JsonObject.java

/*
 * Copyright 2009 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.json.serialization;

import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * JSON object.
 */
public class JsonObject implements JsonValue, Iterable<Pair<String, JsonValue>> {
	private static class Iter implements Iterator<Pair<String, JsonValue>> {
		private final Iterator<Map.Entry<String, JsonValue>> iter;

		Iter(Iterator<Map.Entry<String, JsonValue>> iter) {
			this.iter = iter;
		}

		public boolean hasNext() {
			return iter.hasNext();
		}

		public Pair<String, JsonValue> next() {
			final Map.Entry<String, JsonValue> entry = iter.next();
			return new Pair<String, JsonValue>(entry.getKey(), entry.getValue());
		}

		public void remove() {
			iter.remove();
		}
	}

	public static JsonObject create() {
		return new JsonObject();
	}

	public static JsonObject parse(Reader reader) throws JsonException, IOException {
		return JsonObject.parse(new Tokenizer(reader));
	}

	static JsonObject parse(Tokenizer tokenizer) throws IOException, JsonException {
		final JsonObject object = new JsonObject();
		int c = tokenizer.next();
		if (c != '{') {
			throw new JsonException("Payload does not begin with {");
		}

		while (true) {
			c = tokenizer.nextNonWhitespace();
			switch (c) {
			case '}':
				// We're done.
				return object;
			case '"':
				tokenizer.back(c);
				// Ready to start a key.
				final String key = tokenizer.nextString();
				if (tokenizer.nextNonWhitespace() != ':') {
					throw new JsonException("Invalid object: expecting \":\"");
				}
				// TODO(knorton): Make sure this key is not already set.
				object.put(key, tokenizer.nextValue());
				switch (tokenizer.nextNonWhitespace()) {
				case ',':
					break;
				case '}':
					return object;
				default:
					throw new JsonException("Invalid object: expecting } or ,");
				}
				break;
			case ',':
				break;
			default:
				throw new JsonException("Invalid object: ");
			}
		}
	}

	private final Map<String, JsonValue> properties = new HashMap<String, JsonValue>();

	public JsonObject() {
	}

	public JsonArray asArray() {
		return null;
	}

	public JsonBoolean asBoolean() {
		return null;
	}

	public JsonNumber asNumber() {
		return null;
	}

	public JsonObject asObject() {
		return this;
	}

	public JsonString asString() {
		return null;
	}

	public JsonValue get(String key) {
		final JsonValue value = properties.get(key);
		return (value == null) ? JsonValue.NULL : value;
	}

	public boolean isArray() {
		return false;
	}

	public boolean isBoolean() {
		return false;
	}

	public boolean isEmpty() {
		return properties.isEmpty();
	}

	public boolean isNumber() {
		return false;
	}

	public boolean isObject() {
		return true;
	}

	public boolean isString() {
		return false;
	}

	public Iterator<Pair<String, JsonValue>> iterator() {
		return new Iter(properties.entrySet().iterator());
	}

	public void put(String key, boolean val) {
		put(key, JsonBoolean.create(val));
	}

	public void put(String key, double val) {
		put(key, JsonNumber.create(val));
	}

	public void put(String key, JsonValue val) {
		properties.put(key, val);
	}

	public void put(String key, long val) {
		put(key, JsonNumber.create(val));
	}

	public void put(String key, String val) {
		put(key, JsonString.create(val));
	}

	public void write(Writer writer) throws IOException {
		boolean first = true;
		writer.write('{');
		for (Map.Entry<String, JsonValue> e : properties.entrySet()) {
			if (!first) {
				writer.append(',');
			} else {
				first = false;
			}
			JsonString.write(e.getKey(), writer);
			writer.append(':');
			e.getValue().write(writer);
		}
		writer.write('}');
	}
}