Rewrite comment code for better modularity, and add necessary locking.

Review by Alvaro Herrera, KaiGai Kohei, and Tom Lane.

src/backend/catalog/Makefile

@@ -2,7 +2,7 @@
 #
 # Makefile for backend/catalog
 #
-# $PostgreSQL: pgsql/src/backend/catalog/Makefile,v 1.78 2010/05/13 11:49:48 petere Exp $
+# $PostgreSQL: pgsql/src/backend/catalog/Makefile,v 1.79 2010/08/27 11:47:41 rhaas Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -11,9 +11,10 @@ top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = catalog.o dependency.o heap.o index.o indexing.o namespace.o aclchk.o \
-       pg_aggregate.o pg_constraint.o pg_conversion.o pg_depend.o pg_enum.o \
-       pg_inherits.o pg_largeobject.o pg_namespace.o pg_operator.o pg_proc.o \
-       pg_db_role_setting.o pg_shdepend.o pg_type.o storage.o toasting.o
+       objectaddress.o pg_aggregate.o pg_constraint.o pg_conversion.o \
+       pg_depend.o pg_enum.o pg_inherits.o pg_largeobject.o pg_namespace.o \
+       pg_operator.o pg_proc.o pg_db_role_setting.o pg_shdepend.o pg_type.o \
+       storage.o toasting.o
 
 BKIFILES = postgres.bki postgres.description postgres.shdescription
 

src/include/catalog/dependency.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/dependency.h,v 1.45 2010/04/05 01:09:53 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/dependency.h,v 1.46 2010/08/27 11:47:41 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -15,6 +15,7 @@
 #define DEPENDENCY_H
 
 #include "nodes/parsenodes.h"	/* for DropBehavior */
+#include "catalog/objectaddress.h"
 
 
 /*
@@ -100,17 +101,6 @@ typedef enum SharedDependencyType
 	SHARED_DEPENDENCY_INVALID = 0
 } SharedDependencyType;
 
-
-/*
- * The two objects related by a dependency are identified by ObjectAddresses.
- */
-typedef struct ObjectAddress
-{
-	Oid			classId;		/* Class Id from pg_class */
-	Oid			objectId;		/* OID of the object */
-	int32		objectSubId;	/* Subitem within object (eg column), or 0 */
-} ObjectAddress;
-
 /* expansible list of ObjectAddresses (private in dependency.c) */
 typedef struct ObjectAddresses ObjectAddresses;
 

src/include/catalog/objectaddress.h

+/*-------------------------------------------------------------------------
+ *
+ * objectaddress.h
+ *	  functions for working with object addresses
+ *
+ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * $PostgreSQL: pgsql/src/include/catalog/objectaddress.h,v 1.1 2010/08/27 11:47:41 rhaas Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef OBJECTADDRESS_H 
+#define OBJECTADDRESS_H
+
+#include "nodes/parsenodes.h"
+#include "storage/lock.h"
+#include "utils/rel.h"
+
+/*
+ * An ObjectAddress represents a database object of any type.
+ */
+typedef struct ObjectAddress
+{
+	Oid			classId;		/* Class Id from pg_class */
+	Oid			objectId;		/* OID of the object */
+	int32		objectSubId;	/* Subitem within object (eg column), or 0 */
+} ObjectAddress;
+
+ObjectAddress get_object_address(ObjectType objtype, List *objname,
+				   List *objargs, Relation *relp, LOCKMODE lockmode);
+
+#endif   /* PARSE_OBJECT_H */