Haml generates template_source and can be used with compiled templates

lib/tilt.rb

@@ -377,11 +377,33 @@ def prepare
       @engine = ::Haml::Engine.new(data, haml_options)
     end
 
-    def evaluate(scope, locals, &block)
-      @engine.render(scope, locals, &block)
+    # Precompiled Haml source. Taken from the precompiled_with_ambles
+    # method in Haml::Precompiler:
+    # http://github.com/nex3/haml/blob/master/lib/haml/precompiler.rb#L111-126
+    def template_source
+      @engine.instance_eval do
+        <<-RUBY
+          _haml_locals = locals
+          begin
+            extend Haml::Helpers
+            _hamlout = @haml_buffer = Haml::Buffer.new(@haml_buffer, #{options_for_buffer.inspect})
+            _erbout = _hamlout.buffer
+            __in_erb_template = true
+            #{precompiled}
+            #{precompiled_method_return_value}
+          ensure
+            @haml_buffer = @haml_buffer.upper
+          end
+        RUBY
+      end
     end
 
   private
+    def local_assignment_code(locals)
+      source, offset = super
+      [source, offset + 6]
+    end
+
     def haml_options
       options.merge(:filename => eval_file, :line => line)
     end

test/tilt_hamltemplate_test.rb

@@ -66,6 +66,59 @@ class HamlTemplateTest < Test::Unit::TestCase
     end
   end
 
+  class CompiledHamlTemplateTest < Test::Unit::TestCase
+    class Scope
+      include Tilt::CompileSite
+    end
+
+    test "passing locals" do
+      template = Tilt::HamlTemplate.new { "%p= 'Hey ' + name + '!'" }
+      assert_equal "<p>Hey Joe!</p>\n", template.render(Scope.new, :name => 'Joe')
+    end
+
+    test "evaluating in an object scope" do
+      template = Tilt::HamlTemplate.new { "%p= 'Hey ' + @name + '!'" }
+      scope = Scope.new
+      scope.instance_variable_set :@name, 'Joe'
+      assert_equal "<p>Hey Joe!</p>\n", template.render(scope)
+    end
+
+    test "passing a block for yield" do
+      template = Tilt::HamlTemplate.new { "%p= 'Hey ' + yield + '!'" }
+      assert_equal "<p>Hey Joe!</p>\n", template.render(Scope.new) { 'Joe' }
+    end
+
+    test "backtrace file and line reporting without locals" do
+      data = File.read(__FILE__).split("\n__END__\n").last
+      fail unless data[0] == ?%
+      template = Tilt::HamlTemplate.new('test.haml', 10) { data }
+      begin
+        template.render(Scope.new)
+        fail 'should have raised an exception'
+      rescue => boom
+        assert_kind_of NameError, boom
+        line = boom.backtrace.first
+        file, line, meth = line.split(":")
+        assert_equal 'test.haml', file
+        assert_equal '12', line
+      end
+    end
+
+    test "backtrace file and line reporting with locals" do
+      data = File.read(__FILE__).split("\n__END__\n").last
+      fail unless data[0] == ?%
+      template = Tilt::HamlTemplate.new('test.haml') { data }
+      begin
+        res = template.render(Scope.new, :name => 'Joe', :foo => 'bar')
+      rescue => boom
+        assert_kind_of MockError, boom
+        line = boom.backtrace.first
+        file, line, meth = line.split(":")
+        assert_equal 'test.haml', file
+        assert_equal '5', line
+      end
+    end
+  end
 rescue LoadError => boom
   warn "Tilt::HamlTemplate (disabled)\n"
 end