Types.java
/*
* Copyright 2010-present Stephen Colebourne
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Copied from Guava and altered. Original copyright:
*
* Copyright (C) 2011 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package org.joda.convert;
import java.io.Serializable;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Array;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.GenericDeclaration;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Proxy;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import java.security.AccessControlException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;
/**
* Utilities for working with {@link Type}.
*/
final class Types {
/** Returns the array type of {@code componentType}. */
static Type newArrayType(Type componentType) {
if (componentType instanceof WildcardType) {
WildcardType wildcard = (WildcardType) componentType;
Type[] lowerBounds = wildcard.getLowerBounds();
checkArgument(lowerBounds.length <= 1, "Wildcard cannot have more than one lower bounds.");
if (lowerBounds.length == 1) {
return supertypeOf(newArrayType(lowerBounds[0]));
} else {
Type[] upperBounds = wildcard.getUpperBounds();
checkArgument(upperBounds.length == 1, "Wildcard should have only one upper bound.");
return subtypeOf(newArrayType(upperBounds[0]));
}
}
return JavaVersion.CURRENT.newArrayType(componentType);
}
/**
* Returns a type where {@code rawType} is parameterized by {@code arguments} and is owned by
* {@code ownerType}.
*/
static ParameterizedType newParameterizedTypeWithOwner(
Type ownerType, Class<?> rawType, Type... arguments) {
if (ownerType == null) {
return newParameterizedType(rawType, arguments);
}
// ParameterizedTypeImpl constructor already checks, but we want to throw NPE before IAE
checkNotNull(arguments);
checkArgument(rawType.getEnclosingClass() != null, "Owner type for unenclosed %s", rawType);
return new ParameterizedTypeImpl(ownerType, rawType, arguments);
}
/**
* Returns a type where {@code rawType} is parameterized by {@code arguments}.
*/
static ParameterizedType newParameterizedType(Class<?> rawType, Type... arguments) {
return new ParameterizedTypeImpl(
ClassOwnership.JVM_BEHAVIOR.getOwnerType(rawType), rawType, arguments);
}
/** Decides what owner type to use for constructing {@link ParameterizedType} from a raw class. */
private enum ClassOwnership {
OWNED_BY_ENCLOSING_CLASS {
@Override
Class<?> getOwnerType(Class<?> rawType) {
return rawType.getEnclosingClass();
}
},
LOCAL_CLASS_HAS_NO_OWNER {
@Override
Class<?> getOwnerType(Class<?> rawType) {
if (rawType.isLocalClass()) {
return null;
} else {
return rawType.getEnclosingClass();
}
}
};
abstract Class<?> getOwnerType(Class<?> rawType);
static final ClassOwnership JVM_BEHAVIOR = detectJvmBehavior();
private static ClassOwnership detectJvmBehavior() {
class LocalClass<T> {
}
LocalClass<String> localClass = new LocalClass<String>() {}; // CSIGNORE
Class<?> subclass = localClass.getClass();
ParameterizedType parameterizedType = (ParameterizedType) subclass.getGenericSuperclass();
for (ClassOwnership behavior : ClassOwnership.values()) {
if (behavior.getOwnerType(LocalClass.class) == parameterizedType.getOwnerType()) {
return behavior;
}
}
throw new AssertionError();
}
}
/**
* Returns a new {@link TypeVariable} that belongs to {@code declaration} with {@code name} and
* {@code bounds}.
*/
static <D extends GenericDeclaration> TypeVariable<D> newArtificialTypeVariable(
D declaration, String name, Type... bounds) {
return newTypeVariableImpl(
declaration, name, (bounds.length == 0) ? new Type[] {Object.class} : bounds);
}
/** Returns a new {@link WildcardType} with {@code upperBound}. */
static WildcardType subtypeOf(Type upperBound) {
return new WildcardTypeImpl(new Type[0], new Type[] {upperBound});
}
/** Returns a new {@link WildcardType} with {@code lowerBound}. */
static WildcardType supertypeOf(Type lowerBound) {
return new WildcardTypeImpl(new Type[] {lowerBound}, new Type[] {Object.class});
}
/**
* Returns human readable string representation of {@code type}.
* <ul>
* <li>For array type {@code Foo[]}, {@code "com.mypackage.Foo[]"} are returned.
* <li>For any class, {@code theClass.getName()} are returned.
* <li>For all other types, {@code type.toString()} are returned.
