/*

* Copyright 2012-2022 The Feign 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 feign;

import java.lang.reflect.Array;

import java.lang.reflect.GenericArrayType;

import java.lang.reflect.GenericDeclaration;

import java.lang.reflect.ParameterizedType;

import java.lang.reflect.Type;

import java.lang.reflect.TypeVariable;

import java.lang.reflect.WildcardType;

import java.util.Arrays;

import java.util.NoSuchElementException;

/**

* Static methods for working with types.

*

* @author Bob Lee

* @author Jesse Wilson

*/

public final class Types {

private static final Type[] EMPTY_TYPE_ARRAY = new Type[0];

private Types() {

// No instances.

}

public static Class<?> getRawType(Type type) {

if (type instanceof Class<?>) {

// Type is a normal class.

return (Class<?>) type;

} else if (type instanceof ParameterizedType) {

ParameterizedType parameterizedType = (ParameterizedType) type;

// I'm not exactly sure why getRawType() returns Type instead of Class. Neal isn't either but

// suspects some pathological case related to nested classes exists.

Type rawType = parameterizedType.getRawType();

if (!(rawType instanceof Class)) {

throw new IllegalArgumentException();

}

return (Class<?>) rawType;

} else if (type instanceof GenericArrayType) {

Type componentType = ((GenericArrayType) type).getGenericComponentType();

return Array.newInstance(getRawType(componentType), 0).getClass();

} else if (type instanceof TypeVariable) {

// We could use the variable's bounds, but that won't work if there are multiple. Having a raw

// type that's more general than necessary is okay.

return Object.class;

} else if (type instanceof WildcardType) {

return getRawType(((WildcardType) type).getUpperBounds()[0]);

} else {

String className = type == null ? "null" : type.getClass().getName();

throw new IllegalArgumentException("Expected a Class, ParameterizedType, or "

+ "GenericArrayType, but <" + type + "> is of type "

+ className);

}

}

/**

* Returns true if {@code a} and {@code b} are equal.

*/

static boolean equals(Type a, Type b) {

if (a == b) {

return true; // Also handles (a == null && b == null).

} else if (a instanceof Class) {

return a.equals(b); // Class already specifies equals().

} else if (a instanceof ParameterizedType) {

if (!(b instanceof ParameterizedType)) {

return false;

}

ParameterizedType pa = (ParameterizedType) a;

ParameterizedType pb = (ParameterizedType) b;

return equal(pa.getOwnerType(), pb.getOwnerType())

&& pa.getRawType().equals(pb.getRawType())

&& Arrays.equals(pa.getActualTypeArguments(), pb.getActualTypeArguments());

} else if (a instanceof GenericArrayType) {

if (!(b instanceof GenericArrayType)) {

return false;

}

GenericArrayType ga = (GenericArrayType) a;

GenericArrayType gb = (GenericArrayType) b;

return equals(ga.getGenericComponentType(), gb.getGenericComponentType());

} else if (a instanceof WildcardType) {

if (!(b instanceof WildcardType)) {

return false;

}

WildcardType wa = (WildcardType) a;

WildcardType wb = (WildcardType) b;

return Arrays.equals(wa.getUpperBounds(), wb.getUpperBounds())

&& Arrays.equals(wa.getLowerBounds(), wb.getLowerBounds());

} else if (a instanceof TypeVariable) {

if (!(b instanceof TypeVariable)) {

return false;

}

TypeVariable<?> va = (TypeVariable<?>) a;

TypeVariable<?> vb = (TypeVariable<?>) b;

return va.getGenericDeclaration() == vb.getGenericDeclaration()

&& va.getName().equals(vb.getName());

} else {

return false; // This isn't a type we support!

}

}

/**

* Returns the generic supertype for {@code supertype}. For example, given a class {@code

* IntegerSet}, the result for when supertype is {@code Set.class} is {@code Set<Integer>} and the

* result when the supertype is {@code Collection.class} is {@code Collection<Integer>}.

*/

static Type getGenericSupertype(Type context, Class<?> rawType, Class<?> toResolve) {

if (toResolve == rawType) {

return context;

}

// We skip searching through interfaces if unknown is an interface.

if (toResolve.isInterface()) {

Class<?>[] interfaces = rawType.getInterfaces();

for (int i = 0, length = interfaces.length; i < length; i++) {

if (interfaces[i] == toResolve) {

return rawType.getGenericInterfaces()[i];

} else if (toResolve.isAssignableFrom(interfaces[i])) {

return getGenericSupertype(rawType.getGenericInterfaces()[i], interfaces[i], toResolve);

}

}

}

// Check our supertypes.

if (!rawType.isInterface()) {

while (rawType != Object.class) {

Class<?> rawSupertype = rawType.getSuperclass();

if (rawSupertype == toResolve) {

return rawType.getGenericSuperclass();

} else if (toResolve.isAssignableFrom(rawSupertype)) {

return getGenericSupertype(rawType.getGenericSuperclass(), rawSupertype, toResolve);

