187 lines
5.3 KiB
Java
187 lines
5.3 KiB
Java
/*
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* Copyright (C) 2011 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.google.gson.internal.bind;
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import com.google.gson.Gson;
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import com.google.gson.ToNumberPolicy;
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import com.google.gson.ToNumberStrategy;
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import com.google.gson.TypeAdapter;
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import com.google.gson.TypeAdapterFactory;
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import com.google.gson.internal.LinkedTreeMap;
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import com.google.gson.reflect.TypeToken;
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import com.google.gson.stream.JsonReader;
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import com.google.gson.stream.JsonToken;
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import com.google.gson.stream.JsonWriter;
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import java.io.IOException;
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import java.util.ArrayDeque;
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import java.util.ArrayList;
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import java.util.Deque;
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import java.util.List;
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import java.util.Map;
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/**
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* Adapts types whose static type is only 'Object'. Uses getClass() on serialization and a
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* primitive/Map/List on deserialization.
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*/
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public final class ObjectTypeAdapter extends TypeAdapter<Object> {
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/** Gson default factory using {@link ToNumberPolicy#DOUBLE}. */
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private static final TypeAdapterFactory DOUBLE_FACTORY = newFactory(ToNumberPolicy.DOUBLE);
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private final Gson gson;
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private final ToNumberStrategy toNumberStrategy;
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private ObjectTypeAdapter(Gson gson, ToNumberStrategy toNumberStrategy) {
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this.gson = gson;
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this.toNumberStrategy = toNumberStrategy;
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}
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private static TypeAdapterFactory newFactory(final ToNumberStrategy toNumberStrategy) {
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return new TypeAdapterFactory() {
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@SuppressWarnings("unchecked")
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@Override
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public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
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if (type.getRawType() == Object.class) {
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return (TypeAdapter<T>) new ObjectTypeAdapter(gson, toNumberStrategy);
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}
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return null;
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}
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};
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}
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public static TypeAdapterFactory getFactory(ToNumberStrategy toNumberStrategy) {
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if (toNumberStrategy == ToNumberPolicy.DOUBLE) {
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return DOUBLE_FACTORY;
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} else {
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return newFactory(toNumberStrategy);
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}
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}
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/**
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* Tries to begin reading a JSON array or JSON object, returning {@code null} if the next element
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* is neither of those.
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*/
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private Object tryBeginNesting(JsonReader in, JsonToken peeked) throws IOException {
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switch (peeked) {
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case BEGIN_ARRAY:
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in.beginArray();
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return new ArrayList<>();
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case BEGIN_OBJECT:
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in.beginObject();
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return new LinkedTreeMap<>();
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default:
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return null;
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}
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}
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/** Reads an {@code Object} which cannot have any nested elements */
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private Object readTerminal(JsonReader in, JsonToken peeked) throws IOException {
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switch (peeked) {
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case STRING:
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return in.nextString();
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case NUMBER:
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return toNumberStrategy.readNumber(in);
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case BOOLEAN:
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return in.nextBoolean();
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case NULL:
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in.nextNull();
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return null;
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default:
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// When read(JsonReader) is called with JsonReader in invalid state
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throw new IllegalStateException("Unexpected token: " + peeked);
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}
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}
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@Override
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public Object read(JsonReader in) throws IOException {
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// Either List or Map
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Object current;
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JsonToken peeked = in.peek();
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current = tryBeginNesting(in, peeked);
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if (current == null) {
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return readTerminal(in, peeked);
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}
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Deque<Object> stack = new ArrayDeque<>();
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while (true) {
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while (in.hasNext()) {
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String name = null;
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// Name is only used for JSON object members
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if (current instanceof Map) {
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name = in.nextName();
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}
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peeked = in.peek();
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Object value = tryBeginNesting(in, peeked);
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boolean isNesting = value != null;
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if (value == null) {
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value = readTerminal(in, peeked);
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}
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if (current instanceof List) {
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@SuppressWarnings("unchecked")
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List<Object> list = (List<Object>) current;
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list.add(value);
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} else {
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@SuppressWarnings("unchecked")
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Map<String, Object> map = (Map<String, Object>) current;
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map.put(name, value);
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}
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if (isNesting) {
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stack.addLast(current);
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current = value;
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}
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}
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// End current element
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if (current instanceof List) {
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in.endArray();
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} else {
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in.endObject();
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}
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if (stack.isEmpty()) {
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return current;
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} else {
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// Continue with enclosing element
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current = stack.removeLast();
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}
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}
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}
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@Override
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public void write(JsonWriter out, Object value) throws IOException {
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if (value == null) {
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out.nullValue();
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return;
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}
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@SuppressWarnings("unchecked")
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TypeAdapter<Object> typeAdapter = (TypeAdapter<Object>) gson.getAdapter(value.getClass());
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if (typeAdapter instanceof ObjectTypeAdapter) {
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out.beginObject();
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out.endObject();
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return;
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}
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typeAdapter.write(out, value);
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}
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}
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