r2.js

/*!
  * R2 - a CSS LTR ∞ RTL converter
  * Copyright Dustin Diaz 2012
  * https://github.com/ded/r2
  * License MIT
  */

var fs = require('fs')

function quad(v, m) {
  // 1px 2px 3px 4px => 1px 4px 3px 2px
  if ((m = v.trim().split(/\s+/)) && m.length == 4) {
    return [m[0], m[3], m[2], m[1]].join(' ')
  }
  return v
}

function quad_radius(v, m) {
  // 1px 2px 3px 4px => 1px 2px 4px 3px
  //since border-radius: top-left top-right bottom-right bottom-left
  //will be border-radius: top-right top-left bottom-left bottom-right
  if ((m = v.trim().split(/\s+/)) && m.length == 4) {
    return [m[1], m[0], m[3], m[2]].join(' ')
  }
  return v
}

function direction(v) {
  return v.match(/ltr/) ? 'rtl' : v.match(/rtl/) ? 'ltr' : v
}

function rtltr(v) {
  if (v.match(/left/)) return 'right'
  if (v.match(/right/)) return 'left'
  return v
}

var propertyMap = {
    'margin-left': 'margin-right'
  , 'margin-right': 'margin-left'

  , 'padding-left': 'padding-right'
  , 'padding-right': 'padding-left'

  , 'border-left': 'border-right'
  , 'border-right': 'border-left'

  , 'border-left-width': 'border-right-width'
  , 'border-right-width': 'border-left-width'

  , 'border-radius-bottomleft': 'border-radius-bottomright'
  , 'border-radius-bottomright': 'border-radius-bottomleft'
  , 'border-bottom-right-radius': 'border-bottom-left-radius'
  , 'border-bottom-left-radius': 'border-bottom-right-radius'
  , '-webkit-border-bottom-right-radius': '-webkit-border-bottom-left-radius'
  , '-webkit-border-bottom-left-radius': '-webkit-border-bottom-right-radius'
  , '-moz-border-radius-bottomright': '-moz-border-radius-bottomleft'
  , '-moz-border-radius-bottomleft': '-moz-border-radius-bottomright'

  , 'border-radius-topleft': 'border-radius-topright'
  , 'border-radius-topright': 'border-radius-topleft'
  , 'border-top-right-radius': 'border-top-left-radius'
  , 'border-top-left-radius': 'border-top-right-radius'
  , '-webkit-border-top-right-radius': '-webkit-border-top-left-radius'
  , '-webkit-border-top-left-radius': '-webkit-border-top-right-radius'
  , '-moz-border-radius-topright': '-moz-border-radius-topleft'
  , '-moz-border-radius-topleft': '-moz-border-radius-topright'

  , 'left': 'right'
  , 'right': 'left'
}

var valueMap = {
  'padding': quad,
  'margin': quad,
  'text-align': rtltr,
  'float': rtltr,
  'clear': rtltr,
  'direction': direction,
  '-webkit-border-radius' :  quad_radius,
  '-moz-border-radius' :  quad_radius,
  'border-radius' :  quad_radius,
  'border-color': quad,
  'border-width': quad,
  'border-style': quad
}

function r2(css) {

  css = css.trim() // give it a solid trimming to start

  // comments
  .replace(/\/\*[\s\S]+?\*\//g, '')

  // line breaks and carriage returns
  .replace(/[\n\r]/g, '')

  // space between selectors, declarations, properties and values
  .replace(/\s*([:;,{}])\s*/g, '$1')

  // replace multiple spaces with single spaces
  .replace(/\s+/g, ' ')

  var result = css.match(/([^{]+\{[^}]+\})+?/g).map(function (rule) {

    // break rule into selector|declaration parts
    var parts = rule.match(/([^{]+)\{([^}]+)/)
      , selector = parts[1]
      , declarations = parts[2]

    return selector + '{' + declarations.split(/;(?!base64)/).map(function (decl) {
      if (!decl) return ''
      var m = decl.match(/([^:]+):(.+)$/)
      if (!m) return ''
      var prop = m[1]
        , val = m[2]
        , important = /!important/
        , isImportant = val.match(important)
      prop = propertyMap[prop] || prop
      val = valueMap[prop] ? valueMap[prop](val) : val
      if (!val.match(important) && isImportant) val += '!important'
      return prop + ':' + val + ';'
    }).join('') + '}'

  });

  return result.join('')
}


module.exports.exec = function (args) {
  var out
    , read = args[0]
    , out = args[1]
    , data

  /*
  /  If no read arg then read from stdin
  /  allows for standard piping and reading in
  /  ex: lessc file.less | r2 > file-rtl.css
  /  ex:  r2 < file.css
  */
  if (!read) {
    var buffer = ''
    process.stdin.resume()
    process.stdin.setEncoding('utf8')

    process.stdin.on('data', function(chunk) {
      buffer += chunk
    });

    process.stdin.on('end', function() {
      if (buffer) {
        console.log(r2(buffer))
      }
    });
  } else {
    /*
    /  If reading from a file then print to stdout or out arg
    /  To stdout: r2 styles.css
    /  To file: r2 styles.cc styles-rtl.css
    */
    data = fs.readFileSync(read, 'utf8')
    if (out) {
      console.log('Swapping ' + read + ' to ' + out + '...')
      fs.writeFileSync(out, r2(data), 'utf8')
    } else {
      console.log(r2(data))
    }
  }
}

module.exports.swap = function (css) {
  return r2(css)
}