/src/JsonFx/Model/ModelWalker.cs

#region License

/*---------------------------------------------------------------------------------*\



	Distributed under the terms of an MIT-style license:



	The MIT License



	Copyright (c) 2006-2010 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 License



using System;

using System.Collections;

using System.Collections.Generic;



using JsonFx.CodeGen;

using JsonFx.Serialization;

using JsonFx.Serialization.Filters;

using JsonFx.Serialization.GraphCycles;

using JsonFx.Serialization.Resolvers;



namespace JsonFx.Model

{

	/// <summary>

	/// Generates a sequence of tokens from an object graph

	/// </summary>

	public class ModelWalker : IObjectWalker<ModelTokenType>

	{

		#region Fields



		private readonly DataWriterSettings Settings;

		private readonly IEnumerable<IDataFilter<ModelTokenType>> Filters;



		#endregion Fields



		#region Init



		/// <summary>

		/// Ctor

		/// </summary>

		/// <param name="settings"></param>

		public ModelWalker(DataWriterSettings settings)

		{

			if (settings == null)

			{

				throw new ArgumentNullException("settings");

			}

			this.Settings = settings;



			var filters = new List<IDataFilter<ModelTokenType>>();

			if (settings.Filters != null)

			{

				foreach (var filter in settings.Filters)

				{

					if (filter != null)

					{

						filters.Add(filter);

					}

				}

			}

			this.Filters = filters;

		}



		#endregion Init



		#region IObjectWalker<T> Methods



		/// <summary>

		/// Generates a sequence of tokens representing the value

		/// </summary>

		/// <param name="value"></param>

		/// <returns></returns>

		public IEnumerable<Token<ModelTokenType>> GetTokens(object value)

		{

			ICycleDetector detector;

			switch (this.Settings.GraphCycles)

			{

				case GraphCycleType.MaxDepth:

				{

					detector = new DepthCounter(this.Settings.MaxDepth);

					break;

				}

				default:

				{

					detector = new ReferenceSet();

					break;

				}

			}



			List<Token<ModelTokenType>> tokens = new List<Token<ModelTokenType>>();

			this.GetTokens(tokens, detector, value);

			return tokens;

		}



		#endregion IObjectWalker<T> Methods



		#region Walker Methods



		private void GetTokens(List<Token<ModelTokenType>> tokens, ICycleDetector detector, object value)

		{

			if (value == null)

			{

				tokens.Add(ModelGrammar.TokenNull);

				return;

			}



			// test for cycles

			if (detector.Add(value))

			{

				switch (this.Settings.GraphCycles)

				{

					case GraphCycleType.Reference:

					{

						// no need to remove value as was duplicate reference

						throw new GraphCycleException(GraphCycleType.Reference, "Graph cycle detected: repeated references");

					}

					case GraphCycleType.MaxDepth:

					{

						throw new GraphCycleException(GraphCycleType.MaxDepth, "Graph cycle potentially detected: maximum depth exceeded");

					}

					default:

					case GraphCycleType.Ignore:

					{

						// no need to remove value as was duplicate reference

						// replace cycle with null

						tokens.Add(ModelGrammar.TokenNull);

						return;

					}

				}

			}



			try

			{

				foreach (var filter in this.Filters)

				{

					IEnumerable<Token<ModelTokenType>> filterResult;

					if (filter.TryWrite(this.Settings, value, out filterResult))

					{

						// found a successful match

						tokens.AddRange(filterResult);

						return;

					}

				}



				Type type = value.GetType();



				// must test enumerations before other value types

				if (type.IsEnum)

				{

					tokens.Add(ModelGrammar.TokenPrimitive((Enum)value));

					return;

				}



				// Type.GetTypeCode() allows us to more efficiently switch type

				switch (Type.GetTypeCode(type))

				{

					case TypeCode.Boolean:

					{

						tokens.Add(true.Equals(value) ? ModelGrammar.TokenTrue : ModelGrammar.TokenFalse);

						return;

					}

					case TypeCode.Byte:

					case TypeCode.Decimal:

					case TypeCode.Int16:

					case TypeCode.Int32:

					case TypeCode.Int64:

					case TypeCode.SByte:

					case TypeCode.UInt16:

					case TypeCode.UInt32:

					case TypeCode.UInt64:

					{

						tokens.Add(ModelGrammar.TokenPrimitive((ValueType)value));

						return;

					}

					case TypeCode.Double:

					{

						double doubleVal = (double)value;



						if (Double.IsNaN(doubleVal))

						{

							tokens.Add(ModelGrammar.TokenNaN);

						}

						else if (Double.IsPositiveInfinity(doubleVal))

						{

							tokens.Add(ModelGrammar.TokenPositiveInfinity);

						}

						else if (Double.IsNegativeInfinity(doubleVal))

						{

							tokens.Add(ModelGrammar.TokenNegativeInfinity);

						}

						else

						{

							tokens.Add(ModelGrammar.TokenPrimitive(doubleVal));

						}

						return;

					}

					case TypeCode.Single:

					{

						float floatVal = (float)value;



						if (Single.IsNaN(floatVal))

						{

							// use the Double equivalent

							tokens.Add(ModelGrammar.TokenNaN);

						}

						else if (Single.IsPositiveInfinity(floatVal))

						{

							// use the Double equivalent

							tokens.Add(ModelGrammar.TokenPositiveInfinity);

						}

						else if (Single.IsNegativeInfinity(floatVal))

						{

							// use the Double equivalent

							tokens.Add(ModelGrammar.TokenNegativeInfinity);

						}

						else

						{

							tokens.Add(ModelGrammar.TokenPrimitive(floatVal));

						}

						return;

