/*
 * Copyright (C) 2011 the original author or authors.
 * See the notice.md file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * 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.iq80.leveldb.table;

import org.iq80.leveldb.DBComparator;
import org.iq80.leveldb.util.Slice;

public class CustomUserComparator
        implements UserComparator
{
    private final DBComparator comparator;

    public CustomUserComparator(DBComparator comparator)
    {
        this.comparator = comparator;
    }

    @Override
    public String name()
    {
        return comparator.name();
    }

    @Override
    public Slice findShortestSeparator(Slice start, Slice limit)
    {
        return new Slice(comparator.findShortestSeparator(start.getBytes(), limit.getBytes()));
    }

    @Override
    public Slice findShortSuccessor(Slice key)
    {
        return new Slice(comparator.findShortSuccessor(key.getBytes()));
    }

    @Override
    public int compare(Slice o1, Slice o2)
    {
        return comparator.compare(o1.getBytes(), o2.getBytes());
    }
}

@@ -834,16 +834,65 @@
 Slice;%0A%0A
+import static java.util.Objects.requireNonNull;%0A%0A
 public c
@@ -1052,32 +1052,113 @@
 mparator)%0A    %7B%0A
+        requireNonNull(comparator.name(), %22User Comparator name can't be null%22);%0A
         this.com
@@ -1365,33 +1365,43 @@
         
-return new Slice(
+byte%5B%5D shortestSeparator = 
 comparat
@@ -1452,32 +1452,181 @@
 imit.getBytes())
+;%0A        requireNonNull(shortestSeparator, %22User comparator returned null from findShortestSeparator()%22);%0A        return new Slice(shortestSeparator
 );%0A    %7D%0A%0A    @O
@@ -1694,33 +1694,40 @@
         
-return new Slice(
+byte%5B%5D shortSuccessor = 
 comparat
@@ -1763,16 +1763,152 @@
 Bytes())
+;%0A        requireNonNull(comparator, %22User comparator returned null from findShortSuccessor()%22);%0A        return new Slice(shortSuccessor
 );%0A    %7D

Improve failure message on invalid implementation of DBComparator