nNest++;
|
||||
rc = fts3ExprParse(pParse, &zInput[1], nInput-1, ppExpr, &nConsumed);
|
||||
*pnConsumed = (zInput - z) + 1 + nConsumed;
|
||||
return rc;
|
||||
}
|
||||
|
||||
/* Check for a close bracket. */
|
||||
if( *zInput==')' ){
|
||||
pParse->nNest--;
|
||||
*pnConsumed = (zInput - z) + 1;
|
||||
return SQLITE_DONE;
|
||||
}
|
||||
}
|
||||
|
||||
/* See if we are dealing with a quoted phrase. If this is the case, then
|
||||
** search for the closing quote and pass the whole string to getNextString()
|
||||
** for processing. This is easy to do, as fts3 has no syntax for escaping
|
||||
** a quote character embedded in a string.
|
||||
*/
|
||||
if( *zInput=='"' ){
|
||||
for(ii=1; ii<nInput && zInput[ii]!='"'; ii++);
|
||||
*pnConsumed = (zInput - z) + ii + 1;
|
||||
if( ii==nInput ){
|
||||
return SQLITE_ERROR;
|
||||
}
|
||||
return getNextString(pParse, &zInput[1], ii-1, ppExpr);
|
||||
}
|
||||
|
||||
|
||||
/* If control flows to this point, this must be a regular token, or
|
||||
** the end of the input. Read a regular token using the sqlite3_tokenizer
|
||||
** interface. Before doing so, figure out if there is an explicit
|
||||
** column specifier for the token.
|
||||
**
|
||||
** TODO: Strangely, it is not possible to associate a column specifier
|
||||
** with a quoted phrase, only with a single token. Not sure if this was
|
||||
** an implementation artifact or an intentional decision when fts3 was
|
||||
** first implemented. Whichever it was, this module duplicates the
|
||||
** limitation.
|
||||
*/
|
||||
iCol = pParse->iDefaultCol;
|
||||
iColLen = 0;
|
||||
for(ii=0; ii<pParse->nCol; ii++){
|
||||
const char *zStr = pParse->azCol[ii];
|
||||
int nStr = strlen(zStr);
|
||||
if( nInput>nStr && zInput[nStr]==':' && memcmp(zStr, zInput, nStr)==0 ){
|
||||
iCol = ii;
|
||||
iColLen = ((zInput - z) + nStr + 1);
|
||||
break;
|
||||
}
|
||||
}
|
||||
rc = getNextToken(pParse, iCol, &z[iColLen], n-iColLen, ppExpr, pnConsumed);
|
||||
*pnConsumed += iColLen;
|
||||
return rc;
