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/*
** 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.
*/
#include "sqliteInt.h"
#include <stdlib.h>
#include <string.h>
#if !defined(SQLITE_OMIT_WINDOWFUNC)
/*
** Walk all expressions linked into the list of Window objects passed
** as the second argument.
*/
static int walkWindowList(Walker *pWalker, Window *pList){
Window *pWin;
for(pWin=pList; pWin; pWin=pWin->pNextWin){
int rc;
rc = sqlite3WalkExprList(pWalker, pWin->pOrderBy);
if( rc ) return WRC_Abort;
rc = sqlite3WalkExprList(pWalker, pWin->pPartition);
if( rc ) return WRC_Abort;
rc = sqlite3WalkExpr(pWalker, pWin->pFilter);
if( rc ) return WRC_Abort;
/* The next two are purely for calls to sqlite3RenameExprUnmap()
** within sqlite3WindowOffsetExpr(). Because of constraints imposed
** by sqlite3WindowOffsetExpr(), they can never fail. The results do
** not matter anyhow. */
rc = sqlite3WalkExpr(pWalker, pWin->pStart);
if( NEVER(rc) ) return WRC_Abort;
rc = sqlite3WalkExpr(pWalker, pWin->pEnd);
if( NEVER(rc) ) return WRC_Abort;
}
return WRC_Continue;
}
#endif
/*
** Walk an expression tree. Invoke the callback once for each node
** of the expression, while descending. (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 from the top-level walk call.
**
** The return value from this routine is WRC_Abort to abandon the tree walk
** and WRC_Continue to continue.
*/
static SQLITE_NOINLINE int walkExpr(Walker *pWalker, Expr *pExpr){
int rc;
testcase( ExprHasProperty(pExpr, EP_TokenOnly) );
testcase( ExprHasProperty(pExpr, EP_Reduced) );
while(1){
rc = pWalker->xExprCallback(pWalker, pExpr);
if( rc ) return rc & WRC_Abort;
if( !ExprHasProperty(pExpr,(EP_TokenOnly|EP_Leaf)) ){
if( pExpr->pLeft && walkExpr(pWalker, pExpr->pLeft) ) return WRC_Abort;
assert( pExpr->x.pList==0 || pExpr->pRight==0 );
if( pExpr->pRight ){
assert( !ExprHasProperty(pExpr, EP_WinFunc) );
pExpr = pExpr->pRight;
continue;
}else if( ExprHasProperty(pExpr, EP_xIsSelect) ){
assert( !ExprHasProperty(pExpr, EP_WinFunc) );
if( sqlite3WalkSelect(pWalker, pExpr->x.pSelect) ) return WRC_Abort;
}else{
if( pExpr->x.pList ){
if( sqlite3WalkExprList(pWalker, pExpr->x.pList) ) return WRC_Abort;
}
#ifndef SQLITE_OMIT_WINDOWFUNC
if( ExprHasProperty(pExpr, EP_WinFunc) ){
if( walkWindowList(pWalker, pExpr->y.pWin) ) return WRC_Abort;
}
#endif
}
}
break;
}
return WRC_Continue;
}
int sqlite3WalkExpr(Walker *pWalker, Expr *pExpr){
return pExpr ? walkExpr(pWalker,pExpr) : WRC_Continue;
}
/*
** Call sqlite3WalkExpr() for every expression in list p or until
** an abort request is seen.
*/
int sqlite3WalkExprList(Walker *pWalker, ExprList *p){
int i;
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 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 !defined(SQLITE_OMIT_WINDOWFUNC) && !defined(SQLITE_OMIT_ALTERTABLE)
{
Parse *pParse = pWalker->pParse;
if( pParse && IN_RENAME_OBJECT ){
/* The following may return WRC_Abort if there are unresolvable
** symbols (e.g. a table that does not exist) in a window definition. */
int rc = walkWindowList(pWalker, p->pWinDefn);
return rc;
}
}
#endif
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;
assert( pSrc!=0 );
for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
if( pItem->pSelect && sqlite3WalkSelect(pWalker, pItem->pSelect) ){
return WRC_Abort;
}
if( pItem->fg.isTabFunc
&& sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg)
){
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.
**
** If it is not NULL, the xSelectCallback() callback is invoked before
** the walk of the expressions and FROM clause. The xSelectCallback2()
** method is invoked following the walk of the expressions and FROM clause,
** but only if both xSelectCallback and xSelectCallback2 are both non-NULL
** and if the expressions and FROM clause both return WRC_Continue;
**
** 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 ) return WRC_Continue;
if( pWalker->xSelectCallback==0 ) return WRC_Continue;
do{
rc = pWalker->xSelectCallback(pWalker, p);
if( rc ) return rc & WRC_Abort;
if( sqlite3WalkSelectExpr(pWalker, p)
|| sqlite3WalkSelectFrom(pWalker, p)
){
return WRC_Abort;
}
if( pWalker->xSelectCallback2 ){
pWalker->xSelectCallback2(pWalker, p);
}
p = p->pPrior;
}while( p!=0 );
return WRC_Continue;
}
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