From: "Wesley J. Landaker" <wjl@...>
Date: 2003-08-27T04:29:22+09:00
Subject: Named matches for regular expressions (was: Re: Specification of      Ruby regex?)

Apparently, Austin Ziegler recently wrote:
> On Tue, 26 Aug 2003 21:28:07 +0900, Gavin Sinclair wrote:
>> On Tuesday, August 26, 2003, 10:18:24 PM, Emmanuel wrote:
>>> btw, since there is a thread about that, i wanted to ask: does ruby
>>> support named matches (sorry i don't know the proper terminology)? C#
>>> does it like this: "(?<year>\d{4})-(?<month>\d{1,2})-(?<day>\d{1,2})"
>>> matches "2002-4-6"
>>> and then in my match groups i have "year", "month", "day".
>>> (looked in pickaxe + google ruby "regexp match group")
>> I'm 99.99% sure it doesn't.
>
> The latest Oniguruma supports it. I'm not sure how to use/enable that, but
> it does support it.

Something like this?


class NamedMatchRegex
  def initialize(regex)
    regex_string = regex.inspect

    @match_names = ["MATCH"]
    regex_string.gsub!(/\?:<[^>]+>/) { |match|
      name = match[3..-2]
      @match_names << name
      ""
    }

    @regex = eval regex_string
  end

  def match(string)
    match_data = @regex.match(string)
    return nil if match_data.nil?
    match_data = match_data.to_a
    named_match_data = {}
    @match_names.each { |name|
      named_match_data[name] = match_data.shift
    }
    named_match_data
  end
end

irb(main):001:0> load 'test.rb'
=> true
irb(main):002:0> re = /^\s*(?:<number>\d+)\s*(?:<word>\w+).*$/
=> /^\s*(?:<number>\d+)\s*(?:<word>\w+).*$/
irb(main):003:0> string = " 12345678 we thing ruby is really great"
=> " 12345678 we thing ruby is really great"
irb(main):004:0> re.match(string)
=> nil
irb(main):005:0> nmre = NamedMatchRegex.new(re)
=> #<NamedMatchRegex:0x401f5194 @regex=/^\s*(\d+)\s*(\w+).*$/,
@match_names=["MATCH", "number", "word"]>
irb(main):006:0> matches = nmre.match(string)
=> {"number"=>"12345678", "word"=>"we", "MATCH"=>" 12345678 we thing ruby
is really great"}
irb(main):007:0> matches["MATCH"]
=> " 12345678 we thing ruby is really great"
irb(main):008:0> matches["number"]
=> "12345678"
irb(main):009:0> matches["word"]
=> "we"
irb(main):010:0>


Obviously this isn't complete, I just whipped it up to respond to this
message. =)

Wes