Add const qualifiers to node inspection functions

Thomas Munro

src/backend/nodes/list.c

@@ -31,7 +31,7 @@
  * Check that the specified List is valid (so far as we can tell).
  */
 static void
-check_list_invariants(List *list)
+check_list_invariants(const List *list)
 {
 	if (list == NIL)
 		return;
@@ -383,7 +383,7 @@ list_truncate(List *list, int new_size)
  * failure if there is no such cell.
  */
 static ListCell *
-list_nth_cell(List *list, int n)
+list_nth_cell(const List *list, int n)
 {
 	ListCell   *match;
 
@@ -407,7 +407,7 @@ list_nth_cell(List *list, int n)
  * specified list. (List elements begin at 0.)
  */
 void *
-list_nth(List *list, int n)
+list_nth(const List *list, int n)
 {
 	Assert(IsPointerList(list));
 	return lfirst(list_nth_cell(list, n));
@@ -418,7 +418,7 @@ list_nth(List *list, int n)
  * specified list.
  */
 int
-list_nth_int(List *list, int n)
+list_nth_int(const List *list, int n)
 {
 	Assert(IsIntegerList(list));
 	return lfirst_int(list_nth_cell(list, n));
@@ -429,7 +429,7 @@ list_nth_int(List *list, int n)
  * list.
  */
 Oid
-list_nth_oid(List *list, int n)
+list_nth_oid(const List *list, int n)
 {
 	Assert(IsOidList(list));
 	return lfirst_oid(list_nth_cell(list, n));
@@ -441,9 +441,9 @@ list_nth_oid(List *list, int n)
  * Node as 'datum'.
  */
 bool
-list_member(List *list, void *datum)
+list_member(const List *list, const void *datum)
 {
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	Assert(IsPointerList(list));
 	check_list_invariants(list);
@@ -462,9 +462,9 @@ list_member(List *list, void *datum)
  * determined by using simple pointer comparison.
  */
 bool
-list_member_ptr(List *list, void *datum)
+list_member_ptr(const List *list, const void *datum)
 {
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	Assert(IsPointerList(list));
 	check_list_invariants(list);
@@ -482,9 +482,9 @@ list_member_ptr(List *list, void *datum)
  * Return true iff the integer 'datum' is a member of the list.
  */
 bool
-list_member_int(List *list, int datum)
+list_member_int(const List *list, int datum)
 {
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	Assert(IsIntegerList(list));
 	check_list_invariants(list);
@@ -502,9 +502,9 @@ list_member_int(List *list, int datum)
  * Return true iff the OID 'datum' is a member of the list.
  */
 bool
-list_member_oid(List *list, Oid datum)
+list_member_oid(const List *list, Oid datum)
 {
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	Assert(IsOidList(list));
 	check_list_invariants(list);
@@ -694,10 +694,10 @@ list_delete_first(List *list)
  * performance bottleneck.
  */
 List *
-list_union(List *list1, List *list2)
+list_union(const List *list1, const List *list2)
 {
 	List	   *result;
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	Assert(IsPointerList(list1));
 	Assert(IsPointerList(list2));
@@ -718,10 +718,10 @@ list_union(List *list1, List *list2)
  * pointer comparison.
  */
 List *
-list_union_ptr(List *list1, List *list2)
+list_union_ptr(const List *list1, const List *list2)
 {
 	List	   *result;
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	Assert(IsPointerList(list1));
 	Assert(IsPointerList(list2));
@@ -741,10 +741,10 @@ list_union_ptr(List *list1, List *list2)
  * This variant of list_union() operates upon lists of integers.
  */
 List *
-list_union_int(List *list1, List *list2)
+list_union_int(const List *list1, const List *list2)
 {
 	List	   *result;
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	Assert(IsIntegerList(list1));
 	Assert(IsIntegerList(list2));
@@ -764,10 +764,10 @@ list_union_int(List *list1, List *list2)
  * This variant of list_union() operates upon lists of OIDs.
  */
 List *
-list_union_oid(List *list1, List *list2)
+list_union_oid(const List *list1, const List *list2)
 {
 	List	   *result;
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	Assert(IsOidList(list1));
 	Assert(IsOidList(list2));
@@ -797,10 +797,10 @@ list_union_oid(List *list1, List *list2)
  * to in the result.
  */
 List *
-list_intersection(List *list1, List *list2)
+list_intersection(const List *list1, const List *list2)
 {
 	List	   *result;
-	ListCell   *cell;
+	const ListCell   *cell;
 
