/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.bcel;

public class NanoTimer {

    private long time = 0;

    public NanoTimer start() {
        time -= System.nanoTime();
        return this;
    }

    public void stop() {
        time += System.nanoTime();
    }

    public void subtract(final NanoTimer o) {
        time -= o.time;
    }

    public void reset() {
        time = 0;
    }

    /**
     * May ony be called after stop has been called as many times as start.
     */
    @Override
    public String toString() {
        return ((double) time / 1000000000) + " s";
    }


}