Json.cs

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using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Text;

namespace Spine {
	public static class Json {
		public static object Deserialize (TextReader text) {
			SharpJson.JsonDecoder parser = new SharpJson.JsonDecoder();
			parser.parseNumbersAsFloat = true;
			return parser.Decode(text.ReadToEnd());
		}
	}
}

/**
 * Copyright (c) 2016 Adriano Tinoco d'Oliveira Rezende
 *
 * Based on the JSON parser by Patrick van Bergen
 * http://techblog.procurios.nl/k/news/view/14605/14863/how-do-i-write-my-own-parser-(for-json).html
 *
 * Changes made:
 *
 * - Optimized parser speed (deserialize roughly near 3x faster than original)
 * - Added support to handle lexer/parser error messages with line numbers
 * - Added more fine grained control over type conversions during the parsing
 * - Refactory API (Separate Lexer code from Parser code and the Encoder from Decoder)
 *
 * 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.
 */
namespace SharpJson {
	class Lexer {
		public enum Token {
			None,
			Null,
			True,
			False,
			Colon,
			Comma,
			String,
			Number,
			CurlyOpen,
			CurlyClose,
			SquaredOpen,
			SquaredClose,
		};

		public bool hasError {
			get {
				return !success;
			}
		}

		public int lineNumber {
			get;
			private set;
		}

		public bool parseNumbersAsFloat {
			get;
			set;
		}

		char[] json;
		int index = 0;
		bool success = true;
		char[] stringBuffer = new char[4096];

		public Lexer (string text) {
			Reset();

			json = text.ToCharArray();
			parseNumbersAsFloat = false;
		}

		public void Reset () {
			index = 0;
			lineNumber = 1;
			success = true;
		}

		public string ParseString () {
			int idx = 0;
			StringBuilder builder = null;

			SkipWhiteSpaces();

			// "
			char c = json[index++];

			bool failed = false;
			bool complete = false;

			while (!complete && !failed) {
				if (index == json.Length)
					break;

				c = json[index++];
				if (c == '"') {
					complete = true;
					break;
				} else if (c == '\\') {
					if (index == json.Length)
						break;

					c = json[index++];

					switch (c) {
					case '"':
						stringBuffer[idx++] = '"';
						break;
					case '\\':
						stringBuffer[idx++] = '\\';
						break;
					case '/':
						stringBuffer[idx++] = '/';
						break;
					case 'b':
						stringBuffer[idx++] = '\b';
						break;
					case 'f':
						stringBuffer[idx++] = '\f';
						break;
					case 'n':
						stringBuffer[idx++] = '\n';
						break;
					case 'r':
						stringBuffer[idx++] = '\r';
						break;
					case 't':
						stringBuffer[idx++] = '\t';
						break;
					case 'u':
						int remainingLength = json.Length - index;
						if (remainingLength >= 4) {
							string hex = new string(json, index, 4);

							// XXX: handle UTF
							stringBuffer[idx++] = (char)Convert.ToInt32(hex, 16);

							// skip 4 chars
							index += 4;
						} else {
							failed = true;
						}
						break;
					}
				} else {
					stringBuffer[idx++] = c;
				}

				if (idx >= stringBuffer.Length) {
					if (builder == null)
						builder = new StringBuilder();

					builder.Append(stringBuffer, 0, idx);
					idx = 0;
				}
			}

			if (!complete) {
				success = false;
				return null;
			}

			if (builder != null)
				return builder.ToString();
			else
				return new string(stringBuffer, 0, idx);
		}

		string GetNumberString () {
			SkipWhiteSpaces();

			int lastIndex = GetLastIndexOfNumber(index);
			int charLength = (lastIndex - index) + 1;

			string result = new string(json, index, charLength);

			index = lastIndex + 1;

			return result;
		}

		public float ParseFloatNumber () {
			float number;
			string str = GetNumberString();

			if (!float.TryParse(str, NumberStyles.Float, CultureInfo.InvariantCulture, out number))
				return 0;

			return number;
		}

		public double ParseDoubleNumber () {
			double number;
			string str = GetNumberString();

			if (!double.TryParse(str, NumberStyles.Any, CultureInfo.InvariantCulture, out number))
				return 0;

			return number;
		}

		int GetLastIndexOfNumber (int index) {
			int lastIndex;

			for (lastIndex = index; lastIndex < json.Length; lastIndex++) {
				char ch = json[lastIndex];

				if ((ch < '0' || ch > '9') && ch != '+' && ch != '-'
					&& ch != '.' && ch != 'e' && ch != 'E')
					break;
			}

			return lastIndex - 1;
		}

		void SkipWhiteSpaces () {
			for (; index < json.Length; index++) {
				char ch = json[index];

				if (ch == '\n')
					lineNumber++;

				if (!char.IsWhiteSpace(json[index]))
					break;
			}
		}

		public Token LookAhead () {
			SkipWhiteSpaces();

