// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
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//    notice, this list of conditions and the following disclaimer in the
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package net.hasor.utils.asm;
/**
 * An entry of the constant pool, of the BootstrapMethods attribute, or of the (ASM specific) type
 * table of a class.
 *
 * @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>
 * @author Eric Bruneton
 */
abstract class Symbol {
    // Tag values for the constant pool entries (using the same order as in the JVMS).
    /** 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;
    /**
     * The tag value of an {@link Frame#ITEM_UNINITIALIZED} type entry in the type table of a class.
     */
    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 {@link
     *       Frame#ITEM_UNINITIALIZED} 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 {@link SymbolTable} 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;
    }

    /**
     * Returns the result {@link Type#getArgumentsAndReturnSizes} on {@link #value}.
     *
     * @return the result {@link Type#getArgumentsAndReturnSizes} on {@link #value} (memoized in
     *     {@link #info} for efficiency). This should only be used for {@link
     *     #CONSTANT_METHODREF_TAG}, {@link #CONSTANT_INTERFACE_METHODREF_TAG} and {@link
     *     #CONSTANT_INVOKE_DYNAMIC_TAG} symbols.
     */
    int getArgumentsAndReturnSizes() {
        if (info == 0) {
            info = Type.getArgumentsAndReturnSizes(value);
        }
        return info;
    }
}
