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/*
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* Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.lang.constant;
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import java.lang.invoke.TypeDescriptor;
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import java.util.stream.Stream;
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import sun.invoke.util.Wrapper;
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import static java.lang.constant.ConstantUtils.binaryToInternal;
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import static java.lang.constant.ConstantUtils.dropLastChar;
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import static java.lang.constant.ConstantUtils.internalToBinary;
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import static java.lang.constant.ConstantUtils.validateMemberName;
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import static java.util.Objects.requireNonNull;
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import static java.util.stream.Collectors.joining;
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/**
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* A <a href="package-summary.html#nominal">nominal descriptor</a> for a
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* {@link Class} constant.
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*
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* <p>For common system types, including all the primitive types, there are
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* predefined {@linkplain ClassDesc} constants in {@link ConstantDescs}.
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* (The {@code java.lang.constant} APIs consider {@code void} to be a primitive type.)
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* To create a {@linkplain ClassDesc} for a class or interface type, use {@link #of} or
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* {@link #ofDescriptor(String)}; to create a {@linkplain ClassDesc} for an array
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* type, use {@link #ofDescriptor(String)}, or first obtain a
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* {@linkplain ClassDesc} for the component type and then call the {@link #arrayType()}
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* or {@link #arrayType(int)} methods.
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*
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* @apiNote In the future, if the Java language permits, {@linkplain ClassDesc}
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* may become a {@code sealed} interface, which would prohibit subclassing except
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* by explicitly permitted types. Non-platform classes should not implement
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* {@linkplain ClassDesc} directly.
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*
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* @see ConstantDescs
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*
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* @since 12
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*/
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public interface ClassDesc
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extends ConstantDesc,
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TypeDescriptor.OfField<ClassDesc> {
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/**
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* Returns a {@linkplain ClassDesc} for a class or interface type,
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* given the name of the class or interface, such as {@code "java.lang.String"}.
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* (To create a descriptor for an array type, either use {@link #ofDescriptor(String)}
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* or {@link #arrayType()}; to create a descriptor for a primitive type, use
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* {@link #ofDescriptor(String)} or use the predefined constants in
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* {@link ConstantDescs}).
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*
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* @param name the fully qualified (dot-separated) binary class name
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* @return a {@linkplain ClassDesc} describing the desired class
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* @throws NullPointerException if any argument is {@code null}
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* @throws IllegalArgumentException if the name string is not in the
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* correct format
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*/
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static ClassDesc of(String name) {
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ConstantUtils.validateBinaryClassName(requireNonNull(name));
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return ClassDesc.ofDescriptor("L" + binaryToInternal(name) + ";");
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}
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/**
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* Returns a {@linkplain ClassDesc} for a class or interface type,
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* given a package name and the unqualified (simple) name for the
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* class or interface.
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*
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* @param packageName the package name (dot-separated); if the package
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* name is the empty string, the class is considered to
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* be in the unnamed package
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* @param className the unqualified (simple) class name
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* @return a {@linkplain ClassDesc} describing the desired class
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* @throws NullPointerException if any argument is {@code null}
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* @throws IllegalArgumentException if the package name or class name are
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* not in the correct format
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*/
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static ClassDesc of(String packageName, String className) {
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ConstantUtils.validateBinaryClassName(requireNonNull(packageName));
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validateMemberName(requireNonNull(className));
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return ofDescriptor(String.format("L%s%s%s;",
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binaryToInternal(packageName),
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(packageName.length() > 0 ? "/" : ""),
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className));
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}
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/**
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* Returns a {@linkplain ClassDesc} given a descriptor string for a class,
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* interface, array, or primitive type.
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*
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* @apiNote
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*
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* A field type descriptor string for a non-array type is either
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* a one-letter code corresponding to a primitive type
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* ({@code J,I,C,S,B,D,F,Z,V}), or the letter {@code L}, followed
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* by the fully qualified binary name of a class, followed by {@code ;}.
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* A field type descriptor for an array type is the character {@code [}
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* followed by the field descriptor for the component type. Examples of
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* valid type descriptor strings include {@code Ljava/lang/String;}, {@code I},
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* {@code [I}, {@code V}, {@code [Ljava/lang/String;}, etc.
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* for more detail.
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*
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* @param descriptor a field descriptor string
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* @return a {@linkplain ClassDesc} describing the desired class
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* @throws NullPointerException if any argument is {@code null}
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* @throws IllegalArgumentException if the name string is not in the
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* correct format
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* @jvms 4.3.2 Field Descriptors
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*/
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static ClassDesc ofDescriptor(String descriptor) {
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requireNonNull(descriptor);
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return (descriptor.length() == 1)
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? new PrimitiveClassDescImpl(descriptor)
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: new ReferenceClassDescImpl(descriptor);
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}
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/**
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* Returns a {@linkplain ClassDesc} for an array type whose component type
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* is described by this {@linkplain ClassDesc}.
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*
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* @return a {@linkplain ClassDesc} describing the array type
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*/
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default ClassDesc arrayType() {
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return arrayType(1);
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}
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/**
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* Returns a {@linkplain ClassDesc} for an array type of the specified rank,
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* whose component type is described by this {@linkplain ClassDesc}.
