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 if( ExprHasProperty(pExpr, EP_Filter) ){ 78 if( walkExpr(pWalker, pExpr->y.pFilter) ) return WRC_Abort; 79 } 80 #endif 81 } 82 break; 83 } 84 return WRC_Continue; 85 } 86 int sqlite3WalkExpr(Walker *pWalker, Expr *pExpr){ 87 return pExpr ? walkExpr(pWalker,pExpr) : WRC_Continue; 88 } 89 90 /* 91 ** Call sqlite3WalkExpr() for every expression in list p or until 92 ** an abort request is seen. 93 */ 94 int sqlite3WalkExprList(Walker *pWalker, ExprList *p){ 95 int i; 96 struct ExprList_item *pItem; 97 if( p ){ 98 for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){ 99 if( sqlite3WalkExpr(pWalker, pItem->pExpr) ) return WRC_Abort; 100 } 101 } 102 return WRC_Continue; 103 } 104 105 /* 106 ** Walk all expressions associated with SELECT statement p. Do 107 ** not invoke the SELECT callback on p, but do (of course) invoke 108 ** any expr callbacks and SELECT callbacks that come from subqueries. 109 ** Return WRC_Abort or WRC_Continue. 110 */ 111 int sqlite3WalkSelectExpr(Walker *pWalker, Select *p){ 112 if( sqlite3WalkExprList(pWalker, p->pEList) ) return WRC_Abort; 113 if( sqlite3WalkExpr(pWalker, p->pWhere) ) return WRC_Abort; 114 if( sqlite3WalkExprList(pWalker, p->pGroupBy) ) return WRC_Abort; 115 if( sqlite3WalkExpr(pWalker, p->pHaving) ) return WRC_Abort; 116 if( sqlite3WalkExprList(pWalker, p->pOrderBy) ) return WRC_Abort; 117 if( sqlite3WalkExpr(pWalker, p->pLimit) ) return WRC_Abort; 118 #if !defined(SQLITE_OMIT_WINDOWFUNC) && !defined(SQLITE_OMIT_ALTERTABLE) 119 { 120 Parse *pParse = pWalker->pParse; 121 if( pParse && IN_RENAME_OBJECT ){ 122 int rc = walkWindowList(pWalker, p->pWinDefn); 123 assert( rc==WRC_Continue ); 124 return rc; 125 } 126 } 127 #endif 128 return WRC_Continue; 129 } 130 131 /* 132 ** Walk the parse trees associated with all subqueries in the 133 ** FROM clause of SELECT statement p. Do not invoke the select 134 ** callback on p, but do invoke it on each FROM clause subquery 135 ** and on any subqueries further down in the tree. Return 136 ** WRC_Abort or WRC_Continue; 137 */ 138 int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){ 139 SrcList *pSrc; 140 int i; 141 struct SrcList_item *pItem; 142 143 pSrc = p->pSrc; 144 assert( pSrc!=0 ); 145 for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){ 146 if( pItem->pSelect && sqlite3WalkSelect(pWalker, pItem->pSelect) ){ 147 return WRC_Abort; 148 } 149 if( pItem->fg.isTabFunc 150 && sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg) 151 ){ 152 return WRC_Abort; 153 } 154 } 155 return WRC_Continue; 156 } 157 158 /* 159 ** Call sqlite3WalkExpr() for every expression in Select statement p. 160 ** Invoke sqlite3WalkSelect() for subqueries in the FROM clause and 161 ** on the compound select chain, p->pPrior. 162 ** 163 ** If it is not NULL, the xSelectCallback() callback is invoked before 164 ** the walk of the expressions and FROM clause. The xSelectCallback2() 165 ** method is invoked following the walk of the expressions and FROM clause, 166 ** but only if both xSelectCallback and xSelectCallback2 are both non-NULL 167 ** and if the expressions and FROM clause both return WRC_Continue; 168 ** 169 ** Return WRC_Continue under normal conditions. Return WRC_Abort if 170 ** there is an abort request. 171 ** 172 ** If the Walker does not have an xSelectCallback() then this routine 173 ** is a no-op returning WRC_Continue. 174 */ 175 int sqlite3WalkSelect(Walker *pWalker, Select *p){ 176 int rc; 177 if( p==0 ) return WRC_Continue; 178 if( pWalker->xSelectCallback==0 ) return WRC_Continue; 179 do{ 180 rc = pWalker->xSelectCallback(pWalker, p); 181 if( rc ) return rc & WRC_Abort; 182 if( sqlite3WalkSelectExpr(pWalker, p) 183 || sqlite3WalkSelectFrom(pWalker, p) 184 ){ 185 return WRC_Abort; 186 } 187 if( pWalker->xSelectCallback2 ){ 188 pWalker->xSelectCallback2(pWalker, p); 189 } 190 p = p->pPrior; 191 }while( p!=0 ); 192 return WRC_Continue; 193 } 194