1 files changed, 37 insertions, 0 deletions
diff --git a/src/walker.c b/src/walker.c
index 48d7ddbf3..7649036f5 100644
--- a/src/walker.c
+++ b/src/walker.c
@@ -207,3 +207,40 @@ int sqlite3WalkSelect(Walker *pWalker, Select *p){
   }while( p!=0 );
   return WRC_Continue;
 }
+
+/* Increase the walkerDepth when entering a subquery, and
+** descrease when leaving the subquery.
+*/
+int sqlite3WalkerDepthIncrease(Walker *pWalker, Select *pSelect){
+  UNUSED_PARAMETER(pSelect);
+  pWalker->walkerDepth++;
+  return WRC_Continue;
+}
+void sqlite3WalkerDepthDecrease(Walker *pWalker, Select *pSelect){
+  UNUSED_PARAMETER(pSelect);
+  pWalker->walkerDepth--;
+}
+
+
+/*
+** No-op routine for the parse-tree walker.
+**
+** When this routine is the Walker.xExprCallback then expression trees
+** are walked without any actions being taken at each node.  Presumably,
+** when this routine is used for Walker.xExprCallback then 
+** Walker.xSelectCallback is set to do something useful for every 
+** subquery in the parser tree.
+*/
+int sqlite3ExprWalkNoop(Walker *NotUsed, Expr *NotUsed2){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  return WRC_Continue;
+}
+
+/*
+** No-op routine for the parse-tree walker for SELECT statements.
+** subquery in the parser tree.
+*/
+int sqlite3SelectWalkNoop(Walker *NotUsed, Select *NotUsed2){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  return WRC_Continue;
+}