psql: Tab completion for renaming enum values.

For ALTER TYPE .. RENAME, add "VALUE" to the list of possible
completions.  Complete ALTER TYPE .. RENAME VALUE with possible
enum values.  After that, complete with "TO".

Dagfinn Ilmari Mannsåker, reviewed by Artur Zakirov.

src/bin/psql/tab-complete.c

@@ -202,6 +202,31 @@ do { \
 	matches = completion_matches(text, complete_from_query); \
 } while (0)
 
+#define COMPLETE_WITH_ENUM_VALUE(type) \
+do { \
+	char   *_completion_schema; \
+	char   *_completion_type; \
+\
+	_completion_schema = strtokx(type, " \t\n\r", ".", "\"", 0, \
+								 false, false, pset.encoding); \
+	(void) strtokx(NULL, " \t\n\r", ".", "\"", 0, \
+				   false, false, pset.encoding); \
+	_completion_type = strtokx(NULL, " \t\n\r", ".", "\"", 0, \
+							   false, false, pset.encoding);  \
+	if (_completion_type == NULL)\
+	{ \
+		completion_charp = Query_for_list_of_enum_values; \
+		completion_info_charp = type; \
+	} \
+	else \
+	{ \
+		completion_charp = Query_for_list_of_enum_values_with_schema; \
+		completion_info_charp = _completion_type; \
+		completion_info_charp2 = _completion_schema; \
+	} \
+	matches = completion_matches(text, complete_from_query); \
+} while (0)
+
 #define COMPLETE_WITH_FUNCTION_ARG(function) \
 do { \
 	char   *_completion_schema; \
@@ -598,6 +623,26 @@ static const SchemaQuery Query_for_list_of_matviews = {
 "   AND (pg_catalog.quote_ident(nspname)='%s' "\
 "        OR '\"' || nspname || '\"' ='%s') "
 
+#define Query_for_list_of_enum_values \
+"SELECT pg_catalog.quote_literal(enumlabel) "\
+"  FROM pg_catalog.pg_enum e, pg_catalog.pg_type t "\
+" WHERE t.oid = e.enumtypid "\
+"   AND substring(pg_catalog.quote_literal(enumlabel),1,%d)='%s' "\
+"   AND (pg_catalog.quote_ident(typname)='%s' "\
+"        OR '\"' || typname || '\"'='%s') "\
+"   AND pg_catalog.pg_type_is_visible(t.oid)"
+
+#define Query_for_list_of_enum_values_with_schema \
+"SELECT pg_catalog.quote_literal(enumlabel) "\
+"  FROM pg_catalog.pg_enum e, pg_catalog.pg_type t, pg_catalog.pg_namespace n "\
+" WHERE t.oid = e.enumtypid "\
+"   AND n.oid = t.typnamespace "\
+"   AND substring(pg_catalog.quote_literal(enumlabel),1,%d)='%s' "\
+"   AND (pg_catalog.quote_ident(typname)='%s' "\
+"        OR '\"' || typname || '\"'='%s') "\
+"   AND (pg_catalog.quote_ident(nspname)='%s' "\
+"        OR '\"' || nspname || '\"' ='%s') "
+
 #define Query_for_list_of_template_databases \
 "SELECT pg_catalog.quote_ident(d.datname) "\
 "  FROM pg_catalog.pg_database d "\
@@ -1872,11 +1917,10 @@ psql_completion(const char *text, int start, int end)
 		COMPLETE_WITH_LIST2("ATTRIBUTE", "VALUE");
 	/* ALTER TYPE <foo> RENAME	*/
 	else if (Matches4("ALTER", "TYPE", MatchAny, "RENAME"))
-		COMPLETE_WITH_LIST2("ATTRIBUTE", "TO");
-	/* ALTER TYPE xxx RENAME ATTRIBUTE yyy */
-	else if (Matches6("ALTER", "TYPE", MatchAny, "RENAME", "ATTRIBUTE", MatchAny))
+		COMPLETE_WITH_LIST3("ATTRIBUTE", "TO", "VALUE");
+	/* ALTER TYPE xxx RENAME (ATTRIBUTE|VALUE) yyy */
+	else if (Matches6("ALTER", "TYPE", MatchAny, "RENAME", "ATTRIBUTE|VALUE", MatchAny))
 		COMPLETE_WITH_CONST("TO");
-
 	/*
 	 * If we have ALTER TYPE <sth> ALTER/DROP/RENAME ATTRIBUTE, provide list
 	 * of attributes
@@ -1896,6 +1940,12 @@ psql_completion(const char *text, int start, int end)
 	else if (Matches5("ALTER", "GROUP", MatchAny, "ADD|DROP", "USER"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_roles);
 
+	/*
+	 * If we have ALTER TYPE <sth> RENAME VALUE, provide list of enum values
+	 */
+	else if (Matches5("ALTER", "TYPE", MatchAny, "RENAME", "VALUE"))
+		COMPLETE_WITH_ENUM_VALUE(prev3_wd);
+
 /* BEGIN */
 	else if (Matches1("BEGIN"))
 		COMPLETE_WITH_LIST6("WORK", "TRANSACTION", "ISOLATION LEVEL", "READ", "DEFERRABLE", "NOT DEFERRABLE");