Primitives.java

/*
 * Copyright 2014 mango.jfaster.org
 *
 * The Mango Project licenses this file to you 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.jfaster.mango.util;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * @author ash
 */
public final class Primitives {

  private Primitives() {
  }

  private static final Map<Class<?>, Class<?>> PRIMITIVE_TO_WRAPPER_TYPE;

  private static final Map<Class<?>, Class<?>> WRAPPER_TO_PRIMITIVE_TYPE;

  static {
    Map<Class<?>, Class<?>> primToWrap = new HashMap<Class<?>, Class<?>>(16);
    Map<Class<?>, Class<?>> wrapToPrim = new HashMap<Class<?>, Class<?>>(16);

    add(primToWrap, wrapToPrim, boolean.class, Boolean.class);
    add(primToWrap, wrapToPrim, byte.class, Byte.class);
    add(primToWrap, wrapToPrim, char.class, Character.class);
    add(primToWrap, wrapToPrim, double.class, Double.class);
    add(primToWrap, wrapToPrim, float.class, Float.class);
    add(primToWrap, wrapToPrim, int.class, Integer.class);
    add(primToWrap, wrapToPrim, long.class, Long.class);
    add(primToWrap, wrapToPrim, short.class, Short.class);

    PRIMITIVE_TO_WRAPPER_TYPE = Collections.unmodifiableMap(primToWrap);
    WRAPPER_TO_PRIMITIVE_TYPE = Collections.unmodifiableMap(wrapToPrim);
  }

  private static void add(Map<Class<?>, Class<?>> forward,
                          Map<Class<?>, Class<?>> backward, Class<?> key, Class<?> value) {
    forward.put(key, value);
    backward.put(value, key);
  }

  public static Set<Class<?>> allPrimitiveTypes() {
    return PRIMITIVE_TO_WRAPPER_TYPE.keySet();
  }

  public static Set<Class<?>> allWrapperTypes() {
    return WRAPPER_TO_PRIMITIVE_TYPE.keySet();
  }

  public static boolean isWrapperType(Class<?> type) {
    return WRAPPER_TO_PRIMITIVE_TYPE.containsKey(type);
  }

  public static <T> Class<T> wrap(Class<T> type) {
    // cast is safe: long.class and Long.class are both of type Class<Long>
    @SuppressWarnings("unchecked")
    Class<T> wrapped = (Class<T>) PRIMITIVE_TO_WRAPPER_TYPE.get(type);
    return (wrapped == null) ? type : wrapped;
  }

  public static <T> Class<T> unwrap(Class<T> type) {
    // cast is safe: long.class and Long.class are both of type Class<Long>
    @SuppressWarnings("unchecked")
    Class<T> unwrapped = (Class<T>) WRAPPER_TO_PRIMITIVE_TYPE.get(type);
    return (unwrapped == null) ? type : unwrapped;
  }

}