From 2113b7cd23cbed04a5828142f46a59e0225accda Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Sun, 17 Aug 2025 08:07:30 +0900
Subject: [PATCH] mruby-dir: implement Dir.children in c for improved
 performance

Moved Dir.children from Ruby to C implementation to eliminate
Ruby loop overhead and string comparison inefficiencies.
Uses existing skip_name_p helper to filter out "." and ".." entries
efficiently in C.

Co-authored-by: Claude <noreply@anthropic.com>
---
 mrbgems/mruby-dir/mrblib/dir.rb | 19 ------------------
 mrbgems/mruby-dir/src/dir.c     | 35 +++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 19 deletions(-)

diff --git a/mrbgems/mruby-dir/mrblib/dir.rb b/mrbgems/mruby-dir/mrblib/dir.rb
index 358efd78c..71dd929f1 100644
--- a/mrbgems/mruby-dir/mrblib/dir.rb
+++ b/mrbgems/mruby-dir/mrblib/dir.rb
@@ -44,25 +44,6 @@ class Dir
 
   class << self
 
-    #
-    # call-seq:
-    #   Dir.children(dirname) -> array
-    #
-    # Returns an array containing all of the filenames except for "." and ".."
-    # in the given directory. Will raise a SystemCallError if the named
-    # directory doesn't exist.
-    #
-    #   Dir.children("testdir")   #=> ["config.h", "main.rb"]
-    #
-    def children(path)
-      a = []
-      self.open(path) do |d|
-        while s = d.read
-          a << s unless s == "." || s == ".."
-        end
-      end
-      a
-    end
 
     #
     # call-seq:
diff --git a/mrbgems/mruby-dir/src/dir.c b/mrbgems/mruby-dir/src/dir.c
index cfc7c3b0d..f0af492df 100644
--- a/mrbgems/mruby-dir/src/dir.c
+++ b/mrbgems/mruby-dir/src/dir.c
@@ -453,6 +453,40 @@ mrb_dir_entries(mrb_state *mrb, mrb_value klass)
   return ary;
 }
 
+/*
+ * call-seq:
+ *   Dir.children(dirname) -> array
+ *
+ * Returns an array containing all of the filenames except for "." and ".."
+ * in the given directory. Will raise a SystemCallError if the named
+ * directory doesn't exist.
+ */
+static mrb_value
+mrb_dir_children(mrb_state *mrb, mrb_value klass)
+{
+  const char *path;
+  DIR *dir;
+  struct dirent *dp;
+  mrb_value ary;
+
+  mrb_get_args(mrb, "z", &path);
+
+  dir = opendir(path);
+  if (dir == NULL) {
+    mrb_sys_fail(mrb, path);
+  }
+
+  ary = mrb_ary_new(mrb);
+  while ((dp = readdir(dir)) != NULL) {
+    if (!skip_name_p(dp->d_name)) {
+      mrb_ary_push(mrb, ary, mrb_str_new_cstr(mrb, dp->d_name));
+    }
+  }
+
+  closedir(dir);
+  return ary;
+}
+
 void
 mrb_mruby_dir_gem_init(mrb_state *mrb)
 {
@@ -468,6 +502,7 @@ mrb_mruby_dir_gem_init(mrb_state *mrb)
   mrb_define_class_method_id(mrb, d, MRB_SYM(chroot),  mrb_dir_chroot, MRB_ARGS_REQ(1));
   mrb_define_class_method_id(mrb, d, MRB_SYM_Q(empty), mrb_dir_empty, MRB_ARGS_REQ(1));
   mrb_define_class_method_id(mrb, d, MRB_SYM(entries), mrb_dir_entries, MRB_ARGS_REQ(1));
+  mrb_define_class_method_id(mrb, d, MRB_SYM(children), mrb_dir_children, MRB_ARGS_REQ(1));
 
   mrb_define_method_id(mrb, d, MRB_SYM(close),      mrb_dir_close,  MRB_ARGS_NONE());
   mrb_define_method_id(mrb, d, MRB_SYM(initialize), mrb_dir_init,   MRB_ARGS_REQ(1));