ext/ripper: Introduce a simple DSL for ripper.y code generation

Currently, parse.y actions are hard to read and write because the code
has double meaning (for core parser and for ripper).  I think that, if
it is easy to write ripper's code shortly and simply, the double meaning
trick is not needed.

For the sake, this change adds a simple DSL for ripper's code.  For
example, in parse.y, we can write:

    /*% ripper: stmts_add(stmts_new, void_stmt) %*/

instead of:

    $$ = dispatch2(stmts_add, dispatch0(stmts_new),
                   dispatch0(void_stmt));

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61952 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 4 insertions, 0 deletions

diff --git a/ext/ripper/tools/preproc.rb b/ext/ripper/tools/preproc.rb
index 8b68579164..560a82e54f 100755
--- a/ext/ripper/tools/preproc.rb
+++ b/ext/ripper/tools/preproc.rb
@@ -72,9 +72,13 @@ def prelude(f, out)
   end
 end
 
+require_relative "dsl"
+
 def grammar(f, out)
   while line = f.gets
     case line
+    when %r</\*% *ripper(?:\[(.*?)\])?: *(.*?) *%\*/>
+      out << DSL.new($2, ($1 || "").split(",")).generate << $/
     when %r</\*%%%\*/>
       out << '#if 0' << $/
     when %r</\*%c%\*/>