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Diffstat (limited to 'src/walker.c')
| -rw-r--r-- | src/walker.c | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/src/walker.c b/src/walker.c new file mode 100644 index 0000000..f24c052 --- /dev/null +++ b/src/walker.c @@ -0,0 +1,257 @@ +/* +** 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, int bOneOnly){ + 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; + rc = sqlite3WalkExpr(pWalker, pWin->pStart); + if( rc ) return WRC_Abort; + rc = sqlite3WalkExpr(pWalker, pWin->pEnd); + if( rc ) return WRC_Abort; + if( bOneOnly ) break; + } + 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)) ){ + assert( pExpr->x.pList==0 || pExpr->pRight==0 ); + if( pExpr->pLeft && walkExpr(pWalker, pExpr->pLeft) ) return WRC_Abort; + if( pExpr->pRight ){ + assert( !ExprHasProperty(pExpr, EP_WinFunc) ); + pExpr = pExpr->pRight; + continue; + }else if( ExprUseXSelect(pExpr) ){ + 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, 1) ) 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; +} + +/* +** This is a no-op callback for Walker->xSelectCallback2. If this +** callback is set, then the Select->pWinDefn list is traversed. +*/ +void sqlite3WalkWinDefnDummyCallback(Walker *pWalker, Select *p){ + UNUSED_PARAMETER(pWalker); + UNUSED_PARAMETER(p); + /* No-op */ +} + +/* +** 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) + if( p->pWinDefn ){ + Parse *pParse; + if( pWalker->xSelectCallback2==sqlite3WalkWinDefnDummyCallback + || ((pParse = pWalker->pParse)!=0 && IN_RENAME_OBJECT) +#ifndef SQLITE_OMIT_CTE + || pWalker->xSelectCallback2==sqlite3SelectPopWith +#endif + ){ + /* 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, 0); + 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; + SrcItem *pItem; + + pSrc = p->pSrc; + if( ALWAYS(pSrc) ){ + 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; +} + +/* Increase the walkerDepth when entering a subquery, and +** descrease when leaving the subquery. +*/ +int sqlite3WalkerDepthIncrease(Walker *pWalker, Select *pSelect){ + UNUSED_PARAMETER(pSelect); + pWalker->walkerDepth++; + return WRC_Continue; +} +void sqlite3WalkerDepthDecrease(Walker *pWalker, Select *pSelect){ + UNUSED_PARAMETER(pSelect); + pWalker->walkerDepth--; +} + + +/* +** No-op routine for the parse-tree walker. +** +** When this routine is the Walker.xExprCallback then expression trees +** are walked without any actions being taken at each node. Presumably, +** when this routine is used for Walker.xExprCallback then +** Walker.xSelectCallback is set to do something useful for every +** subquery in the parser tree. +*/ +int sqlite3ExprWalkNoop(Walker *NotUsed, Expr *NotUsed2){ + UNUSED_PARAMETER2(NotUsed, NotUsed2); + return WRC_Continue; +} + +/* +** No-op routine for the parse-tree walker for SELECT statements. +** subquery in the parser tree. +*/ +int sqlite3SelectWalkNoop(Walker *NotUsed, Select *NotUsed2){ + UNUSED_PARAMETER2(NotUsed, NotUsed2); + return WRC_Continue; +} |