#region BuildTools License
/*---------------------------------------------------------------------------------*\

	BuildTools distributed under the terms of an MIT-style license:

	The MIT License

	Copyright (c) 2006-2008 Stephen M. McKamey

	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.

\*---------------------------------------------------------------------------------*/
#endregion BuildTools License

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

namespace JsonFx.Json
{
	/// <summary>
	/// Reader for consuming JSON data
	/// </summary>
	public class JsonReader
	{
		#region Constants

		internal const string LiteralFalse = "false";
		internal const string LiteralTrue = "true";
		internal const string LiteralNull = "null";
		internal const string LiteralNotANumber = "NaN";
		internal const string LiteralPositiveInfinity = "Infinity";
		internal const string LiteralNegativeInfinity = "-Infinity";

		internal const char OperatorNegate = '-';
		internal const char OperatorUnaryPlus = '+';
		internal const char OperatorArrayStart = '[';
		internal const char OperatorArrayEnd = ']';
		internal const char OperatorObjectStart = '{';
		internal const char OperatorObjectEnd = '}';
		internal const char OperatorStringDelim = '"';
		internal const char OperatorStringDelimAlt = '\'';
		internal const char OperatorValueDelim = ',';
		internal const char OperatorNameDelim = ':';
		internal const char OperatorCharEscape = '\\';

		private const string CommentStart = "/*";
		private const string CommentEnd = "*/";
		private const string CommentLine = "//";
		private const string LineEndings = "\r\n";

		private const string ErrorUnrecognizedToken = "Illegal JSON sequence.";
		private const string ErrorUnterminatedComment = "Unterminated comment block.";
		private const string ErrorUnterminatedObject = "Unterminated JSON object.";
		private const string ErrorUnterminatedArray = "Unterminated JSON array.";
		private const string ErrorUnterminatedString = "Unterminated JSON string.";
		private const string ErrorIllegalNumber = "Illegal JSON number.";
		private const string ErrorExpectedString = "Expected JSON string.";
		private const string ErrorExpectedObject = "Expected JSON object.";
		private const string ErrorExpectedArray = "Expected JSON array.";
		private const string ErrorExpectedPropertyName = "Expected JSON object property name.";
		private const string ErrorExpectedPropertyNameDelim = "Expected JSON object property name delimiter.";
		private const string ErrorNullValueType = "{0} does not accept null as a value";
		private const string ErrorDefaultCtor = "Only objects with default constructors can be deserialized.";
		private const string ErrorGenericIDictionary = "Types which implement Generic IDictionary<TKey, TValue> also need to implement IDictionary to be deserialized.";

		#endregion Constants
		
		#region Fields

		private Dictionary<Type, Dictionary<string, MemberInfo>> MemberMapCache = null;
		private readonly string Source = null;
		private readonly int SourceLength = 0;
		private int index = 0;
		private bool allowNullValueTypes = false;
		private string typeHintName = null;

		#endregion Fields

		#region Init

		/// <summary>
		/// Ctor.
		/// </summary>
		/// <param name="input">TextReader containing source</param>
		public JsonReader(TextReader input)
		{
			this.Source = input.ReadToEnd();
			this.SourceLength = this.Source.Length;
		}

		/// <summary>
		/// Ctor.
		/// </summary>
		/// <param name="input">Stream containing source</param>
		public JsonReader(Stream input)
		{
			using (StreamReader reader = new StreamReader(input, true))
			{
				this.Source = reader.ReadToEnd();
			}
			this.SourceLength = this.Source.Length;
		}

		/// <summary>
		/// Ctor.
		/// </summary>
		/// <param name="input">string containing source</param>
		public JsonReader(string input)
		{
			this.Source = input;
			this.SourceLength = this.Source.Length;
		}

		/// <summary>
		/// Ctor.
		/// </summary>
		/// <param name="input">StringBuilder containing source</param>
		public JsonReader(StringBuilder input)
		{
			this.Source = input.ToString();
			this.SourceLength = this.Source.Length;
		}

		#endregion Init

		#region Properties

		/// <summary>
		/// Gets and sets if ValueTypes can accept values of null
		/// </summary>
		/// <remarks>
		/// Only affects deserialization: if a ValueType is assigned the
		/// value of null, it will receive the value default(TheType).
		/// Setting this to false, throws an exception if null is
		/// specified for a ValueType member.
		/// </remarks>
		public bool AllowNullValueTypes
		{
			get { return this.allowNullValueTypes; }
			set { this.allowNullValueTypes = value; }
		}

