/*
 * 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,
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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:
 *
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the name of the copyright holders nor the names of its
 *    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 THE COPYRIGHT OWNER OR CONTRIBUTORS 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.org.objectweb.asm;

/**
 * The path to a type argument, wildcard bound, array element type, or static inner type within an
 * enclosing type.
 *
 * @author Eric Bruneton
 */
public final class TypePath {

    /** A type path step that steps into the element type of an array type. See {@link #getStep}. */
    public static final int ARRAY_ELEMENT = 0;

    /** A type path step that steps into the nested type of a class type. See {@link #getStep}. */
    public static final int INNER_TYPE = 1;

    /** A type path step that steps into the bound of a wildcard type. See {@link #getStep}. */
    public static final int WILDCARD_BOUND = 2;

    /** A type path step that steps into a type argument of a generic type. See {@link #getStep}. */
    public static final int TYPE_ARGUMENT = 3;

    /**
      * The byte array where the 'type_path' structure - as defined in the Java Virtual Machine
      * Specification (JVMS) - corresponding to this TypePath is stored. The first byte of the
      * structure in this array is given by {@link #typePathOffset}.
      *
      * @see <a
      *     href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.20.2">JVMS
      *     4.7.20.2</a>
      */
    private final byte[] typePathContainer;

    /** The offset of the first byte of the type_path JVMS structure in {@link #typePathContainer}. */
    private final int typePathOffset;

    /**
      * Constructs a new TypePath.
      *
      * @param typePathContainer a byte array containing a type_path JVMS structure.
      * @param typePathOffset the offset of the first byte of the type_path structure in
      *     typePathContainer.
      */
    TypePath(final byte[] typePathContainer, final int typePathOffset) {
        this.typePathContainer = typePathContainer;
        this.typePathOffset = typePathOffset;
    }

    /**
      * Returns the length of this path, i.e. its number of steps.
      *
      * @return the length of this path.
      */
    public int getLength() {
        // path_length is stored in the first byte of a type_path.
        return typePathContainer[typePathOffset];
    }

    /**
      * Returns the value of the given step of this path.
      *
      * @param index an index between 0 and {@link #getLength()}, exclusive.
      * @return one of {@link #ARRAY_ELEMENT}, {@link #INNER_TYPE}, {@link #WILDCARD_BOUND}, or {@link
      *     #TYPE_ARGUMENT}.
      */
    public int getStep(final int index) {
        // Returns the type_path_kind of the path element of the given index.
        return typePathContainer[typePathOffset + 2 * index + 1];
    }

    /**
      * Returns the index of the type argument that the given step is stepping into. This method should
      * only be used for steps whose value is {@link #TYPE_ARGUMENT}.
      *
      * @param index an index between 0 and {@link #getLength()}, exclusive.
      * @return the index of the type argument that the given step is stepping into.
      */
    public int getStepArgument(final int index) {
        // Returns the type_argument_index of the path element of the given index.
        return typePathContainer[typePathOffset + 2 * index + 2];
    }

    /**
      * Converts a type path in string form, in the format used by {@link #toString()}, into a TypePath
      * object.
      *
      * @param typePath a type path in string form, in the format used by {@link #toString()}. May be
      *     {@literal null} or empty.
      * @return the corresponding TypePath object, or {@literal null} if the path is empty.
      */
    public static TypePath fromString(final String typePath) {
        if (typePath == null || typePath.isEmpty()) {
            return null;
        }
        int typePathLength = typePath.length();
        ByteVector output = new ByteVector(typePathLength);
        output.putByte(0);
        int typePathIndex = 0;
        while (typePathIndex < typePathLength) {
            char c = typePath.charAt(typePathIndex++);
            if (c == '[') {
                output.put11(ARRAY_ELEMENT, 0);
            } else if (c == '.') {
                output.put11(INNER_TYPE, 0);
            } else if (c == '*') {
                output.put11(WILDCARD_BOUND, 0);
            } else if (c >= '0' && c <= '9') {
                int typeArg = c - '0';
                while (typePathIndex < typePathLength) {
                    c = typePath.charAt(typePathIndex++);
                    if (c >= '0' && c <= '9') {
                        typeArg = typeArg * 10 + c - '0';
                    } else if (c == ';') {
                        break;
                    } else {
                        throw new IllegalArgumentException();
                    }
                }
                output.put11(TYPE_ARGUMENT, typeArg);
            } else {
                throw new IllegalArgumentException();
            }
        }
        output.data[0] = (byte) (output.length / 2);
        return new TypePath(output.data, 0);
    }

    /**
      * Returns a string representation of this type path. {@link #ARRAY_ELEMENT} steps are represented
      * with '[', {@link #INNER_TYPE} steps with '.', {@link #WILDCARD_BOUND} steps with '*' and {@link
      * #TYPE_ARGUMENT} steps with their type argument index in decimal form followed by ';'.
      */
    @Override
    public String toString() {
        int length = getLength();
        StringBuilder result = new StringBuilder(length * 2);
        for (int i = 0; i < length; ++i) {
            switch (getStep(i)) {
                case ARRAY_ELEMENT:
                    result.append('[');
                    break;
                case INNER_TYPE:
                    result.append('.');
                    break;
                case WILDCARD_BOUND:
                    result.append('*');
                    break;
                case TYPE_ARGUMENT:
                    result.append(getStepArgument(i)).append(';');
                    break;
                default:
                    throw new AssertionError();
            }
        }
        return result.toString();
    }

    /**
      * Puts the type_path JVMS structure corresponding to the given TypePath into the given
      * ByteVector.
      *
      * @param typePath a TypePath instance, or {@literal null} for empty paths.
      * @param output where the type path must be put.
      */
    static void put(final TypePath typePath, final ByteVector output) {
        if (typePath == null) {
            output.putByte(0);
        } else {
            int length = typePath.typePathContainer[typePath.typePathOffset] * 2 + 1;
            output.putByteArray(typePath.typePathContainer, typePath.typePathOffset, length);
        }
    }
}