|
||||
}
|
||||
|
||||
/*
|
||||
** The argument is an Fts3Expr structure for a binary operator (any type
|
||||
** except an FTSQUERY_PHRASE). Return an integer value representing the
|
||||
** precedence of the operator. Lower values have a higher precedence (i.e.
|
||||
** group more tightly). For example, in the C language, the == operator
|
||||
** groups more tightly than ||, and would therefore have a higher precedence.
|
||||
**
|
||||
** When using the new fts3 query syntax (when SQLITE_ENABLE_FTS3_PARENTHESIS
|
||||
** is defined), the order of the operators in precedence from highest to
|
||||
** lowest is:
|
||||
**
|
||||
** NEAR
|
||||
** NOT
|
||||
** AND (including implicit ANDs)
|
||||
** OR
|
||||
**
|
||||
** Note that when using the old query syntax, the OR operator has a higher
|
||||
** precedence than the AND operator.
|
||||
*/
|
||||
static int opPrecedence(Fts3Expr *p){
|
||||
assert( p->eType!=FTSQUERY_PHRASE );
|
||||
if( sqlite3_fts3_enable_parentheses ){
|
||||
return p->eType;
|
||||
}else if( p->eType==FTSQUERY_NEAR ){
|
||||
return 1;
|
||||
}else if( p->eType==FTSQUERY_OR ){
|
||||
return 2;
|
||||
}
|
||||
assert( p->eType==FTSQUERY_AND );
|
||||
return 3;
|
||||
}
|
||||
|
||||
/*
|
||||
** Argument ppHead contains a pointer to the current head of a query
|
||||
** expression tree being parsed. pPrev is the expression node most recently
|
||||
** inserted into the tree. This function adds pNew, which is always a binary
|
||||
** operator node, into the expression tree based on the relative precedence
|
||||
** of pNew and the existing nodes of the tree. This may result in the head
|
||||
** of the tree changing, in which case *ppHead is set to the new root node.
|
||||
*/
|
||||
static void insertBinaryOperator(
|
||||
Fts3Expr **ppHead, /* Pointer to the root node of a tree */
|
||||
Fts3Expr *pPrev, /* Node most recently inserted into the tree */
|
||||
Fts3Expr *pNew /* New binary node to insert into expression tree */
|
||||
){
|
||||
Fts3Expr *pSplit = pPrev;
|
||||
while( pSplit->pParent && opPrecedence(pSplit->pParent)<=opPrecedence(pNew) ){
|
||||
pSplit = pSplit->pParent;
|
||||
}
|
||||
|
||||
if( pSplit->pParent ){
|
||||
assert( pSplit->pParent->pRight==pSplit );
|
||||
pSplit->pParent->pRight = pNew;
|
||||
pNew->pParent = pSplit->pParent;
|
||||
}else{
|
||||
*ppHead = pNew;
|
||||
}
|
||||
pNew->pLeft = pSplit;
|
||||
pSplit->pParent = pNew;
|
||||
}
|
||||
|
||||
/*
|
||||
** Parse the fts3 query expression found in buffer z, length n. This function
|
||||
** returns either when the end of the buffer is reached or an unmatched
|
||||
** closing bracket - ')' - is encountered.
|
||||
**
|
||||
** If successful, SQLITE_OK is returned, *ppExpr is set to point to the
|
||||
** parsed form of the expression and *pnConsumed is set to the number of
|
||||
** bytes read from buffer z. Otherwise, *ppExpr is set to 0 and SQLITE_NOMEM
|
||||
** (out of memory error) or SQLITE_ERROR (parse error) is returned.
|
||||
*/
|
||||
static int fts3ExprParse(
|
||||
ParseContext *pParse, /* fts3 query parse context */
|
||||
const char *z, int n, /* Text of MATCH query */
|
||||
Fts3Expr **ppExpr, /* OUT: Parsed query structure */
|
||||