* </ul>
*/
static String toString(Type type) {
return (type instanceof Class) ? ((Class<?>) type).getName() : type.toString();
}
static Type getComponentType(Type type) {
checkNotNull(type);
final AtomicReference<Type> result = new AtomicReference<Type>();
new TypeVisitor() {
@Override
void visitTypeVariable(TypeVariable<?> t) {
result.set(subtypeOfComponentType(t.getBounds()));
}
@Override
void visitWildcardType(WildcardType t) {
result.set(subtypeOfComponentType(t.getUpperBounds()));
}
@Override
void visitGenericArrayType(GenericArrayType t) {
result.set(t.getGenericComponentType());
}
@Override
void visitClass(Class<?> t) {
result.set(t.getComponentType());
}
}.visit(type);
return result.get();
}
/**
* Visitor pattern to evaluate {@code Type}.
*/
private abstract static class TypeVisitor {
private final Set<Type> visited = new HashSet<Type>();
/**
* Visits the given types. Null types are ignored. This allows subclasses to call
* {@code visit(parameterizedType.getOwnerType())} safely without having to check nulls.
*/
public final void visit(Type... types) {
for (Type type : types) {
if (type == null || !visited.add(type)) {
// null owner type, or already visited;
continue;
}
boolean succeeded = false;
try {
if (type instanceof TypeVariable) {
visitTypeVariable((TypeVariable<?>) type);
} else if (type instanceof WildcardType) {
visitWildcardType((WildcardType) type);
} else if (type instanceof ParameterizedType) {
visitParameterizedType((ParameterizedType) type);
} else if (type instanceof Class) {
visitClass((Class<?>) type);
} else if (type instanceof GenericArrayType) {
visitGenericArrayType((GenericArrayType) type);
} else {
throw new AssertionError("Unknown type: " + type);
}
succeeded = true;
} finally {
if (!succeeded) { // When the visitation failed, we don't want to ignore the second.
visited.remove(type);
}
}
}
}
void visitClass(Class<?> t) {
}
void visitGenericArrayType(GenericArrayType t) {
}
void visitParameterizedType(ParameterizedType t) {
}
void visitTypeVariable(TypeVariable<?> t) {
}
void visitWildcardType(WildcardType t) {
}
}
/**
* Returns {@code ? extends X} if any of {@code bounds} is a subtype of {@code X[]}; or null
* otherwise.
*/
private static Type subtypeOfComponentType(Type[] bounds) {
for (Type bound : bounds) {
Type componentType = getComponentType(bound);
if (componentType != null) {
// Only the first bound can be a class or array.
// Bounds after the first can only be interfaces.
if (componentType instanceof Class) {
Class<?> componentClass = (Class<?>) componentType;
if (componentClass.isPrimitive()) {
return componentClass;
}
}
return subtypeOf(componentType);
}
}
return null;
}
private static final class GenericArrayTypeImpl implements GenericArrayType, Serializable {
private final Type componentType;
GenericArrayTypeImpl(Type componentType) {
this.componentType = JavaVersion.CURRENT.usedInGenericType(componentType);
}
@Override
public Type getGenericComponentType() {
return componentType;
}
@Override
public String toString() {
return Types.toString(componentType) + "[]";
}
@Override
public int hashCode() {
return componentType.hashCode();
}
@Override
public boolean equals(Object obj) {
if (obj instanceof GenericArrayType) {
GenericArrayType that = (GenericArrayType) obj;
return equal(getGenericComponentType(), that.getGenericComponentType());
}
return false;
}
private static final long serialVersionUID = 0;
}
private static final class ParameterizedTypeImpl implements ParameterizedType, Serializable {
private final Type ownerType;
private final List<Type> argumentsList;
private final Class<?> rawType;
ParameterizedTypeImpl(Type ownerType, Class<?> rawType, Type[] typeArguments) {
checkNotNull(rawType);
checkArgument(typeArguments.length == rawType.getTypeParameters().length);
disallowPrimitiveType(typeArguments, "type parameter");
this.ownerType = ownerType;
this.rawType = rawType;
this.argumentsList = JavaVersion.CURRENT.usedInGenericType(typeArguments);
