298 lines
12 KiB
C#
298 lines
12 KiB
C#
#region License
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// Copyright (c) 2007 James Newton-King
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//
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// Permission is hereby granted, free of charge, to any person
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// obtaining a copy of this software and associated documentation
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// files (the "Software"), to deal in the Software without
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// restriction, including without limitation the rights to use,
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// copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following
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// conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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// OTHER DEALINGS IN THE SOFTWARE.
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#endregion
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#if HAVE_FSHARP_TYPES
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using LC.Newtonsoft.Json.Linq;
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using System;
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using System.Collections;
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using System.Collections.Generic;
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#if !HAVE_LINQ
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using LC.Newtonsoft.Json.Utilities.LinqBridge;
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#else
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using System.Linq;
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#endif
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using System.Reflection;
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using LC.Newtonsoft.Json.Serialization;
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using System.Globalization;
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using LC.Newtonsoft.Json.Utilities;
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namespace LC.Newtonsoft.Json.Converters
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{
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/// <summary>
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/// Converts a F# discriminated union type to and from JSON.
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/// </summary>
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public class DiscriminatedUnionConverter : JsonConverter
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{
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#region UnionDefinition
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internal class Union
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{
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public readonly FSharpFunction TagReader;
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public readonly List<UnionCase> Cases;
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public Union(FSharpFunction tagReader, List<UnionCase> cases)
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{
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TagReader = tagReader;
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Cases = cases;
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}
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}
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internal class UnionCase
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{
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public readonly int Tag;
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public readonly string Name;
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public readonly PropertyInfo[] Fields;
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public readonly FSharpFunction FieldReader;
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public readonly FSharpFunction Constructor;
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public UnionCase(int tag, string name, PropertyInfo[] fields, FSharpFunction fieldReader, FSharpFunction constructor)
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{
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Tag = tag;
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Name = name;
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Fields = fields;
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FieldReader = fieldReader;
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Constructor = constructor;
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}
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}
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#endregion
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private const string CasePropertyName = "Case";
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private const string FieldsPropertyName = "Fields";
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private static readonly ThreadSafeStore<Type, Union> UnionCache = new ThreadSafeStore<Type, Union>(CreateUnion);
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private static readonly ThreadSafeStore<Type, Type> UnionTypeLookupCache = new ThreadSafeStore<Type, Type>(CreateUnionTypeLookup);
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private static Type CreateUnionTypeLookup(Type t)
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{
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// this lookup is because cases with fields are derived from union type
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// need to get declaring type to avoid duplicate Unions in cache
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// hacky but I can't find an API to get the declaring type without GetUnionCases
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object[] cases = (object[])FSharpUtils.Instance.GetUnionCases(null, t, null)!;
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object caseInfo = cases.First();
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Type unionType = (Type)FSharpUtils.Instance.GetUnionCaseInfoDeclaringType(caseInfo)!;
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return unionType;
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}
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private static Union CreateUnion(Type t)
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{
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Union u = new Union((FSharpFunction)FSharpUtils.Instance.PreComputeUnionTagReader(null, t, null), new List<UnionCase>());
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object[] cases = (object[])FSharpUtils.Instance.GetUnionCases(null, t, null)!;
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foreach (object unionCaseInfo in cases)
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{
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UnionCase unionCase = new UnionCase(
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(int)FSharpUtils.Instance.GetUnionCaseInfoTag(unionCaseInfo),
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(string)FSharpUtils.Instance.GetUnionCaseInfoName(unionCaseInfo),
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(PropertyInfo[])FSharpUtils.Instance.GetUnionCaseInfoFields(unionCaseInfo)!,
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(FSharpFunction)FSharpUtils.Instance.PreComputeUnionReader(null, unionCaseInfo, null),
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(FSharpFunction)FSharpUtils.Instance.PreComputeUnionConstructor(null, unionCaseInfo, null));
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u.Cases.Add(unionCase);
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}
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return u;
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}
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/// <summary>
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/// Writes the JSON representation of the object.
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/// </summary>
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/// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
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/// <param name="value">The value.</param>
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/// <param name="serializer">The calling serializer.</param>
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public override void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer)
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{
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if (value == null)
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{
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writer.WriteNull();
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return;
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}
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DefaultContractResolver? resolver = serializer.ContractResolver as DefaultContractResolver;
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Type unionType = UnionTypeLookupCache.Get(value.GetType());
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Union union = UnionCache.Get(unionType);
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int tag = (int)union.TagReader.Invoke(value);
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UnionCase caseInfo = union.Cases.Single(c => c.Tag == tag);
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writer.WriteStartObject();
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writer.WritePropertyName((resolver != null) ? resolver.GetResolvedPropertyName(CasePropertyName) : CasePropertyName);
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writer.WriteValue(caseInfo.Name);
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if (caseInfo.Fields != null && caseInfo.Fields.Length > 0)
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{
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object[] fields = (object[])caseInfo.FieldReader.Invoke(value)!;
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writer.WritePropertyName((resolver != null) ? resolver.GetResolvedPropertyName(FieldsPropertyName) : FieldsPropertyName);
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writer.WriteStartArray();
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foreach (object field in fields)
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{
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serializer.Serialize(writer, field);
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}
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writer.WriteEndArray();
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}
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writer.WriteEndObject();
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}
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/// <summary>
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/// Reads the JSON representation of the object.
