JavaScript RegExp monad

reBuild.coffee

# Need this in JavaScript? Use coffeescript.org "Try CoffeeScript"


# A micro DSL for building maintainable, complex, dynamic regular expressions

reBuild = -> 
  re = ''
  self = {

    # Append regular expression
    re: (s) ->
      re += s
      self

    # Append literal text, escape regexp chars
    text: (s) -> 
      re += (s + '').replace(/([.?*+^$[\]\\(){}|-])/g, '\\$1')
      self

    # open capturing group
    capture: ->
      re += '('
      self

    # open non-capturing group
    group: ->
      re += '(?:'
      self

    # end group
    end: ->
      re += ')'
      self

    # add other helpers, if needed


    # result
    asString: -> re
    asRegExp: -> new RegExp(re)
  }


# Define your primitive regular expressions

RE_IDENTIFIER = '\\w+'
RE_ANYTHING = '[\\s\\S]*?'


# Build your regexp, like

reBuild()
  .re(RE_ANYTHING)
  .group().re(IDENTIFIER).end()
  .text(' followed by this literal text')
  .asRegExp()