int *pnConsumed /* OUT: Number of bytes consumed */
|
||||
){
|
||||
Fts3Expr *pRet = 0;
|
||||
Fts3Expr *pPrev = 0;
|
||||
Fts3Expr *pNotBranch = 0; /* Only used in legacy parse mode */
|
||||
int nIn = n;
|
||||
const char *zIn = z;
|
||||
int rc = SQLITE_OK;
|
||||
int isRequirePhrase = 1;
|
||||
|
||||
while( rc==SQLITE_OK ){
|
||||
Fts3Expr *p = 0;
|
||||
int nByte;
|
||||
rc = getNextNode(pParse, zIn, nIn, &p, &nByte);
|
||||
if( rc==SQLITE_OK ){
|
||||
int isPhrase;
|
||||
|
||||
if( !sqlite3_fts3_enable_parentheses
|
||||
&& p->eType==FTSQUERY_PHRASE && p->pPhrase->isNot
|
||||
){
|
||||
/* Create an implicit NOT operator. */
|
||||
Fts3Expr *pNot = sqlite3_malloc(sizeof(Fts3Expr));
|
||||
if( !pNot ){
|
||||
sqlite3Fts3ExprFree(p);
|
||||
rc = SQLITE_NOMEM;
|
||||
goto exprparse_out;
|
||||
}
|
||||
memset(pNot, 0, sizeof(Fts3Expr));
|
||||
pNot->eType = FTSQUERY_NOT;
|
||||
pNot->pRight = p;
|
||||
if( pNotBranch ){
|
||||
pNotBranch->pLeft = p;
|
||||
pNot->pRight = pNotBranch;
|
||||
}
|
||||
pNotBranch = pNot;
|
||||
}else{
|
||||
assert( p->eType!=FTSQUERY_PHRASE || !p->pPhrase->isNot );
|
||||
isPhrase = (p->eType==FTSQUERY_PHRASE || p->pLeft);
|
||||
if( !isPhrase && isRequirePhrase ){
|
||||
sqlite3Fts3ExprFree(p);
|
||||
rc = SQLITE_ERROR;
|
||||
goto exprparse_out;
|
||||
}
|
||||
|
||||
if( isPhrase && !isRequirePhrase ){
|
||||
/* Insert an implicit AND operator. */
|
||||
Fts3Expr *pAnd;
|
||||
assert( pRet && pPrev );
|
||||
pAnd = sqlite3_malloc(sizeof(Fts3Expr));
|
||||
if( !pAnd ){
|
||||
sqlite3Fts3ExprFree(p);
|
||||
rc = SQLITE_NOMEM;
|
||||
goto exprparse_out;
|
||||
}
|
||||
memset(pAnd, 0, sizeof(Fts3Expr));
|
||||
pAnd->eType = FTSQUERY_AND;
|
||||
insertBinaryOperator(&pRet, pPrev, pAnd);
|
||||
pPrev = pAnd;
|
||||
}
|
||||
|
||||
if( pPrev && (
|
||||
(pPrev->eType==FTSQUERY_NEAR && p->eType!=FTSQUERY_PHRASE)
|
||||
|| (p->eType==FTSQUERY_NEAR && pPrev->eType!=FTSQUERY_PHRASE)
|
||||
)){
|
||||
/* This is an attempt to do "phrase NEAR (bracketed expression)"
|
||||
** or "(bracketed expression) NEAR phrase", both of which are
|
||||
** illegal. Return an error.
|
||||
*/
|
||||
sqlite3Fts3ExprFree(p);
|
||||
rc = SQLITE_ERROR;
|
||||
goto exprparse_out;
|
||||
}
|
||||
|
||||
if( isPhrase ){
|
||||
if( pRet ){
|
||||
assert( pPrev && pPrev->pLeft && pPrev->pRight==0 );
|
||||
pPrev->pRight = p;
|
||||
p->pParent = pPrev;
|
||||
}else{
|
||||
pRet = p;
|
||||
}
|
||||
}else{
|
||||
insertBinaryOperator(&pRet, pPrev, p);
|
||||
}
|
||||
isRequirePhrase = !isPhrase;
|
||||
}
|
||||
assert( nByte>0 );
|
||||
}
|
||||
nIn -= nByte;
|
||||
zIn += nByte;
|
||||
pPrev = p;
|
||||
}
|
||||
|
||||
if( rc==SQLITE_DONE && pRet && isRequirePhrase ){
|
||||
rc = SQLITE_ERROR;
|
||||
}
|
||||
|
||||
if( rc==SQLITE_DONE ){
|
||||
rc = SQLITE_OK;
|
||||
if( !sqlite3_fts3_enable_parentheses && pNotBranch ){
|
||||
if( !pRet ){
|
||||
rc = SQLITE_ERROR;
|
||||
}else{
|
||||
pNotBranch->pLeft = pRet;
|
||||
pRet = pNotBranch;
|
||||
}
|
||||
}
|
||||
}
|
||||
*pnConsumed = n - nIn;
|
||||
|
||||
exprparse_out:
|
||||
if( rc!=SQLITE_OK ){
|
||||
sqlite3Fts3ExprFree(pRet);
|
||||
sqlite3Fts3ExprFree(pNotBranch);
|
||||
pRet = 0;
|
||||
}
|
||||
*ppExpr = pRet;
|
||||
return rc;
