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   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