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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
namespace System.Text.Json.Serialization.Metadata
{
/// <summary>
/// Represents a strongly-typed property to prevent boxing and to create a direct delegate to the getter\setter.
/// </summary>
internal sealed class JsonPropertyInfo<T> : JsonPropertyInfo
{
private Func<object, T>? _typedGet;
private Action<object, T>? _typedSet;
internal JsonPropertyInfo(Type declaringType, JsonTypeInfo? declaringTypeInfo, JsonSerializerOptions options)
: base(declaringType, propertyType: typeof(T), declaringTypeInfo, options)
{
}
internal new Func<object, T>? Get
{
get => _typedGet;
set => SetGetter(value);
}
internal new Action<object, T>? Set
{
get => _typedSet;
set => SetSetter(value);
}
private protected override void SetGetter(Delegate? getter)
{
Debug.Assert(getter is null or Func<object, object?> or Func<object, T>);
Debug.Assert(!IsConfigured);
if (getter is null)
{
_typedGet = null;
_untypedGet = null;
}
else if (getter is Func<object, T> typedGetter)
{
_typedGet = typedGetter;
_untypedGet = getter is Func<object, object?> untypedGet ? untypedGet : obj => typedGetter(obj);
}
else
{
Func<object, object?> untypedGet = (Func<object, object?>)getter;
_typedGet = (obj => (T)untypedGet(obj)!);
_untypedGet = untypedGet;
}
}
private protected override void SetSetter(Delegate? setter)
{
Debug.Assert(setter is null or Action<object, object?> or Action<object, T>);
Debug.Assert(!IsConfigured);
if (setter is null)
{
_typedSet = null;
_untypedSet = null;
}
else if (setter is Action<object, T> typedSetter)
{
_typedSet = typedSetter;
_untypedSet = setter is Action<object, object?> untypedSet ? untypedSet : (obj, value) => typedSetter(obj, (T)value!);
}
else
{
Action<object, object?> untypedSet = (Action<object, object?>)setter;
_typedSet = ((obj, value) => untypedSet(obj, value));
_untypedSet = untypedSet;
}
}
internal new Func<object, T?, bool>? ShouldSerialize
{
get => _shouldSerializeTyped;
set => SetShouldSerialize(value);
}
private Func<object, T?, bool>? _shouldSerializeTyped;
private protected override void SetShouldSerialize(Delegate? predicate)
{
Debug.Assert(predicate is null or Func<object, object?, bool> or Func<object, T?, bool>);
Debug.Assert(!IsConfigured);
if (predicate is null)
{
_shouldSerializeTyped = null;
_shouldSerialize = null;
}
else if (predicate is Func<object, T?, bool> typedPredicate)
{
_shouldSerializeTyped = typedPredicate;
_shouldSerialize = typedPredicate is Func<object, object?, bool> untypedPredicate ? untypedPredicate : (obj, value) => typedPredicate(obj, (T?)value);
}
else
{
Func<object, object?, bool> untypedPredicate = (Func<object, object?, bool>)predicate;
_shouldSerializeTyped = (obj, value) => untypedPredicate(obj, value);
_shouldSerialize = untypedPredicate;
}
}
internal override object? DefaultValue => default(T);
internal override bool PropertyTypeCanBeNull => default(T) is null;
internal override JsonParameterInfo CreateJsonParameterInfo(JsonParameterInfoValues parameterInfoValues)
=> new JsonParameterInfo<T>(parameterInfoValues, this);
internal new JsonConverter<T> EffectiveConverter
{
get
{
Debug.Assert(_typedEffectiveConverter != null);
return _typedEffectiveConverter;
}
}
private JsonConverter<T>? _typedEffectiveConverter;
[RequiresUnreferencedCode(JsonSerializer.SerializationUnreferencedCodeMessage)]
[RequiresDynamicCode(JsonSerializer.SerializationRequiresDynamicCodeMessage)]
internal override void DetermineReflectionPropertyAccessors(MemberInfo memberInfo, bool useNonPublicAccessors)
=> DefaultJsonTypeInfoResolver.DeterminePropertyAccessors<T>(this, memberInfo, useNonPublicAccessors);
private protected override void DetermineEffectiveConverter(JsonTypeInfo jsonTypeInfo)
{
Debug.Assert(jsonTypeInfo is JsonTypeInfo<T>);
JsonConverter<T> converter =
Options.ExpandConverterFactory(CustomConverter, PropertyType) // Expand any property-level custom converters.