|
||||
}
|
||||
|
||||
/*
|
||||
** Parameters z and n contain a pointer to and length of a buffer containing
|
||||
** an fts3 query expression, respectively. This function attempts to parse the
|
||||
** query expression and create a tree of Fts3Expr structures representing the
|
||||
** parsed expression. If successful, *ppExpr is set to point to the head
|
||||
** of the parsed expression tree and SQLITE_OK is returned. If an error
|
||||
** occurs, either SQLITE_NOMEM (out-of-memory error) or SQLITE_ERROR (parse
|
||||
** error) is returned and *ppExpr is set to 0.
|
||||
**
|
||||
** If parameter n is a negative number, then z is assumed to point to a
|
||||
** nul-terminated string and the length is determined using strlen().
|
||||
**
|
||||
** The first parameter, pTokenizer, is passed the fts3 tokenizer module to
|
||||
** use to normalize query tokens while parsing the expression. The azCol[]
|
||||
** array, which is assumed to contain nCol entries, should contain the names
|
||||
** of each column in the target fts3 table, in order from left to right.
|
||||
** Column names must be nul-terminated strings.
|
||||
**
|
||||
** The iDefaultCol parameter should be passed the index of the table column
|
||||
** that appears on the left-hand-side of the MATCH operator (the default
|
||||
** column to match against for tokens for which a column name is not explicitly
|
||||
** specified as part of the query string), or -1 if tokens may by default
|
||||
** match any table column.
|
||||
*/
|
||||
int sqlite3Fts3ExprParse(
|
||||
sqlite3_tokenizer *pTokenizer, /* Tokenizer module */
|
||||
char **azCol, /* Array of column names for fts3 table */
|
||||
int nCol, /* Number of entries in azCol[] */
|
||||
int iDefaultCol, /* Default column to query */
|
||||
const char *z, int n, /* Text of MATCH query */
|
||||
Fts3Expr **ppExpr /* OUT: Parsed query structure */
|
||||
){
|
||||
int nParsed;
|
||||
int rc;
|
||||
ParseContext sParse;
|
||||
sParse.pTokenizer = pTokenizer;
|
||||
sParse.azCol = (const char **)azCol;
|
||||
sParse.nCol = nCol;
|
||||
sParse.iDefaultCol = iDefaultCol;
|
||||
sParse.nNest = 0;
|
||||
if( z==0 ){
|
||||
*ppExpr = 0;
|
||||
return SQLITE_OK;
|
||||
}
|
||||
if( n<0 ){
|
||||
n = strlen(z);
|
||||
}
|
||||
rc = fts3ExprParse(&sParse, z, n, ppExpr, &nParsed);
|
||||
|
||||
/* Check for mismatched parenthesis */
|
||||
if( rc==SQLITE_OK && sParse.nNest ){
|
||||
rc = SQLITE_ERROR;
|
||||
sqlite3Fts3ExprFree(*ppExpr);
|
||||
*ppExpr = 0;
|
||||
}
|
||||
|
||||
return rc;
|
||||
}
|
||||
|
||||
/*
|
||||
** Free a parsed fts3 query expression allocated by sqlite3Fts3ExprParse().
|
||||
*/
|
||||
void sqlite3Fts3ExprFree(Fts3Expr *p){
|
||||
if( p ){
|
||||
sqlite3Fts3ExprFree(p->pLeft);
|
||||
sqlite3Fts3ExprFree(p->pRight);
|
||||
sqlite3_free(p);