		/// <summary>
		/// Gets and sets the property name used for type hinting.
		/// </summary>
		public string TypeHintName
		{
			get { return this.typeHintName; }
			set { this.typeHintName = value; }
		}

		#endregion Properties

		#region Parsing Methods

		/// <summary>
		/// Convert from JSON string to Object graph
		/// </summary>
		/// <returns></returns>
		public object Deserialize()
		{
			return this.Deserialize(null);
		}

		/// <summary>
		/// Convert from JSON string to Object graph of specific Type
		/// </summary>
		/// <param name="type"></param>
		/// <returns></returns>
		public object Deserialize(Type type)
		{
			// should this run through a preliminary test here?
			return this.Read(type, false);
		}

		private object Read(Type expectedType, bool typeIsHint)
		{
			if (expectedType == typeof(Object))
			{
				expectedType = null;
			}

			JsonToken token = this.Tokenize();

			switch (token)
			{
				case JsonToken.ObjectStart:
				{
					return this.ReadObject(typeIsHint ? null : expectedType);
				}
				case JsonToken.ArrayStart:
				{
					return this.ReadArray(typeIsHint ? null : expectedType);
				}
				case JsonToken.String:
				{
					return this.ReadString(typeIsHint ? null : expectedType);
				}
				case JsonToken.Number:
				{
					return this.ReadNumber(typeIsHint ? null : expectedType);
				}
				case JsonToken.False:
				{
					this.index += JsonReader.LiteralFalse.Length;
					return false;
				}
				case JsonToken.True:
				{
					this.index += JsonReader.LiteralTrue.Length;
					return true;
				}
				case JsonToken.Null:
				{
					this.index += JsonReader.LiteralNull.Length;
					return null;
				}
				case JsonToken.NaN:
				{
					this.index += JsonReader.LiteralNotANumber.Length;
					return Double.NaN;
				}
				case JsonToken.PositiveInfinity:
				{
					this.index += JsonReader.LiteralPositiveInfinity.Length;
					return Double.PositiveInfinity;
				}
				case JsonToken.NegativeInfinity:
				{
					this.index += JsonReader.LiteralNegativeInfinity.Length;
					return Double.NegativeInfinity;
				}
				case JsonToken.End:
				default:
				{
					return null;
				}
			}
		}

		private object ReadObject(Type objectType)
		{
			if (this.Source[this.index] != JsonReader.OperatorObjectStart)
			{
				throw new JsonDeserializationException(JsonReader.ErrorExpectedObject, this.index);
			}

			Dictionary<string, MemberInfo> memberMap = null;
			Object result;
			if (objectType != null)
			{
				result = this.InstantiateObject(objectType, ref memberMap);
			}
			else
			{
				result = new Dictionary<String, Object>();
			}

			JsonToken token;
			do
			{
				Type memberType;
				MemberInfo memberInfo;

				// consume opening brace or delim
				this.index++;
				if (this.index >= this.SourceLength)
				{
					throw new JsonDeserializationException(JsonReader.ErrorUnterminatedObject, this.index);
				}

				// get next token
				token = this.Tokenize();
				if (token == JsonToken.ObjectEnd)
				{
					break;
				}

				if (token != JsonToken.String)
				{
					throw new JsonDeserializationException(JsonReader.ErrorExpectedPropertyName, this.index);
				}

				// parse object member value
				string memberName = (String)this.ReadString(null);

				// determine the type of the property/field
				JsonReader.GetMemberInfo(memberMap, memberName, out memberType, out memberInfo);

				// get next token
				token = this.Tokenize();
				if (token != JsonToken.NameDelim)
				{
					throw new JsonDeserializationException(JsonReader.ErrorExpectedPropertyNameDelim, this.index);
				}

				// consume delim
				index++;
				if (this.index >= this.SourceLength)
				{
					throw new JsonDeserializationException(JsonReader.ErrorUnterminatedObject, this.index);
				}

				// parse object member value
				object value = this.Read(memberType, false);

				if (result is IDictionary)
				{
					if (objectType == null &&
						!String.IsNullOrEmpty(this.typeHintName) &&
						this.typeHintName.Equals(memberName, StringComparison.InvariantCulture))
					{
						result = this.ProcessTypeHint(ref objectType, ref memberMap, (IDictionary)result, value as string);
					}
					else
					{
						((IDictionary)result)[memberName] = value;
					}
				}
				else if (objectType.GetInterface(JsonWriter.TypeGenericIDictionary) != null)
				{
					throw new JsonDeserializationException(JsonReader.ErrorGenericIDictionary, this.index);
				}
				else
				{
					this.SetMemberValue(result, memberType, memberInfo, value);
				}

