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TouchSocket/RRQMCore/XREF/Newtonsoft.Json/Converters/DiscriminatedUnionConverter.cs
2022-03-20 10:51:15 +08:00

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//------------------------------------------------------------------------------
// 此代码版权除特别声明或在RRQMCore.XREF命名空间的代码归作者本人若汝棋茗所有
// 源代码使用协议遵循本仓库的开源协议及附加协议若本仓库没有设置则按MIT开源协议授权
// CSDN博客https://blog.csdn.net/qq_40374647
// 哔哩哔哩视频https://space.bilibili.com/94253567
// Gitee源代码仓库https://gitee.com/RRQM_Home
// Github源代码仓库https://github.com/RRQM
// API首页https://www.yuque.com/eo2w71/rrqm
// 交流QQ群234762506
// 感谢您的下载和使用
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------
#region License
// Copyright (c) 2007 James Newton-King
//
// 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
#if HAVE_FSHARP_TYPES
using RRQMCore.XREF.Newtonsoft.Json.Linq;
using System;
using System.Collections;
using System.Collections.Generic;
#if !HAVE_LINQ
using RRQMCore.XREF.Newtonsoft.Json.Utilities.LinqBridge;
#else
using System.Linq;
#endif
using System.Reflection;
using RRQMCore.XREF.Newtonsoft.Json.Serialization;
using System.Globalization;
using RRQMCore.XREF.Newtonsoft.Json.Utilities;
namespace RRQMCore.XREF.Newtonsoft.Json.Converters
{
/// <summary>
/// Converts a F# discriminated union type to and from JSON.
/// </summary>
public class DiscriminatedUnionConverter : JsonConverter
{
#region UnionDefinition
internal class Union
{
public List<UnionCase> Cases;
public FSharpFunction TagReader { get; set; }
}
internal class UnionCase
{
public int Tag;
public string Name;
public PropertyInfo[] Fields;
public FSharpFunction FieldReader;
public FSharpFunction Constructor;
}
#endregion UnionDefinition
private const string CasePropertyName = "Case";
private const string FieldsPropertyName = "Fields";
private static readonly ThreadSafeStore<Type, Union> UnionCache = new ThreadSafeStore<Type, Union>(CreateUnion);
private static readonly ThreadSafeStore<Type, Type> UnionTypeLookupCache = new ThreadSafeStore<Type, Type>(CreateUnionTypeLookup);
private static Type CreateUnionTypeLookup(Type t)
{
// this lookup is because cases with fields are derived from union type
// need to get declaring type to avoid duplicate Unions in cache
// hacky but I can't find an API to get the declaring type without GetUnionCases
object[] cases = (object[])FSharpUtils.GetUnionCases(null, t, null);
object caseInfo = cases.First();
Type unionType = (Type)FSharpUtils.GetUnionCaseInfoDeclaringType(caseInfo);
return unionType;
}
private static Union CreateUnion(Type t)
{
Union u = new Union();
u.TagReader = (FSharpFunction)FSharpUtils.PreComputeUnionTagReader(null, t, null);
u.Cases = new List<UnionCase>();
object[] cases = (object[])FSharpUtils.GetUnionCases(null, t, null);
foreach (object unionCaseInfo in cases)
{
UnionCase unionCase = new UnionCase();
unionCase.Tag = (int)FSharpUtils.GetUnionCaseInfoTag(unionCaseInfo);
unionCase.Name = (string)FSharpUtils.GetUnionCaseInfoName(unionCaseInfo);
unionCase.Fields = (PropertyInfo[])FSharpUtils.GetUnionCaseInfoFields(unionCaseInfo);
unionCase.FieldReader = (FSharpFunction)FSharpUtils.PreComputeUnionReader(null, unionCaseInfo, null);
unionCase.Constructor = (FSharpFunction)FSharpUtils.PreComputeUnionConstructor(null, unionCaseInfo, null);
u.Cases.Add(unionCase);
}
return u;
}
/// <summary>
/// Writes the JSON representation of the object.