|
||||
}
|
||||
}
|
||||
|
||||
/****************************************************************************
|
||||
*****************************************************************************
|
||||
** Everything after this point is just test code.
|
||||
*/
|
||||
|
||||
#ifdef SQLITE_TEST
|
||||
|
||||
#include <stdio.h>
|
||||
|
||||
/*
|
||||
** Function to query the hash-table of tokenizers (see README.tokenizers).
|
||||
*/
|
||||
static int queryTokenizer(
|
||||
sqlite3 *db,
|
||||
const char *zName,
|
||||
const sqlite3_tokenizer_module **pp
|
||||
){
|
||||
int rc;
|
||||
sqlite3_stmt *pStmt;
|
||||
const char zSql[] = "SELECT fts3_tokenizer(?)";
|
||||
|
||||
*pp = 0;
|
||||
rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
|
||||
if( rc!=SQLITE_OK ){
|
||||
return rc;
|
||||
}
|
||||
|
||||
sqlite3_bind_text(pStmt, 1, zName, -1, SQLITE_STATIC);
|
||||
if( SQLITE_ROW==sqlite3_step(pStmt) ){
|
||||
if( sqlite3_column_type(pStmt, 0)==SQLITE_BLOB ){
|
||||
memcpy(pp, sqlite3_column_blob(pStmt, 0), sizeof(*pp));
|
||||
}
|
||||
}
|
||||
|
||||
return sqlite3_finalize(pStmt);
|
||||
}
|
||||
|
||||
/*
|
||||
** This function is part of the test interface for the query parser. It
|
||||
** writes a text representation of the query expression pExpr into the
|
||||
** buffer pointed to by argument zBuf. It is assumed that zBuf is large
|
||||
** enough to store the required text representation.
|
||||
*/
|
||||
static void exprToString(Fts3Expr *pExpr, char *zBuf){
|
||||
switch( pExpr->eType ){
|
||||
case FTSQUERY_PHRASE: {
|
||||
Fts3Phrase *pPhrase = pExpr->pPhrase;
|
||||
int i;
|
||||
zBuf += sprintf(zBuf, "PHRASE %d %d", pPhrase->iColumn, pPhrase->isNot);
|
||||
for(i=0; i<pPhrase->nToken; i++){
|
||||
zBuf += sprintf(zBuf," %.*s",pPhrase->aToken[i].n,pPhrase->aToken[i].z);
|
||||
zBuf += sprintf(zBuf,"%s", (pPhrase->aToken[i].isPrefix?"+":""));
|
||||
}
|
||||
return;
|
||||
}
|
||||
|
||||
case FTSQUERY_NEAR:
|
||||
zBuf += sprintf(zBuf, "NEAR/%d ", pExpr->nNear);
|
||||
break;
|
||||
case FTSQUERY_NOT:
|
||||
zBuf += sprintf(zBuf, "NOT ");
|
||||
break;
|
||||
case FTSQUERY_AND:
|
||||
zBuf += sprintf(zBuf, "AND ");
|
||||
break;
|
||||
case FTSQUERY_OR:
|
||||
zBuf += sprintf(zBuf, "OR ");
|
||||
break;
|
||||
}
|
||||
|
||||
zBuf += sprintf(zBuf, "{");
|
||||
exprToString(pExpr->pLeft, zBuf);
|
||||
zBuf += strlen(zBuf);
|
||||
zBuf += sprintf(zBuf, "} ");
|
||||
|
||||
zBuf += sprintf(zBuf, "{");
|
||||
exprToString(pExpr->pRight, zBuf);
|
||||
zBuf += strlen(zBuf);
|
||||
zBuf += sprintf(zBuf, "}");
