1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/os/persistentdata/persistentstorage/sql/SQLite364/walker.c Fri Jun 15 03:10:57 2012 +0200
1.3 @@ -0,0 +1,134 @@
1.4 +/*
1.5 +** 2008 August 16
1.6 +**
1.7 +** The author disclaims copyright to this source code. In place of
1.8 +** a legal notice, here is a blessing:
1.9 +**
1.10 +** May you do good and not evil.
1.11 +** May you find forgiveness for yourself and forgive others.
1.12 +** May you share freely, never taking more than you give.
1.13 +**
1.14 +*************************************************************************
1.15 +** This file contains routines used for walking the parser tree for
1.16 +** an SQL statement.
1.17 +**
1.18 +** $Id: walker.c,v 1.1 2008/08/20 16:35:10 drh Exp $
1.19 +*/
1.20 +#include "sqliteInt.h"
1.21 +#include <stdlib.h>
1.22 +#include <string.h>
1.23 +
1.24 +
1.25 +/*
1.26 +** Walk an expression tree. Invoke the callback once for each node
1.27 +** of the expression, while decending. (In other words, the callback
1.28 +** is invoked before visiting children.)
1.29 +**
1.30 +** The return value from the callback should be one of the WRC_*
1.31 +** constants to specify how to proceed with the walk.
1.32 +**
1.33 +** WRC_Continue Continue descending down the tree.
1.34 +**
1.35 +** WRC_Prune Do not descend into child nodes. But allow
1.36 +** the walk to continue with sibling nodes.
1.37 +**
1.38 +** WRC_Abort Do no more callbacks. Unwind the stack and
1.39 +** return the top-level walk call.
1.40 +**
1.41 +** The return value from this routine is WRC_Abort to abandon the tree walk
1.42 +** and WRC_Continue to continue.
1.43 +*/
1.44 +int sqlite3WalkExpr(Walker *pWalker, Expr *pExpr){
1.45 + int rc;
1.46 + if( pExpr==0 ) return WRC_Continue;
1.47 + rc = pWalker->xExprCallback(pWalker, pExpr);
1.48 + if( rc==WRC_Continue ){
1.49 + if( sqlite3WalkExpr(pWalker, pExpr->pLeft) ) return WRC_Abort;
1.50 + if( sqlite3WalkExpr(pWalker, pExpr->pRight) ) return WRC_Abort;
1.51 + if( sqlite3WalkExprList(pWalker, pExpr->pList) ) return WRC_Abort;
1.52 + if( sqlite3WalkSelect(pWalker, pExpr->pSelect) ){
1.53 + return WRC_Abort;
1.54 + }
1.55 + }
1.56 + return rc & WRC_Abort;
1.57 +}
1.58 +
1.59 +/*
1.60 +** Call sqlite3WalkExpr() for every expression in list p or until
1.61 +** an abort request is seen.
1.62 +*/
1.63 +int sqlite3WalkExprList(Walker *pWalker, ExprList *p){
1.64 + int i, rc = WRC_Continue;
1.65 + struct ExprList_item *pItem;
1.66 + if( p ){
1.67 + for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){
1.68 + if( sqlite3WalkExpr(pWalker, pItem->pExpr) ) return WRC_Abort;
1.69 + }
1.70 + }
1.71 + return rc & WRC_Continue;
1.72 +}
1.73 +
1.74 +/*
1.75 +** Walk all expressions associated with SELECT statement p. Do
1.76 +** not invoke the SELECT callback on p, but do (of course) invoke
1.77 +** any expr callbacks and SELECT callbacks that come from subqueries.
1.78 +** Return WRC_Abort or WRC_Continue.
1.79 +*/
1.80 +int sqlite3WalkSelectExpr(Walker *pWalker, Select *p){
1.81 + if( sqlite3WalkExprList(pWalker, p->pEList) ) return WRC_Abort;
1.82 + if( sqlite3WalkExpr(pWalker, p->pWhere) ) return WRC_Abort;
1.83 + if( sqlite3WalkExprList(pWalker, p->pGroupBy) ) return WRC_Abort;
1.84 + if( sqlite3WalkExpr(pWalker, p->pHaving) ) return WRC_Abort;
1.85 + if( sqlite3WalkExprList(pWalker, p->pOrderBy) ) return WRC_Abort;
1.86 + if( sqlite3WalkExpr(pWalker, p->pLimit) ) return WRC_Abort;
1.87 + if( sqlite3WalkExpr(pWalker, p->pOffset) ) return WRC_Abort;
1.88 + return WRC_Continue;
1.89 +}
1.90 +
1.91 +/*
1.92 +** Walk the parse trees associated with all subqueries in the
1.93 +** FROM clause of SELECT statement p. Do not invoke the select
1.94 +** callback on p, but do invoke it on each FROM clause subquery
1.95 +** and on any subqueries further down in the tree. Return
1.96 +** WRC_Abort or WRC_Continue;
1.97 +*/
1.98 +int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){
1.99 + SrcList *pSrc;
1.100 + int i;
1.101 + struct SrcList_item *pItem;
1.102 +
1.103 + pSrc = p->pSrc;
1.104 + if( pSrc ){
1.105 + for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
1.106 + if( sqlite3WalkSelect(pWalker, pItem->pSelect) ){
1.107 + return WRC_Abort;
1.108 + }
1.109 + }
1.110 + }
1.111 + return WRC_Continue;
1.112 +}
1.113 +
1.114 +/*
1.115 +** Call sqlite3WalkExpr() for every expression in Select statement p.
1.116 +** Invoke sqlite3WalkSelect() for subqueries in the FROM clause and
1.117 +** on the compound select chain, p->pPrior.
1.118 +**
1.119 +** Return WRC_Continue under normal conditions. Return WRC_Abort if
1.120 +** there is an abort request.
1.121 +**
1.122 +** If the Walker does not have an xSelectCallback() then this routine
1.123 +** is a no-op returning WRC_Continue.
1.124 +*/
1.125 +int sqlite3WalkSelect(Walker *pWalker, Select *p){
1.126 + int rc;
1.127 + if( p==0 || pWalker->xSelectCallback==0 ) return WRC_Continue;
1.128 + rc = WRC_Continue;
1.129 + while( p ){
1.130 + rc = pWalker->xSelectCallback(pWalker, p);
1.131 + if( rc ) break;
1.132 + if( sqlite3WalkSelectExpr(pWalker, p) ) return WRC_Abort;
1.133 + if( sqlite3WalkSelectFrom(pWalker, p) ) return WRC_Abort;
1.134 + p = p->pPrior;
1.135 + }
1.136 + return rc & WRC_Abort;
1.137 +}