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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.Diagnostics;
using System.Text.Json.Schema;
namespace System.Text.Json.Serialization.Converters
{
internal sealed class CharConverter : JsonPrimitiveConverter<char>
{
private const int MaxEscapedCharacterLength = JsonConstants.MaxExpansionFactorWhileEscaping;
public override char Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
if (reader.TokenType is not (JsonTokenType.String or JsonTokenType.PropertyName))
{
ThrowHelper.ThrowInvalidOperationException_ExpectedString(reader.TokenType);
}
if (!JsonHelpers.IsInRangeInclusive(reader.ValueLength, 1, MaxEscapedCharacterLength))
{
ThrowHelper.ThrowInvalidOperationException_ExpectedChar(reader.TokenType);
}
Span<char> buffer = stackalloc char[MaxEscapedCharacterLength];
int charsWritten = reader.CopyString(buffer);
if (charsWritten != 1)
{
ThrowHelper.ThrowInvalidOperationException_ExpectedChar(reader.TokenType);
}
return buffer[0];
}
public override void Write(Utf8JsonWriter writer, char value, JsonSerializerOptions options)
{
writer.WriteStringValue(
#if NET
new ReadOnlySpan<char>(in value)
#else
value.ToString()
#endif
);
}
internal override char ReadAsPropertyNameCore(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
Debug.Assert(reader.TokenType == JsonTokenType.PropertyName);
return Read(ref reader, typeToConvert, options);
}
internal override void WriteAsPropertyNameCore(Utf8JsonWriter writer, char value, JsonSerializerOptions options, bool isWritingExtensionDataProperty)
{
writer.WritePropertyName(
#if NET
new ReadOnlySpan<char>(in value)
#else
value.ToString()
#endif
);
}
internal override JsonSchema? GetSchema(JsonNumberHandling _) =>
new() { Type = JsonSchemaType.String, MinLength = 1, MaxLength = 1 };
}
}
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