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/*
 * Copyright (C) 2007 Google 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 org.fakereplace.com.google.common.collect;

import java.util.Collection;

import org.fakereplace.com.google.common.annotations.GwtCompatible;
import org.fakereplace.com.google.common.annotations.GwtIncompatible;


/**
 * Static utility methods pertaining to object arrays.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
public final class ObjectArrays {
    private ObjectArrays() {
    }

    /**
     * Returns a new array of the given length with the specified component type.
     *
     * @param type   the component type
     * @param length the length of the new array
     */
    @GwtIncompatible("Array.newInstance(Class, int)")
    @SuppressWarnings("unchecked")
    public static  T[] newArray(Class type, int length) {
        return Platform.newArray(type, length);
    }

    /**
     * Returns a new array of the given length with the same type as a reference
     * array.
     *
     * @param reference any array of the desired type
     * @param length    the length of the new array
     */
    public static  T[] newArray(T[] reference, int length) {
        return Platform.newArray(reference, length);
    }

    /**
     * Returns a new array that contains the concatenated contents of two arrays.
     *
     * @param first  the first array of elements to concatenate
     * @param second the second array of elements to concatenate
     * @param type   the component type of the returned array
     */
    @GwtIncompatible("Array.newInstance(Class, int)")
    public static  T[] concat(T[] first, T[] second, Class type) {
        T[] result = newArray(type, first.length + second.length);
        System.arraycopy(first, 0, result, 0, first.length);
        System.arraycopy(second, 0, result, first.length, second.length);
        return result;
    }

    /**
     * Returns a new array that prepends {@code element} to {@code array}.
     *
     * @param element the element to prepend to the front of {@code array}
     * @param array   the array of elements to append
     * @return an array whose size is one larger than {@code array}, with
     *         {@code element} occupying the first position, and the
     *         elements of {@code array} occupying the remaining elements.
     */
    public static  T[] concat(T element, T[] array) {
        T[] result = newArray(array, array.length + 1);
        result[0] = element;
        System.arraycopy(array, 0, result, 1, array.length);
        return result;
    }

    /**
     * Returns a new array that appends {@code element} to {@code array}.
     *
     * @param array   the array of elements to prepend
     * @param element the element to append to the end
     * @return an array whose size is one larger than {@code array}, with
     *         the same contents as {@code array}, plus {@code element} occupying the
     *         last position.
     */
    public static  T[] concat(T[] array, T element) {
        T[] result = arraysCopyOf(array, array.length + 1);
        result[array.length] = element;
        return result;
    }

    /**
     * GWT safe version of Arrays.copyOf.
     */
    private static  T[] arraysCopyOf(T[] original, int newLength) {
        T[] copy = newArray(original, newLength);
        System.arraycopy(
                original, 0, copy, 0, Math.min(original.length, newLength));
        return copy;
    }

    /**
     * Returns an array containing all of the elements in the specified
     * collection; the runtime type of the returned array is that of the specified
     * array. If the collection fits in the specified array, it is returned
     * therein. Otherwise, a new array is allocated with the runtime type of the
     * specified array and the size of the specified collection.
     * 

*

If the collection fits in the specified array with room to spare (i.e., * the array has more elements than the collection), the element in the array * immediately following the end of the collection is set to null. This is * useful in determining the length of the collection only if the * caller knows that the collection does not contain any null elements. *

*

This method returns the elements in the order they are returned by the * collection's iterator. *

*

TODO: Support concurrent collections whose size can change while the * method is running. * * @param c the collection for which to return an array of elements * @param array the array in which to place the collection elements * @throws ArrayStoreException if the runtime type of the specified array is * not a supertype of the runtime type of every element in the specified * collection */ static T[] toArrayImpl(Collection c, T[] array) { int size = c.size(); if (array.length < size) { array = newArray(array, size); } fillArray(c, array); if (array.length > size) { array[size] = null; } return array; } /** * Returns an array containing all of the elements in the specified * collection. This method returns the elements in the order they are returned * by the collection's iterator. The returned array is "safe" in that no * references to it are maintained by the collection. The caller is thus free * to modify the returned array. *

*

This method assumes that the collection size doesn't change while the * method is running. *

*

TODO: Support concurrent collections whose size can change while the * method is running. * * @param c the collection for which to return an array of elements */ static Object[] toArrayImpl(Collection c) { return fillArray(c, new Object[c.size()]); } private static Object[] fillArray(Iterable elements, Object[] array) { int i = 0; for (Object element : elements) { array[i++] = element; } return array; } }





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