 	if (list1 == NIL || list2 == NIL)
 		return NIL;
@@ -829,9 +829,9 @@ list_intersection(List *list1, List *list2)
  * membership via equal()
  */
 List *
-list_difference(List *list1, List *list2)
+list_difference(const List *list1, const List *list2)
 {
-	ListCell   *cell;
+	const ListCell   *cell;
 	List	   *result = NIL;
 
 	Assert(IsPointerList(list1));
@@ -855,9 +855,9 @@ list_difference(List *list1, List *list2)
  * simple pointer equality.
  */
 List *
-list_difference_ptr(List *list1, List *list2)
+list_difference_ptr(const List *list1, const List *list2)
 {
-	ListCell   *cell;
+	const ListCell   *cell;
 	List	   *result = NIL;
 
 	Assert(IsPointerList(list1));
@@ -880,9 +880,9 @@ list_difference_ptr(List *list1, List *list2)
  * This variant of list_difference() operates upon lists of integers.
  */
 List *
-list_difference_int(List *list1, List *list2)
+list_difference_int(const List *list1, const List *list2)
 {
-	ListCell   *cell;
+	const ListCell   *cell;
 	List	   *result = NIL;
 
 	Assert(IsIntegerList(list1));
@@ -905,9 +905,9 @@ list_difference_int(List *list1, List *list2)
  * This variant of list_difference() operates upon lists of OIDs.
  */
 List *
-list_difference_oid(List *list1, List *list2)
+list_difference_oid(const List *list1, const List *list2)
 {
-	ListCell   *cell;
+	const ListCell   *cell;
 	List	   *result = NIL;
 
 	Assert(IsOidList(list1));
@@ -1131,7 +1131,7 @@ list_free_deep(List *list)
  * Return a shallow copy of the specified list.
  */
 List *
-list_copy(List *oldlist)
+list_copy(const List *oldlist)
 {
 	List	   *newlist;
 	ListCell   *newlist_prev;
@@ -1174,7 +1174,7 @@ list_copy(List *oldlist)
  * Return a shallow copy of the specified list, without the first N elements.
  */
 List *
-list_copy_tail(List *oldlist, int nskip)
+list_copy_tail(const List *oldlist, int nskip)
 {
 	List	   *newlist;
 	ListCell   *newlist_prev;
@@ -1230,7 +1230,7 @@ list_copy_tail(List *oldlist, int nskip)
 #ifndef USE_INLINE
 
 ListCell *
-list_head(List *l)
+list_head(const List *l)
 {
 	return l ? l->head : NULL;
 }
@@ -1242,7 +1242,7 @@ list_tail(List *l)
 }
 
 int
-list_length(List *l)
+list_length(const List *l)
 {
 	return l ? l->length : 0;
 }
@@ -1264,10 +1264,10 @@ list_length(List *l)
  * list_length() macro in order to avoid the overhead of a function
  * call.
  */
-int			length(List *list);
+int			length(const List *list);
 
 int
-length(List *list)
+length(const List *list)
 {
 	return list_length(list);
 }

src/backend/nodes/print.c

@@ -31,7 +31,7 @@
  *	  print contents of Node to stdout
  */
 void
-print(void *obj)
+print(const void *obj)
 {
 	char	   *s;
 	char	   *f;
@@ -49,7 +49,7 @@ print(void *obj)
  *	  pretty-print contents of Node to stdout
  */
 void
-pprint(void *obj)
+pprint(const void *obj)
 {
 	char	   *s;
 	char	   *f;
@@ -67,7 +67,7 @@ pprint(void *obj)
  *	  send pretty-printed contents of Node to postmaster log
  */
 void
-elog_node_display(int lev, const char *title, void *obj, bool pretty)
+elog_node_display(int lev, const char *title, const void *obj, bool pretty)
 {
 	char	   *s;
 	char	   *f;
@@ -249,9 +249,9 @@ pretty_format_node_dump(const char *dump)
  *	  print contents of range table
  */
 void
-print_rt(List *rtable)
+print_rt(const List *rtable)
 {
-	ListCell   *l;
+	const ListCell   *l;
 	int			i = 1;
 
