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e459b07601
sqlite/ext/fts3/fts3_expr.c
dan e459b07601 Merge the fts4-content branch with the trunk. 
FossilOrigin-Name: 8a4077057ddeb08e8edc5f20a75abaaba7a278ba
2011-10-19 16:20:40 +00:00

985 lines
31 KiB
C
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/*
** 2008 Nov 28
**
** 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.
**
******************************************************************************
**
** This module contains code that implements a parser for fts3 query strings
** (the right-hand argument to the MATCH operator). Because the supported
** syntax is relatively simple, the whole tokenizer/parser system is
** hand-coded.
*/
#include "fts3Int.h"
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
/*
** By default, this module parses the legacy syntax that has been
** traditionally used by fts3. Or, if SQLITE_ENABLE_FTS3_PARENTHESIS
** is defined, then it uses the new syntax. The differences between
** the new and the old syntaxes are:
**
** a) The new syntax supports parenthesis. The old does not.
**
** b) The new syntax supports the AND and NOT operators. The old does not.
**
** c) The old syntax supports the "-" token qualifier. This is not
** supported by the new syntax (it is replaced by the NOT operator).
**
** d) When using the old syntax, the OR operator has a greater precedence
** than an implicit AND. When using the new, both implicity and explicit
** AND operators have a higher precedence than OR.
**
** If compiled with SQLITE_TEST defined, then this module exports the
** symbol "int sqlite3_fts3_enable_parentheses". Setting this variable
** to zero causes the module to use the old syntax. If it is set to
** non-zero the new syntax is activated. This is so both syntaxes can
** be tested using a single build of testfixture.
**
** The following describes the syntax supported by the fts3 MATCH
** operator in a similar format to that used by the lemon parser
** generator. This module does not use actually lemon, it uses a
** custom parser.
**
** query ::= andexpr (OR andexpr)*.
**
** andexpr ::= notexpr (AND? notexpr)*.
**
** notexpr ::= nearexpr (NOT nearexpr|-TOKEN)*.
** notexpr ::= LP query RP.
**
** nearexpr ::= phrase (NEAR distance_opt nearexpr)*.
**
** distance_opt ::= .
** distance_opt ::= / INTEGER.
**
** phrase ::= TOKEN.
** phrase ::= COLUMN:TOKEN.
** phrase ::= "TOKEN TOKEN TOKEN...".
*/
#ifdef SQLITE_TEST
int sqlite3_fts3_enable_parentheses = 0;
#else
# ifdef SQLITE_ENABLE_FTS3_PARENTHESIS
# define sqlite3_fts3_enable_parentheses 1
# else
# define sqlite3_fts3_enable_parentheses 0
# endif
#endif
/*
** Default span for NEAR operators.
*/
#define SQLITE_FTS3_DEFAULT_NEAR_PARAM 10
#include <string.h>
#include <assert.h>
/*
** isNot:
** This variable is used by function getNextNode(). When getNextNode() is
** called, it sets ParseContext.isNot to true if the 'next node' is a
** FTSQUERY_PHRASE with a unary "-" attached to it. i.e. "mysql" in the
** FTS3 query "sqlite -mysql". Otherwise, ParseContext.isNot is set to
** zero.
*/
typedef struct ParseContext ParseContext;
struct ParseContext {
sqlite3_tokenizer *pTokenizer; /* Tokenizer module */
const char **azCol; /* Array of column names for fts3 table */
int bFts4; /* True to allow FTS4-only syntax */
int nCol; /* Number of entries in azCol[] */
int iDefaultCol; /* Default column to query */
int isNot; /* True if getNextNode() sees a unary - */
sqlite3_context *pCtx; /* Write error message here */
int nNest; /* Number of nested brackets */
};
/*
** This function is equivalent to the standard isspace() function.
**
** The standard isspace() can be awkward to use safely, because although it
** is defined to accept an argument of type int, its behaviour when passed
** an integer that falls outside of the range of the unsigned char type
** is undefined (and sometimes, "undefined" means segfault). This wrapper
** is defined to accept an argument of type char, and always returns 0 for
** any values that fall outside of the range of the unsigned char type (i.e.
** negative values).
*/
static int fts3isspace(char c){
return c==' ' || c=='\t' || c=='\n' || c=='\r' || c=='\v' || c=='\f';
