v8-0001-Allow-transformation-only-of-a-sublist-of-subscri.patch

From 0dc5c192db78e352201f5a778eb0f545835fdb56 Mon Sep 17 00:00:00 2001
From: Nikita Glukhov <n.gluhov@postgrespro.ru>
Date: Fri, 14 Oct 2022 15:35:22 +0300
Subject: [PATCH v8 1/7] Allow transformation only of a sublist of subscripts

---
 contrib/hstore/hstore_subs.c      | 10 ++++++----
 src/backend/parser/parse_expr.c   |  9 ++++-----
 src/backend/parser/parse_node.c   |  4 ++--
 src/backend/parser/parse_target.c |  2 +-
 src/backend/utils/adt/arraysubs.c |  6 ++++--
 src/backend/utils/adt/jsonbsubs.c |  6 ++++--
 src/include/nodes/subscripting.h  |  7 ++++++-
 src/include/parser/parse_node.h   |  2 +-
 8 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/contrib/hstore/hstore_subs.c b/contrib/hstore/hstore_subs.c
index 3d03f66fa0d..1b29543ab67 100644
--- a/contrib/hstore/hstore_subs.c
+++ b/contrib/hstore/hstore_subs.c
@@ -40,7 +40,7 @@
  */
 static void
 hstore_subscript_transform(SubscriptingRef *sbsref,
-						   List *indirection,
+						   List **indirection,
 						   ParseState *pstate,
 						   bool isSlice,
 						   bool isAssignment)
@@ -49,15 +49,15 @@ hstore_subscript_transform(SubscriptingRef *sbsref,
 	Node	   *subexpr;
 
 	/* We support only single-subscript, non-slice cases */
-	if (isSlice || list_length(indirection) != 1)
+	if (isSlice || list_length(*indirection) != 1)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("hstore allows only one subscript"),
 				 parser_errposition(pstate,
-									exprLocation((Node *) indirection))));
+									exprLocation((Node *) *indirection))));
 
 	/* Transform the subscript expression to type text */
-	ai = linitial_node(A_Indices, indirection);
+	ai = linitial_node(A_Indices, *indirection);
 	Assert(ai->uidx != NULL && ai->lidx == NULL && !ai->is_slice);
 
 	subexpr = transformExpr(pstate, ai->uidx, pstate->p_expr_kind);
@@ -81,6 +81,8 @@ hstore_subscript_transform(SubscriptingRef *sbsref,
 	/* Determine the result type of the subscripting operation; always text */
 	sbsref->refrestype = TEXTOID;
 	sbsref->reftypmod = -1;
+
+	*indirection = NIL;
 }
 
 /*
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index bad1df732ea..2c0f4a50b21 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -466,14 +466,13 @@ transformIndirection(ParseState *pstate, A_Indirection *ind)
 			Assert(IsA(n, String));
 
 			/* process subscripts before this field selection */
-			if (subscripts)
+			while (subscripts)
 				result = (Node *) transformContainerSubscripts(pstate,
 															   result,
 															   exprType(result),
 															   exprTypmod(result),
-															   subscripts,
+															   &subscripts,
 															   false);
-			subscripts = NIL;
 
 			newresult = ParseFuncOrColumn(pstate,
 										  list_make1(n),
@@ -488,12 +487,12 @@ transformIndirection(ParseState *pstate, A_Indirection *ind)
 		}
 	}
 	/* process trailing subscripts, if any */
-	if (subscripts)
+	while (subscripts)
 		result = (Node *) transformContainerSubscripts(pstate,
 													   result,
 													   exprType(result),
 													   exprTypmod(result),
-													   subscripts,
+													   &subscripts,
 													   false);
 
 	return result;
diff --git a/src/backend/parser/parse_node.c b/src/backend/parser/parse_node.c
index d6feb16aef3..19a6b678e67 100644
--- a/src/backend/parser/parse_node.c
+++ b/src/backend/parser/parse_node.c
@@ -244,7 +244,7 @@ transformContainerSubscripts(ParseState *pstate,
 							 Node *containerBase,
 							 Oid containerType,
 							 int32 containerTypMod,
-							 List *indirection,
+							 List **indirection,
 							 bool isAssignment)
 {
 	SubscriptingRef *sbsref;
@@ -280,7 +280,7 @@ transformContainerSubscripts(ParseState *pstate,
 	 * element.  If any of the items are slice specifiers (lower:upper), then
 	 * the subscript expression means a container slice operation.
 	 */
-	foreach(idx, indirection)
+	foreach(idx, *indirection)
 	{
 		A_Indices  *ai = lfirst_node(A_Indices, idx);
 
