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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package java.lang.constant;
import java.lang.invoke.TypeDescriptor;
import java.util.stream.Stream;
import sun.invoke.util.Wrapper;
import static java.lang.constant.ConstantUtils.binaryToInternal;
import static java.lang.constant.ConstantUtils.dropLastChar;
import static java.lang.constant.ConstantUtils.internalToBinary;
import static java.lang.constant.ConstantUtils.validateMemberName;
import static java.util.Objects.requireNonNull;
import static java.util.stream.Collectors.joining;
/**
* A nominal descriptor for a
* {@link Class} constant.
*
* For common system types, including all the primitive types, there are
* predefined {@linkplain ClassDesc} constants in {@link ConstantDescs}.
* (The {@code java.lang.constant} APIs consider {@code void} to be a primitive type.)
* To create a {@linkplain ClassDesc} for a class or interface type, use {@link #of} or
* {@link #ofDescriptor(String)}; to create a {@linkplain ClassDesc} for an array
* type, use {@link #ofDescriptor(String)}, or first obtain a
* {@linkplain ClassDesc} for the component type and then call the {@link #arrayType()}
* or {@link #arrayType(int)} methods.
*
* @see ConstantDescs
*
* @since 12
*/
public sealed interface ClassDesc
extends ConstantDesc,
TypeDescriptor.OfField
permits PrimitiveClassDescImpl,
ReferenceClassDescImpl {
/**
* Returns a {@linkplain ClassDesc} for a class or interface type,
* given the name of the class or interface, such as {@code "java.lang.String"}.
* (To create a descriptor for an array type, either use {@link #ofDescriptor(String)}
* or {@link #arrayType()}; to create a descriptor for a primitive type, use
* {@link #ofDescriptor(String)} or use the predefined constants in
* {@link ConstantDescs}).
*
* @param name the fully qualified (dot-separated) binary class name
* @return a {@linkplain ClassDesc} describing the desired class
* @throws NullPointerException if the argument is {@code null}
* @throws IllegalArgumentException if the name string is not in the
* correct format
*/
static ClassDesc of(String name) {
ConstantUtils.validateBinaryClassName(requireNonNull(name));
return ClassDesc.ofDescriptor("L" + binaryToInternal(name) + ";");
}
/**
* Returns a {@linkplain ClassDesc} for a class or interface type,
* given a package name and the unqualified (simple) name for the
* class or interface.
*
* @param packageName the package name (dot-separated); if the package
* name is the empty string, the class is considered to
* be in the unnamed package
* @param className the unqualified (simple) class name
* @return a {@linkplain ClassDesc} describing the desired class
* @throws NullPointerException if any argument is {@code null}
* @throws IllegalArgumentException if the package name or class name are
* not in the correct format
*/
static ClassDesc of(String packageName, String className) {
ConstantUtils.validateBinaryClassName(requireNonNull(packageName));
if (packageName.isEmpty()) {
return of(className);
}
validateMemberName(requireNonNull(className), false);
return ofDescriptor("L" + binaryToInternal(packageName) +
(packageName.length() > 0 ? "/" : "") + className + ";");
}
/**
* Returns a {@linkplain ClassDesc} given a descriptor string for a class,
* interface, array, or primitive type.
*
* @apiNote
*
* A field type descriptor string for a non-array type is either
* a one-letter code corresponding to a primitive type
* ({@code "J", "I", "C", "S", "B", "D", "F", "Z", "V"}), or the letter {@code "L"}, followed
* by the fully qualified binary name of a class, followed by {@code ";"}.
* A field type descriptor for an array type is the character {@code "["}
* followed by the field descriptor for the component type. Examples of
* valid type descriptor strings include {@code "Ljava/lang/String;"}, {@code "I"},
* {@code "[I"}, {@code "V"}, {@code "[Ljava/lang/String;"}, etc.
* See JVMS 4.3.2 ("Field Descriptors") for more detail.
*
* @param descriptor a field descriptor string
* @return a {@linkplain ClassDesc} describing the desired class
* @throws NullPointerException if the argument is {@code null}
* @throws IllegalArgumentException if the name string is not in the
* correct format
* @jvms 4.3.2 Field Descriptors
* @jvms 4.4.1 The CONSTANT_Class_info Structure
*/
static ClassDesc ofDescriptor(String descriptor) {
requireNonNull(descriptor);
if (descriptor.isEmpty()) {
throw new IllegalArgumentException(
"not a valid reference type descriptor: " + descriptor);
}
int depth = ConstantUtils.arrayDepth(descriptor);
if (depth > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
throw new IllegalArgumentException(
"Cannot create an array type descriptor with more than " +
ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
}
return (descriptor.length() == 1)
? new PrimitiveClassDescImpl(descriptor)
: new ReferenceClassDescImpl(descriptor);
}
/**
* Returns a {@linkplain ClassDesc} for an array type whose component type
* is described by this {@linkplain ClassDesc}.
*
* @return a {@linkplain ClassDesc} describing the array type
* @throws IllegalStateException if the resulting {@linkplain ClassDesc} would have an array rank of greater than 255
* @jvms 4.4.1 The CONSTANT_Class_info Structure
*/
default ClassDesc arrayType() {
int depth = ConstantUtils.arrayDepth(descriptorString());
if (depth >= ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
throw new IllegalStateException(
"Cannot create an array type descriptor with more than " +
ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
}
return arrayType(1);
}
/**
* Returns a {@linkplain ClassDesc} for an array type of the specified rank,
* whose component type is described by this {@linkplain ClassDesc}.