}
/*
** Allocate nByte bytes of memory using sqlite3_malloc(). If successful,
** zero the memory before returning a pointer to it. If unsuccessful,
** return NULL.
*/
static void *fts3MallocZero(int nByte){
void *pRet = sqlite3_malloc(nByte);
if( pRet ) memset(pRet, 0, nByte);
return pRet;
}
/*
** Extract the next token from buffer z (length n) using the tokenizer
** and other information (column names etc.) in pParse. Create an Fts3Expr
** structure of type FTSQUERY_PHRASE containing a phrase consisting of this
** single token and set *ppExpr to point to it. If the end of the buffer is
** reached before a token is found, set *ppExpr to zero. It is the
** responsibility of the caller to eventually deallocate the allocated
** Fts3Expr structure (if any) by passing it to sqlite3_free().
**
** Return SQLITE_OK if successful, or SQLITE_NOMEM if a memory allocation
** fails.
*/
static int getNextToken(
ParseContext *pParse, /* fts3 query parse context */
int iCol, /* Value for Fts3Phrase.iColumn */
const char *z, int n, /* Input string */
Fts3Expr **ppExpr, /* OUT: expression */
int *pnConsumed /* OUT: Number of bytes consumed */
){
sqlite3_tokenizer *pTokenizer = pParse->pTokenizer;
sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
int rc;
sqlite3_tokenizer_cursor *pCursor;
Fts3Expr *pRet = 0;
int nConsumed = 0;
rc = pModule->xOpen(pTokenizer, z, n, &pCursor);
if( rc==SQLITE_OK ){
const char *zToken;
int nToken, iStart, iEnd, iPosition;
int nByte; /* total space to allocate */
pCursor->pTokenizer = pTokenizer;
rc = pModule->xNext(pCursor, &zToken, &nToken, &iStart, &iEnd, &iPosition);
if( rc==SQLITE_OK ){
nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase) + nToken;
pRet = (Fts3Expr *)fts3MallocZero(nByte);
if( !pRet ){
rc = SQLITE_NOMEM;
}else{
pRet->eType = FTSQUERY_PHRASE;
pRet->pPhrase = (Fts3Phrase *)&pRet[1];
pRet->pPhrase->nToken = 1;
pRet->pPhrase->iColumn = iCol;
pRet->pPhrase->aToken[0].n = nToken;
pRet->pPhrase->aToken[0].z = (char *)&pRet->pPhrase[1];
memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);
if( iEnd<n && z[iEnd]=='*' ){
pRet->pPhrase->aToken[0].isPrefix = 1;
iEnd++;
}
while( 1 ){
if( !sqlite3_fts3_enable_parentheses
&& iStart>0 && z[iStart-1]=='-'
){
pParse->isNot = 1;
iStart--;
}else if( pParse->bFts4 && iStart>0 && z[iStart-1]=='^' ){
pRet->pPhrase->aToken[0].bFirst = 1;
iStart--;
}else{
break;
}
}
}
nConsumed = iEnd;
}
pModule->xClose(pCursor);
}
*pnConsumed = nConsumed;
*ppExpr = pRet;
return rc;
}
/*
** Enlarge a memory allocation. If an out-of-memory allocation occurs,
** then free the old allocation.
*/
static void *fts3ReallocOrFree(void *pOrig, int nNew){
void *pRet = sqlite3_realloc(pOrig, nNew);
if( !pRet ){
sqlite3_free(pOrig);
}
return pRet;
}
/*
** Buffer zInput, length nInput, contains the contents of a quoted string
** that appeared as part of an fts3 query expression. Neither quote character
** is included in the buffer. This function attempts to tokenize the entire
** input buffer and create an Fts3Expr structure of type FTSQUERY_PHRASE
** containing the results.
**
** If successful, SQLITE_OK is returned and *ppExpr set to point at the
** allocated Fts3Expr structure. Otherwise, either SQLITE_NOMEM (out of memory
** error) or SQLITE_ERROR (tokenization error) is returned and *ppExpr set
** to 0.
*/
static int getNextString(
ParseContext *pParse, /* fts3 query parse context */
const char *zInput, int nInput, /* Input string */
Fts3Expr **ppExpr /* OUT: expression */
){
sqlite3_tokenizer *pTokenizer = pParse->pTokenizer;
sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
int rc;
Fts3Expr *p = 0;
sqlite3_tokenizer_cursor *pCursor = 0;
char *zTemp = 0;
int nTemp = 0;
const int nSpace = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
int nToken = 0;
