Support special DATA constant when __END__ construct is used

opal · Dec 7, 2013 · 4133522 · 4133522
1 parent 17690dc
commit 4133522
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Showing 5 changed files with 39 additions and 3 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -52,7 +52,8 @@
     output javascript.
 
 *   Support parsing `__END__` constructs in ruby code, inside the lexer. The
-    content is gathered up by use of the parser.
+    content is gathered up by use of the parser. The special constant `DATA`
+    is then available inside the ruby code to read the content.
 
 *   Support single character strings (using ? prefix) with escaped characters.
 

diff --git a/lib/opal/compiler.rb b/lib/opal/compiler.rb
@@ -49,6 +49,9 @@ def self.compiler_option(name, default_value, mid = nil)
     # Current case_stmt
     attr_reader :case_stmt
 
+    # Any content in __END__ special construct
+    attr_reader :eof_content
+
     def initialize
       @line = 1
       @indent = ''
@@ -60,8 +63,10 @@ def initialize
     def compile(source, options = {})
       @source = source
       @options.update options
+      @parser = Parser.new
 
-      @sexp = s(:top, Parser.new.parse(@source, self.file) || s(:nil))
+      @sexp = s(:top, @parser.parse(@source, self.file) || s(:nil))
+      @eof_content = @parser.lexer.eof_content
 
       @fragments = process(@sexp).flatten
 

diff --git a/lib/opal/nodes/constants.rb b/lib/opal/nodes/constants.rb
@@ -8,7 +8,9 @@ class ConstNode < Base
       children :name
 
       def compile
-        if compiler.const_missing?
+        if name == :DATA and compiler.eof_content
+          push("$__END__")
+        elsif compiler.const_missing?
           with_temp do |tmp|
             push "((#{tmp} = $scope.#{name}) == null ? $opal.cm('#{name}') : #{tmp})"
           end

diff --git a/lib/opal/nodes/top.rb b/lib/opal/nodes/top.rb
@@ -27,6 +27,7 @@ def compile
 
           compile_method_stubs
           compile_irb_vars
+          compile_end_construct
 
           line body_code
         end
@@ -57,6 +58,14 @@ def compile_method_stubs
         end
       end
 
+      # Any special __END__ content in code
+      def compile_end_construct
+        if content = compiler.eof_content
+          line "var $__END__ = Opal.Object.$new();"
+          line "$__END__.$read = function() { return #{content.inspect}; };"
+        end
+      end
+
       def version_comment
         "/* Generated by Opal #{Opal::VERSION} */"
       end

diff --git a/spec/cli/compiler_spec.rb b/spec/cli/compiler_spec.rb
@@ -38,6 +38,25 @@
     end
   end
 
+  describe "DATA special variable" do
+    it "is not a special case unless __END__ part present in source" do
+      expect_compiled("DATA").to include("DATA")
+      expect_compiled("DATA\n__END__").to_not include("DATA")
+    end
+
+    it "DATA gets compiled as a reference to special $__END__ variable" do
+      expect_compiled("a = DATA\n__END__").to include("a = $__END__")
+    end
+
+    it "causes the compiler to create a reference to special __END__ variable" do
+      expect_compiled("DATA\n__END__\nFord Perfect").to include("$__END__ = ")
+    end
+
+    it "does not create a reference to __END__ vairbale unless __END__ content present" do
+      expect_compiled("DATA").to_not include("$__END__ = ")
+    end
+  end
+
   def expect_compiled(source)
     expect(Opal::Compiler.new.compile source)
   end