				// get next token
				token = this.Tokenize();
			} while (token == JsonToken.ValueDelim);

			if (token != JsonToken.ObjectEnd)
			{
				throw new JsonDeserializationException(JsonReader.ErrorUnterminatedObject, this.index);
			}

			// consume closing brace
			this.index++;

			return result;
		}

		private Array ReadArray(Type arrayType)
		{
			if (this.Source[this.index] != JsonReader.OperatorArrayStart)
			{
				throw new JsonDeserializationException(JsonReader.ErrorExpectedArray, this.index);
			}

			bool isArrayTypeSet = (arrayType != null);
			bool isArrayTypeAHint = !isArrayTypeSet;

			if (isArrayTypeSet)
			{
				if (arrayType.HasElementType)
				{
					arrayType = arrayType.GetElementType();
				}
				else if (arrayType.IsGenericType)
				{
					Type[] generics = arrayType.GetGenericArguments();
					if (generics.Length != 1)
					{
						// could use the first or last, but this more correct
						arrayType = null;
					}
					else
					{
						arrayType = generics[0];
					}
				}
				else
				{
					arrayType = null;
				}
			}

			ArrayList jsArray = new ArrayList();

			JsonToken token;
			do
			{
				// consume opening bracket or delim
				this.index++;
				if (this.index >= this.SourceLength)
				{
					throw new JsonDeserializationException(JsonReader.ErrorUnterminatedArray, this.index);
				}

				// get next token
				token = this.Tokenize();
				if (token == JsonToken.ArrayEnd)
				{
					break;
				}

				// parse array item
				object value = this.Read(arrayType, isArrayTypeAHint);
				jsArray.Add(value);

				// establish if array is of common type
				if (value == null)
				{
					if (arrayType != null && arrayType.IsValueType)
					{
						// use plain object to hold null
						arrayType = null;
					}
					isArrayTypeSet = true;
				}
				else if (arrayType != null && !arrayType.IsAssignableFrom(value.GetType()))
				{
					// use plain object to hold value
					arrayType = null;
					isArrayTypeSet = true;
				}
				else if (!isArrayTypeSet)
				{
					// try out special type
					// if hasn't been set before
					arrayType = value.GetType();
					isArrayTypeSet = true;
				}

				// get next token
				token = this.Tokenize();
			} while (token == JsonToken.ValueDelim);

			if (token != JsonToken.ArrayEnd)
			{
				throw new JsonDeserializationException(JsonReader.ErrorUnterminatedArray, this.index);
			}

			// consume closing bracket
			this.index++;

			// check to see if all the same type and convert to that
			if (arrayType != null && arrayType != typeof(object))
			{
				return jsArray.ToArray(arrayType);
			}

			return jsArray.ToArray();
		}

		private object ReadString(Type expectedType)
		{
			if (this.Source[this.index] != JsonReader.OperatorStringDelim &&
				this.Source[this.index] != JsonReader.OperatorStringDelimAlt)
			{
				throw new JsonDeserializationException(JsonReader.ErrorExpectedString, this.index);
			}

			char startStringDelim = this.Source[this.index];

			// consume opening quote
			this.index++;
			if (this.index >= this.SourceLength)
			{
				throw new JsonDeserializationException(JsonReader.ErrorUnterminatedString, this.index);
			}

			int start = this.index;
			StringBuilder builder = new StringBuilder();

			while (this.Source[this.index] != startStringDelim)
			{
				if (this.Source[this.index] == JsonReader.OperatorCharEscape)
				{
					// copy chunk before decoding
					builder.Append(this.Source, start, this.index - start);

					// consume escape char
					this.index++;
					if (this.index >= this.SourceLength)
					{
						throw new JsonDeserializationException(JsonReader.ErrorUnterminatedString, this.index);
					}

