mirror of
https://github.com/tursodatabase/libsql.git
synced 2025-01-09 08:49:02 +00:00
260 lines
8.1 KiB
C
260 lines
8.1 KiB
C
/*
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** 2008 August 16
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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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** This file contains routines used for walking the parser tree for
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** an SQL statement.
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*/
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#include "sqliteInt.h"
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#include <stdlib.h>
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#include <string.h>
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#if !defined(SQLITE_OMIT_WINDOWFUNC)
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/*
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** Walk all expressions linked into the list of Window objects passed
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** as the second argument.
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*/
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static int walkWindowList(Walker *pWalker, Window *pList, int bOneOnly){
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Window *pWin;
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for(pWin=pList; pWin; pWin=pWin->pNextWin){
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int rc;
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rc = sqlite3WalkExprList(pWalker, pWin->pOrderBy);
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if( rc ) return WRC_Abort;
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rc = sqlite3WalkExprList(pWalker, pWin->pPartition);
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if( rc ) return WRC_Abort;
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rc = sqlite3WalkExpr(pWalker, pWin->pFilter);
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if( rc ) return WRC_Abort;
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rc = sqlite3WalkExpr(pWalker, pWin->pStart);
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if( rc ) return WRC_Abort;
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rc = sqlite3WalkExpr(pWalker, pWin->pEnd);
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if( rc ) return WRC_Abort;
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if( bOneOnly ) break;
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}
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return WRC_Continue;
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}
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#endif
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/*
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** Walk an expression tree. Invoke the callback once for each node
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** of the expression, while descending. (In other words, the callback
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** is invoked before visiting children.)
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**
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** The return value from the callback should be one of the WRC_*
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** constants to specify how to proceed with the walk.
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**
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** WRC_Continue Continue descending down the tree.
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**
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** WRC_Prune Do not descend into child nodes, but allow
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** the walk to continue with sibling nodes.
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**
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** WRC_Abort Do no more callbacks. Unwind the stack and
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** return from the top-level walk call.
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**
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** The return value from this routine is WRC_Abort to abandon the tree walk
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** and WRC_Continue to continue.
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*/
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SQLITE_NOINLINE int sqlite3WalkExprNN(Walker *pWalker, Expr *pExpr){
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int rc;
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testcase( ExprHasProperty(pExpr, EP_TokenOnly) );
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testcase( ExprHasProperty(pExpr, EP_Reduced) );
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while(1){
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rc = pWalker->xExprCallback(pWalker, pExpr);
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if( rc ) return rc & WRC_Abort;
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if( !ExprHasProperty(pExpr,(EP_TokenOnly|EP_Leaf)) ){
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assert( pExpr->x.pList==0 || pExpr->pRight==0 );
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if( pExpr->pLeft && sqlite3WalkExprNN(pWalker, pExpr->pLeft) ){
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return WRC_Abort;
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}
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if( pExpr->pRight ){
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assert( !ExprHasProperty(pExpr, EP_WinFunc) );
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pExpr = pExpr->pRight;
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continue;
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}else if( ExprUseXSelect(pExpr) ){
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assert( !ExprHasProperty(pExpr, EP_WinFunc) );
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if( sqlite3WalkSelect(pWalker, pExpr->x.pSelect) ) return WRC_Abort;
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}else{
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if( pExpr->x.pList ){
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if( sqlite3WalkExprList(pWalker, pExpr->x.pList) ) return WRC_Abort;
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}
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#ifndef SQLITE_OMIT_WINDOWFUNC
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if( ExprHasProperty(pExpr, EP_WinFunc) ){
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if( walkWindowList(pWalker, pExpr->y.pWin, 1) ) return WRC_Abort;
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}
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#endif
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}
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}
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break;
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}
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return WRC_Continue;
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}
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int sqlite3WalkExpr(Walker *pWalker, Expr *pExpr){
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return pExpr ? sqlite3WalkExprNN(pWalker,pExpr) : WRC_Continue;
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}
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/*
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** Call sqlite3WalkExpr() for every expression in list p or until
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** an abort request is seen.
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*/
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int sqlite3WalkExprList(Walker *pWalker, ExprList *p){
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int i;
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struct ExprList_item *pItem;
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if( p ){
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for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){
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if( sqlite3WalkExpr(pWalker, pItem->pExpr) ) return WRC_Abort;
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}
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}
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return WRC_Continue;
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}
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/*
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** This is a no-op callback for Walker->xSelectCallback2. If this
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** callback is set, then the Select->pWinDefn list is traversed.
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*/
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void sqlite3WalkWinDefnDummyCallback(Walker *pWalker, Select *p){
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UNUSED_PARAMETER(pWalker);
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UNUSED_PARAMETER(p);
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/* No-op */
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}
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/*
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** Walk all expressions associated with SELECT statement p. Do
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** not invoke the SELECT callback on p, but do (of course) invoke
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** any expr callbacks and SELECT callbacks that come from subqueries.
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** Return WRC_Abort or WRC_Continue.