}

rawType = rawSupertype;

}

}

// We can't resolve this further.

return toResolve;

}

private static int indexOf(Object[] array, Object toFind) {

for (int i = 0; i < array.length; i++) {

if (toFind.equals(array[i])) {

return i;

}

}

throw new NoSuchElementException();

}

private static boolean equal(Object a, Object b) {

return a == b || (a != null && a.equals(b));

}

private static int hashCodeOrZero(Object o) {

return o != null ? o.hashCode() : 0;

}

static String typeToString(Type type) {

return type instanceof Class ? ((Class<?>) type).getName() : type.toString();

}

/**

* Returns the generic form of {@code supertype}. For example, if this is {@code

* ArrayList<String>}, this returns {@code Iterable<String>} given the input {@code

* Iterable.class}.

*

* @param supertype a superclass of, or interface implemented by, this.

*/

static Type getSupertype(Type context, Class<?> contextRawType, Class<?> supertype) {

if (!supertype.isAssignableFrom(contextRawType)) {

throw new IllegalArgumentException();

}

return resolve(context, contextRawType,

getGenericSupertype(context, contextRawType, supertype));

}

public static Type resolve(Type context, Class<?> contextRawType, Type toResolve) {

// This implementation is made a little more complicated in an attempt to avoid object-creation.

while (true) {

if (toResolve instanceof TypeVariable) {

TypeVariable<?> typeVariable = (TypeVariable<?>) toResolve;

toResolve = resolveTypeVariable(context, contextRawType, typeVariable);

if (toResolve == typeVariable) {

return toResolve;

}

} else if (toResolve instanceof Class && ((Class<?>) toResolve).isArray()) {

Class<?> original = (Class<?>) toResolve;

Type componentType = original.getComponentType();

Type newComponentType = resolve(context, contextRawType, componentType);

return componentType == newComponentType ? original

: new GenericArrayTypeImpl(

newComponentType);

} else if (toResolve instanceof GenericArrayType) {

GenericArrayType original = (GenericArrayType) toResolve;

Type componentType = original.getGenericComponentType();

Type newComponentType = resolve(context, contextRawType, componentType);

return componentType == newComponentType ? original

: new GenericArrayTypeImpl(

newComponentType);

} else if (toResolve instanceof ParameterizedType) {

ParameterizedType original = (ParameterizedType) toResolve;

Type ownerType = original.getOwnerType();

Type newOwnerType = resolve(context, contextRawType, ownerType);

boolean changed = newOwnerType != ownerType;

Type[] args = original.getActualTypeArguments();

for (int t = 0, length = args.length; t < length; t++) {

Type resolvedTypeArgument = resolve(context, contextRawType, args[t]);

if (resolvedTypeArgument != args[t]) {

if (!changed) {

args = args.clone();

changed = true;

}

args[t] = resolvedTypeArgument;

}

}

return changed

? new ParameterizedTypeImpl(newOwnerType, original.getRawType(), args)

: original;

} else if (toResolve instanceof WildcardType) {

WildcardType original = (WildcardType) toResolve;

Type[] originalLowerBound = original.getLowerBounds();

Type[] originalUpperBound = original.getUpperBounds();

if (originalLowerBound.length == 1) {

Type lowerBound = resolve(context, contextRawType, originalLowerBound[0]);

if (lowerBound != originalLowerBound[0]) {

return new WildcardTypeImpl(new Type[] {Object.class}, new Type[] {lowerBound});

}

} else if (originalUpperBound.length == 1) {

Type upperBound = resolve(context, contextRawType, originalUpperBound[0]);

if (upperBound != originalUpperBound[0]) {

return new WildcardTypeImpl(new Type[] {upperBound}, EMPTY_TYPE_ARRAY);

}

}

return original;

} else {

return toResolve;

}

}

}

private static Type resolveTypeVariable(

Type context,

Class<?> contextRawType,

TypeVariable<?> unknown) {

Class<?> declaredByRaw = declaringClassOf(unknown);

// We can't reduce this further.

if (declaredByRaw == null) {

return unknown;

}

Type declaredBy = getGenericSupertype(context, contextRawType, declaredByRaw);

if (declaredBy instanceof ParameterizedType) {

int index = indexOf(declaredByRaw.getTypeParameters(), unknown);

return ((ParameterizedType) declaredBy).getActualTypeArguments()[index];

}

return unknown;

}

/**

* Returns the declaring class of {@code typeVariable}, or {@code null} if it was not declared by

* a class.