					// decode
					switch (this.Source[this.index])
					{
						case '0':
						{
							// don't allow NULL char '\0'
							// causes CStrings to terminate
							break;
						}
						case 'b':
						{
							// backspace
							builder.Append('\b');
							break;
						}
						case 'f':
						{
							// formfeed
							builder.Append('\f');
							break;
						}
						case 'n':
						{
							// newline
							builder.Append('\n');
							break;
						}
						case 'r':
						{
							// carriage return
							builder.Append('\r');
							break;
						}
						case 't':
						{
							// tab
							builder.Append('\t');
							break;
						}
						case 'u':
						{
							// Unicode escape sequence
							// e.g. Copyright: "\u00A9"

							// unicode ordinal
							int utf16;
							if (this.index+4 < this.SourceLength &&
								Int32.TryParse(
									this.Source.Substring(this.index+1, 4),
									NumberStyles.AllowHexSpecifier,
									NumberFormatInfo.InvariantInfo,
									out utf16))
							{
								builder.Append(Char.ConvertFromUtf32(utf16));
								this.index += 4;
							}
							else
							{
								// using FireFox style recovery, if not a valid hex
								// escape sequence then treat as single escaped 'u'
								// followed by rest of string
								builder.Append(this.Source[this.index]);
							}
							break;
						}
						default:
						{
							builder.Append(Source[this.index]);
							break;
						}
					}

					this.index++;
					if (this.index >= this.SourceLength)
					{
						throw new JsonDeserializationException(JsonReader.ErrorUnterminatedString, this.index);
					}

					start = this.index;
				}
				else
				{
					// next char
					index++;
					if (this.index >= this.SourceLength)
					{
						throw new JsonDeserializationException(JsonReader.ErrorUnterminatedString, this.index);
					}
				}
			}

			// copy rest of string
			builder.Append(this.Source, start, this.index-start);

			// consume closing quote
			this.index++;

			if (expectedType != null && expectedType != typeof(String))
			{
				return JsonReader.CoerceType(expectedType, builder.ToString(), this.index, this.AllowNullValueTypes);
			}

			return builder.ToString();
		}

		private object ReadNumber(Type expectedType)
		{
			bool hasDecimal = false;
			bool hasExponent = false;
			int start = this.index;
			int precision = 0;
			int exponent = 0;

			// optional minus part
			if (this.Source[this.index] == JsonReader.OperatorNegate)
			{
				// consume sign
				this.index++;
				if (this.index >= this.SourceLength || !Char.IsDigit(this.Source[this.index]))
					throw new JsonDeserializationException(JsonReader.ErrorIllegalNumber, this.index);
			}

			// integer part
			while ((this.index < this.SourceLength) && Char.IsDigit(this.Source[this.index]))
			{
				// consume digit
				this.index++;
			}

			// optional decimal part
			if ((this.index < this.SourceLength) && (this.Source[this.index] == '.'))
			{
				hasDecimal = true;

				// consume decimal
				this.index++;
				if (this.index >= this.SourceLength || !Char.IsDigit(this.Source[this.index]))
				{
					throw new JsonDeserializationException(JsonReader.ErrorIllegalNumber, this.index);
				}

				// fraction part
				while (this.index < this.SourceLength && Char.IsDigit(this.Source[this.index]))
				{
					// consume digit
					this.index++;
				}
			}

			// note the number of significant digits
			precision = this.index-start - (hasDecimal ? 1 : 0);

			// optional exponent part
			if (this.index < this.SourceLength && (this.Source[this.index] == 'e' || this.Source[this.index] == 'E'))
			{
				hasExponent = true;

				// consume 'e'
				this.index++;
				if (this.index >= this.SourceLength)
				{
					throw new JsonDeserializationException(JsonReader.ErrorIllegalNumber, this.index);
				}

				int expStart = this.index;

				// optional minus/plus part
				if (this.Source[this.index] == JsonReader.OperatorNegate || this.Source[this.index] == JsonReader.OperatorUnaryPlus)
				{
					// consume sign
					this.index++;
					if (this.index >= this.SourceLength || !Char.IsDigit(this.Source[this.index]))
					{
						throw new JsonDeserializationException(JsonReader.ErrorIllegalNumber, this.index);
					}
				}
				else
				{
					if (!Char.IsDigit(this.Source[this.index]))
					{
						throw new JsonDeserializationException(JsonReader.ErrorIllegalNumber, this.index);
					}
				}

				// exp part
				while (this.index < this.SourceLength && Char.IsDigit(this.Source[this.index]))
				{
					// consume digit
					this.index++;
				}

				Int32.TryParse(this.Source.Substring(expStart, this.index-expStart), NumberStyles.Integer,
					NumberFormatInfo.InvariantInfo, out exponent);
			}