/* The final Fts3Expr data structure, including the Fts3Phrase,
** Fts3PhraseToken structures token buffers are all stored as a single
** allocation so that the expression can be freed with a single call to
** sqlite3_free(). Setting this up requires a two pass approach.
**
** The first pass, in the block below, uses a tokenizer cursor to iterate
** through the tokens in the expression. This pass uses fts3ReallocOrFree()
** to assemble data in two dynamic buffers:
**
** Buffer p: Points to the Fts3Expr structure, followed by the Fts3Phrase
** structure, followed by the array of Fts3PhraseToken
** structures. This pass only populates the Fts3PhraseToken array.
**
** Buffer zTemp: Contains copies of all tokens.
**
** The second pass, in the block that begins "if( rc==SQLITE_DONE )" below,
** appends buffer zTemp to buffer p, and fills in the Fts3Expr and Fts3Phrase
** structures.
*/
rc = pModule->xOpen(pTokenizer, zInput, nInput, &pCursor);
if( rc==SQLITE_OK ){
int ii;
pCursor->pTokenizer = pTokenizer;
for(ii=0; rc==SQLITE_OK; ii++){
const char *zByte;
int nByte, iBegin, iEnd, iPos;
rc = pModule->xNext(pCursor, &zByte, &nByte, &iBegin, &iEnd, &iPos);
if( rc==SQLITE_OK ){
Fts3PhraseToken *pToken;
p = fts3ReallocOrFree(p, nSpace + ii*sizeof(Fts3PhraseToken));
if( !p ) goto no_mem;
zTemp = fts3ReallocOrFree(zTemp, nTemp + nByte);
if( !zTemp ) goto no_mem;
assert( nToken==ii );
pToken = &((Fts3Phrase *)(&p[1]))->aToken[ii];
memset(pToken, 0, sizeof(Fts3PhraseToken));
memcpy(&zTemp[nTemp], zByte, nByte);
nTemp += nByte;
pToken->n = nByte;
pToken->isPrefix = (iEnd<nInput && zInput[iEnd]=='*');
pToken->bFirst = (iBegin>0 && zInput[iBegin-1]=='^');
nToken = ii+1;
}
}
pModule->xClose(pCursor);
pCursor = 0;
}
if( rc==SQLITE_DONE ){
int jj;
char *zBuf = 0;
p = fts3ReallocOrFree(p, nSpace + nToken*sizeof(Fts3PhraseToken) + nTemp);
if( !p ) goto no_mem;
memset(p, 0, (char *)&(((Fts3Phrase *)&p[1])->aToken[0])-(char *)p);
p->eType = FTSQUERY_PHRASE;
p->pPhrase = (Fts3Phrase *)&p[1];
p->pPhrase->iColumn = pParse->iDefaultCol;
p->pPhrase->nToken = nToken;
zBuf = (char *)&p->pPhrase->aToken[nToken];
if( zTemp ){
memcpy(zBuf, zTemp, nTemp);
sqlite3_free(zTemp);
}else{
assert( nTemp==0 );
}
for(jj=0; jj<p->pPhrase->nToken; jj++){
p->pPhrase->aToken[jj].z = zBuf;
zBuf += p->pPhrase->aToken[jj].n;
}
rc = SQLITE_OK;
}
*ppExpr = p;
return rc;
no_mem:
if( pCursor ){
pModule->xClose(pCursor);
}
sqlite3_free(zTemp);
sqlite3_free(p);
*ppExpr = 0;
return SQLITE_NOMEM;
}
/*
** Function getNextNode(), which is called by fts3ExprParse(), may itself
** call fts3ExprParse(). So this forward declaration is required.
*/
static int fts3ExprParse(ParseContext *, const char *, int, Fts3Expr **, int *);
/*
** The output variable *ppExpr is populated with an allocated Fts3Expr
** structure, or set to 0 if the end of the input buffer is reached.
**
** Returns an SQLite error code. SQLITE_OK if everything works, SQLITE_NOMEM
** if a malloc failure occurs, or SQLITE_ERROR if a parse error is encountered.
** If SQLITE_ERROR is returned, pContext is populated with an error message.
*/
static int getNextNode(
ParseContext *pParse, /* fts3 query parse context */
const char *z, int n, /* Input string */
Fts3Expr **ppExpr, /* OUT: expression */
int *pnConsumed /* OUT: Number of bytes consumed */
){
static const struct Fts3Keyword {
char *z; /* Keyword text */
unsigned char n; /* Length of the keyword */
unsigned char parenOnly; /* Only valid in paren mode */
unsigned char eType; /* Keyword code */
} aKeyword[] = {
{ "OR" , 2, 0, FTSQUERY_OR },
{ "AND", 3, 1, FTSQUERY_AND },
{ "NOT", 3, 1, FTSQUERY_NOT },
{ "NEAR", 4, 0, FTSQUERY_NEAR }
};
int ii;
int iCol;
int iColLen;
int rc;
Fts3Expr *pRet = 0;
const char *zInput = z;
int nInput = n;
pParse->isNot = 0;