*/

private static Class<?> declaringClassOf(TypeVariable<?> typeVariable) {

GenericDeclaration genericDeclaration = typeVariable.getGenericDeclaration();

return genericDeclaration instanceof Class ? (Class<?>) genericDeclaration : null;

}

private static void checkNotPrimitive(Type type) {

if (type instanceof Class<?> && ((Class<?>) type).isPrimitive()) {

throw new IllegalArgumentException();

}

}

public static Type resolveReturnType(Type baseType, Type overridingType) {

if (baseType instanceof Class && overridingType instanceof Class &&

((Class<?>) baseType).isAssignableFrom((Class<?>) overridingType)) {

// NOTE: javac generates multiple same methods for multiple inherited generic interfaces

return overridingType;

}

if (baseType instanceof Class && overridingType instanceof ParameterizedType) {

// NOTE: javac will generate multiple methods with different return types

// base interface declares generic method, override declares parameterized generic method

return overridingType;

}

if (baseType instanceof Class && overridingType instanceof TypeVariable) {

// NOTE: javac will generate multiple methods with different return types

// base interface declares non generic method, override declares generic method

return overridingType;

}

return baseType;

}

static final class ParameterizedTypeImpl implements ParameterizedType {

private final Type ownerType;

private final Type rawType;

private final Type[] typeArguments;

ParameterizedTypeImpl(Type ownerType, Type rawType, Type... typeArguments) {

// Require an owner type if the raw type needs it.

if (rawType instanceof Class<?>

&& (ownerType == null) != (((Class<?>) rawType).getEnclosingClass() == null)) {

throw new IllegalArgumentException();

}

this.ownerType = ownerType;

this.rawType = rawType;

this.typeArguments = typeArguments.clone();

for (Type typeArgument : this.typeArguments) {

if (typeArgument == null) {

throw new NullPointerException();

}

checkNotPrimitive(typeArgument);

}

}

@Override

public Type[] getActualTypeArguments() {

return typeArguments.clone();

}

@Override

public Type getRawType() {

return rawType;

}

@Override

public Type getOwnerType() {

return ownerType;

}

@Override

public boolean equals(Object other) {

return other instanceof ParameterizedType && Types.equals(this, (ParameterizedType) other);

}

@Override

public int hashCode() {

return Arrays.hashCode(typeArguments) ^ rawType.hashCode() ^ hashCodeOrZero(ownerType);

}

@Override

public String toString() {

StringBuilder result = new StringBuilder(30 * (typeArguments.length + 1));

result.append(typeToString(rawType));

if (typeArguments.length == 0) {

return result.toString();

}

result.append("<").append(typeToString(typeArguments[0]));

for (int i = 1; i < typeArguments.length; i++) {

result.append(", ").append(typeToString(typeArguments[i]));

}

return result.append(">").toString();

}

}

private static final class GenericArrayTypeImpl implements GenericArrayType {

private final Type componentType;

GenericArrayTypeImpl(Type componentType) {

this.componentType = componentType;

}

@Override

public Type getGenericComponentType() {

return componentType;

}

@Override

public boolean equals(Object o) {

return o instanceof GenericArrayType

&& Types.equals(this, (GenericArrayType) o);

}

@Override

public int hashCode() {

return componentType.hashCode();

}

@Override

public String toString() {

return typeToString(componentType) + "[]";

}

}

/**

* The WildcardType interface supports multiple upper bounds and multiple lower bounds. We only

* support what the Java 6 language needs - at most one bound. If a lower bound is set, the upper

* bound must be Object.class.

*/

static final class WildcardTypeImpl implements WildcardType {

private final Type upperBound;

private final Type lowerBound;

WildcardTypeImpl(Type[] upperBounds, Type[] lowerBounds) {

if (lowerBounds.length > 1) {

throw new IllegalArgumentException();

}

if (upperBounds.length != 1) {

throw new IllegalArgumentException();

}

if (lowerBounds.length == 1) {

if (lowerBounds[0] == null) {

throw new NullPointerException();

}

checkNotPrimitive(lowerBounds[0]);

if (upperBounds[0] != Object.class) {

throw new IllegalArgumentException();

}

this.lowerBound = lowerBounds[0];

this.upperBound = Object.class;

} else {

if (upperBounds[0] == null) {

throw new NullPointerException();

}

checkNotPrimitive(upperBounds[0]);

this.lowerBound = null;

this.upperBound = upperBounds[0];

}

}

@Override

public Type[] getUpperBounds() {

return new Type[] {upperBound};

}

@Override

public Type[] getLowerBounds() {

return lowerBound != null ? new Type[] {lowerBound} : EMPTY_TYPE_ARRAY;

}

@Override

public boolean equals(Object other) {

return other instanceof WildcardType && Types.equals(this, (WildcardType) other);

}

@Override

public int hashCode() {

// This equals Arrays.hashCode(getLowerBounds()) ^ Arrays.hashCode(getUpperBounds()).

return (lowerBound != null ? 31 + lowerBound.hashCode() : 1) ^ (31 + upperBound.hashCode());

}

@Override

public String toString() {

if (lowerBound != null) {

return "? super " + typeToString(lowerBound);

}

if (upperBound == Object.class) {

return "?";

}

return "? extends " + typeToString(upperBound);

}

}

}