			// at this point, we have the full number string and know its characteristics
			string numberString = this.Source.Substring(start, this.index - start);

			if (!hasDecimal && !hasExponent && precision < 19)
			{
				// is Integer value

				// parse as most flexible
				decimal number = Decimal.Parse(
					numberString,
					NumberStyles.Integer,
					NumberFormatInfo.InvariantInfo);

				if (expectedType != null)
				{
					return JsonReader.CoerceType(expectedType, number, this.index, this.AllowNullValueTypes);
				}

				if (number >= Int32.MinValue && number <= Int32.MaxValue)
				{
					// use most common
					return (int)number;
				}
				if (number >= Int64.MinValue && number <= Int64.MaxValue)
				{
					// use more flexible
					return (long)number;
				}

				// use most flexible
				return number;
			}
			else
			{
				// is Floating Point value

				if (expectedType == typeof(Decimal))
				{
					// special case since Double does not convert to Decimal
					return Decimal.Parse(
						numberString,
						NumberStyles.Float,
						NumberFormatInfo.InvariantInfo);
				}

				// use native EcmaScript number (IEEE 754)
				double number = Double.Parse(
					numberString,
					NumberStyles.Float,
					NumberFormatInfo.InvariantInfo);

				if (expectedType != null)
				{
					return JsonReader.CoerceType(expectedType, number, this.index, this.AllowNullValueTypes);
				}

				return number;
			}
		}

		#endregion Parsing Methods

		#region Object Methods

		/// <summary>
		/// If a Type Hint is present then this method attempts to
		/// use it and move any previously parsed data over.
		/// </summary>
		/// <param name="objectType">reference to the objectType</param>
		/// <param name="memberMap">reference to the memberMap</param>
		/// <param name="result">the previous result</param>
		/// <param name="typeInfo">the type info string to use</param>
		/// <returns></returns>
		private Object ProcessTypeHint(
			ref Type objectType,
			ref Dictionary<string, MemberInfo> memberMap,
			IDictionary result,
			string typeInfo)
		{
			if (String.IsNullOrEmpty(typeInfo))
			{
				return result;
			}

			Type hintedType = Type.GetType(typeInfo, false);
			if (hintedType == null)
			{
				return result;
			}
			objectType = hintedType;

			object newResult = this.InstantiateObject(hintedType, ref memberMap);
			if (memberMap != null)
			{
				Type memberType;
				MemberInfo memberInfo;

				// copy any values into new object
				foreach (object key in result.Keys)
				{
					JsonReader.GetMemberInfo(memberMap, key as String, out memberType, out memberInfo);
					this.SetMemberValue(newResult, memberType, memberInfo, result[key]);
				}
			}

			return newResult;
		}

		private Object InstantiateObject(Type objectType, ref Dictionary<string, MemberInfo> memberMap)
		{
			Object result;
			ConstructorInfo ctor = objectType.GetConstructor(Type.EmptyTypes);
			if (ctor == null)
			{
				throw new JsonDeserializationException(JsonReader.ErrorDefaultCtor, this.index);
			}
			result = ctor.Invoke(null);

			// don't incurr the cost of member map if a dictionary
			if (!typeof(IDictionary).IsAssignableFrom(objectType))
			{
				memberMap = this.CreateMemberMap(objectType);
			}
			return result;
		}

		private Dictionary<string, MemberInfo> CreateMemberMap(Type objectType)
		{
			if (this.MemberMapCache == null)
			{
				// instantiate space for cache
				this.MemberMapCache = new Dictionary<Type, Dictionary<string, MemberInfo>>();
			}
			else if (this.MemberMapCache.ContainsKey(objectType))
			{
				// map was stored in cache
				return this.MemberMapCache[objectType];
			}

			// create a new map
			Dictionary<string, MemberInfo> memberMap = new Dictionary<string, MemberInfo>();

			// load properties into property map
			PropertyInfo[] properties = objectType.GetProperties();
			foreach (PropertyInfo info in properties)
			{
				if (!info.CanRead || !info.CanWrite)
				{
					continue;
				}

				if (JsonIgnoreAttribute.IsJsonIgnore(info))
				{
					continue;
				}

				string jsonName = JsonNameAttribute.GetJsonName(info);
				if (String.IsNullOrEmpty(jsonName))
				{
					memberMap[info.Name] = info;
				}
				else
				{
					memberMap[jsonName] = info;
				}
			}

