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 #include "sqliteInt.h" 16 #include <stdlib.h> 17 #include <string.h> 18 19 20 #if !defined(SQLITE_OMIT_WINDOWFUNC) 21 /* 22 ** Walk all expressions linked into the list of Window objects passed 23 ** as the second argument. 24 */ 25 static int walkWindowList(Walker *pWalker, Window *pList){ 26 Window *pWin; 27 for(pWin=pList; pWin; pWin=pWin->pNextWin){ 28 if( sqlite3WalkExprList(pWalker, pWin->pOrderBy) ) return WRC_Abort; 29 if( sqlite3WalkExprList(pWalker, pWin->pPartition) ) return WRC_Abort; 30 if( sqlite3WalkExpr(pWalker, pWin->pFilter) ) return WRC_Abort; 31 } 32 return WRC_Continue; 33 } 34 #endif 35 36 /* 37 ** Walk an expression tree. Invoke the callback once for each node 38 ** of the expression, while descending. (In other words, the callback 39 ** is invoked before visiting children.) 40 ** 41 ** The return value from the callback should be one of the WRC_* 42 ** constants to specify how to proceed with the walk. 43 ** 44 ** WRC_Continue Continue descending down the tree. 45 ** 46 ** WRC_Prune Do not descend into child nodes, but allow 47 ** the walk to continue with sibling nodes. 48 ** 49 ** WRC_Abort Do no more callbacks. Unwind the stack and 50 ** return from the top-level walk call. 51 ** 52 ** The return value from this routine is WRC_Abort to abandon the tree walk 53 ** and WRC_Continue to continue. 54 */ 55 static SQLITE_NOINLINE int walkExpr(Walker *pWalker, Expr *pExpr){ 56 int rc; 57 testcase( ExprHasProperty(pExpr, EP_TokenOnly) ); 58 testcase( ExprHasProperty(pExpr, EP_Reduced) ); 59 while(1){ 60 rc = pWalker->xExprCallback(pWalker, pExpr); 61 if( rc ) return rc & WRC_Abort; 62 if( !ExprHasProperty(pExpr,(EP_TokenOnly|EP_Leaf)) ){ 63 if( pExpr->pLeft && walkExpr(pWalker, pExpr->pLeft) ) return WRC_Abort; 64 assert( pExpr->x.pList==0 || pExpr->pRight==0 ); 65 if( pExpr->pRight ){ 66 pExpr = pExpr->pRight; 67 continue; 68 }else if( ExprHasProperty(pExpr, EP_xIsSelect) ){ 69 if( sqlite3WalkSelect(pWalker, pExpr->x.pSelect) ) return WRC_Abort; 70 }else if( pExpr->x.pList ){ 71 if( sqlite3WalkExprList(pWalker, pExpr->x.pList) ) return WRC_Abort; 72 } 73 #ifndef SQLITE_OMIT_WINDOWFUNC 74 if( ExprHasProperty(pExpr, EP_WinFunc) ){ 75 if( walkWindowList(pWalker, pExpr->y.pWin) ) return WRC_Abort; 76 } 77 #endif 78 } 79 break; 80 } 81 return WRC_Continue; 82 } 83 int sqlite3WalkExpr(Walker *pWalker, Expr *pExpr){ 84 return pExpr ? walkExpr(pWalker,pExpr) : WRC_Continue; 85 } 86 87 /* 88 ** Call sqlite3WalkExpr() for every expression in list p or until 89 ** an abort request is seen. 90 */ 91 int sqlite3WalkExprList(Walker *pWalker, ExprList *p){ 92 int i; 93 struct ExprList_item *pItem; 94 if( p ){ 95 for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){ 96 if( sqlite3WalkExpr(pWalker, pItem->pExpr) ) return WRC_Abort; 97 } 98 } 99 return WRC_Continue; 100 } 101 102 /* 103 ** Walk all expressions associated with SELECT statement p. Do 104 ** not invoke the SELECT callback on p, but do (of course) invoke 105 ** any expr callbacks and SELECT callbacks that come from subqueries. 