/*
* Copyright 2014 the original author or 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.gradle.model.internal.core;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.reflect.TypeResolver;
import com.google.common.reflect.TypeToken;
import net.jcip.annotations.ThreadSafe;
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.Collections;
import java.util.List;
/**
* A type token for the type of a model element.
* <p>
* Borrows from Guava's type token.
* Represent a fully resolved/bound type.
*/
@ThreadSafe
public abstract class ModelType<T> {
// TODO analyze performance cost of wrapping Guava's type token instead of inlining the code
// TODO there is no handling of TypeVariable here - at least need some validation that the incoming Type is not a variable
private static class Simple<T> extends ModelType<T> {
private Simple(TypeToken<T> typeToken) {
super(typeToken);
}
}
public static final ModelType<Object> UNTYPED = ModelType.of(Object.class);
private final TypeToken<T> typeToken;
private ModelType(TypeToken<T> typeToken) {
this.typeToken = typeToken;
}
protected ModelType() {
typeToken = new TypeToken<T>(getClass()) {
};
}
protected ModelType(final Class<?> clazz) {
this(new TypeToken<T>(clazz) {
});
}
public static <T> ModelType<T> of(Class<T> clazz) {
return new Simple<T>(TypeToken.of(clazz));
}
public static <T> ModelType<T> typeOf(T instance) {
@SuppressWarnings("unchecked") Class<T> clazz = (Class<T>) instance.getClass();
return of(clazz);
}
public static ModelType<?> of(Type type) {
return toModelType(TypeToken.of(type));
}
private static <T> ModelType<T> toModelType(TypeToken<T> type) {
return new Simple<T>(type);
}
public Class<? super T> getRawClass() {
return typeToken.getRawType();
}
public Class<T> getConcreteClass() {
@SuppressWarnings("unchecked")
Class<T> concreteClass = (Class<T>) getRawClass();
return concreteClass;
}
public boolean isParameterized() {
return typeToken.getType() instanceof ParameterizedType;
}
public List<ModelType<?>> getTypeVariables() {
if (isParameterized()) {
List<Type> types = Arrays.asList(((ParameterizedType) typeToken.getType()).getActualTypeArguments());
return ImmutableList.<ModelType<?>>builder().addAll(Iterables.transform(types, new Function<Type, ModelType<?>>() {
public ModelType<?> apply(Type input) {
return ModelType.of(input);
}
})).build();
} else {
return Collections.emptyList();
}
}
public ModelType<? extends T> asSubclass(ModelType<?> modelType) {
if (isWildcard() || modelType.isWildcard()) {
return null;
}
Class<? super T> thisClass = getRawClass();
Class<?> otherClass = modelType.getRawClass();
boolean isSubclass = thisClass.isAssignableFrom(otherClass) && !thisClass.equals(otherClass);
if (isSubclass) {
@SuppressWarnings("unchecked") ModelType<? extends T> cast = (ModelType<? extends T>) modelType;
return cast;
} else {
return null;
}
}
public boolean isAssignableFrom(ModelType<?> modelType) {
return typeToken.isAssignableFrom(modelType.typeToken);
}
public boolean isWildcard() {
return getWildcardType() != null;
}
public ModelType<?> getUpperBound() {
WildcardType wildcardType = getWildcardType();
if (wildcardType == null) {
return null;
} else {
ModelType<?> upperBoundType = ModelType.of(wildcardType.getUpperBounds()[0]);
if (upperBoundType.equals(UNTYPED)) {
return null;
} else {
return upperBoundType;
}
}
}
public ModelType<?> getLowerBound() {
WildcardType wildcardType = getWildcardType();
if (wildcardType == null) {
return null;
} else {
Type[] lowerBounds = wildcardType.getLowerBounds();
if (lowerBounds.length == 0) {
return null;
} else {
return ModelType.of(lowerBounds[0]);
}
}
}
private WildcardType getWildcardType() {
Type type = typeToken.getType();
if (type instanceof WildcardType) {
return (WildcardType) type;
} else {
return null;
}
}
public boolean isHasWildcardTypeVariables() {
if (isWildcard()) {
return true;
} else if (isParameterized()) {
for (ModelType<?> typeVariable : getTypeVariables()) {
if (typeVariable.isHasWildcardTypeVariables()) {
return true;
}
}
}
return false;
}
@Override
public String toString() {
return typeToken.toString();
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof ModelType)) {
return false;
}
ModelType<?> modelType = (ModelType<?>) o;
return typeToken.equals(modelType.typeToken);
}
@Override
public int hashCode() {
return typeToken.hashCode();
}
abstract public static class Builder<T> {
private TypeToken<T> typeToken;
public Builder() {
typeToken = new TypeToken<T>(getClass()) {
};
}
@SuppressWarnings("unchecked")
public <I> Builder<T> where(Parameter<I> parameter, ModelType<I> type) {
TypeResolver resolver = new TypeResolver().where(parameter.typeVariable, type.typeToken.getType());
typeToken = (TypeToken<T>) TypeToken.of(resolver.resolveType(typeToken.getType()));
return this;
}
public ModelType<T> build() {
return new Simple<T>(typeToken);
}
}
@SuppressWarnings("UnusedDeclaration")
abstract public static class Parameter<T> {
private final TypeVariable<?> typeVariable;
public Parameter() {
Type type = new TypeToken<T>(getClass()) {
}.getType();
if (type instanceof TypeVariable<?>) {
this.typeVariable = (TypeVariable<?>) type;
} else {
throw new IllegalStateException("T for Parameter<T> MUST be a type variable");
}
}
}
}