?.CreateCastingConverter<T>() // Cast to JsonConverter<T>, potentially with wrapping.
?? ((JsonTypeInfo<T>)jsonTypeInfo).EffectiveConverter; // Fall back to the effective converter for the type.
_effectiveConverter = converter;
_typedEffectiveConverter = converter;
}
internal override object? GetValueAsObject(object obj)
{
if (IsForTypeInfo)
{
return obj;
}
Debug.Assert(HasGetter);
return Get!(obj);
}
internal override bool GetMemberAndWriteJson(object obj, ref WriteStack state, Utf8JsonWriter writer)
{
T value = Get!(obj);
if (
#if NET
!typeof(T).IsValueType && // treated as a constant by recent versions of the JIT.
#else
!EffectiveConverter.IsValueType &&
#endif
Options.ReferenceHandlingStrategy == ReferenceHandlingStrategy.IgnoreCycles &&
value is not null &&
!state.IsContinuation &&
// .NET types that are serialized as JSON primitive values don't need to be tracked for cycle detection e.g: string.
EffectiveConverter.ConverterStrategy != ConverterStrategy.Value &&
state.ReferenceResolver.ContainsReferenceForCycleDetection(value))
{
// If a reference cycle is detected, treat value as null.
value = default!;
Debug.Assert(value == null);
}
if (IgnoreDefaultValuesOnWrite)
{
// Fast path `ShouldSerialize` check when using JsonIgnoreCondition.WhenWritingNull/Default configuration
if (IsDefaultValue(value))
{
return true;
}
}
else if (ShouldSerialize?.Invoke(obj, value) == false)
{
// We return true here.
// False means that there is not enough data.
return true;
}
if (value is null)
{
Debug.Assert(PropertyTypeCanBeNull);
if (EffectiveConverter.HandleNullOnWrite)
{
if (state.Current.PropertyState < StackFramePropertyState.Name)
{
state.Current.PropertyState = StackFramePropertyState.Name;
writer.WritePropertyNameSection(EscapedNameSection);
}
int originalDepth = writer.CurrentDepth;
EffectiveConverter.Write(writer, value, Options);
if (originalDepth != writer.CurrentDepth)
{
ThrowHelper.ThrowJsonException_SerializationConverterWrite(EffectiveConverter);
}
}
else
{
writer.WriteNullSection(EscapedNameSection);
}
return true;
}
else
{
if (state.Current.PropertyState < StackFramePropertyState.Name)
{
state.Current.PropertyState = StackFramePropertyState.Name;
writer.WritePropertyNameSection(EscapedNameSection);
}
return EffectiveConverter.TryWrite(writer, value, Options, ref state);
}
}
internal override bool GetMemberAndWriteJsonExtensionData(object obj, ref WriteStack state, Utf8JsonWriter writer)
{
bool success;
T value = Get!(obj);
if (ShouldSerialize?.Invoke(obj, value) == false)
{
// We return true here.
// False means that there is not enough data.
return true;
}
if (value == null)
{
success = true;
}
else
{
success = EffectiveConverter.TryWriteDataExtensionProperty(writer, value, Options, ref state);
}
return success;
}
internal override bool ReadJsonAndSetMember(object obj, scoped ref ReadStack state, ref Utf8JsonReader reader)
{
bool success;
bool isNullToken = reader.TokenType == JsonTokenType.Null;
if (isNullToken && !EffectiveConverter.HandleNullOnRead && !state.IsContinuation)
{
if (default(T) is not null || !CanDeserialize)
{
if (default(T) is null)
{
Debug.Assert(CanDeserialize || EffectiveObjectCreationHandling == JsonObjectCreationHandling.Populate);
ThrowHelper.ThrowInvalidOperationException_DeserializeUnableToAssignNull(EffectiveConverter.Type);
}
ThrowHelper.ThrowJsonException_DeserializeUnableToConvertValue(EffectiveConverter.Type);
}
if (!IgnoreNullTokensOnRead)
{
T? value = default;
Set!(obj, value!);
}
success = true;
state.Current.MarkRequiredPropertyAsRead(this);
}
else if (EffectiveConverter.CanUseDirectReadOrWrite && state.Current.NumberHandling == null)
{
// CanUseDirectReadOrWrite == false when using streams
Debug.Assert(!state.IsContinuation);
Debug.Assert(EffectiveObjectCreationHandling != JsonObjectCreationHandling.Populate, "Populating should not be possible for simple types");
if (!isNullToken || !IgnoreNullTokensOnRead || default(T) is not null)
{
// Optimize for internal converters by avoiding the extra call to TryRead.
