SVG.Set = SVG.invent({
  // Initialize
  create: function() {
    /* set initial state */
    this.clear()
  }

  // Add class methods
, extend: {
    // Add element to set
    add: function() {
      var i, il, elements = [].slice.call(arguments)

      for (i = 0, il = elements.length; i < il; i++)
        this.members.push(elements[i])
      
      return this
    }
    // Remove element from set
  , remove: function(element) {
      var i = this.index(element)
      
      /* remove given child */
      if (i > -1)
        this.members.splice(i, 1)

      return this
    }
    // Iterate over all members
  , each: function(block) {
      for (var i = 0, il = this.members.length; i < il; i++)
        block.apply(this.members[i], [i, this.members])

      return this
    }
    // Restore to defaults
  , clear: function() {
      /* initialize store */
      this.members = []

      return this
    }
    // Checks if a given element is present in set
  , has: function(element) {
      return this.index(element) >= 0
    }
    // retuns index of given element in set
  , index: function(element) {
      return this.members.indexOf(element)
    }
    // Get member at given index
  , get: function(i) {
      return this.members[i]
    }
    // Get first member
  , first: function() {
      return this.get(0)
    }
    // Get last member
  , last: function() {
      return this.get(this.members.length - 1)
    }
    // Default value
  , valueOf: function() {
      return this.members
    }
    // Get the bounding box of all members included or empty box if set has no items
  , bbox: function(){
      var box = new SVG.BBox()

      /* return an empty box of there are no members */
      if (this.members.length == 0)
        return box

      /* get the first rbox and update the target bbox */
      var rbox = this.members[0].rbox()
      box.x      = rbox.x
      box.y      = rbox.y
      box.width  = rbox.width
      box.height = rbox.height

      this.each(function() {
        /* user rbox for correct position and visual representation */
        box = box.merge(this.rbox())
      })

      return box
    }
  }
  
  // Add parent method
, construct: {
    // Create a new set
    set: function() {
      return new SVG.Set
    }
  }
})

SVG.SetFX = SVG.invent({
  // Initialize node
  create: function(set) {
    /* store reference to set */
    this.set = set
  }

})

// Alias methods
SVG.Set.inherit = function() {
  var m
    , methods = []
  
  /* gather shape methods */
  for(var m in SVG.Shape.prototype)
    if (typeof SVG.Shape.prototype[m] == 'function' && typeof SVG.Set.prototype[m] != 'function')
      methods.push(m)

  /* apply shape aliasses */
  methods.forEach(function(method) {
    SVG.Set.prototype[method] = function() {
      for (var i = 0, il = this.members.length; i < il; i++)
        if (this.members[i] && typeof this.members[i][method] == 'function')
          this.members[i][method].apply(this.members[i], arguments)

      return method == 'animate' ? (this.fx || (this.fx = new SVG.SetFX(this))) : this
    }
  })

  /* clear methods for the next round */
  methods = []

  /* gather fx methods */
  for(var m in SVG.FX.prototype)
    if (typeof SVG.FX.prototype[m] == 'function' && typeof SVG.SetFX.prototype[m] != 'function')
      methods.push(m)

  /* apply fx aliasses */
  methods.forEach(function(method) {
    SVG.SetFX.prototype[method] = function() {
      for (var i = 0, il = this.set.members.length; i < il; i++)
        this.set.members[i].fx[method].apply(this.set.members[i].fx, arguments)

      return this
    }
  })
}