*
* @param rank the rank of the array
* @return a {@linkplain ClassDesc} describing the array type
* @throws IllegalArgumentException if the rank is less than or equal to zero or if the rank of the resulting array type is
* greater than 255
* @jvms 4.4.1 The CONSTANT_Class_info Structure
*/
default ClassDesc arrayType(int rank) {
int currentDepth = ConstantUtils.arrayDepth(descriptorString());
if (rank <= 0 || currentDepth + rank > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS)
throw new IllegalArgumentException("rank: " + currentDepth + rank);
return ClassDesc.ofDescriptor("[".repeat(rank) + descriptorString());
}
/**
* Returns a {@linkplain ClassDesc} for a nested class of the class or
* interface type described by this {@linkplain ClassDesc}.
*
* @apiNote
*
* Example: If descriptor {@code d} describes the class {@code java.util.Map}, a
* descriptor for the class {@code java.util.Map.Entry} could be obtained
* by {@code d.nested("Entry")}.
*
* @param nestedName the unqualified name of the nested class
* @return a {@linkplain ClassDesc} describing the nested class
* @throws NullPointerException if the argument is {@code null}
* @throws IllegalStateException if this {@linkplain ClassDesc} does not
* describe a class or interface type
* @throws IllegalArgumentException if the nested class name is invalid
*/
default ClassDesc nested(String nestedName) {
validateMemberName(nestedName, false);
if (!isClassOrInterface())
throw new IllegalStateException("Outer class is not a class or interface type");
return ClassDesc.ofDescriptor(dropLastChar(descriptorString()) + "$" + nestedName + ";");
}
/**
* Returns a {@linkplain ClassDesc} for a nested class of the class or
* interface type described by this {@linkplain ClassDesc}.
*
* @param firstNestedName the unqualified name of the first level of nested class
* @param moreNestedNames the unqualified name(s) of the remaining levels of
* nested class
* @return a {@linkplain ClassDesc} describing the nested class
* @throws NullPointerException if any argument or its contents is {@code null}
* @throws IllegalStateException if this {@linkplain ClassDesc} does not
* describe a class or interface type
* @throws IllegalArgumentException if the nested class name is invalid
*/
default ClassDesc nested(String firstNestedName, String... moreNestedNames) {
if (!isClassOrInterface())
throw new IllegalStateException("Outer class is not a class or interface type");
validateMemberName(firstNestedName, false);
requireNonNull(moreNestedNames);
for (String addNestedNames : moreNestedNames) {
validateMemberName(addNestedNames, false);
}
return moreNestedNames.length == 0
? nested(firstNestedName)
: nested(firstNestedName + Stream.of(moreNestedNames).collect(joining("$", "$", "")));
}
/**
* Returns whether this {@linkplain ClassDesc} describes an array type.
*
* @return whether this {@linkplain ClassDesc} describes an array type
*/
default boolean isArray() {
return descriptorString().startsWith("[");
}
/**
* Returns whether this {@linkplain ClassDesc} describes a primitive type.
*
* @return whether this {@linkplain ClassDesc} describes a primitive type
*/
default boolean isPrimitive() {
return descriptorString().length() == 1;
}
/**
* Returns whether this {@linkplain ClassDesc} describes a class or interface type.
*
* @return whether this {@linkplain ClassDesc} describes a class or interface type
*/
default boolean isClassOrInterface() {
return descriptorString().startsWith("L");
}
/**
* Returns the component type of this {@linkplain ClassDesc}, if it describes
* an array type, or {@code null} otherwise.
*
* @return a {@linkplain ClassDesc} describing the component type, or {@code null}
* if this descriptor does not describe an array type
*/
default ClassDesc componentType() {
return isArray() ? ClassDesc.ofDescriptor(descriptorString().substring(1)) : null;
}
/**
* Returns the package name of this {@linkplain ClassDesc}, if it describes
* a class or interface type.
*
* @return the package name, or the empty string if the class is in the
* default package, or this {@linkplain ClassDesc} does not describe a class or interface type
*/
default String packageName() {
if (!isClassOrInterface())
return "";
String className = internalToBinary(ConstantUtils.dropFirstAndLastChar(descriptorString()));
int index = className.lastIndexOf('.');
return (index == -1) ? "" : className.substring(0, index);
}
/**
* Returns a human-readable name for the type described by this descriptor.
*
* @implSpec
* The default implementation returns the simple name
* (e.g., {@code int}) for primitive types, the unqualified class name
* for class or interface types, or the display name of the component type
* suffixed with the appropriate number of {@code []} pairs for array types.
*
* @return the human-readable name
*/
default String displayName() {
if (isPrimitive())
return Wrapper.forBasicType(descriptorString().charAt(0)).primitiveSimpleName();
else if (isClassOrInterface()) {
return descriptorString().substring(Math.max(1, descriptorString().lastIndexOf('/') + 1),
descriptorString().length() - 1);
}
else if (isArray()) {
int depth = ConstantUtils.arrayDepth(descriptorString());
ClassDesc c = this;
for (int i=0; i