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PlantUML is a component that allows to quickly write : * sequence diagram, * use case diagram, * class diagram, * activity diagram, * component diagram, * state diagram * object diagram
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/*******************************************************************************
 * Copyright (c) 2016 EclipseSource.
 *
 * Distributed under MIT license
 * See https://github.com/ralfstx/minimal-json/blob/master/LICENSE
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 ******************************************************************************/
package net.sourceforge.plantuml.json;

import java.io.IOException;
import java.io.Reader;

/**
 * This class serves as the entry point to the minimal-json API.
 * 
 * To parse a given JSON input, use the parse()
 * methods like in this example:
 * 
 * 
 *  * JsonObject object = Json.parse(string).asObject();
 * 
 * 
 * To create a JSON data structure to be serialized, use the
 * methods value(), array(), and
 * object(). For example, the following snippet will produce the
 * JSON string {"foo": 23, "bar": true}:
 * 
 * 
 *  * String string = Json.object().add("foo", 23).add("bar", true).toString();
 * 
 * 
 * To create a JSON array from a given Java array, you can use one of the
 * array() methods with varargs parameters:
 * 
 * 
 *  * String[] names = ...
 * JsonArray array = Json.array(names);
 * 
 */
public final class Json {

	private Json() {
		// not meant to be instantiated
	}

	/**
	 * Represents the JSON literal null.
	 */
	public static final JsonValue NULL = new JsonLiteral("null");

	/**
	 * Represents the JSON literal true.
	 */
	public static final JsonValue TRUE = new JsonLiteral("true");

	/**
	 * Represents the JSON literal false.
	 */
	public static final JsonValue FALSE = new JsonLiteral("false");

	/**
	 * Returns a JsonValue instance that represents the given int
	 * value.
	 *
	 * @param value the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JsonValue value(int value) {
		return new JsonNumber(Integer.toString(value, 10));
	}

	/**
	 * Returns a JsonValue instance that represents the given long
	 * value.
	 *
	 * @param value the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JsonValue value(long value) {
		return new JsonNumber(Long.toString(value, 10));
	}

	/**
	 * Returns a JsonValue instance that represents the given float
	 * value.
	 *
	 * @param value the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JsonValue value(float value) {
		if (Float.isInfinite(value) || Float.isNaN(value)) {
			throw new IllegalArgumentException("Infinite and NaN values not permitted in JSON");
		}
		return new JsonNumber(cutOffPointZero(Float.toString(value)));
	}

	/**
	 * Returns a JsonValue instance that represents the given double
	 * value.
	 *
	 * @param value the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JsonValue value(double value) {
		if (Double.isInfinite(value) || Double.isNaN(value)) {
			throw new IllegalArgumentException("Infinite and NaN values not permitted in JSON");
		}
		return new JsonNumber(cutOffPointZero(Double.toString(value)));
	}

	/**
	 * Returns a JsonValue instance that represents the given string.
	 *
	 * @param string the string to get a JSON representation for
	 * @return a JSON value that represents the given string
	 */
	public static JsonValue value(String string) {
		return string == null ? NULL : new JsonString(string);
	}

	/**
	 * Returns a JsonValue instance that represents the given boolean
	 * value.
	 *
	 * @param value the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JsonValue value(boolean value) {
		return value ? TRUE : FALSE;
	}

	/**
	 * Creates a new empty JsonArray. This is equivalent to creating a new JsonArray
	 * using the constructor.
	 *
	 * @return a new empty JSON array
	 */
	public static JsonArray array() {
		return new JsonArray();
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the given
	 * int values.
	 *
	 * @param values the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JsonArray array(int... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JsonArray array = new JsonArray();
		for (int value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the given
	 * long values.
	 *
	 * @param values the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JsonArray array(long... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JsonArray array = new JsonArray();
		for (long value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the given
	 * float values.
	 *
	 * @param values the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JsonArray array(float... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JsonArray array = new JsonArray();
		for (float value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the given
	 * double values.
	 *
	 * @param values the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JsonArray array(double... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JsonArray array = new JsonArray();
		for (double value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the given
	 * boolean values.
	 *
	 * @param values the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JsonArray array(boolean... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JsonArray array = new JsonArray();
		for (boolean value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the given
	 * strings.
	 *
	 * @param strings the strings to be included in the new JSON array
	 * @return a new JSON array that contains the given strings
	 */
	public static JsonArray array(String... strings) {
		if (strings == null) {
			throw new NullPointerException("values is null");
		}
		JsonArray array = new JsonArray();
		for (String value : strings) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new empty JsonObject. This is equivalent to creating a new
	 * JsonObject using the constructor.
	 *
	 * @return a new empty JSON object
	 */
	public static JsonObject object() {
		return new JsonObject();
	}

	/**
	 * Parses the given input string as JSON. The input must contain a valid JSON
	 * value, optionally padded with whitespace.
	 *
	 * @param string the input string, must be valid JSON
	 * @return a value that represents the parsed JSON
	 * @throws ParseException if the input is not valid JSON
	 */
	public static JsonValue parse(String string) {
		if (string == null) {
			throw new NullPointerException("string is null");
		}
		DefaultHandler handler = new DefaultHandler();
		new JsonParser(handler).parse(string);
		return handler.getValue();
	}

	/**
	 * Reads the entire input from the given reader and parses it as JSON. The input
	 * must contain a valid JSON value, optionally padded with whitespace.
	 * 
	 * Characters are read in chunks into an input buffer. Hence, wrapping a reader
	 * in an additional BufferedReader likely won't improve reading
	 * performance.
	 * 
	 *
	 * @param reader the reader to read the JSON value from
	 * @return a value that represents the parsed JSON
	 * @throws IOException    if an I/O error occurs in the reader
	 * @throws ParseException if the input is not valid JSON
	 */
	public static JsonValue parse(Reader reader) throws IOException {
		if (reader == null) {
			throw new NullPointerException("reader is null");
		}
		DefaultHandler handler = new DefaultHandler();
		new JsonParser(handler).parse(reader);
		return handler.getValue();
	}

	private static String cutOffPointZero(String string) {
		if (string.endsWith(".0")) {
			return string.substring(0, string.length() - 2);
		}
		return string;
	}

	public static class DefaultHandler extends JsonHandler {

		protected JsonValue value;

		@Override
		public JsonArray startArray() {
			return new JsonArray();
		}

		@Override
		public JsonObject startObject() {
			return new JsonObject();
		}

		@Override
		public void endNull() {
			value = NULL;
		}

		@Override
		public void endBoolean(boolean bool) {
			value = bool ? TRUE : FALSE;
		}

		@Override
		public void endString(String string) {
			value = new JsonString(string);
		}

		@Override
		public void endNumber(String string) {
			value = new JsonNumber(string);
		}

		@Override
		public void endArray(JsonArray array) {
			value = array;
		}

		@Override
		public void endObject(JsonObject object) {
			value = object;
		}

		@Override
		public void endArrayValue(JsonArray array) {
			array.add(value);
		}

		@Override
		public void endObjectValue(JsonObject object, String name) {
			object.add(name, value);
		}

		public JsonValue getValue() {
			return value;
		}

	}

}