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namespace Hamcrest\Core;

/*
 Copyright (c) 2009 hamcrest.org
 */
use Hamcrest\BaseMatcher;
use Hamcrest\Description;
use Hamcrest\Matcher;

/**
 * Provides a custom description to another matcher.
 */
class DescribedAs extends BaseMatcher
{

    private $_descriptionTemplate;
    private $_matcher;
    private $_values;

    const ARG_PATTERN = '/%([0-9]+)/';

    public function __construct($descriptionTemplate, Matcher $matcher, array $values)
    {
        $this-&gt;_descriptionTemplate = $descriptionTemplate;
        $this-&gt;_matcher = $matcher;
        $this-&gt;_values = $values;
    }

    public function matches($item)
    {
        return $this-&gt;_matcher-&gt;matches($item);
    }

    public function describeTo(Description $description)
    {
        $textStart = 0;
        while (preg_match(self::ARG_PATTERN, $this-&gt;_descriptionTemplate, $matches, PREG_OFFSET_CAPTURE, $textStart)) {
            $text = $matches[0][0];
            $index = $matches[1][0];
            $offset = $matches[0][1];

            $description-&gt;appendText(substr($this-&gt;_descriptionTemplate, $textStart, $offset - $textStart));
            $description-&gt;appendValue($this-&gt;_values[$index]);

            $textStart = $offset + strlen($text);
        }

        if ($textStart &lt; strlen($this-&gt;_descriptionTemplate)) {
            $description-&gt;appendText(substr($this-&gt;_descriptionTemplate, $textStart));
        }
    }

    /**
     * Wraps an existing matcher and overrides the description when it fails.
     *
     * @factory ...
     */
    public static function describedAs(/* $description, Hamcrest\Matcher $matcher, $values... */)
    {
        $args = func_get_args();
        $description = array_shift($args);
        $matcher = array_shift($args);
        $values = $args;

        return new self($description, $matcher, $values);
    }
}
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