library/HTMLPurifier/Length.php

   1 <?php
   2
   3 /**
   4  * Represents a measurable length, with a string numeric magnitude
   5  * and a unit. This object is immutable.
   6  */
   7 class HTMLPurifier_Length
   8 {
   9
  10     /**
  11      * String numeric magnitude.
  12      */
  13     protected $n;
  14
  15     /**
  16      * String unit. False is permitted if $n = 0.
  17      */
  18     protected $unit;
  19
  20     /**
  21      * Whether or not this length is valid. Null if not calculated yet.
  22      */
  23     protected $isValid;
  24
  25     /**
  26      * Lookup array of units recognized by CSS 2.1
  27      */
  28     protected static $allowedUnits = array(
  29         'em' => true, 'ex' => true, 'px' => true, 'in' => true,
  30         'cm' => true, 'mm' => true, 'pt' => true, 'pc' => true
  31     );
  32
  33     /**
  34      * @param number $n Magnitude
  35      * @param string $u Unit
  36      */
  37     public function __construct($n = '0', $u = false) {
  38         $this->n = (string) $n;
  39         $this->unit = $u !== false ? (string) $u : false;
  40     }
  41
  42     /**
  43      * @param string $s Unit string, like '2em' or '3.4in'
  44      * @warning Does not perform validation.
  45      */
  46     static public function make($s) {
  47         if ($s instanceof HTMLPurifier_Length) return $s;
  48         $n_length = strspn($s, '1234567890.+-');
  49         $n = substr($s, 0, $n_length);
  50         $unit = substr($s, $n_length);
  51         if ($unit === '') $unit = false;
  52         return new HTMLPurifier_Length($n, $unit);
  53     }
  54
  55     /**
  56      * Validates the number and unit.
  57      */
  58     protected function validate() {
  59         // Special case:
  60         if ($this->n === '+0' || $this->n === '-0') $this->n = '0';
  61         if ($this->n === '0' && $this->unit === false) return true;
  62         if (!ctype_lower($this->unit)) $this->unit = strtolower($this->unit);
  63         if (!isset(HTMLPurifier_Length::$allowedUnits[$this->unit])) return false;
  64         // Hack:
  65         $def = new HTMLPurifier_AttrDef_CSS_Number();
  66         $result = $def->validate($this->n, false, false);
  67         if ($result === false) return false;
  68         $this->n = $result;
  69         return true;
  70     }
  71
  72     /**
  73      * Returns string representation of number.
  74      */
  75     public function toString() {
  76         if (!$this->isValid()) return false;
  77         return $this->n . $this->unit;
  78     }
  79
  80     /**
  81      * Retrieves string numeric magnitude.
  82      */
  83     public function getN() {return $this->n;}
  84
  85     /**
  86      * Retrieves string unit.
  87      */
  88     public function getUnit() {return $this->unit;}
  89
  90     /**
  91      * Returns true if this length unit is valid.
  92      */
  93     public function isValid() {
  94         if ($this->isValid === null) $this->isValid = $this->validate();
  95         return $this->isValid;
  96     }
  97
  98     /**
  99      * Compares two lengths, and returns 1 if greater, -1 if less and 0 if equal.
 100      * @warning If both values are too large or small, this calculation will
 101      *          not work properly
 102      */
 103     public function compareTo($l) {
 104         if ($l === false) return false;
 105         if ($l->unit !== $this->unit) {
 106             $converter = new HTMLPurifier_UnitConverter();
 107             $l = $converter->convert($l, $this->unit);
 108             if ($l === false) return false;
 109         }
 110         return $this->n - $l->n;
 111     }
 112
 113 }
 114
 115 // vim: et sw=4 sts=4