/*
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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 cn.emay.sdk.util.json.gson.reflect;
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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.util.HashMap;
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import java.util.Map;
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import cn.emay.sdk.util.json.gson.internal.$Gson$Preconditions;
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import cn.emay.sdk.util.json.gson.internal.$Gson$Types;
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/**
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* Represents a generic type {@code T}. Java doesn't yet provide a way to
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* represent generic types, so this class does. Forces clients to create a
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* subclass of this class which enables retrieval the type information even at
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* runtime.
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*
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* <p>
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* For example, to create a type literal for {@code List<String>}, you can
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* create an empty anonymous inner class:
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*
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* <p>
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* {@code TypeToken<List<String>> list = new TypeToken<List<String>>() {};}
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*
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* <p>
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* This syntax cannot be used to create type literals that have wildcard
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* parameters, such as {@code Class<?>} or {@code List<? extends CharSequence>}.
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*
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* @author Bob Lee
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* @author Sven Mawson
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* @author Jesse Wilson
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*/
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public class TypeToken<T> {
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final Class<? super T> rawType;
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final Type type;
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final int hashCode;
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/**
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* Constructs a new type literal. Derives represented class from type parameter.
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*
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* <p>
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* Clients create an empty anonymous subclass. Doing so embeds the type
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* parameter in the anonymous class's type hierarchy so we can reconstitute it
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* at runtime despite erasure.
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*/
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@SuppressWarnings("unchecked")
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protected TypeToken() {
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this.type = getSuperclassTypeParameter(getClass());
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this.rawType = (Class<? super T>) $Gson$Types.getRawType(type);
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this.hashCode = type.hashCode();
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}
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/**
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* Unsafe. Constructs a type literal manually.
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*/
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@SuppressWarnings("unchecked")
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TypeToken(Type type) {
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this.type = $Gson$Types.canonicalize($Gson$Preconditions.checkNotNull(type));
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this.rawType = (Class<? super T>) $Gson$Types.getRawType(this.type);
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this.hashCode = this.type.hashCode();
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}
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/**
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* Returns the type from super class's type parameter in
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* {@link $Gson$Types#canonicalize canonical form}.
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*/
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static Type getSuperclassTypeParameter(Class<?> subclass) {
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Type superclass = subclass.getGenericSuperclass();
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if (superclass instanceof Class) {
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throw new RuntimeException("Missing type parameter.");
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}
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ParameterizedType parameterized = (ParameterizedType) superclass;
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return $Gson$Types.canonicalize(parameterized.getActualTypeArguments()[0]);
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}
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/**
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* Returns the raw (non-generic) type for this type.
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*/
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public final Class<? super T> getRawType() {
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return rawType;
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}
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/**
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* Gets underlying {@code Type} instance.
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*/
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public final Type getType() {
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return type;
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}
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/**
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* Check if this type is assignable from the given class object.
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*
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* @deprecated this implementation may be inconsistent with javac for types with
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* wildcards.
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*/
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@Deprecated
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public boolean isAssignableFrom(Class<?> cls) {
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return isAssignableFrom((Type) cls);
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}
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/**
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* Check if this type is assignable from the given Type.
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*
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* @deprecated this implementation may be inconsistent with javac for types with
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* wildcards.
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*/
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@Deprecated
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public boolean isAssignableFrom(Type from) {
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if (from == null) {
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return false;
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}
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if (type.equals(from)) {
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return true;
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}
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if (type instanceof Class<?>) {
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return rawType.isAssignableFrom($Gson$Types.getRawType(from));
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} else if (type instanceof ParameterizedType) {
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return isAssignableFrom(from, (ParameterizedType) type, new HashMap<String, Type>());
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} else if (type instanceof GenericArrayType) {
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return rawType.isAssignableFrom($Gson$Types.getRawType(from)) && isAssignableFrom(from, (GenericArrayType) type);
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} else {
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throw buildUnexpectedTypeError(type, Class.class, ParameterizedType.class, GenericArrayType.class);
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}
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}
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/**
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* Check if this type is assignable from the given type token.
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*
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* @deprecated this implementation may be inconsistent with javac for types with
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* wildcards.
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*/
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@Deprecated
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public boolean isAssignableFrom(TypeToken<?> token) {
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return isAssignableFrom(token.getType());
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}
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/**
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* Private helper function that performs some assignability checks for the
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* provided GenericArrayType.