 	printf("resno\trefname  \trelid\tinFromCl\n");
@@ -304,7 +304,7 @@ print_rt(List *rtable)
  *	  print an expression
  */
 void
-print_expr(Node *expr, List *rtable)
+print_expr(const Node *expr, const List *rtable)
 {
 	if (expr == NULL)
 	{
@@ -314,7 +314,7 @@ print_expr(Node *expr, List *rtable)
 
 	if (IsA(expr, Var))
 	{
-		Var		   *var = (Var *) expr;
+		const Var		   *var = (const Var *) expr;
 		char	   *relname,
 				   *attname;
 
@@ -348,7 +348,7 @@ print_expr(Node *expr, List *rtable)
 	}
 	else if (IsA(expr, Const))
 	{
-		Const	   *c = (Const *) expr;
+		const Const	   *c = (const Const *) expr;
 		Oid			typoutput;
 		bool		typIsVarlena;
 		char	   *outputstr;
@@ -368,26 +368,26 @@ print_expr(Node *expr, List *rtable)
 	}
 	else if (IsA(expr, OpExpr))
 	{
-		OpExpr	   *e = (OpExpr *) expr;
+		const OpExpr	   *e = (const OpExpr *) expr;
 		char	   *opname;
 
 		opname = get_opname(e->opno);
 		if (list_length(e->args) > 1)
 		{
-			print_expr(get_leftop((Expr *) e), rtable);
+			print_expr(get_leftop((const Expr *) e), rtable);
 			printf(" %s ", ((opname != NULL) ? opname : "(invalid operator)"));
-			print_expr(get_rightop((Expr *) e), rtable);
+			print_expr(get_rightop((const Expr *) e), rtable);
 		}
 		else
 		{
 			/* we print prefix and postfix ops the same... */
 			printf("%s ", ((opname != NULL) ? opname : "(invalid operator)"));
-			print_expr(get_leftop((Expr *) e), rtable);
+			print_expr(get_leftop((const Expr *) e), rtable);
 		}
 	}
 	else if (IsA(expr, FuncExpr))
 	{
-		FuncExpr   *e = (FuncExpr *) expr;
+		const FuncExpr   *e = (const FuncExpr *) expr;
 		char	   *funcname;
 		ListCell   *l;
 
@@ -410,9 +410,9 @@ print_expr(Node *expr, List *rtable)
  *	  pathkeys list of PathKeys
  */
 void
-print_pathkeys(List *pathkeys, List *rtable)
+print_pathkeys(const List *pathkeys, const List *rtable)
 {
-	ListCell   *i;
+	const ListCell   *i;
 
 	printf("(");
 	foreach(i, pathkeys)
@@ -450,9 +450,9 @@ print_pathkeys(List *pathkeys, List *rtable)
  *	  print targetlist in a more legible way.
  */
 void
-print_tl(List *tlist, List *rtable)
+print_tl(const List *tlist, const List *rtable)
 {
-	ListCell   *tl;
+	const ListCell   *tl;
 
 	printf("(\n");
 	foreach(tl, tlist)

src/backend/optimizer/util/clauses.c

@@ -181,9 +181,9 @@ make_opclause(Oid opno, Oid opresulttype, bool opretset,
  *		or (op expr)
  */
 Node *
-get_leftop(Expr *clause)
+get_leftop(const Expr *clause)
 {
-	OpExpr	   *expr = (OpExpr *) clause;
+	const OpExpr	   *expr = (const OpExpr *) clause;
 
