Add support for rb_define_alias

Closes #413

lib/yard/parser/c_parser.rb

@@ -15,6 +15,7 @@ def parse
         parse_modules
         parse_classes
         parse_methods
+        parse_aliases
         parse_attributes
         parse_constants
         parse_includes
@@ -100,6 +101,30 @@ def handle_method(scope, var_name, name, func_name, source_file = nil)
         obj
       end
 
+      def handle_alias(var_name, new_name, old_name)
+        namespace = P(remove_var_prefix(var_name))
+        ensure_loaded!(namespace)
+        new_meth, old_meth = new_name.to_sym, old_name.to_sym
+        old_obj = namespace.child(:name => old_meth, :scope => :instance)
+        new_obj = YARD::CodeObjects::MethodObject.new(namespace, new_meth, :instance) do |o|
+          o.visibility = :public
+          o.scope = :instance
+          o.add_file(@file)
+          o.source_type = :c
+        end
+
+        if old_obj
+          new_obj.signature = old_obj.signature
+          new_obj.source = old_obj.source
+          new_obj.docstring = old_obj.docstring
+          new_obj.docstring.object = new_obj
+        else
+          new_obj.signature = "def #{new_meth}" # this is all we know.
+        end
+
+        namespace.aliases[new_obj] = old_meth
+      end
+
       def handle_attribute(var_name, name, func_name, read, write, source_file = nil)
         values = {:read => read.to_i, :write => write.to_i}
         {:read => name, :write => "#{name}="}.each do |type, meth_name|
@@ -379,6 +404,18 @@ def parse_methods
         end
       end
 
+      def parse_aliases
+        @content.scan(%r{rb_define_alias
+                       \s*\(\s*([\w\.]+),
+                         \s*"([^"]+)",
+                         \s*"([^"]+)"\s*\)
+                     }xm) do |var_name, new_name, old_name|
+
+          var_name = "rb_cObject" if var_name == "rb_mKernel"
+          handle_alias(var_name, new_name, old_name)
+        end
+      end
+
       def parse_attributes
         @content.scan(%r{rb_define_attr
                        \s*\(\s*([\w\.]+),

spec/parser/c_parser_spec.rb

@@ -165,6 +165,28 @@ def run(read, write, commented = nil)
         Registry.at('Foo#foo=').should be_writer
       end
     end
+
+    describe 'Defining aliases' do
+      before do
+        Registry.clear
+      end
+
+      it "should allow defining of aliases (rb_define_alias)" do
+        @contents = <<-eof
+          /* FOO */
+          VALUE foo(VALUE x) { int value = x; }
+          void Init_Foo() {
+            rb_cFoo = rb_define_class("Foo", rb_cObject);
+            rb_define_method(rb_cFoo, "foo", foo, 1);
+            rb_define_alias(rb_cFoo, "bar", "foo");
+          }
+        eof
+        parse
+
+        Registry.at('Foo#bar').should be_is_alias
+        Registry.at('Foo#bar').docstring.should == 'FOO'
+      end
+    end
   end
 
   describe '#find_override_comment' do