| /* |
| ** 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> |
| |
| |
| /* |
| ** 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; |
| 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( 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( ALWAYS(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; |
| } |