--- /dev/null
+/*
+ * 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 com.google.gson.internal;
+
+import com.google.gson.InstanceCreator;
+import com.google.gson.JsonIOException;
+import com.google.gson.reflect.TypeToken;
+
+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<Type, InstanceCreator<?>> instanceCreators;
+
+ public ConstructorConstructor(Map<Type, InstanceCreator<?>> instanceCreators) {
+ this.instanceCreators = instanceCreators;
+ }
+
+ public <T> ObjectConstructor<T> get(TypeToken<T> typeToken) {
+ final Type type = typeToken.getType();
+ final Class<? super T> rawType = typeToken.getRawType();
+
+ // first try an instance creator
+
+ @SuppressWarnings("unchecked") // types must agree
+ final InstanceCreator<T> typeCreator = (InstanceCreator<T>) instanceCreators.get(type);
+ if (typeCreator != null) {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return typeCreator.createInstance(type);
+ }
+ };
+ }
+
+ // Next try raw type match for instance creators
+ @SuppressWarnings("unchecked") // types must agree
+ final InstanceCreator<T> rawTypeCreator =
+ (InstanceCreator<T>) instanceCreators.get(rawType);
+ if (rawTypeCreator != null) {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return rawTypeCreator.createInstance(type);
+ }
+ };
+ }
+
+ ObjectConstructor<T> defaultConstructor = newDefaultConstructor(rawType);
+ if (defaultConstructor != null) {
+ return defaultConstructor;
+ }
+
+ ObjectConstructor<T> defaultImplementation = newDefaultImplementationConstructor(type, rawType);
+ if (defaultImplementation != null) {
+ return defaultImplementation;
+ }
+
+ // finally try unsafe
+ return newUnsafeAllocator(type, rawType);
+ }
+
+ private <T> ObjectConstructor<T> newDefaultConstructor(Class<? super T> rawType) {
+ try {
+ final Constructor<? super T> constructor = rawType.getDeclaredConstructor();
+ if (!constructor.isAccessible()) {
+ constructor.setAccessible(true);
+ }
+ return new ObjectConstructor<T>() {
+ @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
+ * subytpes.
+ */
+ @SuppressWarnings("unchecked") // use runtime checks to guarantee that 'T' is what it is
+ private <T> ObjectConstructor<T> newDefaultImplementationConstructor(
+ final Type type, Class<? super T> rawType) {
+ if (Collection.class.isAssignableFrom(rawType)) {
+ if (SortedSet.class.isAssignableFrom(rawType)) {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return (T) new TreeSet<Object>();
+ }
+ };
+ } else if (EnumSet.class.isAssignableFrom(rawType)) {
+ return new ObjectConstructor<T>() {
+ @SuppressWarnings("rawtypes")
+ public T construct() {
+ if (type instanceof ParameterizedType) {
+ Type elementType = ((ParameterizedType) type).getActualTypeArguments()[0];
+ if (elementType instanceof Class) {
+ return (T) EnumSet.noneOf((Class)elementType);
+ } else {
+ throw new JsonIOException("Invalid EnumSet type: " + type.toString());
+ }
+ } else {
+ throw new JsonIOException("Invalid EnumSet type: " + type.toString());
+ }
+ }
+ };
+ } else if (Set.class.isAssignableFrom(rawType)) {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return (T) new LinkedHashSet<Object>();
+ }
+ };
+ } else if (Queue.class.isAssignableFrom(rawType)) {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return (T) new LinkedList<Object>();
+ }
+ };
+ } else {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return (T) new ArrayList<Object>();
+ }
+ };
+ }
+ }
+
+ if (Map.class.isAssignableFrom(rawType)) {
+ if (SortedMap.class.isAssignableFrom(rawType)) {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return (T) new TreeMap<Object, Object>();
+ }
+ };
+ } else if (type instanceof ParameterizedType && !(String.class.isAssignableFrom(
+ TypeToken.get(((ParameterizedType) type).getActualTypeArguments()[0]).getRawType()))) {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return (T) new LinkedHashMap<Object, Object>();
+ }
+ };
+ } else {
+ return new ObjectConstructor<T>() {
+ public T construct() {
+ return (T) new LinkedTreeMap<String, Object>();
+ }
+ };
+ }
+ }
+
+ return null;
+ }
+
+ private <T> ObjectConstructor<T> newUnsafeAllocator(
+ final Type type, final Class<? super T> rawType) {
+ return new ObjectConstructor<T>() {
+ private final UnsafeAllocator unsafeAllocator = UnsafeAllocator.create();
+ @SuppressWarnings("unchecked")
+ public T construct() {
+ try {
+ Object newInstance = unsafeAllocator.newInstance(rawType);
+ return (T) newInstance;
+ } catch (Exception e) {
+ throw new RuntimeException(("Unable to invoke no-args constructor for " + type + ". "
+ + "Register an InstanceCreator with Gson for this type may fix this problem."), e);
+ }
+ }
+ };
+ }
+
+ @Override public String toString() {
+ return instanceCreators.toString();
+ }
+}
projects / unical.git / blobdiff