 	if (expr->args != NIL)
 		return linitial(expr->args);
@@ -198,9 +198,9 @@ get_leftop(Expr *clause)
  * NB: result will be NULL if applied to a unary op clause.
  */
 Node *
-get_rightop(Expr *clause)
+get_rightop(const Expr *clause)
 {
-	OpExpr	   *expr = (OpExpr *) clause;
+	const OpExpr	   *expr = (const OpExpr *) clause;
 
 	if (list_length(expr->args) >= 2)
 		return lsecond(expr->args);

src/include/nodes/nodeFuncs.h

@@ -26,17 +26,17 @@
 #define QTW_DONT_COPY_QUERY			0x20		/* do not copy top Query */
 
 
-extern Oid	exprType(Node *expr);
-extern int32 exprTypmod(Node *expr);
-extern bool exprIsLengthCoercion(Node *expr, int32 *coercedTypmod);
+extern Oid	exprType(const Node *expr);
+extern int32 exprTypmod(const Node *expr);
+extern bool exprIsLengthCoercion(const Node *expr, int32 *coercedTypmod);
 extern bool expression_returns_set(Node *clause);
 
-extern Oid	exprCollation(Node *expr);
-extern Oid	exprInputCollation(Node *expr);
+extern Oid	exprCollation(const Node *expr);
+extern Oid	exprInputCollation(const Node *expr);
 extern void exprSetCollation(Node *expr, Oid collation);
 extern void exprSetInputCollation(Node *expr, Oid inputcollation);
 
-extern int	exprLocation(Node *expr);
+extern int	exprLocation(const Node *expr);
 
 extern bool expression_tree_walker(Node *node, bool (*walker) (),
 											   void *context);

src/include/nodes/nodes.h

@@ -431,7 +431,7 @@ typedef struct Node
 	NodeTag		type;
 } Node;
 
-#define nodeTag(nodeptr)		(((Node*)(nodeptr))->type)
+#define nodeTag(nodeptr)		(((const Node*)(nodeptr))->type)
 
 /*
  * newNode -
@@ -487,7 +487,7 @@ extern PGDLLIMPORT Node *newNodeMacroHolder;
 /*
  * nodes/{outfuncs.c,print.c}
  */
-extern char *nodeToString(void *obj);
+extern char *nodeToString(const void *obj);
 
 /*
  * nodes/{readfuncs.c,read.c}
@@ -497,12 +497,12 @@ extern void *stringToNode(char *str);
 /*
  * nodes/copyfuncs.c
  */
-extern void *copyObject(void *obj);
+extern void *copyObject(const void *obj);
 
 /*
  * nodes/equalfuncs.c
  */
-extern bool equal(void *a, void *b);
+extern bool equal(const void *a, const void *b);
 
 
 /*

src/include/nodes/pg_list.h

@@ -77,7 +77,7 @@ struct ListCell
 #ifdef USE_INLINE
 
 static inline ListCell *
-list_head(List *l)
+list_head(const List *l)
 {
 	return l ? l->head : NULL;
 }
@@ -89,15 +89,15 @@ list_tail(List *l)
 }
 
 static inline int
-list_length(List *l)
+list_length(const List *l)
 {
 	return l ? l->length : 0;
 }
 #else
 
-extern ListCell *list_head(List *l);
+extern ListCell *list_head(const List *l);
 extern ListCell *list_tail(List *l);
-extern int	list_length(List *l);
+extern int	list_length(const List *l);
 #endif   /* USE_INLINE */
 
 /*
@@ -206,14 +206,14 @@ extern List *lcons_oid(Oid datum, List *list);
 extern List *list_concat(List *list1, List *list2);
 extern List *list_truncate(List *list, int new_size);
 
-extern void *list_nth(List *list, int n);
-extern int	list_nth_int(List *list, int n);
-extern Oid	list_nth_oid(List *list, int n);
+extern void *list_nth(const List *list, int n);
+extern int	list_nth_int(const List *list, int n);
+extern Oid	list_nth_oid(const List *list, int n);
 
