[Feature #21264] Replace C extension with pure Ruby implementation for Ruby >= 3.3

.github/workflows/update.yml

@@ -31,7 +31,7 @@ jobs:
         echo "diff=true" >> $GITHUB_OUTPUT
     - name: Commit
       run: |
-        git commit --message="Update zonetab.h at $(date +%F)" ext/date
+        git commit --message="Update zonetab at $(date +%F)" ext/date lib/date/zonetab.rb
         git pull --ff-only origin ${GITHUB_REF#refs/heads/}
         git push origin ${GITHUB_REF#refs/heads/}
       env:

Rakefile

@@ -1,30 +1,47 @@
 require "bundler/gem_tasks"
 require "rake/testtask"
-require "shellwords"
-require "rake/extensiontask"
 
-extask = Rake::ExtensionTask.new("date") do |ext|
-  ext.name = "date_core"
-  ext.lib_dir.sub!(%r[(?=/|\z)], "/#{RUBY_VERSION}/#{ext.platform}")
-end
+if RUBY_VERSION >= "3.3"
+  # Pure Ruby — no compilation needed
+  Rake::TestTask.new(:test) do |t|
+    t.libs << "lib"
+    t.libs << "test/lib"
+    t.ruby_opts << "-rhelper"
+    t.test_files = FileList['test/**/test_*.rb']
+  end
 
-Rake::TestTask.new(:test) do |t|
-  t.libs << extask.lib_dir
-  t.libs << "test/lib"
-  t.ruby_opts << "-rhelper"
-  t.test_files = FileList['test/**/test_*.rb']
-end
+  task :compile  # no-op
+
+else
+  # C extension for Ruby < 3.3
+  require "shellwords"
+  require "rake/extensiontask"
+
+  extask = Rake::ExtensionTask.new("date") do |ext|
+    ext.name = "date_core"
+    ext.lib_dir.sub!(%r[(?=/|\z)], "/#{RUBY_VERSION}/#{ext.platform}")
+  end
+
+  Rake::TestTask.new(:test) do |t|
+    t.libs << extask.lib_dir
+    t.libs << "test/lib"
+    t.ruby_opts << "-rhelper"
+    t.test_files = FileList['test/**/test_*.rb']
+  end
+
+  task test: :compile
 
-task compile: "ext/date/zonetab.h"
-file "ext/date/zonetab.h" => "ext/date/zonetab.list" do |t|
-  dir, hdr = File.split(t.name)
-  make_program_name =
-    ENV['MAKE'] || ENV['make'] ||
-    RbConfig::CONFIG['configure_args'][/with-make-prog\=\K\w+/] ||
-    (/mswin/ =~ RUBY_PLATFORM ? 'nmake' : 'make')
-  make_program = Shellwords.split(make_program_name)
-  sh(*make_program, "-f", "prereq.mk", "top_srcdir=.."+"/.."*dir.count("/"),
-     hdr, chdir: dir)
+  task compile: "ext/date/zonetab.h"
+  file "ext/date/zonetab.h" => "ext/date/zonetab.list" do |t|
+    dir, hdr = File.split(t.name)
+    make_program_name =
+      ENV['MAKE'] || ENV['make'] ||
+      RbConfig::CONFIG['configure_args'][/with-make-prog\=\K\w+/] ||
+      (/mswin/ =~ RUBY_PLATFORM ? 'nmake' : 'make')
+    make_program = Shellwords.split(make_program_name)
+    sh(*make_program, "-f", "prereq.mk", "top_srcdir=.."+"/.."*dir.count("/"),
+       hdr, chdir: dir)
+  end
 end
 
 task :default => [:compile, :test]

date.gemspec

@@ -1,29 +1,19 @@
 # frozen_string_literal: true
 
-version = File.foreach(File.expand_path("../lib/date.rb", __FILE__)).find do |line|
-  /^\s*VERSION\s*=\s*["'](.*)["']/ =~ line and break $1
-end
+require_relative "lib/date/version"
 
 Gem::Specification.new do |s|
   s.name = "date"
-  s.version = version
+  s.version = Date::VERSION
   s.summary = "The official date library for Ruby."
   s.description = "The official date library for Ruby."
 
-  if Gem::Platform === s.platform and s.platform =~ 'java' or RUBY_ENGINE == 'jruby'
-    s.platform = 'java'
-    # No files shipped, no require path, no-op for now on JRuby
-  else
-    s.require_path = %w{lib}
+  s.require_path = %w{lib}
 