			int savedIndex = index;
			return NextToken(json, ref savedIndex);
		}

		public Token NextToken () {
			SkipWhiteSpaces();
			return NextToken(json, ref index);
		}

		static Token NextToken (char[] json, ref int index) {
			if (index == json.Length)
				return Token.None;

			char c = json[index++];

			switch (c) {
			case '{':
				return Token.CurlyOpen;
			case '}':
				return Token.CurlyClose;
			case '[':
				return Token.SquaredOpen;
			case ']':
				return Token.SquaredClose;
			case ',':
				return Token.Comma;
			case '"':
				return Token.String;
			case '0':
			case '1':
			case '2':
			case '3':
			case '4':
			case '5':
			case '6':
			case '7':
			case '8':
			case '9':
			case '-':
				return Token.Number;
			case ':':
				return Token.Colon;
			}

			index--;

			int remainingLength = json.Length - index;

			// false
			if (remainingLength >= 5) {
				if (json[index] == 'f' &&
					json[index + 1] == 'a' &&
					json[index + 2] == 'l' &&
					json[index + 3] == 's' &&
					json[index + 4] == 'e') {
					index += 5;
					return Token.False;
				}
			}

			// true
			if (remainingLength >= 4) {
				if (json[index] == 't' &&
					json[index + 1] == 'r' &&
					json[index + 2] == 'u' &&
					json[index + 3] == 'e') {
					index += 4;
					return Token.True;
				}
			}

			// null
			if (remainingLength >= 4) {
				if (json[index] == 'n' &&
					json[index + 1] == 'u' &&
					json[index + 2] == 'l' &&
					json[index + 3] == 'l') {
					index += 4;
					return Token.Null;
				}
			}

			return Token.None;
		}
	}

	public class JsonDecoder {
		public string errorMessage {
			get;
			private set;
		}

		public bool parseNumbersAsFloat {
			get;
			set;
		}

		Lexer lexer;

		public JsonDecoder () {
			errorMessage = null;
			parseNumbersAsFloat = false;
		}

		public object Decode (string text) {
			errorMessage = null;

			lexer = new Lexer(text);
			lexer.parseNumbersAsFloat = parseNumbersAsFloat;

			return ParseValue();
		}

		public static object DecodeText (string text) {
			JsonDecoder builder = new JsonDecoder();
			return builder.Decode(text);
		}

		IDictionary<string, object> ParseObject () {
			Dictionary<string, object> table = new Dictionary<string, object>();

			// {
			lexer.NextToken();

			while (true) {
				Lexer.Token token = lexer.LookAhead();

				switch (token) {
				case Lexer.Token.None:
					TriggerError("Invalid token");
					return null;
				case Lexer.Token.Comma:
					lexer.NextToken();
					break;
				case Lexer.Token.CurlyClose:
					lexer.NextToken();
					return table;
				default:
					// name
					string name = EvalLexer(lexer.ParseString());

					if (errorMessage != null)
						return null;

					// :
					token = lexer.NextToken();

					if (token != Lexer.Token.Colon) {
						TriggerError("Invalid token; expected ':'");
						return null;
					}

					// value
					object value = ParseValue();

					if (errorMessage != null)
						return null;

					table[name] = value;
					break;
				}
			}

			//return null; // Unreachable code
		}

		IList<object> ParseArray () {
			List<object> array = new List<object>();

			// [
			lexer.NextToken();

			while (true) {
				Lexer.Token token = lexer.LookAhead();

				switch (token) {
				case Lexer.Token.None:
					TriggerError("Invalid token");
					return null;
				case Lexer.Token.Comma:
					lexer.NextToken();
					break;
				case Lexer.Token.SquaredClose:
					lexer.NextToken();
					return array;
				default:
					object value = ParseValue();

					if (errorMessage != null)
						return null;

					array.Add(value);
					break;
				}
			}

			//return null; // Unreachable code
		}

		object ParseValue () {
			switch (lexer.LookAhead()) {
			case Lexer.Token.String:
				return EvalLexer(lexer.ParseString());
			case Lexer.Token.Number:
				if (parseNumbersAsFloat)
					return EvalLexer(lexer.ParseFloatNumber());
				else
					return EvalLexer(lexer.ParseDoubleNumber());
			case Lexer.Token.CurlyOpen:
				return ParseObject();
			case Lexer.Token.SquaredOpen:
				return ParseArray();
			case Lexer.Token.True:
				lexer.NextToken();
				return true;
			case Lexer.Token.False:
				lexer.NextToken();
				return false;
			case Lexer.Token.Null:
				lexer.NextToken();
				return null;
			case Lexer.Token.None:
				break;
			}

			TriggerError("Unable to parse value");
			return null;
		}

		void TriggerError (string message) {
			errorMessage = string.Format("Error: '{0}' at line {1}",
										 message, lexer.lineNumber);
		}

		T EvalLexer<T> (T value) {
			if (lexer.hasError)
				TriggerError("Lexical error ocurred");

			return value;
		}
	}
}