<?php
/**
* Represents a measurable length, with a string numeric magnitude
* and a unit. This object is immutable.
*/
class HTMLPurifier_Length
{
/**
* String numeric magnitude.
*/
protected $n;
/**
* String unit. False is permitted if $n = 0.
*/
protected $unit;
/**
* Whether or not this length is valid. Null if not calculated yet.
*/
protected $isValid;
/**
* Lookup array of units recognized by CSS 2.1
*/
protected static $allowedUnits = array(
'em' => true, 'ex' => true, 'px' => true, 'in' => true,
'cm' => true, 'mm' => true, 'pt' => true, 'pc' => true
);
/**
* @param number $n Magnitude
* @param string $u Unit
*/
public function __construct($n = '0', $u = false) {
$this->n = (string) $n;
$this->unit = $u !== false ? (string) $u : false;
}
/**
* @param string $s Unit string, like '2em' or '3.4in'
* @warning Does not perform validation.
*/
static public function make($s) {
if ($s instanceof HTMLPurifier_Length) return $s;
$n_length = strspn($s, '1234567890.+-');
$n = substr($s, 0, $n_length);
$unit = substr($s, $n_length);
if ($unit === '') $unit = false;
return new HTMLPurifier_Length($n, $unit);
}
/**
* Validates the number and unit.
*/
protected function validate() {
// Special case:
if ($this->n === '+0' || $this->n === '-0') $this->n = '0';
if ($this->n === '0' && $this->unit === false) return true;
if (!ctype_lower($this->unit)) $this->unit = strtolower($this->unit);
if (!isset(HTMLPurifier_Length::$allowedUnits[$this->unit])) return false;
// Hack:
$def = new HTMLPurifier_AttrDef_CSS_Number();
$result = $def->validate($this->n, false, false);
if ($result === false) return false;
$this->n = $result;
return true;
}
/**
* Returns string representation of number.
*/
public function toString() {
if (!$this->isValid()) return false;
return $this->n . $this->unit;
}
/**
* Retrieves string numeric magnitude.
*/
public function getN() {return $this->n;}
/**
* Retrieves string unit.
*/
public function getUnit() {return $this->unit;}
/**
* Returns true if this length unit is valid.
*/
public function isValid() {
if ($this->isValid === null) $this->isValid = $this->validate();
return $this->isValid;
}
/**
* Compares two lengths, and returns 1 if greater, -1 if less and 0 if equal.
* @warning If both values are too large or small, this calculation will
* not work properly
*/
public function compareTo($l) {
if ($l === false) return false;
if ($l->unit !== $this->unit) {
$converter = new HTMLPurifier_UnitConverter();
$l = $converter->convert($l, $this->unit);
if ($l === false) return false;
}
return $this->n - $l->n;
}
}
// vim: et sw=4 sts=4