/// </summary>
/// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
/// <param name="value">The value.</param>
/// <param name="serializer">The calling serializer.</param>
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
DefaultContractResolver resolver = serializer.ContractResolver as DefaultContractResolver;
Type unionType = UnionTypeLookupCache.Get(value.GetType());
Union union = UnionCache.Get(unionType);
int tag = (int)union.TagReader.Invoke(value);
UnionCase caseInfo = union.Cases.Single(c => c.Tag == tag);
writer.WriteStartObject();
writer.WritePropertyName((resolver != null) ? resolver.GetResolvedPropertyName(CasePropertyName) : CasePropertyName);
writer.WriteValue(caseInfo.Name);
if (caseInfo.Fields != null && caseInfo.Fields.Length > 0)
{
object[] fields = (object[])caseInfo.FieldReader.Invoke(value);
writer.WritePropertyName((resolver != null) ? resolver.GetResolvedPropertyName(FieldsPropertyName) : FieldsPropertyName);
writer.WriteStartArray();
foreach (object field in fields)
{
serializer.Serialize(writer, field);
}
writer.WriteEndArray();
}
writer.WriteEndObject();
}
/// <summary>
/// Reads the JSON representation of the object.
/// </summary>
/// <param name="reader">The <see cref="JsonReader"/> to read from.</param>
/// <param name="objectType">Type of the object.</param>
/// <param name="existingValue">The existing value of object being read.</param>
/// <param name="serializer">The calling serializer.</param>
/// <returns>The object value.</returns>
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.Null)
{
return null;
}
UnionCase caseInfo = null;
string caseName = null;
JArray fields = null;
// start object
reader.ReadAndAssert();
while (reader.TokenType == JsonToken.PropertyName)
{
string propertyName = reader.Value.ToString();
if (string.Equals(propertyName, CasePropertyName, StringComparison.OrdinalIgnoreCase))
{
reader.ReadAndAssert();
Union union = UnionCache.Get(objectType);
caseName = reader.Value.ToString();
caseInfo = union.Cases.SingleOrDefault(c => c.Name == caseName);
if (caseInfo == null)
{
throw JsonSerializationException.Create(reader, "No union type found with the name '{0}'.".FormatWith(CultureInfo.InvariantCulture, caseName));
}
}
else if (string.Equals(propertyName, FieldsPropertyName, StringComparison.OrdinalIgnoreCase))
{
reader.ReadAndAssert();
if (reader.TokenType != JsonToken.StartArray)
{
throw JsonSerializationException.Create(reader, "Union fields must been an array.");
}
fields = (JArray)JToken.ReadFrom(reader);
}
else
{
throw JsonSerializationException.Create(reader, "Unexpected property '{0}' found when reading union.".FormatWith(CultureInfo.InvariantCulture, propertyName));
}
reader.ReadAndAssert();
}
if (caseInfo == null)
{
throw JsonSerializationException.Create(reader, "No '{0}' property with union name found.".FormatWith(CultureInfo.InvariantCulture, CasePropertyName));
}
object[] typedFieldValues = new object[caseInfo.Fields.Length];
if (caseInfo.Fields.Length > 0 && fields == null)
{
throw JsonSerializationException.Create(reader, "No '{0}' property with union fields found.".FormatWith(CultureInfo.InvariantCulture, FieldsPropertyName));
}
if (fields != null)
{
if (caseInfo.Fields.Length != fields.Count)
{
throw JsonSerializationException.Create(reader, "The number of field values does not match the number of properties defined by union '{0}'.".FormatWith(CultureInfo.InvariantCulture, caseName));
}
for (int i = 0; i < fields.Count; i++)
{
JToken t = fields[i];
PropertyInfo fieldProperty = caseInfo.Fields[i];
typedFieldValues[i] = t.ToObject(fieldProperty.PropertyType, serializer);
}
}
object[] args = { typedFieldValues };
return caseInfo.Constructor.Invoke(args);
}
/// <summary>
/// Determines whether this instance can convert the specified object type.
/// </summary>
/// <param name="objectType">Type of the object.</param>
/// <returns>
/// <c>true</c> if this instance can convert the specified object type; otherwise, <c>false</c>.
/// </returns>
public override bool CanConvert(Type objectType)
{
if (typeof(IEnumerable).IsAssignableFrom(objectType))
{
return false;
}
// all fsharp objects have CompilationMappingAttribute
// get the fsharp assembly from the attribute and initialize latebound methods
object[] attributes;
#if HAVE_FULL_REFLECTION
attributes = objectType.GetCustomAttributes(true);
#else
attributes = objectType.GetTypeInfo().GetCustomAttributes(true).ToArray();
#endif
bool isFSharpType = false;
foreach (object attribute in attributes)
{
Type attributeType = attribute.GetType();
if (attributeType.FullName == "Microsoft.FSharp.Core.CompilationMappingAttribute")
{
FSharpUtils.EnsureInitialized(attributeType.Assembly());
isFSharpType = true;
break;
}
}
if (!isFSharpType)
{
return false;
}
return (bool)FSharpUtils.IsUnion(null, objectType, null);
}
}
}
#endif