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*/
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int sqlite3WalkSelectExpr(Walker *pWalker, Select *p){
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if( sqlite3WalkExprList(pWalker, p->pEList) ) return WRC_Abort;
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if( sqlite3WalkExpr(pWalker, p->pWhere) ) return WRC_Abort;
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if( sqlite3WalkExprList(pWalker, p->pGroupBy) ) return WRC_Abort;
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if( sqlite3WalkExpr(pWalker, p->pHaving) ) return WRC_Abort;
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if( sqlite3WalkExprList(pWalker, p->pOrderBy) ) return WRC_Abort;
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if( sqlite3WalkExpr(pWalker, p->pLimit) ) return WRC_Abort;
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#if !defined(SQLITE_OMIT_WINDOWFUNC)
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if( p->pWinDefn ){
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Parse *pParse;
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if( pWalker->xSelectCallback2==sqlite3WalkWinDefnDummyCallback
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|| ((pParse = pWalker->pParse)!=0 && IN_RENAME_OBJECT)
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#ifndef SQLITE_OMIT_CTE
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|| pWalker->xSelectCallback2==sqlite3SelectPopWith
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#endif
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){
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/* The following may return WRC_Abort if there are unresolvable
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** symbols (e.g. a table that does not exist) in a window definition. */
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int rc = walkWindowList(pWalker, p->pWinDefn, 0);
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return rc;
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}
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}
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#endif
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return WRC_Continue;
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}
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/*
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** Walk the parse trees associated with all subqueries in the
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** FROM clause of SELECT statement p. Do not invoke the select
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** callback on p, but do invoke it on each FROM clause subquery
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** and on any subqueries further down in the tree. Return
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** WRC_Abort or WRC_Continue;
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*/
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int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){
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SrcList *pSrc;
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int i;
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SrcItem *pItem;
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pSrc = p->pSrc;
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if( ALWAYS(pSrc) ){
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for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
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if( pItem->pSelect && sqlite3WalkSelect(pWalker, pItem->pSelect) ){
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return WRC_Abort;
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}
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if( pItem->fg.isTabFunc
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&& sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg)
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){
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return WRC_Abort;
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}
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}
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}
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return WRC_Continue;
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}
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/*
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** Call sqlite3WalkExpr() for every expression in Select statement p.
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** Invoke sqlite3WalkSelect() for subqueries in the FROM clause and
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** on the compound select chain, p->pPrior.
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**
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** If it is not NULL, the xSelectCallback() callback is invoked before
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** the walk of the expressions and FROM clause. The xSelectCallback2()
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** method is invoked following the walk of the expressions and FROM clause,
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** but only if both xSelectCallback and xSelectCallback2 are both non-NULL
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** and if the expressions and FROM clause both return WRC_Continue;
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**
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** Return WRC_Continue under normal conditions. Return WRC_Abort if
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** there is an abort request.
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**
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** If the Walker does not have an xSelectCallback() then this routine
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** is a no-op returning WRC_Continue.
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*/
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int sqlite3WalkSelect(Walker *pWalker, Select *p){
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int rc;
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if( p==0 ) return WRC_Continue;
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if( pWalker->xSelectCallback==0 ) return WRC_Continue;
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do{
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rc = pWalker->xSelectCallback(pWalker, p);
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if( rc ) return rc & WRC_Abort;
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if( sqlite3WalkSelectExpr(pWalker, p)
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|| sqlite3WalkSelectFrom(pWalker, p)
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){
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return WRC_Abort;
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}
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if( pWalker->xSelectCallback2 ){
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pWalker->xSelectCallback2(pWalker, p);
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}
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p = p->pPrior;
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}while( p!=0 );
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return WRC_Continue;
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}
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/* Increase the walkerDepth when entering a subquery, and
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** decrease when leaving the subquery.
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*/
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int sqlite3WalkerDepthIncrease(Walker *pWalker, Select *pSelect){
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UNUSED_PARAMETER(pSelect);
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pWalker->walkerDepth++;
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return WRC_Continue;
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}
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void sqlite3WalkerDepthDecrease(Walker *pWalker, Select *pSelect){
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UNUSED_PARAMETER(pSelect);
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pWalker->walkerDepth--;
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}
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/*
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** No-op routine for the parse-tree walker.
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**
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** When this routine is the Walker.xExprCallback then expression trees
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** are walked without any actions being taken at each node. Presumably,
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** when this routine is used for Walker.xExprCallback then
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** Walker.xSelectCallback is set to do something useful for every
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** subquery in the parser tree.
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*/
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int sqlite3ExprWalkNoop(Walker *NotUsed, Expr *NotUsed2){
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UNUSED_PARAMETER2(NotUsed, NotUsed2);
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return WRC_Continue;
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}
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/*
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** No-op routine for the parse-tree walker for SELECT statements.
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** subquery in the parser tree.
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*/
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int sqlite3SelectWalkNoop(Walker *NotUsed, Select *NotUsed2){
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UNUSED_PARAMETER2(NotUsed, NotUsed2);
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return WRC_Continue;
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}
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