/* Skip over any whitespace before checking for a keyword, an open or
** close bracket, or a quoted string.
*/
while( nInput>0 && fts3isspace(*zInput) ){
nInput--;
zInput++;
}
if( nInput==0 ){
return SQLITE_DONE;
}
/* See if we are dealing with a keyword. */
for(ii=0; ii<(int)(sizeof(aKeyword)/sizeof(struct Fts3Keyword)); ii++){
const struct Fts3Keyword *pKey = &aKeyword[ii];
if( (pKey->parenOnly & ~sqlite3_fts3_enable_parentheses)!=0 ){
continue;
}
if( nInput>=pKey->n && 0==memcmp(zInput, pKey->z, pKey->n) ){
int nNear = SQLITE_FTS3_DEFAULT_NEAR_PARAM;
int nKey = pKey->n;
char cNext;
/* If this is a "NEAR" keyword, check for an explicit nearness. */
if( pKey->eType==FTSQUERY_NEAR ){
assert( nKey==4 );
if( zInput[4]=='/' && zInput[5]>='0' && zInput[5]<='9' ){
nNear = 0;
for(nKey=5; zInput[nKey]>='0' && zInput[nKey]<='9'; nKey++){
nNear = nNear * 10 + (zInput[nKey] - '0');
}
}
}
/* At this point this is probably a keyword. But for that to be true,
** the next byte must contain either whitespace, an open or close
** parenthesis, a quote character, or EOF.
*/
cNext = zInput[nKey];
if( fts3isspace(cNext)
|| cNext=='"' || cNext=='(' || cNext==')' || cNext==0
){
pRet = (Fts3Expr *)fts3MallocZero(sizeof(Fts3Expr));
if( !pRet ){
return SQLITE_NOMEM;
}
pRet->eType = pKey->eType;
pRet->nNear = nNear;
*ppExpr = pRet;
*pnConsumed = (int)((zInput - z) + nKey);
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=='(' ){
int nConsumed;
pParse->nNest++;
rc = fts3ExprParse(pParse, &zInput[1], nInput-1, ppExpr, &nConsumed);
if( rc==SQLITE_OK && !*ppExpr ){
rc = SQLITE_DONE;
}
*pnConsumed = (int)((zInput - z) + 1 + nConsumed);
return rc;
}
/* Check for a close bracket. */
if( *zInput==')' ){
pParse->nNest--;
*pnConsumed = (int)((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 = (int)((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 = (int)strlen(zStr);
if( nInput>nStr && zInput[nStr]==':'
&& sqlite3_strnicmp(zStr, zInput, nStr)==0
){
iCol = ii;
iColLen = (int)((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 = 0;
rc = getNextNode(pParse, zIn, nIn, &p, &nByte);
if( rc==SQLITE_OK ){
int isPhrase;
if( !sqlite3_fts3_enable_parentheses
&& p->eType==FTSQUERY_PHRASE && pParse->isNot
){
/* Create an implicit NOT operator. */
Fts3Expr *pNot = fts3MallocZero(sizeof(Fts3Expr));
if( !pNot ){
sqlite3Fts3ExprFree(p);
rc = SQLITE_NOMEM;
goto exprparse_out;
}
pNot->eType = FTSQUERY_NOT;
pNot->pRight = p;
if( pNotBranch ){
pNot->pLeft = pNotBranch;
}
pNotBranch = pNot;
p = pPrev;
}else{
int eType = p->eType;
isPhrase = (eType==FTSQUERY_PHRASE || p->pLeft);
/* The isRequirePhrase variable is set to true if a phrase or
** an expression contained in parenthesis is required. If a
** binary operator (AND, OR, NOT or NEAR) is encounted when
** isRequirePhrase is set, this is a syntax error.
*/
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 = fts3MallocZero(sizeof(Fts3Expr));
if( !pAnd ){
sqlite3Fts3ExprFree(p);
rc = SQLITE_NOMEM;
goto exprparse_out;
}
pAnd->eType = FTSQUERY_AND;
insertBinaryOperator(&pRet, pPrev, pAnd);
pPrev = pAnd;
