gradle-master/subprojects/core/src/main/java/org/gradle/api/internal/specs/ExplainingSpecs.java
/*
 * Copyright 2012 the original author or authors.
 *
 * 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 org.gradle.api.internal.specs;

import org.gradle.internal.Cast;

public class ExplainingSpecs {

    private static final ExplainingSpec<Object> SATISFIES_ALL = new ExplainingSpec<Object>() {
        @Override
        public boolean isSatisfiedBy(Object element) {
            return true;
        }
        @Override
        public String whyUnsatisfied(Object element) {
            return null;
        }
    };

    public static <T> ExplainingSpec<T> satisfyAll() {
        return Cast.uncheckedNonnullCast(SATISFIES_ALL);
    }

    private static final ExplainingSpec<Object> SATISFIES_NONE = new ExplainingSpec<Object>() {
        @Override
        public boolean isSatisfiedBy(Object element) {
            return false;
        }
        @Override
        public String whyUnsatisfied(Object element) {
            return "Never satisfies any.";
        }
    };

    public static <T> ExplainingSpec<T> satisfyNone() {
        return Cast.uncheckedNonnullCast(SATISFIES_NONE);
    }
}
