// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
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// 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
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//    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
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package com.alibaba.nacos.common.packagescan.classreading;

/**
 * Copy from ASM, with less modifications
 * An entry of the constant pool, of the BootstrapMethods attribute, or of the (ASM specific) type
 * table of a class.
 *
 * @author Eric Bruneton
 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.4">JVMS
 * 4.4</a>
 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.23">JVMS
 * 4.7.23</a>
 */
abstract class Symbol {

    /**
     * The tag value of CONSTANT_Class_info JVMS structures.
     */
    static final int CONSTANT_CLASS_TAG = 7;

    /**
     * The tag value of CONSTANT_Fieldref_info JVMS structures.
     */
    static final int CONSTANT_FIELDREF_TAG = 9;

    /**
     * The tag value of CONSTANT_Methodref_info JVMS structures.
     */
    static final int CONSTANT_METHODREF_TAG = 10;

    /**
     * The tag value of CONSTANT_InterfaceMethodref_info JVMS structures.
     */
    static final int CONSTANT_INTERFACE_METHODREF_TAG = 11;

    /**
     * The tag value of CONSTANT_String_info JVMS structures.
     */
    static final int CONSTANT_STRING_TAG = 8;

    /**
     * The tag value of CONSTANT_Integer_info JVMS structures.
     */
    static final int CONSTANT_INTEGER_TAG = 3;

    /**
     * The tag value of CONSTANT_Float_info JVMS structures.
     */
    static final int CONSTANT_FLOAT_TAG = 4;

    /**
     * The tag value of CONSTANT_Long_info JVMS structures.
     */
    static final int CONSTANT_LONG_TAG = 5;

    /**
     * The tag value of CONSTANT_Double_info JVMS structures.
     */
    static final int CONSTANT_DOUBLE_TAG = 6;

    /**
     * The tag value of CONSTANT_NameAndType_info JVMS structures.
     */
    static final int CONSTANT_NAME_AND_TYPE_TAG = 12;

    /**
     * The tag value of CONSTANT_Utf8_info JVMS structures.
     */
    static final int CONSTANT_UTF8_TAG = 1;

    /**
     * The tag value of CONSTANT_MethodHandle_info JVMS structures.
     */
    static final int CONSTANT_METHOD_HANDLE_TAG = 15;

    /**
     * The tag value of CONSTANT_MethodType_info JVMS structures.
     */
    static final int CONSTANT_METHOD_TYPE_TAG = 16;

    /**
     * The tag value of CONSTANT_Dynamic_info JVMS structures.
     */
    static final int CONSTANT_DYNAMIC_TAG = 17;

    /**
     * The tag value of CONSTANT_InvokeDynamic_info JVMS structures.
     */
    static final int CONSTANT_INVOKE_DYNAMIC_TAG = 18;

    /**
     * The tag value of CONSTANT_Module_info JVMS structures.
     */
    static final int CONSTANT_MODULE_TAG = 19;

    /**
     * The tag value of CONSTANT_Package_info JVMS structures.
     */
    static final int CONSTANT_PACKAGE_TAG = 20;

    // Tag values for the BootstrapMethods attribute entries (ASM specific tag).

    /**
     * The tag value of the BootstrapMethods attribute entries.
     */
    static final int BOOTSTRAP_METHOD_TAG = 64;

    // Tag values for the type table entries (ASM specific tags).

    /**
     * The tag value of a normal type entry in the (ASM specific) type table of a class.
     */
    static final int TYPE_TAG = 128;

    static final int UNINITIALIZED_TYPE_TAG = 129;

    /**
     * The tag value of a merged type entry in the (ASM specific) type table of a class.
     */
    static final int MERGED_TYPE_TAG = 130;

    // Instance fields.

    /**
     * The index of this symbol in the constant pool, in the BootstrapMethods attribute, or in the
     * (ASM specific) type table of a class (depending on the {@link #tag} value).
     */
    final int index;

    /**
     * A tag indicating the type of this symbol. Must be one of the static tag values defined in this
     * class.
     */
    final int tag;

    /**
     * The internal name of the owner class of this symbol. Only used for {@link
     * #CONSTANT_FIELDREF_TAG}, {@link #CONSTANT_METHODREF_TAG}, {@link
     * #CONSTANT_INTERFACE_METHODREF_TAG}, and {@link #CONSTANT_METHOD_HANDLE_TAG} symbols.
     */
    final String owner;

    /**
     * The name of the class field or method corresponding to this symbol. Only used for {@link
     * #CONSTANT_FIELDREF_TAG}, {@link #CONSTANT_METHODREF_TAG}, {@link
     * #CONSTANT_INTERFACE_METHODREF_TAG}, {@link #CONSTANT_NAME_AND_TYPE_TAG}, {@link
     * #CONSTANT_METHOD_HANDLE_TAG}, {@link #CONSTANT_DYNAMIC_TAG} and {@link
     * #CONSTANT_INVOKE_DYNAMIC_TAG} symbols.
     */
    final String name;

