[3.1.1] Added HTMLPurifier_UnitConverter and HTMLPurifier_Length for convenient handling of CSS-style lengths.

- Fixed another de-underscoring in the SimpleTest library

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1746 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/Length.php

@@ -0,0 +1,73 @@
+<?php
+
+/**
+ * Represents a measurable length, with a string numeric magnitude
+ * and a unit.
+ */
+class HTMLPurifier_Length
+{
+    
+    /**
+     * String numeric magnitude.
+     */
+    public $n;
+    
+    /**
+     * String unit. False is permitted if $n = 0.
+     */
+    public $unit;
+    
+    /**
+     * 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 = $n;
+        $this->unit = $u;
+    }
+    
+    /**
+     * @param string $s Unit string, like '2em' or '3.4in'
+     * @warning Does not perform validation.
+     */
+    static public function make($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.
+     * @param bool $non_negative Whether or not to disable negative values.
+     * @note Maybe should be put in another class.
+     */
+    public function validate($non_negative = false, $config, $context) {
+        // Special case:
+        if ($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;
+        $def = new HTMLPurifier_AttrDef_CSS_Number($non_negative);
+        $result = $def->validate($this->n, $config, $context);
+        if ($result === false) return false;
+        $this->n = $result;
+        return true;
+    }
+    
+    /**
+     * Returns string representation of number.
+     */
+    public function toString() {
+        return $this->n . $this->unit;
+    }
+    
+}