Builder template adheres to source template encoding behavior

lib/tilt/builder.rb

@@ -1,8 +1,29 @@
 require 'tilt/template'
 
 module Tilt
-   # Builder template implementation. See:
-  # http://builder.rubyforge.org/
+  # XML Builder Template implementation
+  #
+  # - http://builder.rubyforge.org/
+  #
+  # Builder templates support three types of template input: string, file,
+  # and block. When the initialize block returns a non-string object that
+  # responds to call (Proc), template execution consists of calling the block
+  # with a Builder::XmlMarkup instance:
+  #
+  #     BuilderTemplate.new do
+  #       lambda do |xml|
+  #         xml.h1 'howdy dudy'
+  #         xml.p  'blaahhh'
+  #       end
+  #     end
+  #
+  # Builder templates can also be instantiated from a string or file. In that
+  # case, the source encoding is determined according to the rules documented
+  # in the Tilt README under Encodings. The ruby magic comment line is supported
+  # for specifying an alternative encoding.
+  #
+  # Builder templates always produce utf-8 encoded result strings regardless of
+  # the source string / file encoding.
   class BuilderTemplate < Template
     self.default_mime_type = 'text/xml'
 
@@ -14,7 +35,10 @@ def initialize_engine
       require_template_library 'builder'
     end
 
-    def prepare; end
+    def prepare
+      return if !data.respond_to?(:to_str)
+      @source = assign_source_encoding(data.to_str)
+    end
 
     def evaluate(scope, locals, &block)
       return super(scope, locals, &block) if data.respond_to?(:to_str)
@@ -23,6 +47,10 @@ def evaluate(scope, locals, &block)
       xml.target!
     end
 
+    def precompiled_template(locals)
+      @source
+    end
+
     def precompiled_preamble(locals)
       return super if locals.include? :xml
       "xml = ::Builder::XmlMarkup.new(:indent => 2)\n#{super}"
@@ -31,10 +59,6 @@ def precompiled_preamble(locals)
     def precompiled_postamble(locals)
       "xml.target!"
     end
-
-    def precompiled_template(locals)
-      data.to_str
-    end
   end
 end
 

test/tilt_buildertemplate_test.rb

@@ -1,3 +1,4 @@
+# coding: utf-8
 require 'contest'
 require 'tilt'
 
@@ -53,6 +54,68 @@ class BuilderTemplateTest < Test::Unit::TestCase
           template.render(options) { subtemplate.render(options) }
       end
     end
+
+    ##
+    # Encodings
+
+    if defined?(Encoding) && Encoding.respond_to?(:default_internal)
+      original_encoding = Encoding.default_external
+      setup do
+        Encoding.default_external = 'utf-8'
+        Encoding.default_internal = nil
+      end
+      teardown do
+        Encoding.default_external = original_encoding
+        Encoding.default_internal = nil
+      end
+
+      def tempfile(name='template')
+        f = Tempfile.open(name)
+        f.sync = true
+        yield f
+      ensure
+        f.close rescue nil
+        f.delete
+      end
+
+      test "reading templates using default external encoding" do
+        Encoding.default_external = 'Shift_JIS'
+        tempfile do |f|
+          f.puts("xml.em 'ふが' + @hoge".encode('Shift_JIS'))
+          template = Tilt::BuilderTemplate.new(f.path)
+          assert_equal 'Shift_JIS', template.data.encoding.to_s
+          @hoge = "ほげ".encode('Shift_JIS')
+          assert_equal 'UTF-8', template.render(self).encoding.to_s
+        end
+      end
+
+      test "reading templates using :default_encoding option override" do
+        Encoding.default_external = 'Big5'
+        tempfile do |f|
+          f.puts("xml.em 'ふが' + @hoge".encode('Shift_JIS'))
+          template = Tilt::BuilderTemplate.new(f.path, :default_encoding => 'Shift_JIS')
+          assert_equal 'Shift_JIS', template.data.encoding.to_s
+          @hoge = "ほげ".encode('Shift_JIS')
+          assert_equal 'UTF-8', template.render(self).encoding.to_s
+        end
+      end
+
+      test "reading template with magic encoding comment" do
+        Encoding.default_external = 'Big5'
+        tempfile do |f|
+          f.puts("# coding: Shift_JIS".encode('Shift_JIS'))
+          f.puts("xml.em 'ふが' + @hoge".encode('Shift_JIS'))
+          # require 'ruby-debug'
+          # debugger
+          template = Tilt::BuilderTemplate.new(f.path)
+          assert_equal 'Shift_JIS', template.data.encoding.to_s
+          @hoge = "ほげ".encode('Shift_JIS')
+          output = template.render(self)
+          assert_equal 'UTF-8', output.encoding.to_s
+          assert_equal "<em>ふがほげ</em>\n", output
+        end
+      end
+    end
   end
 rescue LoadError
   warn "Tilt::BuilderTemplate (disabled)"