[ruby/digest] Place common parts in lib and engine specific parts under ext/**/lib

https://github.com/ruby/digest/commit/8d7496c3be

ext/digest/bubblebabble/lib/bubblebabble.rb

@@ -1,9 +0,0 @@
-# frozen_string_literal: false
-
-require 'digest'
-
-if RUBY_ENGINE == 'jruby'
-  JRuby::Util.load_ext("org.jruby.ext.digest.BubbleBabble")
-else
-  require 'digest/bubblebabble.so'
-end

ext/digest/digest.gemspec

@@ -12,60 +12,27 @@ Gem::Specification.new do |spec|
   spec.homepage      = "https://github.com/ruby/digest"
   spec.licenses      = ["Ruby", "BSD-2-Clause"]
 
-  spec.files         = [
-    "LICENSE.txt", "README.md",
-
-    "ext/digest/defs.h", "ext/digest/digest.c", "ext/digest/digest.h",
-    "ext/digest/digest_conf.rb", "ext/digest/extconf.rb",
-    "ext/digest/lib/digest.rb",
-
-    "ext/digest/bubblebabble/bubblebabble.c",
-    "ext/digest/bubblebabble/extconf.rb",
-
-    "ext/digest/md5/extconf.rb", "ext/digest/md5/md5.c",
-    "ext/digest/md5/md5.h", "ext/digest/md5/md5cc.h",
-    "ext/digest/md5/md5init.c",
-
-    "ext/digest/rmd160/extconf.rb", "ext/digest/rmd160/rmd160.c",
-    "ext/digest/rmd160/rmd160.h", "ext/digest/rmd160/rmd160init.c",
-
-    "ext/digest/sha1/extconf.rb", "ext/digest/sha1/sha1.c",
-    "ext/digest/sha1/sha1.h", "ext/digest/sha1/sha1cc.h",
-    "ext/digest/sha1/sha1init.c",
-
-    "ext/digest/sha2/extconf.rb", "ext/digest/sha2/lib/sha2.rb",
-    "ext/digest/sha2/sha2.c", "ext/digest/sha2/sha2.h",
-    "ext/digest/sha2/sha2cc.h", "ext/digest/sha2/sha2init.c",
-
-    "ext/openssl/deprecation.rb",
-    "ext/digest/test.sh",
+  spec.files = [
+    "LICENSE.txt",
+    "README.md",
+    *Dir["lib/digest{.rb,/**/*.rb}"],
   ]
 
   spec.required_ruby_version = ">= 2.5.0"
 
   spec.bindir        = "exe"
   spec.executables   = []
-  spec.require_paths = ["lib"]
 
   if Gem::Platform === spec.platform and spec.platform =~ 'java' or RUBY_ENGINE == 'jruby'
     spec.platform = 'java'
-    spec.files.concat [
-      "lib/digest.jar",
-      "lib/digest/md5.rb",
-      "lib/digest/sha1.rb",
-      "lib/digest/sha2.rb",
-      "lib/digest/rmd160.rb",
-      "lib/digest/bubblebabble.rb"
-    ]
+
+    spec.files += Dir["ext/java/**/*.{rb,java}"]
+    spec.require_paths = %w[lib ext/java/org/jruby/ext/digest/lib]
   else
-    spec.extensions    = %w[
-      ext/digest/extconf.rb
-      ext/digest/bubblebabble/extconf.rb
-      ext/digest/md5/extconf.rb
-      ext/digest/rmd160/extconf.rb
-      ext/digest/sha1/extconf.rb
-      ext/digest/sha2/extconf.rb
-    ]
+    spec.extensions = Dir["ext/digest/**/extconf.rb"]
+
+    spec.files += Dir["ext/digest/**/*.{rb,c,h,sh}"]
+    spec.require_paths = %w[lib]
   end
 
   spec.metadata["msys2_mingw_dependencies"] = "openssl"

ext/digest/lib/digest/loader.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require 'digest.so'

ext/digest/lib/digest/sha2/loader.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require 'digest/sha2.so'

ext/digest/md5/lib/md5.rb

@@ -1,9 +0,0 @@
-# frozen_string_literal: false
-
-require 'digest'
-
-if RUBY_ENGINE == 'jruby'
-  JRuby::Util.load_ext("org.jruby.ext.digest.MD5")
-else
-  require 'digest/md5.so'
-end

ext/digest/rmd160/lib/rmd160.rb

@@ -1,9 +0,0 @@
-# frozen_string_literal: false
-
-require 'digest'
-
-if RUBY_ENGINE == 'jruby'
-  JRuby::Util.load_ext("org.jruby.ext.digest.RMD160")
-else
-  require 'digest/rmd160.so'
-end

ext/digest/sha1/lib/sha1.rb

@@ -1,9 +0,0 @@
-# frozen_string_literal: false
-
-require 'digest'
-
-if RUBY_ENGINE == 'jruby'
-  JRuby::Util.load_ext("org.jruby.ext.digest.SHA1")
-else
-  require 'digest/sha1.so'
-end

lib/digest.rb

@@ -1,9 +1,6 @@
 # frozen_string_literal: false
-if RUBY_ENGINE == 'jruby'
-  JRuby::Util.load_ext("org.jruby.ext.digest.DigestLibrary")
-else
-  require 'digest.so'
-end
+
+require 'digest/loader'
 
 module Digest
   # A mutex for Digest().

lib/digest/sha2.rb

@@ -11,12 +11,7 @@
 #   $Id$
 
 require 'digest'
-
-if RUBY_ENGINE == 'jruby'
-  JRuby::Util.load_ext("org.jruby.ext.digest.SHA2")
-else
-  require 'digest/sha2.so'
-end
+require 'digest/sha2/loader'
 
 module Digest
   #