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| 1 /* | |
| 2 ** 2008 August 16 | |
| 3 ** | |
| 4 ** The author disclaims copyright to this source code. In place of | |
| 5 ** a legal notice, here is a blessing: | |
| 6 ** | |
| 7 ** May you do good and not evil. | |
| 8 ** May you find forgiveness for yourself and forgive others. | |
| 9 ** May you share freely, never taking more than you give. | |
| 10 ** | |
| 11 ************************************************************************* | |
| 12 ** This file contains routines used for walking the parser tree for | |
| 13 ** an SQL statement. | |
| 14 ** | |
| 15 ** $Id: walker.c,v 1.7 2009/06/15 23:15:59 drh Exp $ | |
| 16 */ | |
| 17 #include "sqliteInt.h" | |
| 18 #include <stdlib.h> | |
| 19 #include <string.h> | |
| 20 | |
| 21 | |
| 22 /* | |
| 23 ** Walk an expression tree. Invoke the callback once for each node | |
| 24 ** of the expression, while decending. (In other words, the callback | |
| 25 ** is invoked before visiting children.) | |
| 26 ** | |
| 27 ** The return value from the callback should be one of the WRC_* | |
| 28 ** constants to specify how to proceed with the walk. | |
| 29 ** | |
| 30 ** WRC_Continue Continue descending down the tree. | |
| 31 ** | |
| 32 ** WRC_Prune Do not descend into child nodes. But allow | |
| 33 ** the walk to continue with sibling nodes. | |
| 34 ** | |
| 35 ** WRC_Abort Do no more callbacks. Unwind the stack and | |
| 36 ** return the top-level walk call. | |
| 37 ** | |
| 38 ** The return value from this routine is WRC_Abort to abandon the tree walk | |
| 39 ** and WRC_Continue to continue. | |
| 40 */ | |
| 41 int sqlite3WalkExpr(Walker *pWalker, Expr *pExpr){ | |
| 42 int rc; | |
| 43 if( pExpr==0 ) return WRC_Continue; | |
| 44 testcase( ExprHasProperty(pExpr, EP_TokenOnly) ); | |
| 45 testcase( ExprHasProperty(pExpr, EP_Reduced) ); | |
| 46 rc = pWalker->xExprCallback(pWalker, pExpr); | |
| 47 if( rc==WRC_Continue | |
| 48 && !ExprHasAnyProperty(pExpr,EP_TokenOnly) ){ | |
| 49 if( sqlite3WalkExpr(pWalker, pExpr->pLeft) ) return WRC_Abort; | |
| 50 if( sqlite3WalkExpr(pWalker, pExpr->pRight) ) return WRC_Abort; | |
| 51 if( ExprHasProperty(pExpr, EP_xIsSelect) ){ | |
| 52 if( sqlite3WalkSelect(pWalker, pExpr->x.pSelect) ) return WRC_Abort; | |
| 53 }else{ | |
| 54 if( sqlite3WalkExprList(pWalker, pExpr->x.pList) ) return WRC_Abort; | |
| 55 } | |
| 56 } | |
| 57 return rc & WRC_Abort; | |
| 58 } | |
| 59 | |
| 60 /* | |
| 61 ** Call sqlite3WalkExpr() for every expression in list p or until | |
| 62 ** an abort request is seen. | |
| 63 */ | |
| 64 int sqlite3WalkExprList(Walker *pWalker, ExprList *p){ | |
| 65 int i; | |
| 66 struct ExprList_item *pItem; | |
| 67 if( p ){ | |
| 68 for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){ | |
| 69 if( sqlite3WalkExpr(pWalker, pItem->pExpr) ) return WRC_Abort; | |
| 70 } | |
| 71 } | |
| 72 return WRC_Continue; | |
| 73 } | |
| 74 | |
| 75 /* | |
| 76 ** Walk all expressions associated with SELECT statement p. Do | |
| 77 ** not invoke the SELECT callback on p, but do (of course) invoke | |
| 78 ** any expr callbacks and SELECT callbacks that come from subqueries. | |
| 79 ** Return WRC_Abort or WRC_Continue. | |
| 80 */ | |
| 81 int sqlite3WalkSelectExpr(Walker *pWalker, Select *p){ | |
| 82 if( sqlite3WalkExprList(pWalker, p->pEList) ) return WRC_Abort; | |
| 83 if( sqlite3WalkExpr(pWalker, p->pWhere) ) return WRC_Abort; | |
| 84 if( sqlite3WalkExprList(pWalker, p->pGroupBy) ) return WRC_Abort; | |
| 85 if( sqlite3WalkExpr(pWalker, p->pHaving) ) return WRC_Abort; | |
| 86 if( sqlite3WalkExprList(pWalker, p->pOrderBy) ) return WRC_Abort; | |
| 87 if( sqlite3WalkExpr(pWalker, p->pLimit) ) return WRC_Abort; | |
| 88 if( sqlite3WalkExpr(pWalker, p->pOffset) ) return WRC_Abort; | |
| 89 return WRC_Continue; | |
| 90 } | |
| 91 | |
| 92 /* | |
| 93 ** Walk the parse trees associated with all subqueries in the | |
| 94 ** FROM clause of SELECT statement p. Do not invoke the select | |
| 95 ** callback on p, but do invoke it on each FROM clause subquery | |
| 96 ** and on any subqueries further down in the tree. Return | |
| 97 ** WRC_Abort or WRC_Continue; | |
| 98 */ | |
| 99 int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){ | |
| 100 SrcList *pSrc; | |
| 101 int i; | |
| 102 struct SrcList_item *pItem; | |
| 103 | |
| 104 pSrc = p->pSrc; | |
| 105 if( ALWAYS(pSrc) ){ | |
| 106 for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){ | |
| 107 if( sqlite3WalkSelect(pWalker, pItem->pSelect) ){ | |
| 108 return WRC_Abort; | |
| 109 } | |
| 110 } | |
| 111 } | |
| 112 return WRC_Continue; | |
| 113 } | |
| 114 | |
| 115 /* | |
| 116 ** Call sqlite3WalkExpr() for every expression in Select statement p. | |
| 117 ** Invoke sqlite3WalkSelect() for subqueries in the FROM clause and | |
| 118 ** on the compound select chain, p->pPrior. | |
| 119 ** | |
| 120 ** Return WRC_Continue under normal conditions. Return WRC_Abort if | |
| 121 ** there is an abort request. | |
| 122 ** | |
| 123 ** If the Walker does not have an xSelectCallback() then this routine | |
| 124 ** is a no-op returning WRC_Continue. | |
| 125 */ | |
| 126 int sqlite3WalkSelect(Walker *pWalker, Select *p){ | |
| 127 int rc; | |
| 128 if( p==0 || pWalker->xSelectCallback==0 ) return WRC_Continue; | |
| 129 rc = WRC_Continue; | |
| 130 while( p ){ | |
| 131 rc = pWalker->xSelectCallback(pWalker, p); | |
| 132 if( rc ) break; | |
| 133 if( sqlite3WalkSelectExpr(pWalker, p) ) return WRC_Abort; | |
| 134 if( sqlite3WalkSelectFrom(pWalker, p) ) return WRC_Abort; | |
| 135 p = p->pPrior; | |
| 136 } | |
| 137 return rc & WRC_Abort; | |
| 138 } | |
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Chromium Code Reviews
Issue 3108030:
Move bundled copy of sqlite one level deeper to better separate it... (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src/