time is hard...

corpus/select_statement/value_expression.txt

@@ -244,3 +244,37 @@ SELECT
         (identifier)
         (comparison_null)))))
 
+================================================================================
+time expressions
+================================================================================
+SELECT
+    foo::interval,
+    foo at time zone 'utc',
+    interval '1 day',
+    interval '1' hour to second,
+    interval '1' day + interval '3' month;
+--------------------------------------------------------------------------------
+
+(source_file
+  (select_statement
+    (select_item
+      (op_expression
+        (identifier)
+        (cast)
+        (identifier)))
+    (select_item
+      (time_expression
+        (identifier)
+        (string)))
+    (select_item
+      (time_expression
+        (string)))
+    (select_item
+      (time_expression
+        (string)))
+    (select_item
+      (op_expression
+        (time_expression
+          (string))
+        (time_expression
+          (string))))))

grammar.js

@@ -741,6 +741,19 @@ module.exports = grammar({
 
     time_expression: $ => choice(
       seq($.identifier, kw("at"), kw("time"), kw("zone"), $._value_expression),
+      // TODO(chrde): this is plain wrong - https://www.postgresql.org/docs/13/datatype-datetime.html
+      seq(kw("interval"), $.string, optional($._interval_fields)),
+    ),
+
+    _interval_fields: $ => choice(
+      kw("year"), kw("month"), kw("day"), kw("hour"), kw("minute"), kw("second"),
+      seq(kw("year"), kw("to"), kw("month")),
+      seq(kw("day"), kw("to"), kw("hour")),
+      seq(kw("day"), kw("to"), kw("minute")),
+      seq(kw("day"), kw("to"), kw("second")),
+      seq(kw("hour"), kw("to"), kw("minute")),
+      seq(kw("hour"), kw("to"), kw("second")),
+      seq(kw("minute"), kw("to"), kw("second")),
     ),
 
     function_call: $ => seq(
@@ -754,7 +767,7 @@ module.exports = grammar({
     ),
 
     op_expression: $ => choice(
-      prec.left(12, seq($._value_expression, $.cast, $._value_expression)),
+      prec.left(12, seq($._value_expression, $.cast, $.identifier)),
       // array access
       prec.right(10, seq(choice($.minus, $.plus), $._value_expression)),
       // ^