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/// </summary>
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/// <param name="reader">The <see cref="JsonReader"/> to read from.</param>
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/// <param name="objectType">Type of the object.</param>
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/// <param name="existingValue">The existing value of object being read.</param>
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/// <param name="serializer">The calling serializer.</param>
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/// <returns>The object value.</returns>
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public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer)
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{
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if (reader.TokenType == JsonToken.Null)
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{
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return null;
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}
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UnionCase? caseInfo = null;
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string? caseName = null;
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JArray? fields = null;
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// start object
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reader.ReadAndAssert();
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while (reader.TokenType == JsonToken.PropertyName)
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{
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string propertyName = reader.Value!.ToString();
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if (string.Equals(propertyName, CasePropertyName, StringComparison.OrdinalIgnoreCase))
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{
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reader.ReadAndAssert();
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Union union = UnionCache.Get(objectType);
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caseName = reader.Value!.ToString();
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caseInfo = union.Cases.SingleOrDefault(c => c.Name == caseName);
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if (caseInfo == null)
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{
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throw JsonSerializationException.Create(reader, "No union type found with the name '{0}'.".FormatWith(CultureInfo.InvariantCulture, caseName));
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}
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}
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else if (string.Equals(propertyName, FieldsPropertyName, StringComparison.OrdinalIgnoreCase))
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{
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reader.ReadAndAssert();
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if (reader.TokenType != JsonToken.StartArray)
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{
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throw JsonSerializationException.Create(reader, "Union fields must been an array.");
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}
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fields = (JArray)JToken.ReadFrom(reader);
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}
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else
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{
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throw JsonSerializationException.Create(reader, "Unexpected property '{0}' found when reading union.".FormatWith(CultureInfo.InvariantCulture, propertyName));
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}
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reader.ReadAndAssert();
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}
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if (caseInfo == null)
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{
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throw JsonSerializationException.Create(reader, "No '{0}' property with union name found.".FormatWith(CultureInfo.InvariantCulture, CasePropertyName));
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}
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object?[] typedFieldValues = new object?[caseInfo.Fields.Length];
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if (caseInfo.Fields.Length > 0 && fields == null)
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{
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throw JsonSerializationException.Create(reader, "No '{0}' property with union fields found.".FormatWith(CultureInfo.InvariantCulture, FieldsPropertyName));
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}
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if (fields != null)
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{
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if (caseInfo.Fields.Length != fields.Count)
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{
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throw JsonSerializationException.Create(reader, "The number of field values does not match the number of properties defined by union '{0}'.".FormatWith(CultureInfo.InvariantCulture, caseName));
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}
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for (int i = 0; i < fields.Count; i++)
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{
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JToken t = fields[i];
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PropertyInfo fieldProperty = caseInfo.Fields[i];
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typedFieldValues[i] = t.ToObject(fieldProperty.PropertyType, serializer);
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}
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}
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object[] args = { typedFieldValues };
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return caseInfo.Constructor.Invoke(args);
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}
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/// <summary>
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/// Determines whether this instance can convert the specified object type.
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/// </summary>
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/// <param name="objectType">Type of the object.</param>
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/// <returns>
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/// <c>true</c> if this instance can convert the specified object type; otherwise, <c>false</c>.
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/// </returns>
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public override bool CanConvert(Type objectType)
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{
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if (typeof(IEnumerable).IsAssignableFrom(objectType))
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{
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return false;
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}
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// all fsharp objects have CompilationMappingAttribute
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// get the fsharp assembly from the attribute and initialize latebound methods
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object[] attributes;
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#if HAVE_FULL_REFLECTION
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attributes = objectType.GetCustomAttributes(true);
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#else
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attributes = objectType.GetTypeInfo().GetCustomAttributes(true).ToArray();
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#endif
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bool isFSharpType = false;
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foreach (object attribute in attributes)
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{
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Type attributeType = attribute.GetType();
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if (attributeType.FullName == "Microsoft.FSharp.Core.CompilationMappingAttribute")
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{
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FSharpUtils.EnsureInitialized(attributeType.Assembly());
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isFSharpType = true;
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break;
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}
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}
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if (!isFSharpType)
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{
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return false;
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}
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return (bool)FSharpUtils.Instance.IsUnion(null, objectType, null);
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}
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}
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}
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#endif |