}
@Override
public Type[] getActualTypeArguments() {
return toArray(argumentsList);
}
@Override
public Type getRawType() {
return rawType;
}
@Override
public Type getOwnerType() {
return ownerType;
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
if (ownerType != null && JavaVersion.CURRENT.jdkTypeDuplicatesOwnerName()) {
builder.append(JavaVersion.CURRENT.typeName(ownerType)).append('.');
}
String str = "";
if (argumentsList == null) {
str = "null";
} else {
for (int i = 0; i < argumentsList.size(); i++) {
if (i > 0) {
str += ", ";
}
str += JavaVersion.CURRENT.typeName(argumentsList.get(i));
}
}
return builder
.append(rawType.getName())
.append('<')
.append(str)
.append('>')
.toString();
}
@Override
public int hashCode() {
return (ownerType == null ? 0 : ownerType.hashCode()) ^ argumentsList.hashCode() ^ rawType.hashCode();
}
@Override
public boolean equals(Object other) {
if (!(other instanceof ParameterizedType)) {
return false;
}
ParameterizedType that = (ParameterizedType) other;
return getRawType().equals(that.getRawType()) && equal(getOwnerType(), that.getOwnerType()) &&
Arrays.equals(getActualTypeArguments(), that.getActualTypeArguments());
}
private static final long serialVersionUID = 0;
}
private static <D extends GenericDeclaration> TypeVariable<D> newTypeVariableImpl(
D genericDeclaration, String name, Type[] bounds) {
TypeVariableImpl<D> typeVariableImpl =
new TypeVariableImpl<D>(genericDeclaration, name, bounds);
@SuppressWarnings("unchecked")
TypeVariable<D> typeVariable = newProxy(TypeVariable.class, new TypeVariableInvocationHandler(typeVariableImpl));
return typeVariable;
}
// from Guava `Reflection` class
private static <T> T newProxy(Class<T> interfaceType, InvocationHandler handler) {
checkNotNull(handler);
checkArgument(interfaceType.isInterface(), "%s is not an interface", interfaceType);
Object object =
Proxy.newProxyInstance(
interfaceType.getClassLoader(), new Class<?>[] {interfaceType}, handler);
return interfaceType.cast(object);
}
/**
* Invocation handler to work around a compatibility problem between Java 7 and Java 8.
*
* <p>Java 8 introduced a new method {@code getAnnotatedBounds()} in the {@link TypeVariable}
* interface, whose return type {@code AnnotatedType[]} is also new in Java 8. That means that we
* cannot implement that interface in source code in a way that will compile on both Java 7 and
* Java 8. If we include the {@code getAnnotatedBounds()} method then its return type means it
* won't compile on Java 7, while if we don't include the method then the compiler will complain
* that an abstract method is unimplemented. So instead we use a dynamic proxy to get an
* implementation. If the method being called on the {@code TypeVariable} instance has the same
* name as one of the public methods of {@link TypeVariableImpl}, the proxy calls the same method
* on its instance of {@code TypeVariableImpl}. Otherwise it throws
* {@link UnsupportedOperationException}; this should only apply to {@code getAnnotatedBounds()}.
* This does mean that users on Java 8 who obtain an instance of {@code TypeVariable} from
* {@code TypeResolver#resolveType} will not be able to call {@code getAnnotatedBounds()} on it,
* but that should hopefully be rare.
*
* <p>This workaround should be removed at a distant future time when we no longer support Java
* versions earlier than 8.
*/
private static final class TypeVariableInvocationHandler implements InvocationHandler {
private static final Map<String, Method> typeVariableMethods;
static {
Map<String, Method> builder = new LinkedHashMap<String, Method>();
for (Method method : TypeVariableImpl.class.getMethods()) {
if (method.getDeclaringClass().equals(TypeVariableImpl.class)) {
try {
method.setAccessible(true);
} catch (AccessControlException e) {
// OK: the method is accessible to us anyway. The setAccessible call is only for
// unusual execution environments where that might not be true.
