Merge pull request #30 from kemitchell/magic_comments

Keep magic comments at the top of generated files

lib/treetop/compiler/grammar_compiler.rb

@@ -4,8 +4,17 @@ module Compiler
     class GrammarCompiler
       def compile(source_path, target_path = source_path.gsub(/\.(treetop|tt)\Z/, '.rb'))
         File.open(target_path, 'w') do |target_file|
-          target_file.write(AUTOGENERATED+"\n\n")
-          target_file.write(ruby_source(source_path))
+          generated_source = ruby_source(source_path)
+          first_line_break = generated_source.index("\n")
+          first_line = generated_source.slice(0..first_line_break)
+          if /(coding|encoding): (\S+)/.match(first_line)
+            target_file.write(first_line)
+            target_file.write(AUTOGENERATED+"\n\n")
+            target_file.write(generated_source.slice((first_line_break + 1)..-1))
+          else
+            target_file.write(AUTOGENERATED+"\n\n")
+            target_file.write(generated_source)
+          end
         end
       end
 

spec/compiler/grammar_compiler_spec.rb

@@ -12,8 +12,12 @@
     @source_path_with_treetop_extension = "#{dir}/test_grammar.treetop"
     @source_path_with_do = "#{dir}/test_grammar_do.treetop"
     @source_path_with_tt_extension = "#{dir}/test_grammar.tt"
+    @source_path_with_magic_coding = "#{dir}/test_grammar_magic_coding.treetop"
+    @source_path_with_magic_encoding = "#{dir}/test_grammar_magic_encoding.treetop"
     @target_path = "#{@tmpdir}/test_grammar.rb"
     @target_path_with_do = "#{@tmpdir}/test_grammar_do.rb"
+    @target_path_with_magic_coding = "#{@tmpdir}/test_grammar_magic_coding.rb"
+    @target_path_with_magic_encoding = "#{@tmpdir}/test_grammar_magic_encoding.rb"
     @alternate_target_path = "#{@tmpdir}/test_grammar_alt.rb"
     delete_target_files
   end
@@ -82,6 +86,24 @@
     Test::GrammarParser.new.parse('foo').should_not be_nil
   end
 
+  specify "grammars with magic 'encoding' comments keep those comments at the top" do
+    src_copy = "#{@tmpdir}/test_grammar_magic_encoding.treetop"
+    File.open(@source_path_with_magic_encoding) do |f|
+      File.open(src_copy,'w'){|o|o.write(f.read)}
+    end
+    compiler.compile(src_copy)
+    File.open(@target_path_with_magic_encoding).readline.should == "# encoding: UTF-8\n"
+  end
+
+  specify "grammars with magic 'coding' comments keep those comments at the top" do
+    src_copy = "#{@tmpdir}/test_grammar_magic_coding.treetop"
+    File.open(@source_path_with_magic_coding) do |f|
+      File.open(src_copy,'w'){|o|o.write(f.read)}
+    end
+    compiler.compile(src_copy)
+    File.open(@target_path_with_magic_coding).readline.should == "# coding: UTF-8\n"
+  end
+
   def delete_target_files
     File.delete(target_path) if File.exists?(target_path)
     File.delete(@target_path_with_do) if File.exists?(@target_path_with_do)

spec/compiler/test_grammar_magic_coding.treetop

@@ -0,0 +1,8 @@
+# coding: UTF-8
+module Test
+  grammar Grammar do
+    rule foo do
+      'foo'
+    end
+  end
+end

spec/compiler/test_grammar_magic_encoding.treetop

@@ -0,0 +1,8 @@
+# encoding: UTF-8
+module Test
+  grammar Grammar do
+    rule foo do
+      'foo'
+    end
+  end
+end