function is(el, obj){
  return el instanceof obj
}

// tests if a given selector matches an element
function matches(el, selector) {
  return (el.matches || el.matchesSelector || el.msMatchesSelector || el.mozMatchesSelector || el.webkitMatchesSelector || el.oMatchesSelector).call(el, selector);
}

// Convert dash-separated-string to camelCase
function camelCase(s) { 
  return s.toLowerCase().replace(/-(.)/g, function(m, g) {
    return g.toUpperCase()
  })
}

// Capitalize first letter of a string
function capitalize(s) {
  return s.charAt(0).toUpperCase() + s.slice(1)
}

// Ensure to six-based hex 
function fullHex(hex) {
  return hex.length == 4 ?
    [ '#',
      hex.substring(1, 2), hex.substring(1, 2)
    , hex.substring(2, 3), hex.substring(2, 3)
    , hex.substring(3, 4), hex.substring(3, 4)
    ].join('') : hex
}

// Component to hex value
function compToHex(comp) {
  var hex = comp.toString(16)
  return hex.length == 1 ? '0' + hex : hex
}

// Calculate proportional width and height values when necessary
function proportionalSize(box, width, height) {
  if (height == null)
    height = box.height / box.width * width
  else if (width == null)
    width = box.width / box.height * height
  
  return {
    width:  width
  , height: height
  }
}

// Delta transform point
function deltaTransformPoint(matrix, x, y) {
  return {
    x: x * matrix.a + y * matrix.c + 0
  , y: x * matrix.b + y * matrix.d + 0
  }
}

// Map matrix array to object
function arrayToMatrix(a) {
  return { a: a[0], b: a[1], c: a[2], d: a[3], e: a[4], f: a[5] }
}

// Parse matrix if required
function parseMatrix(matrix) {
  if (!(matrix instanceof SVG.Matrix))
    matrix = new SVG.Matrix(matrix)
  
  return matrix
}

// Add centre point to transform object
function ensureCentre(o, target) {
  o.cx = o.cx == null ? target.bbox().cx : o.cx
  o.cy = o.cy == null ? target.bbox().cy : o.cy
}

// Convert string to matrix
function stringToMatrix(source) {
  // remove matrix wrapper and split to individual numbers
  source = source
    .replace(SVG.regex.whitespace, '')
    .replace(SVG.regex.matrix, '')
    .split(SVG.regex.matrixElements)

  // convert string values to floats and convert to a matrix-formatted object
  return arrayToMatrix(
    SVG.utils.map(source, function(n) {
      return parseFloat(n)
    })
  )
}

// Calculate position according to from and to
function at(o, pos) {
  // number recalculation (don't bother converting to SVG.Number for performance reasons)
  return typeof o.from == 'number' ?
    o.from + (o.to - o.from) * pos :
  
  // instance recalculation
  o instanceof SVG.Color || o instanceof SVG.Number || o instanceof SVG.Matrix ? o.at(pos) :
  
  // for all other values wait until pos has reached 1 to return the final value
  pos < 1 ? o.from : o.to
}

// PathArray Helpers
function arrayToString(a) {
  for (var i = 0, il = a.length, s = ''; i < il; i++) {
    s += a[i][0]

    if (a[i][1] != null) {
      s += a[i][1]

      if (a[i][2] != null) {
        s += ' '
        s += a[i][2]

        if (a[i][3] != null) {
          s += ' '
          s += a[i][3]
          s += ' '
          s += a[i][4]

          if (a[i][5] != null) {
            s += ' '
            s += a[i][5]
            s += ' '
            s += a[i][6]

            if (a[i][7] != null) {
              s += ' '
              s += a[i][7]
            }
          }
        }
      }
    }
  }
  
  return s + ' '
}

// Deep new id assignment
function assignNewId(node) {
  // do the same for SVG child nodes as well
  for (var i = node.childNodes.length - 1; i >= 0; i--)
    if (node.childNodes[i] instanceof SVGElement)
      assignNewId(node.childNodes[i])

  return SVG.adopt(node).id(SVG.eid(node.nodeName))
}

// Add more bounding box properties
function fullBox(b) {
  if (b.x == null) {
    b.x      = 0
    b.y      = 0
    b.width  = 0
    b.height = 0
  }

  b.w  = b.width
  b.h  = b.height
  b.x2 = b.x + b.width
  b.y2 = b.y + b.height
  b.cx = b.x + b.width / 2
  b.cy = b.y + b.height / 2

  return b
}

// Get id from reference string
function idFromReference(url) {
  var m = url.toString().match(SVG.regex.reference)

  if (m) return m[1]
}

// Create matrix array for looping
var abcdef = 'abcdef'.split('')