}
builder.put(method.getName(), method);
}
}
typeVariableMethods = builder;
}
private final TypeVariableImpl<?> typeVariableImpl;
TypeVariableInvocationHandler(TypeVariableImpl<?> typeVariableImpl) {
this.typeVariableImpl = typeVariableImpl;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String methodName = method.getName();
Method typeVariableMethod = typeVariableMethods.get(methodName);
if (typeVariableMethod == null) {
throw new UnsupportedOperationException(methodName);
} else {
try {
return typeVariableMethod.invoke(typeVariableImpl, args);
} catch (InvocationTargetException e) {
throw e.getCause();
}
}
}
}
private static final class TypeVariableImpl<D extends GenericDeclaration> {
private final D genericDeclaration;
private final String name;
private final List<Type> bounds;
TypeVariableImpl(D genericDeclaration, String name, Type[] bounds) {
disallowPrimitiveType(bounds, "bound for type variable");
this.genericDeclaration = checkNotNull(genericDeclaration);
this.name = checkNotNull(name);
this.bounds = new ArrayList<Type>(Arrays.asList(bounds));
}
public D getGenericDeclaration() {
return genericDeclaration;
}
public String getName() {
return name;
}
@Override
public String toString() {
return name;
}
@Override
public int hashCode() {
return genericDeclaration.hashCode() ^ name.hashCode();
}
@Override
public boolean equals(Object obj) {
if (NativeTypeVariableEquals.NATIVE_TYPE_VARIABLE_ONLY) {
// equal only to our TypeVariable implementation with identical bounds
if (obj != null && Proxy.isProxyClass(obj.getClass()) &&
Proxy.getInvocationHandler(obj) instanceof TypeVariableInvocationHandler) {
TypeVariableInvocationHandler typeVariableInvocationHandler =
(TypeVariableInvocationHandler) Proxy.getInvocationHandler(obj);
TypeVariableImpl<?> that = typeVariableInvocationHandler.typeVariableImpl;
return name.equals(that.getName()) && genericDeclaration.equals(that.getGenericDeclaration()) &&
bounds.equals(that.bounds);
}
return false;
} else {
// equal to any TypeVariable implementation regardless of bounds
if (obj instanceof TypeVariable) {
TypeVariable<?> that = (TypeVariable<?>) obj;
return name.equals(that.getName()) && genericDeclaration.equals(that.getGenericDeclaration());
}
return false;
}
}
}
static final class WildcardTypeImpl implements WildcardType, Serializable {
private final List<Type> lowerBounds;
private final List<Type> upperBounds;
WildcardTypeImpl(Type[] lowerBounds, Type[] upperBounds) {
disallowPrimitiveType(lowerBounds, "lower bound for wildcard");
disallowPrimitiveType(upperBounds, "upper bound for wildcard");
this.lowerBounds = JavaVersion.CURRENT.usedInGenericType(lowerBounds);
this.upperBounds = JavaVersion.CURRENT.usedInGenericType(upperBounds);
}
@Override
public Type[] getLowerBounds() {
return toArray(lowerBounds);
}
@Override
public Type[] getUpperBounds() {
return toArray(upperBounds);
}
@Override
public boolean equals(Object obj) {
if (obj instanceof WildcardType) {
WildcardType that = (WildcardType) obj;
return lowerBounds.equals(Arrays.asList(that.getLowerBounds())) &&
upperBounds.equals(Arrays.asList(that.getUpperBounds()));
}
return false;
}
@Override
public int hashCode() {
return lowerBounds.hashCode() ^ upperBounds.hashCode();
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder("?");
for (Type lowerBound : lowerBounds) {
builder.append(" super ").append(JavaVersion.CURRENT.typeName(lowerBound));
}
for (Type upperBound : filterUpperBounds(upperBounds)) {
builder.append(" extends ").append(JavaVersion.CURRENT.typeName(upperBound));
}
return builder.toString();
}
private static final long serialVersionUID = 0;
}
private static Type[] toArray(Collection<Type> types) {
return types.toArray(new Type[types.size()]);
}
private static List<Type> filterUpperBounds(List<Type> bounds) {
List<Type> filtered = new ArrayList<Type>();
for (Type type : bounds) {
if (!type.equals(Object.class)) {
filtered.add(type);
}
}
return filtered;
}
private static void disallowPrimitiveType(Type[] types, String usedAs) {
for (Type type : types) {
if (type instanceof Class) {
Class<?> cls = (Class<?>) type;
checkArgument(!cls.isPrimitive(), "Primitive type '%s' used as %s", cls, usedAs);
}
}
}
/** Returns the {@code Class} object of arrays with {@code componentType}. */
static Class<?> getArrayClass(Class<?> componentType) {
// TODO(user): This is not the most efficient way to handle generic
// arrays, but is there another way to extract the array class in a
// non-hacky way (i.e. using String value class names- "[L...")?
return Array.newInstance(componentType, 0).getClass();
}
// TODO(benyu): Once behavior is the same for all Java versions we support, delete this.
