/*

 * Copyright (c) 2010, 2013, 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

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/*

 * 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, and Oracle licenses the original version of this file under the BSD

 * license:

 */

/*

   Copyright 2009-2013 Attila Szegedi

   Licensed under both the Apache License, Version 2.0 (the "Apache License")

   and the BSD License (the "BSD License"), with licensee being free to

   choose either of the two at their discretion.

   You may not use this file except in compliance with either the Apache

   License or the BSD License.

   If you choose to use this file in compliance with the Apache License, the

   following notice applies to you:

       You may obtain a copy of the Apache 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.

   If you choose to use this file in compliance with the BSD License, the

   following notice applies to you:

       Redistribution and use in source and binary forms, with or without

       modification, are permitted provided that the following conditions are

       met:

       * Redistributions of source code must retain the above copyright

         notice, this list of conditions and the following disclaimer.

       * Redistributions in binary form must reproduce the above copyright

         notice, this list of conditions and the following disclaimer in the

         documentation and/or other materials provided with the distribution.

       * Neither the name of the copyright holder nor the names of

         contributors may be used to endorse or promote products derived from

         this software without specific prior written permission.

       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

       IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

       TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

       PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER

       BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR

       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

package jdk.internal.dynalink.support;

import jdk.internal.dynalink.CallSiteDescriptor;

/**

 * Implements the name mangling and demangling as specified by John Rose's

 * <a href="https://blogs.oracle.com/jrose/entry/symbolic_freedom_in_the_vm"

 * target="_blank">"Symbolic Freedom in the VM"</a> article. It is recommended

 * that implementers of languages on the JVM uniformly adopt this for symbolic

 * interoperability between languages. Normally, you would mangle the names as

 * you're generating bytecode, and then demangle them when you're creating

 * {@link CallSiteDescriptor} objects. Note that you are expected to mangle

 * individual tokens, and not the whole name at the call site, i.e. the colon

 * character normally separating the tokens is never mangled. I.e. you wouldn't

 * mangle {@code dyn:getProp:color} into {@code dyn\!getProp\!color}, but you

 * would mangle {@code dyn:getProp:color$} into {@code dyn:getProp:\=color\%}

 * (only mangling the individual token containing the symbol {@code color$}).

 * {@link CallSiteDescriptor#tokenizeName(String)} already uses

 * {@link #decode(String)} to perform demangling on the passed names. If you use

 * that method when creating call site descriptors, (it is recommended that you

 * do), then you have demangling handled for you already, and only need to

 * ensure that you mangle the names using {@link #encode(String)} when you're

 * emitting them in the bytecode.

 */

public class NameCodec {

    private static final char ESCAPE_CHAR = '\\';

    private static final char EMPTY_ESCAPE = '=';

    private static final String EMPTY_NAME = new String(new char[] { ESCAPE_CHAR, EMPTY_ESCAPE });

    private static final char EMPTY_CHAR = 0xFEFF;

    private static final int MIN_ENCODING = '$';

    private static final int MAX_ENCODING = ']';

    private static final char[] ENCODING = new char[MAX_ENCODING - MIN_ENCODING + 1];

    private static final int MIN_DECODING = '!';

    private static final int MAX_DECODING = '}';

    private static final char[] DECODING = new char[MAX_DECODING - MIN_DECODING + 1];

    static {

        addEncoding('/', '|');

        addEncoding('.', ',');

        addEncoding(';', '?');

        addEncoding('$', '%');

        addEncoding('<', '^');

        addEncoding('>', '_');

        addEncoding('[', '{');

        addEncoding(']', '}');

        addEncoding(':', '!');

        addEncoding('\\', '-');

        DECODING[EMPTY_ESCAPE - MIN_DECODING] = EMPTY_CHAR;

    }

    private NameCodec() {

    }

    /**

     * Encodes ("mangles") an unencoded symbolic name.

     * @param name the symbolic name to mangle

     * @return the mangled form of the symbolic name.

     */

    public static String encode(final String name) {

        final int l = name.length();

        if(l == 0) {

            return EMPTY_NAME;

        }

        StringBuilder b = null;

        int lastEscape = -1;

        for(int i = 0; i < l; ++i) {

            final int encodeIndex = name.charAt(i) - MIN_ENCODING;

            if(encodeIndex >= 0 && encodeIndex < ENCODING.length) {

                final char e = ENCODING[encodeIndex];

                if(e != 0) {

                    if(b == null) {

                        b = new StringBuilder(name.length() + 3);

                        if(name.charAt(0) != ESCAPE_CHAR && i > 0) {

                            b.append(EMPTY_NAME);

                        }

                        b.append(name, 0, i);

                    } else {

                        b.append(name, lastEscape + 1, i);

                    }

                    b.append(ESCAPE_CHAR).append(e);

                    lastEscape = i;

                }

            }

        }

        if(b == null) {

            return name;

        }

        assert lastEscape != -1;

        b.append(name, lastEscape + 1, l);

        return b.toString();

    }

    /**

     * Decodes ("demangles") an encoded symbolic name.

     * @param name the symbolic name to demangle

     * @return the demangled form of the symbolic name.

     */

    public static String decode(final String name) {

        if(name.charAt(0) != ESCAPE_CHAR) {

            return name;

        }

        final int l = name.length();

        if(l == 2 && name.charAt(1) == EMPTY_CHAR) {

            return "";

        }

        final StringBuilder b = new StringBuilder(name.length());

        int lastEscape = -2;

        int lastBackslash = -1;

        for(;;) {

            final int nextBackslash = name.indexOf(ESCAPE_CHAR, lastBackslash + 1);

            if(nextBackslash == -1 || nextBackslash == l - 1) {

                break;

            }

            final int decodeIndex = name.charAt(nextBackslash + 1) - MIN_DECODING;

            if(decodeIndex >= 0 && decodeIndex < DECODING.length) {

                final char d = DECODING[decodeIndex];

                if(d == EMPTY_CHAR) {

                    // "\=" is only valid at the beginning of a mangled string

                    if(nextBackslash == 0) {

                        lastEscape = 0;

                    }

                } else if(d != 0) {

                    b.append(name, lastEscape + 2, nextBackslash).append(d);

                    lastEscape = nextBackslash;

                }

            }

            lastBackslash = nextBackslash;

        }

        b.append(name, lastEscape + 2, l);

        return b.toString();

    }

    private static void addEncoding(final char from, final char to) {

        ENCODING[from - MIN_ENCODING] = to;

        DECODING[to - MIN_DECODING] = from;

    }

}