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Latte is a deep equality comparison and object cloning library
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/*
 * Copyright (C) 2011 Google Inc.
 *
 * 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 xyz.truenight.latte;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collection;
import java.util.EnumSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;

/**
 * Returns a function that can construct an instance of a requested type.
 */
public final class ConstructorConstructor {
    private final Map> instanceCreators;

    public ConstructorConstructor(Map> instanceCreators) {
        this.instanceCreators = instanceCreators;
    }

    public void register(Type type, InstanceCreator typeAdapter) {
        instanceCreators.put(type, typeAdapter);
    }

    public void remove(Type type) {
        instanceCreators.remove(type);
    }

    public  ObjectConstructor get(TypeToken typeToken) {
        final Type type = typeToken.getType();
        final Class rawType = typeToken.getRawType();

        // first try an instance creator

        @SuppressWarnings("unchecked") // types must agree
        final InstanceCreator typeCreator = (InstanceCreator) instanceCreators.get(type);
        if (typeCreator != null) {
            return new ObjectConstructor() {
                public T construct() {
                    return typeCreator.createInstance(type);
                }
            };
        }

        // Next try raw type match for instance creators
        @SuppressWarnings("unchecked") // types must agree
        final InstanceCreator rawTypeCreator =
                (InstanceCreator) instanceCreators.get(rawType);
        if (rawTypeCreator != null) {
            return new ObjectConstructor() {
                public T construct() {
                    return rawTypeCreator.createInstance(type);
                }
            };
        }

        ObjectConstructor defaultConstructor = newDefaultConstructor(rawType);
        if (defaultConstructor != null) {
            return defaultConstructor;
        }

        ObjectConstructor defaultImplementation = newDefaultImplementationConstructor(type, rawType);
        if (defaultImplementation != null) {
            return defaultImplementation;
        }

        // finally try unsafe
        return newUnsafeAllocator(type, rawType);
    }

    private  ObjectConstructor newDefaultConstructor(Class rawType) {
        try {
            final Constructor constructor = rawType.getDeclaredConstructor();
            if (!constructor.isAccessible()) {
                constructor.setAccessible(true);
            }
            return new ObjectConstructor() {
                @SuppressWarnings("unchecked") // T is the same raw type as is requested
                public T construct() {
                    try {
                        Object[] args = null;
                        return (T) constructor.newInstance(args);
                    } catch (InstantiationException e) {
                        // TODO: JsonParseException ?
                        throw new RuntimeException("Failed to invoke " + constructor + " with no args", e);
                    } catch (InvocationTargetException e) {
                        // TODO: don't wrap if cause is unchecked!
                        // TODO: JsonParseException ?
                        throw new RuntimeException("Failed to invoke " + constructor + " with no args",
                                e.getTargetException());
                    } catch (IllegalAccessException e) {
                        throw new AssertionError(e);
                    }
                }
            };
        } catch (NoSuchMethodException e) {
            return null;
        }
    }

    /**
     * Constructors for common interface types like Map and List and their
     * subtypes.
     */
    @SuppressWarnings("unchecked") // use runtime checks to guarantee that 'T' is what it is
    private  ObjectConstructor newDefaultImplementationConstructor(
            final Type type, Class rawType) {
        if (Collection.class.isAssignableFrom(rawType)) {
            if (SortedSet.class.isAssignableFrom(rawType)) {
                return new ObjectConstructor() {
                    public T construct() {
                        return (T) new TreeSet