/*
* 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<>();
}
}