Add public ruleutils.c entry point to deparse a Query.

This has no in-core callers but will be wanted by extensions.
It's just a thin wrapper around get_query_def, so it adds little code.

Also, fix get_from_clause_item() to force insertion of an alias
for a SUBQUERY RTE item.  This is irrelevant to existing uses because
RTE_SUBQUERY items made by the parser always have aliases already.
However, if one tried to use pg_get_querydef() to inspect a post-rewrite
Query, it could be an issue.  In any case, get_from_clause_item already
contained logic to force alias insertion for VALUES items, so the lack
of the same for SUBQUERY is a pretty clear oversight.

In passing, replace duplicated code for selection of pretty-print
options with a common macro.

Julien Rouhaud, reviewed by Pavel Stehule, Gilles Darold, and myself

Discussion: https://postgr.es/m/20210627041138.zklczwmu3ms4ufnk@nol

1 files changed, 42 insertions, 12 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 82dc849a301..38da2695197 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -90,6 +90,11 @@
 #define PRETTYFLAG_INDENT		0x0002
 #define PRETTYFLAG_SCHEMA		0x0004
 
+/* Standard conversion of a "bool pretty" option to detailed flags */
+#define GET_PRETTY_FLAGS(pretty) \
+	((pretty) ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) \
+	 : PRETTYFLAG_INDENT)
+
 /* Default line length for pretty-print wrapping: 0 means wrap always */
 #define WRAP_COLUMN_DEFAULT		0
 
@@ -532,7 +537,7 @@ pg_get_ruledef_ext(PG_FUNCTION_ARGS)
 	int			prettyFlags;
 	char	   *res;
 
-	prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
 
 	res = pg_get_ruledef_worker(ruleoid, prettyFlags);
 
@@ -653,7 +658,7 @@ pg_get_viewdef_ext(PG_FUNCTION_ARGS)
 	int			prettyFlags;
 	char	   *res;
 
-	prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
 
 	res = pg_get_viewdef_worker(viewoid, prettyFlags, WRAP_COLUMN_DEFAULT);
 
@@ -673,7 +678,7 @@ pg_get_viewdef_wrap(PG_FUNCTION_ARGS)
 	char	   *res;
 
 	/* calling this implies we want pretty printing */
-	prettyFlags = PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA;
+	prettyFlags = GET_PRETTY_FLAGS(true);
 
 	res = pg_get_viewdef_worker(viewoid, prettyFlags, wrap);
 
@@ -719,7 +724,7 @@ pg_get_viewdef_name_ext(PG_FUNCTION_ARGS)
 	Oid			viewoid;
 	char	   *res;
 
-	prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
 
 	/* Look up view name.  Can't lock it - we might not have privileges. */
 	viewrel = makeRangeVarFromNameList(textToQualifiedNameList(viewname));
@@ -1062,7 +1067,7 @@ pg_get_triggerdef_worker(Oid trigid, bool pretty)
 		context.windowClause = NIL;
 		context.windowTList = NIL;
 		context.varprefix = true;
-		context.prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+		context.prettyFlags = GET_PRETTY_FLAGS(pretty);
 		context.wrapColumn = WRAP_COLUMN_DEFAULT;
 		context.indentLevel = PRETTYINDENT_STD;
 		context.special_exprkind = EXPR_KIND_NONE;
@@ -1152,7 +1157,7 @@ pg_get_indexdef_ext(PG_FUNCTION_ARGS)
 	int			prettyFlags;
 	char	   *res;
 
-	prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
 
 	res = pg_get_indexdef_worker(indexrelid, colno, NULL,
 								 colno != 0, false,
@@ -1185,7 +1190,7 @@ pg_get_indexdef_columns(Oid indexrelid, bool pretty)
 {
 	int			prettyFlags;
 
-	prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
 
 	return pg_get_indexdef_worker(indexrelid, 0, NULL,
 								  true, true,
@@ -1516,6 +1521,30 @@ pg_get_indexdef_worker(Oid indexrelid, int colno,
 	return buf.data;
 }
 
+/* ----------
+ * pg_get_querydef
+ *
+ * Public entry point to deparse one query parsetree.
+ * The pretty flags are determined by GET_PRETTY_FLAGS(pretty).
+ *
+ * The result is a palloc'd C string.
+ * ----------
+ */
+char *
+pg_get_querydef(Query *query, bool pretty)
+{
+	StringInfoData buf;
+	int			prettyFlags;
+
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
+
+	initStringInfo(&buf);
+
+	get_query_def(query, &buf, NIL, NULL, prettyFlags, WRAP_COLUMN_DEFAULT, 0);
+
+	return buf.data;
+}
+
 /*
  * pg_get_statisticsobjdef
  *		Get the definition of an extended statistics object
@@ -1848,7 +1877,7 @@ pg_get_partkeydef_columns(Oid relid, bool pretty)
 {
 	int			prettyFlags;
 
-	prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
 
 	return pg_get_partkeydef_worker(relid, prettyFlags, true, false);
 }
@@ -2095,7 +2124,7 @@ pg_get_constraintdef_ext(PG_FUNCTION_ARGS)
 	int			prettyFlags;
 	char	   *res;
 
-	prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
 
 	res = pg_get_constraintdef_worker(constraintId, false, prettyFlags, true);
 
@@ -2625,7 +2654,7 @@ pg_get_expr_ext(PG_FUNCTION_ARGS)
 	int			prettyFlags;
 	char	   *relname;
 
-	prettyFlags = pretty ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) : PRETTYFLAG_INDENT;
+	prettyFlags = GET_PRETTY_FLAGS(pretty);
 
 	if (OidIsValid(relid))
 	{
@@ -11210,9 +11239,10 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 			 */
 			printalias = true;
 		}
-		else if (rte->rtekind == RTE_VALUES)
+		else if (rte->rtekind == RTE_SUBQUERY ||
+				 rte->rtekind == RTE_VALUES)
 		{
-			/* Alias is syntactically required for VALUES */
+			/* Alias is syntactically required for SUBQUERY and VALUES */
 			printalias = true;
 		}
 		else if (rte->rtekind == RTE_CTE)