drh
33e619fc1c
expressions. Change Expr.zToken to Expr.u.zToken and added Expr.u.iValue. Remove an unnecessary ExprDup from CHECK constraint processing. And so forth. (CVS 6682) FossilOrigin-Name: 4ac2bdfbb4230b6ceaae87e738fa61036bbe03cb
139 lines
4.5 KiB
C
139 lines
4.5 KiB
C
/*
|
|
** 2008 August 16
|
|
**
|
|
** 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 file contains routines used for walking the parser tree for
|
|
** an SQL statement.
|
|
**
|
|
** $Id: walker.c,v 1.6 2009/05/28 01:00:55 drh Exp $
|
|
*/
|
|
#include "sqliteInt.h"
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
|
|
|
|
/*
|
|
** Walk an expression tree. Invoke the callback once for each node
|
|
** of the expression, while decending. (In other words, the callback
|
|
** is invoked before visiting children.)
|
|
**
|
|
** The return value from the callback should be one of the WRC_*
|
|
** constants to specify how to proceed with the walk.
|
|
**
|
|
** WRC_Continue Continue descending down the tree.
|
|
**
|
|
** WRC_Prune Do not descend into child nodes. But allow
|
|
** the walk to continue with sibling nodes.
|
|
**
|
|
** WRC_Abort Do no more callbacks. Unwind the stack and
|
|
** return the top-level walk call.
|
|
**
|
|
** The return value from this routine is WRC_Abort to abandon the tree walk
|
|
** and WRC_Continue to continue.
|
|
*/
|
|
int sqlite3WalkExpr(Walker *pWalker, Expr *pExpr){
|
|
int rc;
|
|
if( pExpr==0 ) return WRC_Continue;
|
|
testcase( ExprHasProperty(pExpr, EP_TokenOnly) );
|
|
testcase( ExprHasProperty(pExpr, EP_Reduced) );
|
|
rc = pWalker->xExprCallback(pWalker, pExpr);
|
|
if( rc==WRC_Continue
|
|
&& !ExprHasAnyProperty(pExpr,EP_TokenOnly) ){
|
|
if( sqlite3WalkExpr(pWalker, pExpr->pLeft) ) return WRC_Abort;
|
|
if( sqlite3WalkExpr(pWalker, pExpr->pRight) ) return WRC_Abort;
|
|
if( ExprHasProperty(pExpr, EP_xIsSelect) ){
|
|
if( sqlite3WalkSelect(pWalker, pExpr->x.pSelect) ) return WRC_Abort;
|
|
}else{
|
|
if( sqlite3WalkExprList(pWalker, pExpr->x.pList) ) return WRC_Abort;
|
|
}
|
|
}
|
|
return rc & WRC_Abort;
|
|
}
|
|
|
|
/*
|
|
** Call sqlite3WalkExpr() for every expression in list p or until
|
|
** an abort request is seen.
|
|
*/
|
|
int sqlite3WalkExprList(Walker *pWalker, ExprList *p){
|
|
int i, rc = WRC_Continue;
|
|
struct ExprList_item *pItem;
|
|
if( p ){
|
|
for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){
|
|
if( sqlite3WalkExpr(pWalker, pItem->pExpr) ) return WRC_Abort;
|
|
}
|
|
}
|
|
return rc & WRC_Continue;
|
|
}
|
|
|
|
/*
|
|
** Walk all expressions associated with SELECT statement p. Do
|
|
** not invoke the SELECT callback on p, but do (of course) invoke
|
|
** any expr callbacks and SELECT callbacks that come from subqueries.
|
|
** Return WRC_Abort or WRC_Continue.
|
|
*/
|
|
int sqlite3WalkSelectExpr(Walker *pWalker, Select *p){
|
|
if( sqlite3WalkExprList(pWalker, p->pEList) ) return WRC_Abort;
|
|
if( sqlite3WalkExpr(pWalker, p->pWhere) ) return WRC_Abort;
|
|
if( sqlite3WalkExprList(pWalker, p->pGroupBy) ) return WRC_Abort;
|
|
if( sqlite3WalkExpr(pWalker, p->pHaving) ) return WRC_Abort;
|
|
if( sqlite3WalkExprList(pWalker, p->pOrderBy) ) return WRC_Abort;
|
|
if( sqlite3WalkExpr(pWalker, p->pLimit) ) return WRC_Abort;
|
|
if( sqlite3WalkExpr(pWalker, p->pOffset) ) return WRC_Abort;
|
|
return WRC_Continue;
|
|
}
|
|
|
|
/*
|
|
** Walk the parse trees associated with all subqueries in the
|
|
** FROM clause of SELECT statement p. Do not invoke the select
|
|
** callback on p, but do invoke it on each FROM clause subquery
|
|
** and on any subqueries further down in the tree. Return
|
|
** WRC_Abort or WRC_Continue;
|
|
*/
|
|
int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){
|
|
SrcList *pSrc;
|
|
int i;
|
|
struct SrcList_item *pItem;
|
|
|
|
pSrc = p->pSrc;
|
|
if( pSrc ){
|
|
for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
|
|
if( sqlite3WalkSelect(pWalker, pItem->pSelect) ){
|
|
return WRC_Abort;
|
|
}
|
|
}
|
|
}
|
|
return WRC_Continue;
|
|
}
|
|
|
|
/*
|
|
** Call sqlite3WalkExpr() for every expression in Select statement p.
|
|
** Invoke sqlite3WalkSelect() for subqueries in the FROM clause and
|
|
** on the compound select chain, p->pPrior.
|
|
**
|
|
** Return WRC_Continue under normal conditions. Return WRC_Abort if
|
|
** there is an abort request.
|
|
**
|
|
** If the Walker does not have an xSelectCallback() then this routine
|
|
** is a no-op returning WRC_Continue.
|
|
*/
|
|
int sqlite3WalkSelect(Walker *pWalker, Select *p){
|
|
int rc;
|
|
if( p==0 || pWalker->xSelectCallback==0 ) return WRC_Continue;
|
|
rc = WRC_Continue;
|
|
while( p ){
|
|
rc = pWalker->xSelectCallback(pWalker, p);
|
|
if( rc ) break;
|
|
if( sqlite3WalkSelectExpr(pWalker, p) ) return WRC_Abort;
|
|
if( sqlite3WalkSelectFrom(pWalker, p) ) return WRC_Abort;
|
|
p = p->pPrior;
|
|
}
|
|
return rc & WRC_Abort;
|
|
}
|