On Fri, May 10, 2013 at 9:13 AM, bozhidar (Bozhidar Batsov) <
bozhidar / batsov.com> wrote:

>
> Issue #8321 has been updated by bozhidar (Bozhidar Batsov).
>
>
> The example outlined in the proposal is exactly what I think we need.  A
> lot of Ruby code analysis tools need exact coordinates of keywords and
> currently there is no easy and reliable way to get them.  This is even more
> important, now that you've rejected #8383


You can use the `parser` gem: https://github.com/whitequark/parser

It gives you a nice AST together with source maps:

  require 'parser/current'
  ast = Parser::CurrentRuby.parse('if a; b; else; c; end')

(if
  (send nil :a)
  (send nil :b)
  (send nil :c))

  ast.source_map.expression # => 0...21 (the whole expression)
  ast.source_map.keyword # => 0...2 (the "if")
  ast.source_map.begin # => 4...5 (the ";")
  ast.source_map.else # => 9...13 (the "else")
  ast.source_map.end # => 18...12 (the "end")

And you can then check the children for more data:

  (cond, tbranch, fbranch) = *ast

  cond.source_map.expression # => 3...4 ("a")

All of these return a Source::Range which allows you to extract the source
and lineno/column:

  cond.source_map.expression.to_source # => "a"
  cond.source_map.expression.line # => 1
  cond.source_map.expression.column # => 3

Parser also supports 1.8, 1.9, 2.0 and 2.1/trunk, *and* it ships with a
rewriter tool:
http://whitequark.org/blog/2013/04/26/lets-play-with-ruby-code/