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 4aba0d9d4d5..4675a523045 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -936,7 +936,7 @@ transformAssignmentSubscripts(ParseState *pstate,
 										  basenode,
 										  containerType,
 										  containerTypMod,
-										  subscripts,
+										  &subscripts,
 										  true);
 
 	typeNeeded = sbsref->refrestype;
diff --git a/src/backend/utils/adt/arraysubs.c b/src/backend/utils/adt/arraysubs.c
index 2940fb8e8d7..234c2c278c1 100644
--- a/src/backend/utils/adt/arraysubs.c
+++ b/src/backend/utils/adt/arraysubs.c
@@ -54,7 +54,7 @@ typedef struct ArraySubWorkspace
  */
 static void
 array_subscript_transform(SubscriptingRef *sbsref,
-						  List *indirection,
+						  List **indirection,
 						  ParseState *pstate,
 						  bool isSlice,
 						  bool isAssignment)
@@ -71,7 +71,7 @@ array_subscript_transform(SubscriptingRef *sbsref,
 	 * indirection items to slices by treating the single subscript as the
 	 * upper bound and supplying an assumed lower bound of 1.
 	 */
-	foreach(idx, indirection)
+	foreach(idx, *indirection)
 	{
 		A_Indices  *ai = lfirst_node(A_Indices, idx);
 		Node	   *subexpr;
@@ -152,6 +152,8 @@ array_subscript_transform(SubscriptingRef *sbsref,
 						list_length(upperIndexpr), MAXDIM)));
 	/* We need not check lowerIndexpr separately */
 
+	*indirection = NIL;
+
 	/*
 	 * Determine the result type of the subscripting operation.  It's the same
 	 * as the array type if we're slicing, else it's the element type.  In
diff --git a/src/backend/utils/adt/jsonbsubs.c b/src/backend/utils/adt/jsonbsubs.c
index de64d498512..8ad6aa1ad4f 100644
--- a/src/backend/utils/adt/jsonbsubs.c
+++ b/src/backend/utils/adt/jsonbsubs.c
@@ -41,7 +41,7 @@ typedef struct JsonbSubWorkspace
  */
 static void
 jsonb_subscript_transform(SubscriptingRef *sbsref,
-						  List *indirection,
+						  List **indirection,
 						  ParseState *pstate,
 						  bool isSlice,
 						  bool isAssignment)
@@ -53,7 +53,7 @@ jsonb_subscript_transform(SubscriptingRef *sbsref,
 	 * Transform and convert the subscript expressions. Jsonb subscripting
 	 * does not support slices, look only and the upper index.
 	 */
-	foreach(idx, indirection)
+	foreach(idx, *indirection)
 	{
 		A_Indices  *ai = lfirst_node(A_Indices, idx);
 		Node	   *subExpr;
@@ -159,6 +159,8 @@ jsonb_subscript_transform(SubscriptingRef *sbsref,
 	/* Determine the result type of the subscripting operation; always jsonb */
 	sbsref->refrestype = JSONBOID;
 	sbsref->reftypmod = -1;
+
+	*indirection = NIL;
 }
 
 /*
diff --git a/src/include/nodes/subscripting.h b/src/include/nodes/subscripting.h
index 234e8ad8012..5d576af346f 100644
--- a/src/include/nodes/subscripting.h
+++ b/src/include/nodes/subscripting.h
@@ -71,6 +71,11 @@ struct SubscriptExecSteps;
  * does not care to support slicing, it can just throw an error if isSlice.)
  * See array_subscript_transform() for sample code.
  *
+ * The transform method receives a pointer to a list of raw indirections.
+ * This allows the method to parse a sublist of the indirections (typically
+ * the prefix) and modify the original list in place, enabling the caller to
+ * either process the remaining indirections differently or raise an error.
+ *
  * The transform method is also responsible for identifying the result type
  * of the subscripting operation.  At call, refcontainertype and reftypmod
  * describe the container type (this will be a base type not a domain), and
@@ -93,7 +98,7 @@ struct SubscriptExecSteps;
  * assignment must return.
  */
 typedef void (*SubscriptTransform) (SubscriptingRef *sbsref,
-									List *indirection,
+									List **indirection,
 									struct ParseState *pstate,
 									bool isSlice,
 									bool isAssignment);
diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 994284019fb..5ae11ccec33 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -377,7 +377,7 @@ extern SubscriptingRef *transformContainerSubscripts(ParseState *pstate,
 													 Node *containerBase,
 													 Oid containerType,
 													 int32 containerTypMod,
-													 List *indirection,
+													 List **indirection,
 													 bool isAssignment);
 extern Const *make_const(ParseState *pstate, A_Const *aconst);
 
-- 
2.39.5 (Apple Git-154)