com.github.benmanes.caffeine.cache.IsValidLinkedDeque.java Source code

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Here is the source code for com.github.benmanes.caffeine.cache.IsValidLinkedDeque.java

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/*
 * Copyright 2014 Ben Manes. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.github.benmanes.caffeine.cache;

import static com.github.benmanes.caffeine.testing.IsEmptyIterable.deeplyEmpty;
import static org.hamcrest.Matchers.hasSize;
import static org.hamcrest.Matchers.is;
import static org.hamcrest.Matchers.not;
import static org.hamcrest.Matchers.nullValue;

import java.util.Iterator;
import java.util.Set;
import java.util.function.Supplier;

import org.hamcrest.Description;
import org.hamcrest.TypeSafeDiagnosingMatcher;

import com.github.benmanes.caffeine.testing.DescriptionBuilder;
import com.google.common.collect.Sets;

/**
 * A matcher that evaluates a {@link LinkedDeque} to determine if it is in a valid state.
 *
 * @author ben.manes@gmail.com (Ben Manes)
 */
public final class IsValidLinkedDeque<E> extends TypeSafeDiagnosingMatcher<LinkedDeque<E>> {

    @Override
    public void describeTo(Description description) {
        description.appendText("valid");
    }

    @Override
    protected boolean matchesSafely(LinkedDeque<E> deque, Description description) {
        DescriptionBuilder desc = new DescriptionBuilder(description);

        if (deque.isEmpty()) {
            checkEmpty(deque, desc);
        }
        checkIterator(deque, deque.iterator(), desc);
        checkIterator(deque, deque.descendingIterator(), desc);

        return desc.matches();
    }

    void checkEmpty(LinkedDeque<? extends E> deque, DescriptionBuilder desc) {
        desc.expectThat("empty deque", deque, deeplyEmpty());
        desc.expectThat("empty deque", deque.pollFirst(), is(nullValue()));
        desc.expectThat("empty deque", deque.pollLast(), is(nullValue()));
        desc.expectThat("empty deque", deque.poll(), is(nullValue()));
    }

    void checkIterator(LinkedDeque<E> deque, Iterator<E> iterator, DescriptionBuilder desc) {
        Set<E> seen = Sets.newIdentityHashSet();
        while (iterator.hasNext()) {
            E element = iterator.next();
            checkElement(deque, element, desc);
            Supplier<String> errorMsg = () -> String.format("Loop detected: %s in %s", element, seen);
            desc.expectThat(errorMsg, seen.add(element), is(true));
        }
        desc.expectThat("deque size", deque, hasSize(seen.size()));
    }

    void checkElement(LinkedDeque<E> deque, E element, DescriptionBuilder desc) {
        E first = deque.peekFirst();
        E last = deque.peekLast();
        if (element == first) {
            desc.expectThat("not null prev", deque.getPrevious(element), is(nullValue()));
        }
        if (element == last) {
            desc.expectThat("not null next", deque.getNext(element), is(nullValue()));
        }
        if ((element != first) && (element != last)) {
            desc.expectThat("empty deque", deque.getPrevious(element), is(not(nullValue())));
            desc.expectThat("empty deque", deque.getNext(element), is(not(nullValue())));
        }
    }

    public static <E> IsValidLinkedDeque<E> validLinkedDeque() {
        return new IsValidLinkedDeque<>();
    }
}