TypeTokens.java

/*
 *      Copyright (C) 2012-2015 DataStax Inc.
 *
 *   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.datastax.driver.core;

import com.google.common.reflect.TypeParameter;
import com.google.common.reflect.TypeToken;

import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Utility methods to create {@code TypeToken} instances.
 */
public final class TypeTokens {
    private TypeTokens() {
    }

    /**
     * Create a {@link TypeToken} that represents a {@link List} whose elements
     * are of the given type.
     *
     * @param eltType The list element type.
     * @param <T>     The list element type.
     * @return A {@link TypeToken} that represents a {@link List} whose elements
     * are of the given type.
     */
    public static <T> TypeToken<List<T>> listOf(Class<T> eltType) {
        // @formatter:off
        return new TypeToken<List<T>>(){}.where(new TypeParameter<T>(){}, eltType);
        // @formatter:on
    }

    /**
     * Create a {@link TypeToken} that represents a {@link List} whose elements
     * are of the given type.
     *
     * @param eltType The list element type.
     * @param <T>     The list element type.
     * @return A {@link TypeToken} that represents a {@link List} whose elements
     * are of the given type.
     */
    public static <T> TypeToken<List<T>> listOf(TypeToken<T> eltType) {
        // @formatter:off
        return new TypeToken<List<T>>(){}.where(new TypeParameter<T>(){}, eltType);
        // @formatter:on
    }

    /**
     * Create a {@link TypeToken} that represents a {@link Set} whose elements
     * are of the given type.
     *
     * @param eltType The set element type.
     * @param <T>     The set element type.
     * @return A {@link TypeToken} that represents a {@link Set} whose elements
     * are of the given type.
     */
    public static <T> TypeToken<Set<T>> setOf(Class<T> eltType) {
        // @formatter:off
        return new TypeToken<Set<T>>(){}.where(new TypeParameter<T>(){}, eltType);
        // @formatter:on
    }

    /**
     * Create a {@link TypeToken} that represents a {@link Set} whose elements
     * are of the given type.
     *
     * @param eltType The set element type.
     * @param <T>     The set element type.
     * @return A {@link TypeToken} that represents a {@link Set} whose elements
     * are of the given type.
     */
    public static <T> TypeToken<Set<T>> setOf(TypeToken<T> eltType) {
        // @formatter:off
        return new TypeToken<Set<T>>(){}.where(new TypeParameter<T>(){}, eltType);
        // @formatter:on
    }

    /**
     * Create a {@link TypeToken} that represents a {@link Map} whose keys
     * and values are of the given key and value types.
     *
     * @param keyType   The map key type.
     * @param valueType The map value type
     * @param <K>       The map key type.
     * @param <V>       The map value type
     * @return A {@link TypeToken} that represents a {@link Map} whose keys
     * and values are of the given key and value types
     */
    public static <K, V> TypeToken<Map<K, V>> mapOf(Class<K> keyType, Class<V> valueType) {
        // @formatter:off
        return new TypeToken<Map<K, V>>(){}
            .where(new TypeParameter<K>(){}, keyType)
            .where(new TypeParameter<V>(){}, valueType);
        // @formatter:on
    }

    /**
     * Create a {@link TypeToken} that represents a {@link Map} whose keys
     * and values are of the given key and value types.
     *
     * @param keyType   The map key type.
     * @param valueType The map value type
     * @param <K>       The map key type.
     * @param <V>       The map value type
     * @return A {@link TypeToken} that represents a {@link Map} whose keys
     * and values are of the given key and value types
     */
    public static <K, V> TypeToken<Map<K, V>> mapOf(TypeToken<K> keyType, TypeToken<V> valueType) {
        // @formatter:off
        return new TypeToken<Map<K, V>>(){}
            .where(new TypeParameter<K>(){}, keyType)
            .where(new TypeParameter<V>(){}, valueType);
        // @formatter:on
    }
}