001    /*  Copyright (c) 2000-2006 hamcrest.org
002     */
003    package 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     */
022    public 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    }