					}

					case TypeCode.Char:

					case TypeCode.DateTime:

					case TypeCode.String:

					{

						tokens.Add(ModelGrammar.TokenPrimitive(value));

						return;

					}

					case TypeCode.DBNull:

					case TypeCode.Empty:

					{

						tokens.Add(ModelGrammar.TokenNull);

						return;

					}

				}



				if (value is IEnumerable)

				{

					this.GetArrayTokens(tokens, detector, (IEnumerable)value);

					return;

				}



				if (value is Guid || value is Uri || value is Version)

				{

					tokens.Add(ModelGrammar.TokenPrimitive(value));

					return;

				}



				if (value is TimeSpan)

				{

					tokens.Add(ModelGrammar.TokenPrimitive((TimeSpan)value));

					return;

				}



#if NET40 && !WINDOWS_PHONE

				if (value is System.Dynamic.DynamicObject)

				{

					// TODO: expand to all IDynamicMetaObjectProvider?

					this.GetObjectTokens(tokens, detector, type, (System.Dynamic.DynamicObject)value);

					return;

				}

#endif



				// all other structs and classes

				this.GetObjectTokens(tokens, detector, type, value);

			}

			finally

			{

				detector.Remove(value);

			}

		}



		private void GetArrayTokens(List<Token<ModelTokenType>> tokens, ICycleDetector detector, IEnumerable value)

		{

			DataName typeName = this.GetTypeName(value);

			IEnumerator enumerator = value.GetEnumerator();



			if (enumerator is IEnumerator<KeyValuePair<string, object>>)

			{

				this.GetObjectTokens(tokens, detector, typeName, (IEnumerator<KeyValuePair<string, object>>)enumerator);

				return;

			}



			if (enumerator is IDictionaryEnumerator)

			{

				this.GetObjectTokens(tokens, detector, typeName, (IDictionaryEnumerator)enumerator);

				return;

			}



			tokens.Add(ModelGrammar.TokenArrayBegin(typeName));



			while (enumerator.MoveNext())

			{

				this.GetTokens(tokens, detector, enumerator.Current);

			}



			tokens.Add(ModelGrammar.TokenArrayEnd);

		}



		private void GetObjectTokens(List<Token<ModelTokenType>> tokens, ICycleDetector detector, DataName typeName, IDictionaryEnumerator enumerator)

		{

			tokens.Add(ModelGrammar.TokenObjectBegin(typeName));



			while (enumerator.MoveNext())

			{

				tokens.Add(ModelGrammar.TokenProperty(enumerator.Key));

				this.GetTokens(tokens, detector, enumerator.Value);

			}



			tokens.Add(ModelGrammar.TokenObjectEnd);

		}



		private void GetObjectTokens(List<Token<ModelTokenType>> tokens, ICycleDetector detector, DataName typeName, IEnumerator<KeyValuePair<string, object>> enumerator)

		{

			tokens.Add(ModelGrammar.TokenObjectBegin(typeName));



			while (enumerator.MoveNext())

			{

				KeyValuePair<string, object> pair = enumerator.Current;

				tokens.Add(ModelGrammar.TokenProperty(pair.Key));

				this.GetTokens(tokens, detector, pair.Value);

			}



			tokens.Add(ModelGrammar.TokenObjectEnd);

		}



#if NET40 && !WINDOWS_PHONE

		private void GetObjectTokens(List<Token<ModelTokenType>> tokens, ICycleDetector detector, Type type, System.Dynamic.DynamicObject value)

		{

			DataName typeName = this.GetTypeName(value);

			tokens.Add(ModelGrammar.TokenObjectBegin(typeName));



			foreach (var memberName in value.GetDynamicMemberNames())

			{

				object propertyValue;

				if (!value.TryGetMember(new DynamicGetter(memberName), out propertyValue))

				{

					continue;

				}



				tokens.Add(ModelGrammar.TokenProperty(memberName));

				this.GetTokens(tokens, detector, propertyValue);

			}



			tokens.Add(ModelGrammar.TokenObjectEnd);

		}

#endif



		private void GetObjectTokens(List<Token<ModelTokenType>> tokens, ICycleDetector detector, Type type, object value)

		{

			DataName typeName = this.GetTypeName(value);

			tokens.Add(ModelGrammar.TokenObjectBegin(typeName));



			IDictionary<string, MemberMap> maps = this.Settings.Resolver.LoadMaps(type);

			if (maps == null)

			{

				// TODO: verify no other valid situations here

				tokens.Add(ModelGrammar.TokenObjectEnd);

				return;

			}



			// allow the resolver to optionally sort the members

			IEnumerable<MemberMap> members = this.Settings.Resolver.SortMembers(maps.Values);



			foreach (var map in members)

			{

				if (map.IsAlternate ||

					map.Getter == null)

				{

					continue;

				}



				object propertyValue = map.Getter(value);

				if (map.IsIgnored != null &&

					map.IsIgnored(value, propertyValue))

				{

					continue;

				}



				tokens.Add(ModelGrammar.TokenProperty(map.DataName));

				this.GetTokens(tokens, detector, propertyValue);

			}



			tokens.Add(ModelGrammar.TokenObjectEnd);

		}



		#endregion Walker Methods



		#region Utility Methods



		private DataName GetTypeName(object value)

		{

			IEnumerable<DataName> typeNames = this.Settings.Resolver.LoadTypeName((value != null) ? value.GetType() : null);



			if (typeNames != null)

			{

				foreach (DataName n in typeNames)

				{

					if (!n.IsEmpty)

					{

						return n;

					}

				}

			}



			return DataName.Empty;

		}



		#endregion Utility Methods

	}

}