T? fastValue = EffectiveConverter.Read(ref reader, PropertyType, Options);
Set!(obj, fastValue!);
}
success = true;
state.Current.MarkRequiredPropertyAsRead(this);
}
else
{
success = true;
if (!isNullToken || !IgnoreNullTokensOnRead || default(T) is not null || state.IsContinuation)
{
state.Current.ReturnValue = obj;
success = EffectiveConverter.TryRead(ref reader, PropertyType, Options, ref state, out T? value, out bool populatedValue);
if (success)
{
if (typeof(T).IsValueType || !populatedValue)
{
// note: populatedValue value may be different than when CreationHandling is Populate
// i.e. when initial value of property is null
// We cannot do reader.Skip early because converter decides if populating will happen or not
if (CanDeserialize)
{
Set!(obj, value!);
}
}
state.Current.MarkRequiredPropertyAsRead(this);
}
}
}
return success;
}
internal override bool ReadJsonAsObject(scoped ref ReadStack state, ref Utf8JsonReader reader, out object? value)
{
bool success;
bool isNullToken = reader.TokenType == JsonTokenType.Null;
if (isNullToken && !EffectiveConverter.HandleNullOnRead && !state.IsContinuation)
{
if (default(T) is not null)
{
ThrowHelper.ThrowJsonException_DeserializeUnableToConvertValue(EffectiveConverter.Type);
}
value = default(T);
success = true;
}
else
{
// Optimize for internal converters by avoiding the extra call to TryRead.
if (EffectiveConverter.CanUseDirectReadOrWrite && state.Current.NumberHandling == null)
{
// CanUseDirectReadOrWrite == false when using streams
Debug.Assert(!state.IsContinuation);
value = EffectiveConverter.Read(ref reader, PropertyType, Options);
success = true;
}
else
{
success = EffectiveConverter.TryRead(ref reader, PropertyType, Options, ref state, out T? typedValue, out _);
value = typedValue;
}
}
return success;
}
private protected override void ConfigureIgnoreCondition(JsonIgnoreCondition? ignoreCondition)
{
switch (ignoreCondition)
{
case null:
break;
case JsonIgnoreCondition.Never:
ShouldSerialize = ShouldSerializeIgnoreConditionNever;
break;
case JsonIgnoreCondition.Always:
ShouldSerialize = ShouldSerializeIgnoreConditionAlways;
break;
case JsonIgnoreCondition.WhenWritingNull:
if (PropertyTypeCanBeNull)
{
ShouldSerialize = ShouldSerializeIgnoreWhenWritingDefault;
IgnoreDefaultValuesOnWrite = true;
}
else
{
ThrowHelper.ThrowInvalidOperationException_IgnoreConditionOnValueTypeInvalid(MemberName!, DeclaringType);
}
break;
case JsonIgnoreCondition.WhenWritingDefault:
ShouldSerialize = ShouldSerializeIgnoreWhenWritingDefault;
IgnoreDefaultValuesOnWrite = true;
break;
default:
Debug.Fail($"Unknown value of JsonIgnoreCondition '{ignoreCondition}'");
break;
}
static bool ShouldSerializeIgnoreConditionNever(object _, T? value) => true;
static bool ShouldSerializeIgnoreConditionAlways(object _, T? value) => false;
static bool ShouldSerializeIgnoreWhenWritingDefault(object _, T? value)
{
return default(T) is null ? value is not null : !EqualityComparer<T>.Default.Equals(default, value);
}
}
private static bool IsDefaultValue(T? value)
{
return default(T) is null ? value is null : EqualityComparer<T>.Default.Equals(default, value);
}
}
}
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