From f6f670834b158aec01cf9ee869160e1aad58acc6 Mon Sep 17 00:00:00 2001
From: Eugene Yokota <eed3si9n@gmail.com>
Date: Sat, 14 Dec 2024 02:16:59 -0500
Subject: [PATCH] SIP-58 Named Tuples support

**Problem**
Named tuples are now available as an experimental feature.

**Solution**
This implements a support for them.
---
 grammar.js               | 38 +++++++++++++++++++++++++++++++++++++-
 test/corpus/patterns.txt | 25 +++++++++++++++++++++++++
 test/corpus/types.txt    | 23 +++++++++++++++++++++++
 3 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/grammar.js b/grammar.js
index 42b1b82..a50fa50 100644
--- a/grammar.js
+++ b/grammar.js
@@ -91,6 +91,11 @@ module.exports = grammar({
     [$.class_parameters],
     // 'for'  operator_identifier  ':'  _annotated_type  •  ':'  …
     [$._type, $.compound_type],
+    // 'given'  '('  operator_identifier  ':'  _type  •  ','  …
+    [$.name_and_type, $.parameter],
+    [$._simple_expression, $.binding, $.tuple_pattern],
+    [$._simple_expression, $.tuple_pattern],
+    [$._simple_expression, $._type_identifier],
     // 'if'  parenthesized_expression  •  '{'  …
     [$._if_condition, $._simple_expression],
     // _postfix_expression_choice  ':'  '('  wildcard  •  ':'  …
@@ -785,6 +790,19 @@ module.exports = grammar({
         ),
       ),
 
+    /*
+     * NameAndType       ::=  id ':' Type
+     */
+    name_and_type: $ =>
+      prec.left(
+        PREC.control,
+        seq(
+          field("name", $._identifier),
+          ":",
+          field("type", $._param_type),
+        ),
+      ),
+
     _block: $ =>
       prec.left(
         seq(
@@ -837,6 +855,7 @@ module.exports = grammar({
         $.generic_type,
         $.projected_type,
         $.tuple_type,
+        $.named_tuple_type,
         $.singleton_type,
         $.stable_type_identifier,
         $._type_identifier,
@@ -897,6 +916,12 @@ module.exports = grammar({
 
     tuple_type: $ => seq("(", trailingCommaSep1($._type), ")"),
 
+    named_tuple_type: $ => seq(
+      "(",
+      trailingCommaSep1($.name_and_type),
+      ")",
+    ),
+
     singleton_type: $ =>
       prec.left(
         PREC.stable_type_id,
@@ -991,6 +1016,7 @@ module.exports = grammar({
         $.interpolated_string_expression,
         $.capture_pattern,
         $.tuple_pattern,
+        $.named_tuple_pattern,
         $.case_class_pattern,
         $.infix_pattern,
         $.alternative_pattern,
@@ -1034,16 +1060,26 @@ module.exports = grammar({
 
     typed_pattern: $ =>
       prec.right(
+        -1,
         seq(field("pattern", $._pattern), ":", field("type", $._type)),
       ),
 
     given_pattern: $ => seq("given", field("type", $._type)),
 
     // TODO: Flatten this.
-    alternative_pattern: $ => prec.left(-1, seq($._pattern, "|", $._pattern)),
+    alternative_pattern: $ => prec.left(-2, seq($._pattern, "|", $._pattern)),
 
     tuple_pattern: $ => seq("(", $._pattern, repeat(seq(",", $._pattern)), ")"),
 
+    named_pattern: $ => prec.left(-1, seq($._identifier, "=", $._pattern)),
+
+    named_tuple_pattern: $ => seq(
+      "(",
+      $.named_pattern,
+      repeat(seq(",", $.named_pattern)),
+      ")",
+    ),
+
     // ---------------------------------------------------------------
     // Expressions
 
diff --git a/test/corpus/patterns.txt b/test/corpus/patterns.txt
index 503b62d..d7117ed 100644
--- a/test/corpus/patterns.txt
+++ b/test/corpus/patterns.txt
@@ -111,6 +111,31 @@ val x = y match {
             (identifier))
           (identifier))))))
 
+================================================================================
+Name tuple patterns (Scala 3 syntax)
+================================================================================
+
+val x = y match
+  case (a = A, b = B) => ???
+
+--------------------------------------------------------------------------------
+
+(compilation_unit
+  (val_definition
+    (identifier)
+    (match_expression
+      (identifier)
+      (indented_cases
+        (case_clause
+          (named_tuple_pattern
+            (named_pattern
+              (identifier)
+              (identifier))
+            (named_pattern
+              (identifier)
+              (identifier)))
+          (operator_identifier))))))
+
 ================================================================================
 Case class patterns
 ================================================================================
diff --git a/test/corpus/types.txt b/test/corpus/types.txt
index a239d0b..ff18e85 100644
--- a/test/corpus/types.txt
+++ b/test/corpus/types.txt
@@ -97,6 +97,29 @@ object Main {
           (type_identifier)
           (type_identifier))))))
 
+================================================================================
+Named tuple types (Scala 3 syntax)
+================================================================================
+
+object O:
+  type A = (name: String, age: Int)
+
+--------------------------------------------------------------------------------
+
+(compilation_unit
+  (object_definition
+    (identifier)
+    (template_body
+      (type_definition
+        (type_identifier)
+        (named_tuple_type
+          (name_and_type
+            (identifier)
+            (type_identifier))
+          (name_and_type
+            (identifier)
+            (type_identifier)))))))
+
 ================================================================================
 Function types
 ================================================================================