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      * @type string
  13      */
  14     protected $n;
  15
  16     /**
  17      * String unit. False is permitted if $n = 0.
  18      * @type string|bool
  19      */
  20     protected $unit;
  21
  22     /**
  23      * Whether or not this length is valid. Null if not calculated yet.
  24      * @type bool
  25      */
  26     protected $isValid;
  27
  28     /**
  29      * Array Lookup array of units recognized by CSS 3
  30      * @type array
  31      */
  32     protected static $allowedUnits = array(
  33         'em' => true, 'ex' => true, 'px' => true, 'in' => true,
  34         'cm' => true, 'mm' => true, 'pt' => true, 'pc' => true,
  35         'ch' => true, 'rem' => true, 'vw' => true, 'vh' => true,
  36         'vmin' => true, 'vmax' => true
  37     );
  38
  39     /**
  40      * @param string $n Magnitude
  41      * @param bool|string $u Unit
  42      */
  43     public function __construct($n = '0', $u = false)
  44     {
  45         $this->n = (string) $n;
  46         $this->unit = $u !== false ? (string) $u : false;
  47     }
  48
  49     /**
  50      * @param string $s Unit string, like '2em' or '3.4in'
  51      * @return HTMLPurifier_Length
  52      * @warning Does not perform validation.
  53      */
  54     public static function make($s)
  55     {
  56         if ($s instanceof HTMLPurifier_Length) {
  57             return $s;
  58         }
  59         $n_length = strspn($s, '1234567890.+-');
  60         $n = substr($s, 0, $n_length);
  61         $unit = substr($s, $n_length);
  62         if ($unit === '') {
  63             $unit = false;
  64         }
  65         return new HTMLPurifier_Length($n, $unit);
  66     }
  67
  68     /**
  69      * Validates the number and unit.
  70      * @return bool
  71      */
  72     protected function validate()
  73     {
  74         // Special case:
  75         if ($this->n === '+0' || $this->n === '-0') {
  76             $this->n = '0';
  77         }
  78         if ($this->n === '0' && $this->unit === false) {
  79             return true;
  80         }
  81         if (!ctype_lower($this->unit)) {
  82             $this->unit = strtolower($this->unit);
  83         }
  84         if (!isset(HTMLPurifier_Length::$allowedUnits[$this->unit])) {
  85             return false;
  86         }
  87         // Hack:
  88         $def = new HTMLPurifier_AttrDef_CSS_Number();
  89         $result = $def->validate($this->n, false, false);
  90         if ($result === false) {
  91             return false;
  92         }
  93         $this->n = $result;
  94         return true;
  95     }
  96
  97     /**
  98      * Returns string representation of number.
  99      * @return string
 100      */
 101     public function toString()
 102     {
 103         if (!$this->isValid()) {
 104             return false;
 105         }
 106         return $this->n . $this->unit;
 107     }
 108
 109     /**
 110      * Retrieves string numeric magnitude.
 111      * @return string
 112      */
 113     public function getN()
 114     {
 115         return $this->n;
 116     }
 117
 118     /**
 119      * Retrieves string unit.
 120      * @return string
 121      */
 122     public function getUnit()
 123     {
 124         return $this->unit;
 125     }
 126
 127     /**
 128      * Returns true if this length unit is valid.
 129      * @return bool
 130      */
 131     public function isValid()
 132     {
 133         if ($this->isValid === null) {
 134             $this->isValid = $this->validate();
 135         }
 136         return $this->isValid;
 137     }
 138
 139     /**
 140      * Compares two lengths, and returns 1 if greater, -1 if less and 0 if equal.
 141      * @param HTMLPurifier_Length $l
 142      * @return int
 143      * @warning If both values are too large or small, this calculation will
 144      *          not work properly
 145      */
 146     public function compareTo($l)
 147     {
 148         if ($l === false) {
 149             return false;
 150         }
 151         if ($l->unit !== $this->unit) {
 152             $converter = new HTMLPurifier_UnitConverter();
 153             $l = $converter->convert($l, $this->unit);
 154             if ($l === false) {
 155                 return false;
 156             }
 157         }
 158         return $this->n - $l->n;
 159     }
 160 }
 161
 162 // vim: et sw=4 sts=4