enum JavaVersion {
JAVA6 {
@Override
GenericArrayType newArrayType(Type componentType) {
return new GenericArrayTypeImpl(componentType);
}
@Override
Type usedInGenericType(Type type) {
checkNotNull(type);
if (type instanceof Class) {
Class<?> cls = (Class<?>) type;
if (cls.isArray()) {
return new GenericArrayTypeImpl(cls.getComponentType());
}
}
return type;
}
},
JAVA7 {
@Override
Type newArrayType(Type componentType) {
if (componentType instanceof Class) {
return getArrayClass((Class<?>) componentType);
} else {
return new GenericArrayTypeImpl(componentType);
}
}
@Override
Type usedInGenericType(Type type) {
return checkNotNull(type);
}
},
JAVA8 {
@Override
Type newArrayType(Type componentType) {
return JAVA7.newArrayType(componentType);
}
@Override
Type usedInGenericType(Type type) {
return JAVA7.usedInGenericType(type);
}
@Override
String typeName(Type type) {
try {
Method getTypeName = Type.class.getMethod("getTypeName");
return (String) getTypeName.invoke(type);
} catch (NoSuchMethodException e) {
throw new AssertionError("Type.getTypeName should be available in Java 8");
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
}
},
JAVA9 {
@Override
Type newArrayType(Type componentType) {
return JAVA8.newArrayType(componentType);
}
@Override
Type usedInGenericType(Type type) {
return JAVA8.usedInGenericType(type);
}
@Override
String typeName(Type type) {
return JAVA8.typeName(type);
}
@Override
boolean jdkTypeDuplicatesOwnerName() {
return false;
}
};
static final JavaVersion CURRENT;
static {
if (AnnotatedElement.class.isAssignableFrom(TypeVariable.class)) {
if (new TypeCapture<Map.Entry<String, int[][]>>() {}.capture() // CSIGNORE
.toString()
.contains("java.util.Map.java.util.Map")) {
CURRENT = JAVA8;
} else {
CURRENT = JAVA9;
}
} else if (new TypeCapture<int[]>() {}.capture() instanceof Class) { // CSIGNORE
CURRENT = JAVA7;
} else {
CURRENT = JAVA6;
}
}
abstract Type newArrayType(Type componentType);
abstract Type usedInGenericType(Type type);
String typeName(Type type) {
return Types.toString(type);
}
boolean jdkTypeDuplicatesOwnerName() {
return true;
}
List<Type> usedInGenericType(Type[] types) {
List<Type> builder = new ArrayList<Type>();
for (Type type : types) {
builder.add(usedInGenericType(type));
}
return builder;
}
}
/**
* Per <a href="https://code.google.com/p/guava-libraries/issues/detail?id=1635">issue 1635</a>,
* In JDK 1.7.0_51-b13, {@code TypeVariableImpl#equals(Object)} is changed to no longer be equal
* to custom TypeVariable implementations. As a result, we need to make sure our TypeVariable
* implementation respects symmetry. Moreover, we don't want to reconstruct a native type variable
* {@code <A>} using our implementation unless some of its bounds have changed in resolution. This
* avoids creating unequal TypeVariable implementation unnecessarily. When the bounds do change,
* however, it's fine for the synthetic TypeVariable to be unequal to any native TypeVariable
* anyway.
*/
static final class NativeTypeVariableEquals<X> {
static final boolean NATIVE_TYPE_VARIABLE_ONLY =
!NativeTypeVariableEquals.class.getTypeParameters()[0]
.equals(newArtificialTypeVariable(NativeTypeVariableEquals.class, "X"));
}
//-----------------------------------------------------------------------
// utilities
private static <T> T checkNotNull(T reference) {
if (reference == null) {
throw new NullPointerException();
}
return reference;
}
private static void checkArgument(boolean expression) {
if (!expression) {
throw new IllegalArgumentException();
}
}
private static void checkArgument(boolean expression, Object errorMessage) {
if (!expression) {
throw new IllegalArgumentException(String.valueOf(errorMessage));
}
}
static void checkArgument(
boolean expression,
String errorMessageTemplate,
Object... errorMessageArgs) {
if (!expression) {
throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
}
}
private static String format(String template, Object... args) {
template = String.valueOf(template); // null -> "null"
args = args == null ? new Object[] {"(Object[])null"} : args;
// start substituting the arguments into the '%s' placeholders
StringBuilder builder = new StringBuilder(template.length() + 16 * args.length);
int templateStart = 0;
int i = 0;
while (i < args.length) {
int placeholderStart = template.indexOf("%s", templateStart);
if (placeholderStart == -1) {
break;
}
builder.append(template, templateStart, placeholderStart);
builder.append(args[i++]);
templateStart = placeholderStart + 2;
}
builder.append(template, templateStart, template.length());
// if we run out of placeholders, append the extra args in square braces
if (i < args.length) {
builder.append(" [");
builder.append(args[i++]);
while (i < args.length) {
builder.append(", ");
builder.append(args[i++]);
}
builder.append(']');
}
return builder.toString();
}
private static boolean equal(Object obj1, Object obj2) {
return obj1 == obj2 || (obj1 != null && obj1.equals(obj2));
}
private Types() {
}
}