106 ** Return WRC_Abort or WRC_Continue. 107 */ 108 int sqlite3WalkSelectExpr(Walker *pWalker, Select *p){ 109 if( sqlite3WalkExprList(pWalker, p->pEList) ) return WRC_Abort; 110 if( sqlite3WalkExpr(pWalker, p->pWhere) ) return WRC_Abort; 111 if( sqlite3WalkExprList(pWalker, p->pGroupBy) ) return WRC_Abort; 112 if( sqlite3WalkExpr(pWalker, p->pHaving) ) return WRC_Abort; 113 if( sqlite3WalkExprList(pWalker, p->pOrderBy) ) return WRC_Abort; 114 if( sqlite3WalkExpr(pWalker, p->pLimit) ) return WRC_Abort; 115 #if !defined(SQLITE_OMIT_WINDOWFUNC) && !defined(SQLITE_OMIT_ALTERTABLE) 116 { 117 Parse *pParse = pWalker->pParse; 118 if( pParse && IN_RENAME_OBJECT ){ 119 int rc = walkWindowList(pWalker, p->pWinDefn); 120 assert( rc==WRC_Continue ); 121 return rc; 122 } 123 } 124 #endif 125 return WRC_Continue; 126 } 127 128 /* 129 ** Walk the parse trees associated with all subqueries in the 130 ** FROM clause of SELECT statement p. Do not invoke the select 131 ** callback on p, but do invoke it on each FROM clause subquery 132 ** and on any subqueries further down in the tree. Return 133 ** WRC_Abort or WRC_Continue; 134 */ 135 int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){ 136 SrcList *pSrc; 137 int i; 138 struct SrcList_item *pItem; 139 140 pSrc = p->pSrc; 141 assert( pSrc!=0 ); 142 for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){ 143 if( pItem->pSelect && sqlite3WalkSelect(pWalker, pItem->pSelect) ){ 144 return WRC_Abort; 145 } 146 if( pItem->fg.isTabFunc 147 && sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg) 148 ){ 149 return WRC_Abort; 150 } 151 } 152 return WRC_Continue; 153 } 154 155 /* 156 ** Call sqlite3WalkExpr() for every expression in Select statement p. 157 ** Invoke sqlite3WalkSelect() for subqueries in the FROM clause and 158 ** on the compound select chain, p->pPrior. 159 ** 160 ** If it is not NULL, the xSelectCallback() callback is invoked before 161 ** the walk of the expressions and FROM clause. The xSelectCallback2() 162 ** method is invoked following the walk of the expressions and FROM clause, 163 ** but only if both xSelectCallback and xSelectCallback2 are both non-NULL 164 ** and if the expressions and FROM clause both return WRC_Continue; 165 ** 166 ** Return WRC_Continue under normal conditions. Return WRC_Abort if 167 ** there is an abort request. 168 ** 169 ** If the Walker does not have an xSelectCallback() then this routine 170 ** is a no-op returning WRC_Continue. 171 */ 172 int sqlite3WalkSelect(Walker *pWalker, Select *p){ 173 int rc; 174 if( p==0 ) return WRC_Continue; 175 if( pWalker->xSelectCallback==0 ) return WRC_Continue; 176 do{ 177 rc = pWalker->xSelectCallback(pWalker, p); 178 if( rc ) return rc & WRC_Abort; 179 if( sqlite3WalkSelectExpr(pWalker, p) 180 || sqlite3WalkSelectFrom(pWalker, p) 181 ){ 182 return WRC_Abort; 183 } 184 if( pWalker->xSelectCallback2 ){ 185 pWalker->xSelectCallback2(pWalker, p); 186 } 187 p = p->pPrior; 188 }while( p!=0 ); 189 return WRC_Continue; 190 } 191