From: Alexandre Mutel <alexandre_mutel@...>
Date: 2009-11-19T23:15:57+09:00
Subject: How to strip ruby comments in a ruby line of code?

Short description : My question is : do you know any available method,
giving the string of a Ruby line of code, to remove comments from this
line of code?

________________

Long description :

For my dsl project, i'm loading my dsl files and applying a small
preprocess on each line before performing a global instance_eval on the
preprocessed file.

Basically, in my dsl language, it is possible to put a label followed by
a ":" starting at the beginning of a line like this:
    my_label:     here_is_a_dsl(arg1, arg2)

This label may be followed by a dsl instruction.

The preprocessor is transforming the previous line to this line:

    newLabel(:my_label) { here_is_a_dsl(arg1, arg2) }

using the following code:
    append = ""
    File.open(file).each do |line|
      match = line.match(/^([a-zA-Z_]\w+):[\s\r\n]+(.*)/)
      if ( match.nil?)
        append += line
      else
        append += "newLabel(:#{match[1]}) { #{match[2]} }\n"
      end
    end

The problem arise when there is a comment at the end of the input line :
    my_label:     here_is_a_dsl(arg1, arg2)         # my comments

It's then generating the following line:
    newLabel(:my_label) { here_is_a_dsl(arg1, arg2) # my comments }

Meanning that the "}" end block is commented and having a parse error on
the whole file.

I could put a newline after the match like this :
    newLabel(:my_label) { here_is_a_dsl(arg1, arg2) # my comments
    }

Unfornutately, i'm no longer able to debug my dsl language, because the
lines are not matching the preprocessed line.

-----

I would like to have something really simple and not being forced to use
a full ruby language parser to parse those lines and remove the
comments.

Any idea?

Thanks!
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