Continued refactoring of the name resolution logic and query optimizer. (CVS 2236)
FossilOrigin-Name: d8b2a7e09187564fe66a2b4bf0992c6a017146cf
diff --git a/src/expr.c b/src/expr.c
index 88ca91f..0256934 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -12,7 +12,7 @@
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
-** $Id: expr.c,v 1.181 2005/01/18 17:20:10 drh Exp $
+** $Id: expr.c,v 1.182 2005/01/19 23:24:50 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -1095,6 +1095,9 @@
return 0;
}
+/* Forward declaration */
+static int sqlite3ExprCodeSubquery(Parse*, NameContext*, Expr*);
+
/*
** This routine walks an expression tree and resolves references to
** table columns. Nodes of the form ID.ID or ID resolve into an
@@ -1117,12 +1120,13 @@
** property on the expression.
*/
int sqlite3ExprResolveNames(
- Parse *pParse, /* The parser context */
- SrcList *pSrcList, /* List of tables used to resolve column names */
- ExprList *pEList, /* List of expressions used to resolve "AS" */
- Expr *pExpr, /* The expression to be analyzed. */
- int allowAgg, /* True to allow aggregate expressions */
- int codeSubquery /* If true, then generate code for subqueries too */
+ Parse *pParse, /* The parser context */
+ SrcList *pSrcList, /* List of tables used to resolve column names */
+ ExprList *pEList, /* List of expressions used to resolve "AS" */
+ NameContext *pNC, /* Namespace of enclosing statement */
+ Expr *pExpr, /* The expression to be analyzed. */
+ int allowAgg, /* True to allow aggregate expressions */
+ int codeSubquery /* If true, then generate code for subqueries too */
){
NameContext sNC;
@@ -1132,18 +1136,29 @@
sNC.pParse = pParse;
sNC.pEList = pEList;
sNC.allowAgg = allowAgg;
+ sNC.pNext = pNC;
walkExprTree(pExpr, nameResolverStep, &sNC);
if( sNC.hasAgg ){
ExprSetProperty(pExpr, EP_Agg);
}
if( sNC.nErr>0 ){
ExprSetProperty(pExpr, EP_Error);
- }else if( codeSubquery && sqlite3ExprCodeSubquery(pParse, pExpr) ){
+ }else if( codeSubquery && sqlite3ExprCodeSubquery(pParse, &sNC, pExpr) ){
return 1;
}
return ExprHasProperty(pExpr, EP_Error);
}
+/*
+** A pointer instance of this structure is used to pass information
+** through walkExprTree into codeSubqueryStep().
+*/
+typedef struct QueryCoder QueryCoder;
+struct QueryCoder {
+ Parse *pParse; /* The parsing context */
+ NameContext *pNC; /* Namespace of first enclosing query */
+};
+
/*
** Generate code for subqueries and IN operators.
@@ -1167,7 +1182,8 @@
** additional information.
*/
static int codeSubqueryStep(void *pArg, Expr *pExpr){
- Parse *pParse = (Parse*)pArg;
+ QueryCoder *pCoder = (QueryCoder*)pArg;
+ Parse *pParse = pCoder->pParse;
switch( pExpr->op ){
case TK_IN: {
@@ -1207,7 +1223,7 @@
int iParm = pExpr->iTable + (((int)affinity)<<16);
ExprList *pEList;
assert( (pExpr->iTable&0x0000FFFF)==pExpr->iTable );
- sqlite3Select(pParse, pExpr->pSelect, SRT_Set, iParm, 0, 0, 0, 0);
+ sqlite3Select(pParse, pExpr->pSelect, SRT_Set, iParm, 0, 0, 0, 0, 0);
pEList = pExpr->pSelect->pEList;
if( pEList && pEList->nExpr>0 ){
keyInfo.aColl[0] = binaryCompareCollSeq(pParse, pExpr->pLeft,
@@ -1237,7 +1253,7 @@
"right-hand side of IN operator must be constant");
return 2;
}
- if( sqlite3ExprResolveNames(pParse, 0, 0, pE2, 0, 0) ){
+ if( sqlite3ExprResolveNames(pParse, 0, 0, 0, pE2, 0, 0) ){
return 2;
}
@@ -1257,8 +1273,27 @@
** value of this select in a memory cell and record the number
** of the memory cell in iColumn.
*/
+ NameContext *pNC;
+ int nRef;
+ Vdbe *v;
+ int addr;
+
+ pNC = pCoder->pNC;
+ if( pNC ) nRef = pNC->nRef;
+ v = sqlite3GetVdbe(pParse);
+ addr = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
pExpr->iColumn = pParse->nMem++;
- sqlite3Select(pParse, pExpr->pSelect, SRT_Mem,pExpr->iColumn,0,0,0,0);
+ sqlite3Select(pParse, pExpr->pSelect, SRT_Mem,pExpr->iColumn,0,0,0,0,pNC);
+ if( pNC && pNC->nRef>nRef ){
+ /* Subquery value changes. Evaluate at each use */
+ pExpr->iTable = addr+1;
+ sqlite3VdbeAddOp(v, OP_Return, 0, 0);
+ sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v));
+ }else{
+ /* Subquery value is constant. evaluate only once. */
+ pExpr->iTable = -1;
+ sqlite3VdbeChangeP2(v, addr, addr+1);
+ }
return 1;
}
}
@@ -1269,8 +1304,15 @@
** Generate code to evaluate subqueries and IN operators contained
** in expression pExpr.
*/
-int sqlite3ExprCodeSubquery(Parse *pParse, Expr *pExpr){
- walkExprTree(pExpr, codeSubqueryStep, pParse);
+static int sqlite3ExprCodeSubquery(
+ Parse *pParse, /* Parser */
+ NameContext *pNC, /* First enclosing namespace. Often NULL */
+ Expr *pExpr /* Subquery to be coded */
+){
+ QueryCoder sCoder;
+ sCoder.pParse = pParse;
+ sCoder.pNC = pNC;
+ walkExprTree(pExpr, codeSubqueryStep, &sCoder);
return 0;
}
@@ -1478,6 +1520,10 @@
break;
}
case TK_SELECT: {
+ if( pExpr->iTable>=0 ){
+ sqlite3VdbeAddOp(v, OP_Gosub, 0, pExpr->iTable);
+ VdbeComment((v, "# run subquery"));
+ }
sqlite3VdbeAddOp(v, OP_MemLoad, pExpr->iColumn, 0);
VdbeComment((v, "# load subquery result"));
break;