001/*  Copyright (c) 2000-2006 hamcrest.org
002 */
003package org.hamcrest;
004
005/**
006 * A matcher over acceptable values.
007 * A matcher is able to describe itself to give feedback when it fails.
008 * <p/>
009 * Matcher implementations should <b>NOT directly implement this interface</b>.
010 * Instead, <b>extend</b> the {@link BaseMatcher} abstract class,
011 * which will ensure that the Matcher API can grow to support
012 * new features and remain compatible with all Matcher implementations.
013 * <p/>
014 * For easy access to common Matcher implementations, use the static factory
015 * methods in {@link CoreMatchers}.
016 * <p/>
017 * N.B. Well designed matchers should be immutable.
018 * 
019 * @see CoreMatchers
020 * @see BaseMatcher
021 */
022public interface Matcher<T> extends SelfDescribing {
023
024    /**
025     * Evaluates the matcher for argument <var>item</var>.
026     * <p/>
027     * This method matches against Object, instead of the generic type T. This is
028     * because the caller of the Matcher does not know at runtime what the type is
029     * (because of type erasure with Java generics). It is down to the implementations
030     * to check the correct type.
031     *
032     * @param item the object against which the matcher is evaluated.
033     * @return <code>true</code> if <var>item</var> matches, otherwise <code>false</code>.
034     *
035     * @see BaseMatcher
036     */
037    boolean matches(Object item);
038    
039    /**
040     * Generate a description of why the matcher has not accepted the item.
041     * The description will be part of a larger description of why a matching
042     * failed, so it should be concise. 
043     * This method assumes that <code>matches(item)</code> is false, but 
044     * will not check this.
045     *
046     * @param item The item that the Matcher has rejected.
047     * @param mismatchDescription
048     *     The description to be built or appended to.
049     */
050    void describeMismatch(Object item, Description mismatchDescription);
051
052    /**
053     * This method simply acts a friendly reminder not to implement Matcher directly and
054     * instead extend BaseMatcher. It's easy to ignore JavaDoc, but a bit harder to ignore
055     * compile errors .
056     *
057     * @see Matcher for reasons why.
058     * @see BaseMatcher
059     * @deprecated to make
060     */
061    @Deprecated
062    void _dont_implement_Matcher___instead_extend_BaseMatcher_();
063}