			// load public fields into property map
			FieldInfo[] fields = objectType.GetFields();
			foreach (FieldInfo info in fields)
			{
				if (!info.IsPublic)
				{
					continue;
				}

				if (JsonIgnoreAttribute.IsJsonIgnore(info))
				{
					continue;
				}

				string jsonName = JsonNameAttribute.GetJsonName(info);
				if (String.IsNullOrEmpty(jsonName))
				{
					memberMap[info.Name] = info;
				}
				else
				{
					memberMap[jsonName] = info;
				}
			}

			// store in cache for repeated usage
			this.MemberMapCache[objectType] = memberMap;

			return memberMap;
		}

		private static void GetMemberInfo(
			Dictionary<string, MemberInfo> memberMap,
			string memberName,
			out Type memberType,
			out MemberInfo memberInfo)
		{
			memberType = null;
			memberInfo = null;

			if (memberMap != null &&
				memberMap.ContainsKey(memberName))
			{
				// Check properties for object member
				memberInfo = memberMap[memberName];

				if (memberInfo is PropertyInfo)
				{
					// maps to public property
					memberType = ((PropertyInfo)memberInfo).PropertyType;
				}
				else if (memberInfo is FieldInfo)
				{
					// maps to public field
					memberType = ((FieldInfo)memberInfo).FieldType;
				}
				else
				{
					// none found
					memberType = null;
				}
			}
			else
			{
				// none found
				memberType = null;
			}
		}

		/// <summary>
		/// Helper method to set value of either property or field
		/// </summary>
		/// <param name="result"></param>
		/// <param name="memberType"></param>
		/// <param name="memberInfo"></param>
		/// <param name="value"></param>
		private void SetMemberValue(Object result, Type memberType, MemberInfo memberInfo, object value)
		{
			if (memberInfo is PropertyInfo)
			{
				// set value of public property
				((PropertyInfo)memberInfo).SetValue(
					result,
					JsonReader.CoerceType(memberType, value, this.index, this.AllowNullValueTypes),
					null);
			}
			else if (memberInfo is FieldInfo)
			{
				// set value of public field
				((FieldInfo)memberInfo).SetValue(
					result,
					JsonReader.CoerceType(memberType, value, this.index, this.AllowNullValueTypes));
			}

			// all other values are ignored
		}

		#endregion Object Methods

		#region Type Methods

		public static object CoerceType(Type targetType, object value)
		{
			return JsonReader.CoerceType(targetType, value, -1, false);
		}

		private static object CoerceType(Type targetType, object value, int index, bool allowNullValueTypes)
		{
			bool isNullable = JsonReader.IsNullable(targetType);
			if (value == null)
			{
				if (allowNullValueTypes &&
					targetType.IsValueType &&
					!isNullable)
				{
					throw new JsonDeserializationException(String.Format(JsonReader.ErrorNullValueType, targetType.FullName), index);
				}
				return value;
			}

			if (isNullable)
			{
				// nullable types have a real underlying struct
				Type[] genericArgs = targetType.GetGenericArguments();
				if (genericArgs.Length == 1)
				{
					targetType = genericArgs[0];
				}
			}

			Type actualType = value.GetType();
			if (targetType.IsAssignableFrom(actualType))
			{
				return value;
			}

			if (targetType.IsEnum)
			{
				if (!Enum.IsDefined(targetType, value))
				{
					// if isn't a defined value perhaps it is the JsonName
					foreach (FieldInfo field in targetType.GetFields())
					{
						string jsonName = JsonNameAttribute.GetJsonName(field);
						if (((string)value).Equals(jsonName))
						{
							value = field.Name;
							break;
						}
					}
				}

				if (value is String)
				{
					return Enum.Parse(targetType, (string)value);
				}
				else
				{
					return Convert.ChangeType(value, targetType);
				}
			}

			if (actualType.IsArray && !targetType.IsArray)
			{
				return JsonReader.CoerceArray(targetType, actualType, value, index, allowNullValueTypes);
			}

			if (value is String)
			{
				if (targetType == typeof(DateTime))
				{
					DateTime date;
					if (DateTime.TryParse(
						(string)value,
						DateTimeFormatInfo.InvariantInfo,
						DateTimeStyles.RoundtripKind|DateTimeStyles.AllowWhiteSpaces|DateTimeStyles.NoCurrentDateDefault,
						out date))
					{
						return date;
					}
				}
				else if (targetType == typeof(Guid))
				{
					// try-catch is pointless since will throw upon generic conversion
					return new Guid((string)value);
				}
				else if (targetType == typeof(Uri))
				{
					Uri uri;
					if (Uri.TryCreate((string)value, UriKind.RelativeOrAbsolute, out uri))
					{
						return uri;
					}
				}
				else if (targetType == typeof(Version))
				{
					// try-catch is pointless since will throw upon generic conversion
					return new Version((string)value);
				}
			}

			else if (targetType == typeof(TimeSpan))
			{
				return new TimeSpan((long)JsonReader.CoerceType(typeof(Int64), value, index, allowNullValueTypes));
			}