-extern bool list_member(List *list, void *datum);
-extern bool list_member_ptr(List *list, void *datum);
-extern bool list_member_int(List *list, int datum);
-extern bool list_member_oid(List *list, Oid datum);
+extern bool list_member(const List *list, const void *datum);
+extern bool list_member_ptr(const List *list, const void *datum);
+extern bool list_member_int(const List *list, int datum);
+extern bool list_member_oid(const List *list, Oid datum);
 
 extern List *list_delete(List *list, void *datum);
 extern List *list_delete_ptr(List *list, void *datum);
@@ -222,19 +222,19 @@ extern List *list_delete_oid(List *list, Oid datum);
 extern List *list_delete_first(List *list);
 extern List *list_delete_cell(List *list, ListCell *cell, ListCell *prev);
 
-extern List *list_union(List *list1, List *list2);
-extern List *list_union_ptr(List *list1, List *list2);
-extern List *list_union_int(List *list1, List *list2);
-extern List *list_union_oid(List *list1, List *list2);
+extern List *list_union(const List *list1, const List *list2);
+extern List *list_union_ptr(const List *list1, const List *list2);
+extern List *list_union_int(const List *list1, const List *list2);
+extern List *list_union_oid(const List *list1, const List *list2);
 
-extern List *list_intersection(List *list1, List *list2);
+extern List *list_intersection(const List *list1, const List *list2);
 
 /* currently, there's no need for list_intersection_int etc */
 
-extern List *list_difference(List *list1, List *list2);
-extern List *list_difference_ptr(List *list1, List *list2);
-extern List *list_difference_int(List *list1, List *list2);
-extern List *list_difference_oid(List *list1, List *list2);
+extern List *list_difference(const List *list1, const List *list2);
+extern List *list_difference_ptr(const List *list1, const List *list2);
+extern List *list_difference_int(const List *list1, const List *list2);
+extern List *list_difference_oid(const List *list1, const List *list2);
 
 extern List *list_append_unique(List *list, void *datum);
 extern List *list_append_unique_ptr(List *list, void *datum);
@@ -249,8 +249,8 @@ extern List *list_concat_unique_oid(List *list1, List *list2);
 extern void list_free(List *list);
 extern void list_free_deep(List *list);
 
-extern List *list_copy(List *list);
-extern List *list_copy_tail(List *list, int nskip);
+extern List *list_copy(const List *list);
+extern List *list_copy_tail(const List *list, int nskip);
 
 /*
  * To ease migration to the new list API, a set of compatibility

src/include/nodes/print.h

@@ -19,16 +19,16 @@
 
 #define nodeDisplay(x)		pprint(x)
 
-extern void print(void *obj);
-extern void pprint(void *obj);
+extern void print(const void *obj);
+extern void pprint(const void *obj);
 extern void elog_node_display(int lev, const char *title,
-				  void *obj, bool pretty);
+				  const void *obj, bool pretty);
 extern char *format_node_dump(const char *dump);
 extern char *pretty_format_node_dump(const char *dump);
-extern void print_rt(List *rtable);
-extern void print_expr(Node *expr, List *rtable);
-extern void print_pathkeys(List *pathkeys, List *rtable);
-extern void print_tl(List *tlist, List *rtable);
+extern void print_rt(const List *rtable);
+extern void print_expr(const Node *expr, const List *rtable);
+extern void print_pathkeys(const List *pathkeys, const List *rtable);
+extern void print_tl(const List *tlist, const List *rtable);
 extern void print_slot(TupleTableSlot *slot);
 
 #endif   /* PRINT_H */

src/include/optimizer/clauses.h

@@ -31,8 +31,8 @@ typedef struct
 extern Expr *make_opclause(Oid opno, Oid opresulttype, bool opretset,
 			  Expr *leftop, Expr *rightop,
 			  Oid opcollid, Oid inputcollid);
-extern Node *get_leftop(Expr *clause);
-extern Node *get_rightop(Expr *clause);
+extern Node *get_leftop(const Expr *clause);
+extern Node *get_rightop(const Expr *clause);
 
 extern bool not_clause(Node *clause);
 extern Expr *make_notclause(Expr *notclause);