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*
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* @param rank the rank of the array
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* @return a {@linkplain ClassDesc} describing the array type
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* @throws IllegalArgumentException if the rank is zero or negative
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*/
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default ClassDesc arrayType(int rank) {
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if (rank <= 0)
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throw new IllegalArgumentException("rank: " + rank);
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return ClassDesc.ofDescriptor("[".repeat(rank) + descriptorString());
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}
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/**
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* Returns a {@linkplain ClassDesc} for a nested class of the class or
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* interface type described by this {@linkplain ClassDesc}.
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*
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* @param nestedName the unqualified name of the nested class
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* @return a {@linkplain ClassDesc} describing the nested class
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* @throws NullPointerException if any argument is {@code null}
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* @throws IllegalStateException if this {@linkplain ClassDesc} does not
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* describe a class or interface type
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* @throws IllegalArgumentException if the nested class name is invalid
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*/
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default ClassDesc nested(String nestedName) {
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validateMemberName(nestedName);
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if (!isClassOrInterface())
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throw new IllegalStateException("Outer class is not a class or interface type");
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return ClassDesc.ofDescriptor(String.format("%s$%s;", dropLastChar(descriptorString()), nestedName));
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}
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/**
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* Returns a {@linkplain ClassDesc} for a nested class of the class or
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* interface type described by this {@linkplain ClassDesc}.
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*
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* @param firstNestedName the unqualified name of the first level of nested class
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* @param moreNestedNames the unqualified name(s) of the remaining levels of
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* nested class
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* @return a {@linkplain ClassDesc} describing the nested class
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* @throws NullPointerException if any argument is {@code null}
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* @throws IllegalStateException if this {@linkplain ClassDesc} does not
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* describe a class or interface type
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* @throws IllegalArgumentException if the nested class name is invalid
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*/
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default ClassDesc nested(String firstNestedName, String... moreNestedNames) {
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if (!isClassOrInterface())
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throw new IllegalStateException("Outer class is not a class or interface type");
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return moreNestedNames.length == 0
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? nested(firstNestedName)
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: nested(firstNestedName + Stream.of(moreNestedNames).collect(joining("$", "$", "")));
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}
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/**
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* Returns whether this {@linkplain ClassDesc} describes an array type.
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*
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* @return whether this {@linkplain ClassDesc} describes an array type
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*/
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default boolean isArray() {
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return descriptorString().startsWith("[");
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}
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/**
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* Returns whether this {@linkplain ClassDesc} describes a primitive type.
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*
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* @return whether this {@linkplain ClassDesc} describes a primitive type
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*/
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default boolean isPrimitive() {
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return descriptorString().length() == 1;
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}
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/**
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* Returns whether this {@linkplain ClassDesc} describes a class or interface type.
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*
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* @return whether this {@linkplain ClassDesc} describes a class or interface type
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*/
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default boolean isClassOrInterface() {
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return descriptorString().startsWith("L");
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}
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/**
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* Returns the component type of this {@linkplain ClassDesc}, if it describes
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* an array type, or {@code null} otherwise.
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*
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* @return a {@linkplain ClassDesc} describing the component type, or {@code null}
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* if this descriptor does not describe an array type
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*/
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default ClassDesc componentType() {
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return isArray() ? ClassDesc.ofDescriptor(descriptorString().substring(1)) : null;
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}
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/**
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* Returns the package name of this {@linkplain ClassDesc}, if it describes
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* a class or interface type.
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*
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* @return the package name, or the empty string if the class is in the
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* default package, or this {@linkplain ClassDesc} does not describe a class or interface type
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*/
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default String packageName() {
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if (!isClassOrInterface())
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return "";
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String className = internalToBinary(ConstantUtils.dropFirstAndLastChar(descriptorString()));
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int index = className.lastIndexOf('.');
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return (index == -1) ? "" : className.substring(0, index);
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}
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/**
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* Returns a human-readable name for the type described by this descriptor.
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*
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* @implSpec
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* <p>The default implementation returns the simple name
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* (e.g., {@code int}) for primitive types, the unqualified class name
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* for class or interface types, or the display name of the component type
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* suffixed with the appropriate number of {@code []} pairs for array types.
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*
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* @return the human-readable name
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*/
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default String displayName() {
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if (isPrimitive())
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return Wrapper.forBasicType(descriptorString().charAt(0)).primitiveSimpleName();
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else if (isClassOrInterface()) {
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return descriptorString().substring(Math.max(1, descriptorString().lastIndexOf('/') + 1),
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descriptorString().length() - 1);
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}
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else if (isArray()) {
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int depth = ConstantUtils.arrayDepth(descriptorString());
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ClassDesc c = this;
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for (int i=0; i<depth; i++)
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c = c.componentType();
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return c.displayName() + "[]".repeat(depth);
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}
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else
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throw new IllegalStateException(descriptorString());
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}
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/**
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* Returns a field type descriptor string for this type
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*
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* @return the descriptor string
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* @jvms 4.3.2 Field Descriptors
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*/
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String descriptorString();
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/**
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* Compare the specified object with this descriptor for equality. Returns
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* {@code true} if and only if the specified object is also a
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* {@linkplain ClassDesc} and both describe the same type.
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*
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* @param o the other object
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* @return whether this descriptor is equal to the other object
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*/
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boolean equals(Object o);
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}
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