			TypeConverter converter = TypeDescriptor.GetConverter(targetType);
			if (converter.CanConvertFrom(actualType))
			{
				return converter.ConvertFrom(value);
			}

			converter = TypeDescriptor.GetConverter(actualType);
			if (converter.CanConvertTo(targetType))
			{
				return converter.ConvertTo(value, targetType);
			}

			return Convert.ChangeType(value, targetType);
		}

		private static object CoerceArray(Type targetType, Type arrayType, object value, int index, bool allowNullValueTypes)
		{
			// targetType serializes as a JSON array but is not an array
			// assume is an ICollection / IEnumerable with AddRange, Add,
			// or custom Constructor with which we can populate it

			ConstructorInfo ctor = targetType.GetConstructor(Type.EmptyTypes);
			if (ctor == null)
			{
				throw new JsonDeserializationException(JsonReader.ErrorDefaultCtor, index);
			}
			object collection = ctor.Invoke(null);

			Array arrayValue = (Array)value;

			// many ICollection types have an AddRange method
			// which adds all items at once
			MethodInfo method = targetType.GetMethod("AddRange");
			ParameterInfo[] parameters = (method == null) ?
					null : method.GetParameters();
			Type paramType = (parameters == null || parameters.Length != 1) ?
					null : parameters[0].ParameterType;
			if (paramType != null &&
					paramType.IsAssignableFrom(arrayType))
			{
				// add all members in one method
				method.Invoke(
					collection,
					new object[] { arrayValue });
				return collection;
			}
			else
			{
				// many ICollection types have an Add method
				// which adds items one at a time
				method = targetType.GetMethod("Add");
				parameters = (method == null) ?
						null : method.GetParameters();
				paramType = (parameters == null || parameters.Length != 1) ?
						null : parameters[0].ParameterType;
				if (paramType != null)
				{
					// loop through adding items to collection
					foreach (object item in arrayValue)
					{
						method.Invoke(
							collection,
							new object[] {
									JsonReader.CoerceType(paramType, item, index, allowNullValueTypes)
								});
					}
					return collection;
				}
			}

			// many ICollection types take an IEnumerable or ICollection
			// as a constructor argument.  look through constructors for
			// a compatible match.
			ConstructorInfo[] ctors = targetType.GetConstructors();
			foreach (ConstructorInfo ctor2 in ctors)
			{
				ParameterInfo[] paramList = ctor2.GetParameters();
				if (paramList.Length == 1 &&
						paramList[0].ParameterType.IsAssignableFrom(arrayType))
				{
					try
					{
						// invoke first constructor that can take this value as an argument
						return ctor2.Invoke(
								new object[] { value }
							);
					}
					catch
					{
						// there might exist a better match
						continue;
					}
				}
			}

			return Convert.ChangeType(value, targetType);
		}

		private static bool IsNullable(Type type)
		{
			return type.IsGenericType && (typeof(Nullable<>) == type.GetGenericTypeDefinition());
		}

		#endregion Type Methods

		#region Tokenizing Methods

		private JsonToken Tokenize()
		{
			if (this.index >= this.SourceLength)
			{
				return JsonToken.End;
			}

			// skip whitespace
			while (Char.IsWhiteSpace(this.Source[this.index]))
			{
				this.index++;
				if (this.index >= this.SourceLength)
				{
					return JsonToken.End;
				}
			}

			#region Skip Comments

			// skip block and line comments
			if (this.Source[this.index] == JsonReader.CommentStart[0])
			{
				if (this.index+1 >= this.SourceLength)
				{
					throw new JsonDeserializationException(JsonReader.ErrorUnrecognizedToken, this.index);
				}

