/*
 * Copyright (c) 2009, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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.
 */

/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * The MIT License
 *
 * Copyright (c) 2004-2015 Paul R. Holser, Jr.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package jdk.internal.joptsimple.util;

import static jdk.internal.joptsimple.internal.Strings.*;

/**
 * <p>A simple string key/string value pair.</p>
 *
 * <p>This is useful as an argument type for options whose values take on the form {@code key=value}, such as JVM
 * command line system properties.</p>
 *
 * @author <a href="mailto:pholser@alumni.rice.edu">Paul Holser</a>
 */
public final class KeyValuePair {
    public final String key;
    public final String value;

    private KeyValuePair( String key, String value ) {
        this.key = key;
        this.value = value;
    }

    /**
     * Parses a string assumed to be of the form {@code key=value} into its parts.
     *
     * @param asString key-value string
     * @return a key-value pair
     * @throws NullPointerException if {@code stringRepresentation} is {@code null}
     */
    public static KeyValuePair valueOf( String asString ) {
        int equalsIndex = asString.indexOf( '=' );
        if ( equalsIndex == -1 )
            return new KeyValuePair( asString, null );

        String aKey = asString.substring( 0, equalsIndex );
        String aValue = equalsIndex == asString.length() - 1 ? EMPTY : asString.substring( equalsIndex + 1 );

        return new KeyValuePair( aKey, aValue );
    }

    @Override
    public boolean equals( Object that ) {
        if ( !( that instanceof KeyValuePair ) )
            return false;

        KeyValuePair other = (KeyValuePair) that;
        return key.equals( other.key ) && value.equals( other.value );
    }

    @Override
    public int hashCode() {
        return key.hashCode() ^ value.hashCode();
    }

    @Override
    public String toString() {
        return key + '=' + value;
    }
}
