test/langtools/tools/javac/util/list/ListBufferTest.java

/*
 * Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 8004504
 * @summary Ensure that ListBuffer is working properly
 * @modules jdk.compiler/com.sun.tools.javac.util
 */

import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.ListBuffer;
import java.util.Iterator;
import java.util.Objects;

public class ListBufferTest {
    public static void main(String... args) {
        testRemove();
        testCopiedEndsWithList_nil();
    }

    private static void testCopiedEndsWithList_nil() {
        ListBuffer<String> lb = new ListBuffer<>();

        lb.add("a");
        lb.add("b");
        lb.add("c");

        List<String> l1 = lb.toList();

        assertListEquals(l1, "a", "b", "c");
        assertEndsWithNil(l1);

        lb.add("d");

        List<String> l2 = lb.toList();
        assertListEquals(l2, "a", "b", "c", "d");
        assertEndsWithNil(l2);
        assertListEquals(l1, "a", "b", "c");
    }

    private static void testRemove() {
        ListBuffer<String> lb1 = new ListBuffer<>();

        lb1.add("a");
        lb1.add("b");
        lb1.add("c");

        assertListEquals(lb1.toList(), "a", "b", "c");
        assertEquals(lb1.next(), "a");
        assertListEquals(lb1.toList(), "b", "c");
        assertEquals(lb1.next(), "b");
        assertListEquals(lb1.toList(), "c");
        assertEquals(lb1.next(), "c");
        assertListEquals(lb1.toList());
        assertEquals(lb1.next(), null);

        lb1.add("d");

        assertEquals(lb1.next(), "d");
    }

    private static void assertEndsWithNil(List<?> list) {
        while (!list.isEmpty()) {
            list = list.tail;
        }

        if (list != List.nil()) throw new IllegalStateException("Not ending with List.nil()");
    }

    private static <T> void assertListEquals(Iterable<T> list, T... data) {
        int i = 0;
        Iterator<T> it = list.iterator();

        while (it.hasNext() && i < data.length) {
            assertEquals(it.next(), data[i++]);
        }

        if (it.hasNext()) {
            throw new IllegalStateException("Too many elements in the list");
        }

        if (i < data.length) {
            throw new IllegalStateException("Too few elements in the list");
        }
    }

    private static void assertEquals(Object expected, Object actual) {
        if (!Objects.equals(expected, actual)) {
            throw new IllegalStateException("Incorrect content. Expected: " + expected + ", actual: " + actual);
        }
    }
}