176 lines
7.2 KiB
Java
176 lines
7.2 KiB
Java
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/*
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* Copyright (C) 2008 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.bukkit.mcteam.gson;
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import java.lang.reflect.Field;
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import java.lang.reflect.GenericArrayType;
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import java.lang.reflect.ParameterizedType;
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import java.lang.reflect.Type;
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import java.lang.reflect.TypeVariable;
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import java.lang.reflect.WildcardType;
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/**
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* A static factory class used to construct the "TypeInfo" objects.
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*
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* @author Inderjeet Singh
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* @author Joel Leitch
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*/
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final class TypeInfoFactory {
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private TypeInfoFactory() {
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// Not instantiable since it provides factory methods only.
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}
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public static TypeInfoArray getTypeInfoForArray(Type type) {
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Preconditions.checkArgument(TypeUtils.isArray(type));
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return new TypeInfoArray(type);
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}
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/**
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* Evaluates the "actual" type for the field. If the field is a "TypeVariable" or has a
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* "TypeVariable" in a parameterized type then it evaluates the real type.
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*
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* @param f the actual field object to retrieve the type from
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* @param typeDefiningF the type that contains the field {@code f}
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* @return the type information for the field
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*/
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public static TypeInfo getTypeInfoForField(Field f, Type typeDefiningF) {
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Class<?> classDefiningF = TypeUtils.toRawClass(typeDefiningF);
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Type type = f.getGenericType();
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Type actualType = getActualType(type, typeDefiningF, classDefiningF);
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return new TypeInfo(actualType);
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}
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private static Type getActualType(
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Type typeToEvaluate, Type parentType, Class<?> rawParentClass) {
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if (typeToEvaluate instanceof Class<?>) {
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return typeToEvaluate;
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} else if (typeToEvaluate instanceof ParameterizedType) {
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ParameterizedType castedType = (ParameterizedType) typeToEvaluate;
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Type owner = castedType.getOwnerType();
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Type[] actualTypeParameters =
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extractRealTypes(castedType.getActualTypeArguments(), parentType, rawParentClass);
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Type rawType = castedType.getRawType();
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return new ParameterizedTypeImpl(rawType, actualTypeParameters, owner);
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} else if (typeToEvaluate instanceof GenericArrayType) {
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GenericArrayType castedType = (GenericArrayType) typeToEvaluate;
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Type componentType = castedType.getGenericComponentType();
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Type actualType = getActualType(componentType, parentType, rawParentClass);
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if (componentType.equals(actualType)) {
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return castedType;
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}
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return actualType instanceof Class<?> ?
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TypeUtils.wrapWithArray(TypeUtils.toRawClass(actualType))
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: new GenericArrayTypeImpl(actualType);
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} else if (typeToEvaluate instanceof TypeVariable<?>) {
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if (parentType instanceof ParameterizedType) {
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// The class definition has the actual types used for the type variables.
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// Find the matching actual type for the Type Variable used for the field.
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// For example, class Foo<A> { A a; }
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// new Foo<Integer>(); defines the actual type of A to be Integer.
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// So, to find the type of the field a, we will have to look at the class'
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// actual type arguments.
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TypeVariable<?> fieldTypeVariable = (TypeVariable<?>) typeToEvaluate;
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TypeVariable<?>[] classTypeVariables = rawParentClass.getTypeParameters();
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ParameterizedType objParameterizedType = (ParameterizedType) parentType;
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int indexOfActualTypeArgument = getIndex(classTypeVariables, fieldTypeVariable);
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Type[] actualTypeArguments = objParameterizedType.getActualTypeArguments();
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return actualTypeArguments[indexOfActualTypeArgument];
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} else if (typeToEvaluate instanceof TypeVariable<?>) {
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Type theSearchedType = null;
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do {
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theSearchedType = extractTypeForHierarchy(parentType, (TypeVariable<?>) typeToEvaluate);
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} while ((theSearchedType != null) && (theSearchedType instanceof TypeVariable<?>));
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if (theSearchedType != null) {
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return theSearchedType;
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}
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}
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throw new UnsupportedOperationException("Expecting parameterized type, got " + parentType
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+ ".\n Are you missing the use of TypeToken idiom?\n See "
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+ "http://sites.google.com/site/gson/gson-user-guide#TOC-Serializing-and-Deserializing-Gener");
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} else if (typeToEvaluate instanceof WildcardType) {
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WildcardType castedType = (WildcardType) typeToEvaluate;
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return getActualType(castedType.getUpperBounds()[0], parentType, rawParentClass);
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} else {
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throw new IllegalArgumentException("Type \'" + typeToEvaluate + "\' is not a Class, "
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+ "ParameterizedType, GenericArrayType or TypeVariable. Can't extract type.");
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}
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}
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private static Type extractTypeForHierarchy(Type parentType, TypeVariable<?> typeToEvaluate) {
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Class<?> rawParentType = null;
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if (parentType instanceof Class<?>) {
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rawParentType = (Class<?>) parentType;
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} else if (parentType instanceof ParameterizedType) {
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ParameterizedType parentTypeAsPT = (ParameterizedType) parentType;
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rawParentType = (Class<?>) parentTypeAsPT.getRawType();
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} else {
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return null;
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}
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Type superClass = rawParentType.getGenericSuperclass();
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if (superClass instanceof ParameterizedType
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&& ((ParameterizedType) superClass).getRawType() == typeToEvaluate.getGenericDeclaration()) {
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// Evaluate type on this type
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TypeVariable<?>[] classTypeVariables =
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((Class<?>) ((ParameterizedType) superClass).getRawType()).getTypeParameters();
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int indexOfActualTypeArgument = getIndex(classTypeVariables, typeToEvaluate);
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Type[] actualTypeArguments = null;
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if (parentType instanceof Class<?>) {
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actualTypeArguments = ((ParameterizedType) superClass).getActualTypeArguments();
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} else if (parentType instanceof ParameterizedType) {
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actualTypeArguments = ((ParameterizedType) parentType).getActualTypeArguments();
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} else {
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return null;
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}
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return actualTypeArguments[indexOfActualTypeArgument];
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}
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Type searchedType = null;
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if (superClass != null) {
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searchedType = extractTypeForHierarchy(superClass, typeToEvaluate);
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}
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return searchedType;
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}
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private static Type[] extractRealTypes(
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Type[] actualTypeArguments, Type parentType, Class<?> rawParentClass) {
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Preconditions.checkNotNull(actualTypeArguments);
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Type[] retTypes = new Type[actualTypeArguments.length];
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for (int i = 0; i < actualTypeArguments.length; ++i) {
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retTypes[i] = getActualType(actualTypeArguments[i], parentType, rawParentClass);
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}
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return retTypes;
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}
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private static int getIndex(TypeVariable<?>[] types, TypeVariable<?> type) {
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for (int i = 0; i < types.length; ++i) {
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if (type.equals(types[i])) {
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return i;
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}
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}
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throw new IllegalStateException(
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"How can the type variable not be present in the class declaration!");
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}
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}
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