[ruby/erb] Define ERB::Escape module

(https://github.com/ruby/erb/pull/38)

Close #32

ext/erb/escape/escape.c

@@ -1,7 +1,7 @@
 #include "ruby.h"
 #include "ruby/encoding.h"
 
-static VALUE rb_cERB, rb_mUtil, rb_cCGI;
+static VALUE rb_cERB, rb_mEscape, rb_cCGI;
 static ID id_escapeHTML;
 
 #define HTML_ESCAPE_MAX_LEN 6
@@ -87,8 +87,8 @@ void
 Init_escape(void)
 {
     rb_cERB = rb_define_class("ERB", rb_cObject);
-    rb_mUtil = rb_define_module_under(rb_cERB, "Util");
-    rb_define_module_function(rb_mUtil, "html_escape", erb_escape_html, 1);
+    rb_mEscape = rb_define_module_under(rb_cERB, "Escape");
+    rb_define_module_function(rb_mEscape, "html_escape", erb_escape_html, 1);
 
     rb_cCGI = rb_define_class("CGI", rb_cObject);
     id_escapeHTML = rb_intern("escapeHTML");

lib/erb/util.rb

@@ -1,8 +1,20 @@
+#--
+# ERB::Escape
+#
+# A subset of ERB::Util. Unlike ERB::Util#html_escape, we expect/hope
+# Rails will not monkey-patch ERB::Escape#html_escape.
 begin
-  # ERB::Util.html_escape
   require 'erb/escape'
 rescue LoadError # JRuby can't load .so
 end
+unless defined?(ERB::Escape) # JRuby
+  module ERB::Escape
+    def html_escape(s)
+      CGI.escapeHTML(s.to_s)
+    end
+    module_function :html_escape
+  end
+end
 
 #--
 # ERB::Util
@@ -21,12 +33,8 @@ module ERB::Util
   #
   #   is a > 0 & a < 10?
   #
-  unless defined?(ERB::Util.html_escape) # for JRuby
-    def html_escape(s)
-      CGI.escapeHTML(s.to_s)
-    end
-    module_function :html_escape
-  end
+  include ERB::Escape # html_escape
+  module_function :html_escape
   alias h html_escape
   module_function :h