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*/
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private static boolean isAssignableFrom(Type from, GenericArrayType to) {
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Type toGenericComponentType = to.getGenericComponentType();
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if (toGenericComponentType instanceof ParameterizedType) {
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Type t = from;
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if (from instanceof GenericArrayType) {
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t = ((GenericArrayType) from).getGenericComponentType();
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} else if (from instanceof Class<?>) {
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Class<?> classType = (Class<?>) from;
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while (classType.isArray()) {
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classType = classType.getComponentType();
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}
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t = classType;
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}
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return isAssignableFrom(t, (ParameterizedType) toGenericComponentType, new HashMap<String, Type>());
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}
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// No generic defined on "to"; therefore, return true and let other
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// checks determine assignability
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return true;
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}
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/**
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* Private recursive helper function to actually do the type-safe checking of
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* assignability.
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*/
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private static boolean isAssignableFrom(Type from, ParameterizedType to, Map<String, Type> typeVarMap) {
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if (from == null) {
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return false;
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}
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if (to.equals(from)) {
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return true;
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}
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// First figure out the class and any type information.
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Class<?> clazz = $Gson$Types.getRawType(from);
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ParameterizedType ptype = null;
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if (from instanceof ParameterizedType) {
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ptype = (ParameterizedType) from;
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}
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// Load up parameterized variable info if it was parameterized.
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if (ptype != null) {
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Type[] tArgs = ptype.getActualTypeArguments();
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TypeVariable<?>[] tParams = clazz.getTypeParameters();
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for (int i = 0; i < tArgs.length; i++) {
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Type arg = tArgs[i];
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TypeVariable<?> var = tParams[i];
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while (arg instanceof TypeVariable<?>) {
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TypeVariable<?> v = (TypeVariable<?>) arg;
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arg = typeVarMap.get(v.getName());
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}
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typeVarMap.put(var.getName(), arg);
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}
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// check if they are equivalent under our current mapping.
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if (typeEquals(ptype, to, typeVarMap)) {
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return true;
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}
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}
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for (Type itype : clazz.getGenericInterfaces()) {
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if (isAssignableFrom(itype, to, new HashMap<String, Type>(typeVarMap))) {
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return true;
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}
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}
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// Interfaces didn't work, try the superclass.
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Type sType = clazz.getGenericSuperclass();
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return isAssignableFrom(sType, to, new HashMap<String, Type>(typeVarMap));
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}
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/**
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* Checks if two parameterized types are exactly equal, under the variable
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* replacement described in the typeVarMap.
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*/
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private static boolean typeEquals(ParameterizedType from, ParameterizedType to, Map<String, Type> typeVarMap) {
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if (from.getRawType().equals(to.getRawType())) {
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Type[] fromArgs = from.getActualTypeArguments();
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Type[] toArgs = to.getActualTypeArguments();
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for (int i = 0; i < fromArgs.length; i++) {
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if (!matches(fromArgs[i], toArgs[i], typeVarMap)) {
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return false;
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}
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}
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return true;
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}
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return false;
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}
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private static AssertionError buildUnexpectedTypeError(Type token, Class<?>... expected) {
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// Build exception message
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StringBuilder exceptionMessage = new StringBuilder("Unexpected type. Expected one of: ");
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for (Class<?> clazz : expected) {
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exceptionMessage.append(clazz.getName()).append(", ");
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}
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exceptionMessage.append("but got: ").append(token.getClass().getName()).append(", for type token: ").append(token.toString()).append('.');
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return new AssertionError(exceptionMessage.toString());
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}
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/**
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* Checks if two types are the same or are equivalent under a variable mapping
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* given in the type map that was provided.
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*/
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private static boolean matches(Type from, Type to, Map<String, Type> typeMap) {
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return to.equals(from) || (from instanceof TypeVariable && to.equals(typeMap.get(((TypeVariable<?>) from).getName())));
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}
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@Override
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public final int hashCode() {
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return this.hashCode;
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}
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@Override
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public final boolean equals(Object o) {
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return o instanceof TypeToken<?> && $Gson$Types.equals(type, ((TypeToken<?>) o).type);
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}
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@Override
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public final String toString() {
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return $Gson$Types.typeToString(type);
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}
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/**
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* Gets type literal for the given {@code Type} instance.
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*/
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public static TypeToken<?> get(Type type) {
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return new TypeToken<Object>(type);
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}
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/**
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* Gets type literal for the given {@code Class} instance.
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*/
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public static <T> TypeToken<T> get(Class<T> type) {
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return new TypeToken<T>(type);
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}
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}
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