}
/* This test catches attempts to make either operand of a NEAR
** operator something other than a phrase. For example, either of
** the following:
**
** (bracketed expression) NEAR phrase
** phrase NEAR (bracketed expression)
**
** Return an error in either case.
*/
if( pPrev && (
(eType==FTSQUERY_NEAR && !isPhrase && pPrev->eType!=FTSQUERY_PHRASE)
|| (eType!=FTSQUERY_PHRASE && isPhrase && pPrev->eType==FTSQUERY_NEAR)
)){
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 );
}
assert( rc!=SQLITE_OK || (nByte>0 && nByte<=nIn) );
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{
Fts3Expr *pIter = pNotBranch;
while( pIter->pLeft ){
pIter = pIter->pLeft;
}
pIter->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 bFts4, /* True to allow FTS4-only syntax */
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;
sParse.bFts4 = bFts4;
if( z==0 ){
*ppExpr = 0;
return SQLITE_OK;
}
if( n<0 ){
n = (int)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 ){
assert( p->eType==FTSQUERY_PHRASE || p->pPhrase==0 );
sqlite3Fts3ExprFree(p->pLeft);
sqlite3Fts3ExprFree(p->pRight);
sqlite3Fts3EvalPhraseCleanup(p->pPhrase);
sqlite3_free(p->aMI);
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 queryTestTokenizer(
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((void *)pp, sqlite3_column_blob(pStmt, 0), sizeof(*pp));
}
}
return sqlite3_finalize(pStmt);
}
/*
** Return a pointer to a buffer containing a text representation of the
** expression passed as the first argument. The buffer is obtained from
** sqlite3_malloc(). It is the responsibility of the caller to use
** sqlite3_free() to release the memory. If an OOM condition is encountered,
** NULL is returned.
**
** If the second argument is not NULL, then its contents are prepended to
** the returned expression text and then freed using sqlite3_free().
*/
static char *exprToString(Fts3Expr *pExpr, char *zBuf){
switch( pExpr->eType ){
case FTSQUERY_PHRASE: {
Fts3Phrase *pPhrase = pExpr->pPhrase;
int i;
zBuf = sqlite3_mprintf(
"%zPHRASE %d 0", zBuf, pPhrase->iColumn);
for(i=0; zBuf && i<pPhrase->nToken; i++){
zBuf = sqlite3_mprintf("%z %.*s%s", zBuf,
pPhrase->aToken[i].n, pPhrase->aToken[i].z,
(pPhrase->aToken[i].isPrefix?"+":"")
);
}
return zBuf;
}
case FTSQUERY_NEAR:
zBuf = sqlite3_mprintf("%zNEAR/%d ", zBuf, pExpr->nNear);
break;
case FTSQUERY_NOT:
zBuf = sqlite3_mprintf("%zNOT ", zBuf);
break;
case FTSQUERY_AND:
zBuf = sqlite3_mprintf("%zAND ", zBuf);
break;
case FTSQUERY_OR:
zBuf = sqlite3_mprintf("%zOR ", zBuf);
break;
}
if( zBuf ) zBuf = sqlite3_mprintf("%z{", zBuf);
if( zBuf ) zBuf = exprToString(pExpr->pLeft, zBuf);
if( zBuf ) zBuf = sqlite3_mprintf("%z} {", zBuf);
if( zBuf ) zBuf = exprToString(pExpr->pRight, zBuf);
if( zBuf ) zBuf = sqlite3_mprintf("%z}", zBuf);
return 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 = 0;
int rc;
char **azCol = 0;
const char *zExpr;
int nExpr;
int nCol;
int ii;
Fts3Expr *pExpr;
char *zBuf = 0;
sqlite3 *db = sqlite3_context_db_handle(context);
if( argc<3 ){
sqlite3_result_error(context,
"Usage: fts3_exprtest(tokenizer, expr, col1, ...", -1
);
return;
}
rc = queryTestTokenizer(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, 0, nCol, nCol, zExpr, nExpr, &pExpr
);
if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM ){
sqlite3_result_error(context, "Error parsing expression", -1);
}else if( rc==SQLITE_NOMEM || !(zBuf = exprToString(pExpr, 0)) ){
sqlite3_result_error_nomem(context);
}else{
sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
sqlite3_free(zBuf);
}
sqlite3Fts3ExprFree(pExpr);
exprtest_out:
if( pModule && pTokenizer ){
rc = pModule->xDestroy(pTokenizer);
}
sqlite3_free(azCol);
}
/*
** Register the query expression parser test function fts3_exprtest()
** with database connection db.
*/
int sqlite3Fts3ExprInitTestInterface(sqlite3* db){
return sqlite3_create_function(
db, "fts3_exprtest", -1, SQLITE_UTF8, 0, fts3ExprTest, 0, 0
);
}
#endif
#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
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