1<?php
2/*
3 * This file is part of the Comparator package.
4 *
5 * (c) Sebastian Bergmann <sebastian@phpunit.de>
6 *
7 * For the full copyright and license information, please view the LICENSE
8 * file that was distributed with this source code.
9 */
10
11namespace SebastianBergmann\Comparator;
12
13/**
14 * Factory for comparators which compare values for equality.
15 */
16class Factory
17{
18    /**
19     * @var Comparator[]
20     */
21    private $comparators = array();
22
23    /**
24     * @var Factory
25     */
26    private static $instance;
27
28    /**
29     * Constructs a new factory.
30     */
31    public function __construct()
32    {
33        $this->register(new TypeComparator);
34        $this->register(new ScalarComparator);
35        $this->register(new NumericComparator);
36        $this->register(new DoubleComparator);
37        $this->register(new ArrayComparator);
38        $this->register(new ResourceComparator);
39        $this->register(new ObjectComparator);
40        $this->register(new ExceptionComparator);
41        $this->register(new SplObjectStorageComparator);
42        $this->register(new DOMNodeComparator);
43        $this->register(new MockObjectComparator);
44        $this->register(new DateTimeComparator);
45    }
46
47    /**
48     * @return Factory
49     */
50    public static function getInstance()
51    {
52        if (self::$instance === null) {
53            self::$instance = new self;
54        }
55
56        return self::$instance;
57    }
58
59    /**
60     * Returns the correct comparator for comparing two values.
61     *
62     * @param  mixed      $expected The first value to compare
63     * @param  mixed      $actual   The second value to compare
64     * @return Comparator
65     */
66    public function getComparatorFor($expected, $actual)
67    {
68        foreach ($this->comparators as $comparator) {
69            if ($comparator->accepts($expected, $actual)) {
70                return $comparator;
71            }
72        }
73    }
74
75    /**
76     * Registers a new comparator.
77     *
78     * This comparator will be returned by getInstance() if its accept() method
79     * returns TRUE for the compared values. It has higher priority than the
80     * existing comparators, meaning that its accept() method will be tested
81     * before those of the other comparators.
82     *
83     * @param Comparator $comparator The registered comparator
84     */
85    public function register(Comparator $comparator)
86    {
87        array_unshift($this->comparators, $comparator);
88
89        $comparator->setFactory($this);
90    }
91
92    /**
93     * Unregisters a comparator.
94     *
95     * This comparator will no longer be returned by getInstance().
96     *
97     * @param Comparator $comparator The unregistered comparator
98     */
99    public function unregister(Comparator $comparator)
100    {
101        foreach ($this->comparators as $key => $_comparator) {
102            if ($comparator === $_comparator) {
103                unset($this->comparators[$key]);
104            }
105        }
106    }
107}
108