    /**
     * The string value of this symbol. This is:
     *
     * <ul>
     *   <li>a field or method descriptor for {@link #CONSTANT_FIELDREF_TAG}, {@link
     *       #CONSTANT_METHODREF_TAG}, {@link #CONSTANT_INTERFACE_METHODREF_TAG}, {@link
     *       #CONSTANT_NAME_AND_TYPE_TAG}, {@link #CONSTANT_METHOD_HANDLE_TAG}, {@link
     *       #CONSTANT_METHOD_TYPE_TAG}, {@link #CONSTANT_DYNAMIC_TAG} and {@link
     *       #CONSTANT_INVOKE_DYNAMIC_TAG} symbols,
     *   <li>an arbitrary string for {@link #CONSTANT_UTF8_TAG} and {@link #CONSTANT_STRING_TAG}
     *       symbols,
     *   <li>an internal class name for {@link #CONSTANT_CLASS_TAG}, {@link #TYPE_TAG} and {@link
     *       #UNINITIALIZED_TYPE_TAG} symbols,
     *   <li>{@literal null} for the other types of symbol.
     * </ul>
     */
    final String value;

    /**
     * The numeric value of this symbol. This is:
     *
     * <ul>
     *   <li>the symbol's value for {@link #CONSTANT_INTEGER_TAG},{@link #CONSTANT_FLOAT_TAG}, {@link
     *       #CONSTANT_LONG_TAG}, {@link #CONSTANT_DOUBLE_TAG},
     *   <li>the CONSTANT_MethodHandle_info reference_kind field value for {@link
     *       #CONSTANT_METHOD_HANDLE_TAG} symbols,
     *   <li>the CONSTANT_InvokeDynamic_info bootstrap_method_attr_index field value for {@link
     *       #CONSTANT_INVOKE_DYNAMIC_TAG} symbols,
     *   <li>the offset of a bootstrap method in the BootstrapMethods boostrap_methods array, for
     *       {@link #CONSTANT_DYNAMIC_TAG} or {@link #BOOTSTRAP_METHOD_TAG} symbols,
     *   <li>the bytecode offset of the NEW instruction that created an  type for {@link #UNINITIALIZED_TYPE_TAG} symbols,
     *   <li>the indices (in the class' type table) of two {@link #TYPE_TAG} source types for {@link
     *       #MERGED_TYPE_TAG} symbols,
     *   <li>0 for the other types of symbol.
     * </ul>
     */
    final long data;

    /**
     * Additional information about this symbol, generally computed lazily. <i>Warning: the value of
     * this field is ignored when comparing Symbol instances</i> (to avoid duplicate entries in a
     * SymbolTable). Therefore, this field should only contain data that can be computed from the
     * other fields of this class. It contains:
     *
     * <ul>
     *   <li>the {@link Type#getArgumentsAndReturnSizes} of the symbol's method descriptor for {@link
     *       #CONSTANT_METHODREF_TAG}, {@link #CONSTANT_INTERFACE_METHODREF_TAG} and {@link
     *       #CONSTANT_INVOKE_DYNAMIC_TAG} symbols,
     *   <li>the index in the InnerClasses_attribute 'classes' array (plus one) corresponding to this
     *       class, for {@link #CONSTANT_CLASS_TAG} symbols,
     *   <li>the index (in the class' type table) of the merged type of the two source types for
     *       {@link #MERGED_TYPE_TAG} symbols,
     *   <li>0 for the other types of symbol, or if this field has not been computed yet.
     * </ul>
     */
    int info;

    /**
     * Constructs a new Symbol. This constructor can't be used directly because the Symbol class is
     * abstract. Instead, use the factory methods of the  class.
     *
     * @param index the symbol index in the constant pool, in the BootstrapMethods attribute, or in
     *              the (ASM specific) type table of a class (depending on 'tag').
     * @param tag   the symbol type. Must be one of the static tag values defined in this class.
     * @param owner The internal name of the symbol's owner class. Maybe {@literal null}.
     * @param name  The name of the symbol's corresponding class field or method. Maybe {@literal
     *              null}.
     * @param value The string value of this symbol. Maybe {@literal null}.
     * @param data  The numeric value of this symbol.
     */
    Symbol(
            final int index,
            final int tag,
            final String owner,
            final String name,
            final String value,
            final long data) {
        this.index = index;
        this.tag = tag;
        this.owner = owner;
        this.name = name;
        this.value = value;
        this.data = data;
    }

}