-    s.files = [
-      "README.md", "COPYING", "BSDL",
-      "lib/date.rb", "ext/date/date_core.c", "ext/date/date_parse.c", "ext/date/date_strftime.c",
-      "ext/date/date_strptime.c", "ext/date/date_tmx.h", "ext/date/extconf.rb", "ext/date/prereq.mk",
-      "ext/date/zonetab.h", "ext/date/zonetab.list"
-    ]
-    s.extensions = "ext/date/extconf.rb"
-  end
+  s.files = Dir["README.md", "COPYING", "BSDL", "lib/**/*.rb",
+                "ext/date/*.c", "ext/date/*.h", "ext/date/extconf.rb",
+                "ext/date/prereq.mk", "ext/date/zonetab.list"]
+  s.extensions = ["ext/date/extconf.rb"]
 
   s.required_ruby_version = ">= 2.6.0"
 

ext/date/extconf.rb

@@ -1,13 +1,16 @@
 # frozen_string_literal: true
 require 'mkmf'
 
-config_string("strict_warnflags") {|w| $warnflags += " #{w}"}
-
-append_cflags("-Wno-compound-token-split-by-macro") if RUBY_VERSION < "2.7."
-have_func("rb_category_warn")
-with_werror("", {:werror => true}) do |opt, |
-  have_var("timezone", "time.h", opt)
-  have_var("altzone", "time.h", opt)
+if RUBY_VERSION >= "3.3"
+  # Pure Ruby implementation; skip C extension build
+  File.write("Makefile", dummy_makefile($srcdir).join(""))
+else
+  config_string("strict_warnflags") {|w| $warnflags += " #{w}"}
+  append_cflags("-Wno-compound-token-split-by-macro") if RUBY_VERSION < "2.7."
+  have_func("rb_category_warn")
+  with_werror("", {:werror => true}) do |opt, |
+    have_var("timezone", "time.h", opt)
+    have_var("altzone", "time.h", opt)
+  end
+  create_makefile('date_core')
 end
-
-create_makefile('date_core')

ext/date/generate-zonetab-rb

@@ -0,0 +1,59 @@
+# -*- mode: ruby -*-
+# Generate lib/date/zonetab.rb from ext/date/zonetab.list
+#
+# Usage: ruby -C ext/date generate-zonetab-rb
+#
+# This script reads zonetab.list (the same source used to generate zonetab.h
+# via gperf) and produces the equivalent Ruby hash table.
+
+list_path = File.join(__dir__, 'zonetab.list')
+output_path = File.join(__dir__, '..', '..', 'lib', 'date', 'zonetab.rb')
+
+entries = {}
+in_entries = false
+
+File.foreach(list_path) do |line|
+  line.chomp!
+  if line == '%%'
+    if in_entries
+      break
+    else
+      in_entries = true
+      next
+    end
+  end
+  next unless in_entries
+
+  abbr, offset_expr = line.split(',', 2)
+  next unless offset_expr
+
+  abbr.strip!
+  offset_expr.strip!
+
+  # Evaluate offset expression (e.g., "0*3600", "-5*3600", "-(1*3600+1800)", "16200")
+  offset = eval(offset_expr)
+
+  entries[abbr] = offset
+end
+
+sorted = entries.sort_by { |k, _| k }
+
+max_key_len = sorted.map { |k, _| k.length }.max
+
+File.open(output_path, 'w') do |f|
+  f.puts '# frozen_string_literal: true'
+  f.puts
+  f.puts '# Timezone name => UTC offset (seconds) mapping table.'
+  f.puts '# Auto-generated from ext/date/zonetab.list by ext/date/generate-zonetab-rb.'
+  f.puts '# Do not edit manually.'
+  f.puts 'class Date'
+  f.puts '  ZONE_TABLE = {'
+  sorted.each do |abbr, offset|
+    key = abbr.include?(' ') ? %Q("#{abbr}") : %Q("#{abbr}")
+    f.puts "    %-#{max_key_len + 3}s => %d," % [key, offset]
+  end
+  f.puts '  }.freeze'
+  f.puts 'end'
+end
+
+puts "Generated #{output_path} with #{entries.size} entries."

ext/date/prereq.mk

@@ -10,6 +10,7 @@ zonetab.h: zonetab.list
 .PHONY: update-zonetab
 update-zonetab:
 	$(RUBY) -C $(srcdir) update-abbr
+	$(RUBY) -C $(srcdir) generate-zonetab-rb
 
 .PHONY: update-nothing
 update-nothing:

lib/date.rb

@@ -1,11 +1,24 @@
 # frozen_string_literal: true
 # date.rb: Written by Tadayoshi Funaba 1998-2011
 
-require 'date_core'
+require 'timeout'
+require 'strscan'
 
-class Date
-  VERSION = "3.5.1" # :nodoc:
+if RUBY_VERSION >= "3.3"
+  require_relative "date/version"
+  require_relative "date/constants"
+  require_relative "date/shared"
+  require_relative "date/core"
+  require_relative "date/strftime"
+  require_relative "date/parse"
+  require_relative "date/strptime"
+  require_relative "date/time"
+  require_relative "date/datetime"
+else
+  require 'date_core'
+end
 
+class Date
   # call-seq:
   #   infinite? -> false
   #
@@ -64,7 +77,5 @@ def to_f
         -Float::INFINITY
       end
     end
-
   end
-
 end