Use erb/escape for faster html escaping if available

ERB::Escape#html_escape will return input strings as is without
allocating new strings if no escaping is needed, which can result
in better performance for such strings. This shouldn't cause any
issues in Erubi, because the result of Erubi.h is only used to
concat to an existing string.

CHANGELOG

@@ -1,5 +1,7 @@
 === master
 
+* Use erb/escape for faster html escaping if available (jeremyevans)
+
 * Default :freeze_template_literals option to false if running with --enable-frozen-string-literal (casperisfine) (#35)
 
 === 1.11.0 (2022-08-02)

lib/erubi.rb

@@ -18,30 +18,35 @@ module Erubi
   # :nocov:
 
   begin
-    require 'cgi/escape'
-    # :nocov:
-    unless CGI.respond_to?(:escapeHTML) # work around for JRuby 9.1
-      CGI = Object.new
-      CGI.extend(defined?(::CGI::Escape) ? ::CGI::Escape : ::CGI::Util)
-    end
-    # :nocov:
-    # Escape characters with their HTML/XML equivalents.
-    def self.h(value)
-      CGI.escapeHTML(value.to_s)
-    end
+    require 'erb/escape'
+    define_singleton_method(:h, ERB::Escape.instance_method(:html_escape))
   rescue LoadError
-    # :nocov:
-    ESCAPE_TABLE = {'&' => '&amp;'.freeze, '<' => '&lt;'.freeze, '>' => '&gt;'.freeze, '"' => '&quot;'.freeze, "'" => '&#39;'.freeze}.freeze
-    if RUBY_VERSION >= '1.9'
-      def self.h(value)
-        value.to_s.gsub(/[&<>"']/, ESCAPE_TABLE)
+    begin
+      require 'cgi/escape'
+      # :nocov:
+      unless CGI.respond_to?(:escapeHTML) # work around for JRuby 9.1
+        CGI = Object.new
+        CGI.extend(defined?(::CGI::Escape) ? ::CGI::Escape : ::CGI::Util)
       end
-    else
+      # :nocov:
+      # Escape characters with their HTML/XML equivalents.
       def self.h(value)
-        value.to_s.gsub(/[&<>"']/){|s| ESCAPE_TABLE[s]}
+        CGI.escapeHTML(value.to_s)
+      end
+    rescue LoadError
+      # :nocov:
+      ESCAPE_TABLE = {'&' => '&amp;'.freeze, '<' => '&lt;'.freeze, '>' => '&gt;'.freeze, '"' => '&quot;'.freeze, "'" => '&#39;'.freeze}.freeze
+      if RUBY_VERSION >= '1.9'
+        def self.h(value)
+          value.to_s.gsub(/[&<>"']/, ESCAPE_TABLE)
+        end
+      else
+        def self.h(value)
+          value.to_s.gsub(/[&<>"']/){|s| ESCAPE_TABLE[s]}
+        end
       end
+      # :nocov:
     end
-    # :nocov:
   end
 
   class Engine