From 512d25607bcaaffd9232783d309fa768c66e6066 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20=C5=9Awi=C4=85tkowski?= <katafrakt@vivaldi.net>
Date: Mon, 14 Jul 2025 15:06:12 +0200
Subject: [PATCH] Support :keyword_init argument when defining a new struct

---
 mrbgems/mruby-struct/src/struct.c   | 44 ++++++++++++++++++++----
 mrbgems/mruby-struct/test/struct.rb | 52 +++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+), 6 deletions(-)

diff --git a/mrbgems/mruby-struct/src/struct.c b/mrbgems/mruby-struct/src/struct.c
index 9b78a5169..bc14dcd86 100644
--- a/mrbgems/mruby-struct/src/struct.c
+++ b/mrbgems/mruby-struct/src/struct.c
@@ -258,12 +258,24 @@ mrb_struct_s_def(mrb_state *mrb, mrb_value klass)
   mrb_value b;
   const mrb_value *argv;
   mrb_int argc;
+  mrb_value keyword_init_val = mrb_nil_value();
 
   mrb_get_args(mrb, "*&", &argv, &argc, &b);
   if (argc == 0) {
     mrb_raise(mrb, E_ARGUMENT_ERROR, "wrong number of arguments (given 0, expected 1+)");
   }
 
+  /* Check for keyword_init option in arguments */
+  if (argc > 0 && mrb_hash_p(argv[argc-1])) {
+    mrb_value options = argv[argc-1];
+    mrb_sym keyword_init_sym = mrb_intern_lit(mrb, "keyword_init");
+
+    if (mrb_hash_key_p(mrb, options, mrb_symbol_value(keyword_init_sym))) {
+      keyword_init_val = mrb_hash_get(mrb, options, mrb_symbol_value(keyword_init_sym));
+      argc--; /* Don't treat the options hash as a member name */
+    }
+  }
+
   const mrb_value *pargv = argv;
   mrb_int argcnt = argc;
   if (argc > 0 && !mrb_symbol_p(argv[0])) {
@@ -290,6 +302,10 @@ mrb_struct_s_def(mrb_state *mrb, mrb_value klass)
   }
 
   mrb_value st = make_struct(mrb, name, members, mrb_class_ptr(klass));
+
+  /* Set keyword_init value on the struct class */
+  mrb_iv_set(mrb, st, mrb_intern_lit(mrb, "@__keyword_init__"), keyword_init_val);
+
   if (!mrb_nil_p(b)) {
     mrb_yield_with_class(mrb, b, 1, &st, st, mrb_class_ptr(st));
   }
@@ -335,6 +351,7 @@ mrb_struct_initialize_withKw(mrb_state *mrb, mrb_value hash, mrb_value self)
     }
   }
 
+
   /* Check if all keys in the hash are valid members */
   mrb_value keys = mrb_hash_keys(mrb, hash);
   mrb_value invalid_keys = mrb_ary_new(mrb);
@@ -350,8 +367,7 @@ mrb_struct_initialize_withKw(mrb_state *mrb, mrb_value hash, mrb_value self)
   /* If there are any invalid keys, raise an error with all of them */
   if (RARRAY_LEN(invalid_keys) > 0) {
     mrb_value keys_str = mrb_funcall(mrb, invalid_keys, "join", 1, mrb_str_new_lit(mrb, ", "));
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unknown keyword%s: %S",
-              RARRAY_LEN(invalid_keys) > 1 ? "s" : "", keys_str);
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unknown keywords: %S", keys_str);
   }
 
   return self;
@@ -362,15 +378,31 @@ mrb_struct_initialize(mrb_state *mrb, mrb_value self)
 {
   const mrb_value *argv;
   mrb_int argc;
+  mrb_value klass, keyword_init;
 
   mrb_get_args(mrb, "*", &argv, &argc);
 
-  /* If we get a single hash argument, treat it as keyword arguments */
-  if (argc == 1 && mrb_hash_p(argv[0])) {
-    return mrb_struct_initialize_withKw(mrb, argv[0], self);
-  } else {
+  klass = mrb_obj_value(mrb_obj_class(mrb, self));
+  keyword_init = mrb_iv_get(mrb, klass, mrb_intern_lit(mrb, "@__keyword_init__"));
+
+  if (mrb_test(keyword_init)) { /* keyword_init: true or other truthy value */
+    if (argc > 1 || (argc == 1 && !mrb_hash_p(argv[0]))) {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "wrong arguments, expected keyword arguments");
+    }
+    mrb_value hash = (argc == 1) ? argv[0] : mrb_hash_new(mrb);
+    return mrb_struct_initialize_withKw(mrb, hash, self);
+  }
+  else if (mrb_equal(mrb, keyword_init, mrb_false_value())) { /* keyword_init: false */
     return mrb_struct_initialize_withArg(mrb, argc, argv, self);
   }
+  else { /* keyword_init: nil (default) */
+    if (argc == 1 && mrb_hash_p(argv[0])) {
+      return mrb_struct_initialize_withKw(mrb, argv[0], self);
+    }
+    else {
+      return mrb_struct_initialize_withArg(mrb, argc, argv, self);
+    }
+  }
 }
 
 /* 15.2.18.4.9  */
diff --git a/mrbgems/mruby-struct/test/struct.rb b/mrbgems/mruby-struct/test/struct.rb
index da41d04cb..a2fbcdc3d 100644
--- a/mrbgems/mruby-struct/test/struct.rb
+++ b/mrbgems/mruby-struct/test/struct.rb
@@ -245,7 +245,59 @@ assert "Struct initialize with keyword arguments" do
   assert_equal :test, o3.foo
   assert_equal nil, o3.bar
 
+  o4 = c.new
+  assert_equal nil, o4.foo
+  assert_equal nil, o4.bar
+
   assert_raise_with_message_pattern(ArgumentError, "unknown keywords: roo, baq") do
     c.new(foo: 1, roo: nil, baq: :test)
   end
 end
+
+assert "Struct initialize when :keyword_init is true" do
+  c = Struct.new(:foo, :bar, keyword_init: true)
+
+  o = c.new(foo: 1, bar: 2)
+  assert_equal 1, o.foo
+  assert_equal 2, o.bar
+
+  o2 = c.new
+  assert_equal nil, o2.foo
+  assert_equal nil, o2.bar
+
+  assert_raise(ArgumentError) do
+    c.new(1, 2)
+  end
+
+  assert_raise(ArgumentError) do
+    c.new({foo: 1}, {bar: 2})
+  end
+end
+
+assert "Struct initialize when :keyword_init is false" do
+  c = Struct.new(:foo, :bar, keyword_init: false)
+  
+  o = c.new(1, 2)
+  assert_equal 1, o.foo
+  assert_equal 2, o.bar
+
+  o2 = c.new(foo: 1, bar: 2)
+  assert_equal({foo: 1, bar: 2}, o2.foo)
+  assert_equal nil, o2.bar
+
+  o3 = c.new
+  assert_equal nil, o3.foo
+  assert_equal nil, o3.bar
+end
+
+assert "Struct initialize when :keyword_init is non-boolean value (treat as true)" do
+  c = Struct.new(:foo, :bar, keyword_init: 12)
+
+  o = c.new(foo: 1, bar: 2)
+  assert_equal 1, o.foo
+  assert_equal 2, o.bar
+
+  assert_raise(ArgumentError) do
+    c.new(1, 2)
+  end
+end