Add tab-completion for psql meta-commands.

Based on the original code from David Christensen, modified by me.

Author: MasaoFujii

src/bin/psql/tab-complete.c

@@ -897,14 +897,16 @@ psql_completion(const char *text, int start, int end)
 
 	static const char *const backslash_commands[] = {
 		"\\a", "\\connect", "\\conninfo", "\\C", "\\cd", "\\copy", "\\copyright",
-		"\\d", "\\da", "\\db", "\\dc", "\\dC", "\\dd", "\\dD", "\\des", "\\det", "\\deu", "\\dew", "\\df",
+		"\\d", "\\da", "\\db", "\\dc", "\\dC", "\\dd", "\\ddp", "\\dD",
+		"\\des", "\\det", "\\deu", "\\dew", "\\dE", "\\df",
 		"\\dF", "\\dFd", "\\dFp", "\\dFt", "\\dg", "\\di", "\\dl", "\\dL",
-		"\\dn", "\\do", "\\dp", "\\drds", "\\ds", "\\dS", "\\dt", "\\dT", "\\dv", "\\du", "\\dx",
+		"\\dm", "\\dn", "\\do", "\\dO", "\\dp", "\\drds", "\\ds", "\\dS",
+		"\\dt", "\\dT", "\\dv", "\\du", "\\dx", "\\dy",
 		"\\e", "\\echo", "\\ef", "\\encoding", "\\ev",
 		"\\f", "\\g", "\\gset", "\\h", "\\help", "\\H", "\\i", "\\ir", "\\l",
 		"\\lo_import", "\\lo_export", "\\lo_list", "\\lo_unlink",
 		"\\o", "\\p", "\\password", "\\prompt", "\\pset", "\\q", "\\qecho", "\\r",
-		"\\set", "\\sf", "\\sv", "\\t", "\\T",
+		"\\s", "\\set", "\\setenv", "\\sf", "\\sv", "\\t", "\\T",
 		"\\timing", "\\unset", "\\x", "\\w", "\\watch", "\\z", "\\!", NULL
 	};
 
@@ -3791,6 +3793,10 @@ psql_completion(const char *text, int start, int end)
 		COMPLETE_WITH_QUERY(Query_for_list_of_extensions);
 	else if (strncmp(prev_wd, "\\dm", strlen("\\dm")) == 0)
 		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_matviews, NULL);
+	else if (strncmp(prev_wd, "\\dE", strlen("\\dE")) == 0)
+		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_foreign_tables, NULL);
+	else if (strncmp(prev_wd, "\\dy", strlen("\\dy")) == 0)
+		COMPLETE_WITH_QUERY(Query_for_list_of_event_triggers);
 
 	/* must be at end of \d list */
 	else if (strncmp(prev_wd, "\\d", strlen("\\d")) == 0)