				// skip over first char of comment start
				this.index++;

				bool isBlockComment = false;
				if (this.Source[this.index] == JsonReader.CommentStart[1])
				{
					isBlockComment = true;
				}
				else if (this.Source[this.index] != JsonReader.CommentLine[1])
				{
					throw new JsonDeserializationException(JsonReader.ErrorUnrecognizedToken, this.index);
				}
				// skip over second char of comment start
				this.index++;

				if (isBlockComment)
				{
					// store index for unterminated case
					int commentStart = this.index-2;

					if (this.index+1 >= this.SourceLength)
					{
						throw new JsonDeserializationException(JsonReader.ErrorUnterminatedComment, commentStart);
					}

					// skip over everything until reach block comment ending
					while (this.Source[this.index] != JsonReader.CommentEnd[0] ||
						this.Source[this.index+1] != JsonReader.CommentEnd[1])
					{
						this.index++;
						if (this.index+1 >= this.SourceLength)
						{
							throw new JsonDeserializationException(JsonReader.ErrorUnterminatedComment, commentStart);
						}
					}

					// skip block comment end token
					this.index += 2;
					if (this.index >= this.SourceLength)
					{
						return JsonToken.End;
					}
				}
				else
				{
					// skip over everything until reach line ending
					while (JsonReader.LineEndings.IndexOf(this.Source[this.index]) < 0)
					{
						this.index++;
						if (this.index >= this.SourceLength)
						{
							return JsonToken.End;
						}
					}
				}

				// skip whitespace again
				while (Char.IsWhiteSpace(this.Source[this.index]))
				{
					this.index++;
					if (this.index >= this.SourceLength)
					{
						return JsonToken.End;
					}
				}
			}

			#endregion Skip Comments

			// consume positive signing (as is extraneous)
			if (this.Source[this.index] == JsonReader.OperatorUnaryPlus)
			{
				this.index++;
				if (this.index >= this.SourceLength)
				{
					return JsonToken.End;
				}
			}

			switch (this.Source[this.index])
			{
				case JsonReader.OperatorArrayStart:
				{
					return JsonToken.ArrayStart;
				}
				case JsonReader.OperatorArrayEnd:
				{
					return JsonToken.ArrayEnd;
				}
				case JsonReader.OperatorObjectStart:
				{
					return JsonToken.ObjectStart;
				}
				case JsonReader.OperatorObjectEnd:
				{
					return JsonToken.ObjectEnd;
				}
				case JsonReader.OperatorStringDelim:
				case JsonReader.OperatorStringDelimAlt:
				{
					return JsonToken.String;
				}
				case JsonReader.OperatorValueDelim:
				{
					return JsonToken.ValueDelim;
				}
				case JsonReader.OperatorNameDelim:
				{
					return JsonToken.NameDelim;
				}
				default:
				{
					break;
				}
			}

			// number
			if (Char.IsDigit(this.Source[this.index]) ||
				((this.Source[this.index] == JsonReader.OperatorNegate) && (this.index+1 < this.SourceLength) && Char.IsDigit(this.Source[this.index+1])))
			{
				return JsonToken.Number;
			}

			// "false" literal
			if (this.MatchLiteral(JsonReader.LiteralFalse))
			{
				return JsonToken.False;
			}

			// "true" literal
			if (this.MatchLiteral(JsonReader.LiteralTrue))
			{
				return JsonToken.True;
			}

			// "null" literal
			if (this.MatchLiteral(JsonReader.LiteralNull))
			{
				return JsonToken.Null;
			}

			// "NaN" literal
			if (this.MatchLiteral(JsonReader.LiteralNotANumber))
			{
				return JsonToken.NaN;
			}

			// "Infinity" literal
			if (this.MatchLiteral(JsonReader.LiteralPositiveInfinity))
			{
				return JsonToken.PositiveInfinity;
			}

			// "-Infinity" literal
			if (this.MatchLiteral(JsonReader.LiteralNegativeInfinity))
			{
				return JsonToken.NegativeInfinity;
			}

			throw new JsonDeserializationException(JsonReader.ErrorUnrecognizedToken, this.index);
		}

		/// <summary>
		/// Determines if the next token is the given literal
		/// </summary>
		/// <param name="literal"></param>
		/// <returns></returns>
		private bool MatchLiteral(string literal)
		{
			int literalLength = literal.Length;
			for (int i=0, j=this.index; i<literalLength && j<this.SourceLength; i++, j++)
			{
				if (literal[i] != this.Source[j])
				{
					return false;
				}
			}

			return true;
		}

		#endregion Tokenizing Methods
	}
}