|
||||
}
|
||||
|
||||
/*
|
||||
** This is the implementation of a scalar SQL function used to test the
|
||||
** expression parser. It should be called as follows:
|
||||
**
|
||||
** fts3_exprtest(<tokenizer>, <expr>, <column 1>, ...);
|
||||
**
|
||||
** The first argument, <tokenizer>, is the name of the fts3 tokenizer used
|
||||
** to parse the query expression (see README.tokenizers). The second argument
|
||||
** is the query expression to parse. Each subsequent argument is the name
|
||||
** of a column of the fts3 table that the query expression may refer to.
|
||||
** For example:
|
||||
**
|
||||
** SELECT fts3_exprtest('simple', 'Bill col2:Bloggs', 'col1', 'col2');
|
||||
*/
|
||||
static void fts3ExprTest(
|
||||
sqlite3_context *context,
|
||||
int argc,
|
||||
sqlite3_value **argv
|
||||
){
|
||||
sqlite3_tokenizer_module const *pModule = 0;
|
||||
sqlite3_tokenizer *pTokenizer;
|
||||
int rc;
|
||||
char **azCol = 0;
|
||||
const char *zExpr;
|
||||
int nExpr;
|
||||
int nCol;
|
||||
int ii;
|
||||
Fts3Expr *pExpr;
|
||||
sqlite3 *db = sqlite3_context_db_handle(context);
|
||||
|
||||
if( argc<3 ){
|
||||
sqlite3_result_error(context,
|
||||
"Usage: fts3_exprtest(tokenizer, expr, col1, ...", -1
|
||||
);
|
||||
return;
|
||||
}
|
||||
|
||||
rc = queryTokenizer(db, (const char *)sqlite3_value_text(argv[0]), &pModule);
|
||||
if( rc==SQLITE_NOMEM ){
|
||||
sqlite3_result_error_nomem(context);
|
||||
goto exprtest_out;
|
||||
}else if( !pModule ){
|
||||
sqlite3_result_error(context, "No such tokenizer module", -1);
|
||||
goto exprtest_out;
|
||||
}
|
||||
|
||||
rc = pModule->xCreate(0, 0, &pTokenizer);
|
||||
assert( rc==SQLITE_NOMEM || rc==SQLITE_OK );
|
||||
if( rc==SQLITE_NOMEM ){
|
||||
sqlite3_result_error_nomem(context);
|
||||
goto exprtest_out;
|
||||
}
|
||||
pTokenizer->pModule = pModule;
|
||||
|
||||
zExpr = (const char *)sqlite3_value_text(argv[1]);
|
||||
nExpr = sqlite3_value_bytes(argv[1]);
|
||||
nCol = argc-2;
|
||||
azCol = (char **)sqlite3_malloc(nCol*sizeof(char *));
|
||||
if( !azCol ){
|
||||
sqlite3_result_error_nomem(context);
|
||||
goto exprtest_out;
|
||||
}
|
||||
for(ii=0; ii<nCol; ii++){
|
||||
azCol[ii] = (char *)sqlite3_value_text(argv[ii+2]);
|
||||
}
|
||||
|
||||
rc = sqlite3Fts3ExprParse(
|
||||
pTokenizer, azCol, nCol, nCol, zExpr, nExpr, &pExpr
|
||||
);
|
||||
if( rc==SQLITE_NOMEM ){
|
||||
sqlite3_result_error_nomem(context);
|
||||
goto exprtest_out;
|
||||
}else if( rc==SQLITE_OK ){
|
||||
char zBuf[4096];
|
||||
exprToString(pExpr, zBuf);
|
||||
sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
|
||||
sqlite3Fts3ExprFree(pExpr);
|
||||
}else{
|
||||
sqlite3_result_error(context, "Error parsing expression", -1);
|
||||
}
|
||||
|
||||
exprtest_out:
|
||||
if( pTokenizer ){
|
||||
rc = pModule->xDestroy(pTokenizer);
|
||||
}
|
||||
sqlite3_free(azCol);
|
||||
}
|
||||
|
||||
/*
|
||||
** Register the query expression parser test function fts3_exprtest()
|
||||
** with database connection db.
|
||||
*/
|
||||
void sqlite3Fts3ExprInitTestInterface(sqlite3* db){
|
||||
sqlite3_create_function(
|
||||
db, "fts3_exprtest", -1, SQLITE_UTF8, 0, fts3ExprTest, 0, 0
|
||||
);
|
||||
}
|
||||
|
||||
#endif
|
||||
Reference in New Issue
Block a user