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Utf8JsonWriter.WriteValues.Float.cs
173 lines (146 loc) · 5.79 KB
/
Utf8JsonWriter.WriteValues.Float.cs
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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.Buffers;
using System.Buffers.Text;
using System.Diagnostics;
using System.Globalization;
namespace System.Text.Json
{
public sealed partial class Utf8JsonWriter
{
/// <summary>
/// Writes the <see cref="float"/> value (as a JSON number) as an element of a JSON array.
/// </summary>
/// <param name="value">The value to write.</param>
/// <exception cref="InvalidOperationException">
/// Thrown if this would result in invalid JSON being written (while validation is enabled).
/// </exception>
/// <remarks>
/// Writes the <see cref="float"/> using the default <see cref="StandardFormat"/> on .NET Core 3 or higher
/// and 'G9' on any other framework.
/// </remarks>
public void WriteNumberValue(float value)
{
JsonWriterHelper.ValidateSingle(value);
if (!_options.SkipValidation)
{
ValidateWritingValue();
}
if (_options.Indented)
{
WriteNumberValueIndented(value);
}
else
{
WriteNumberValueMinimized(value);
}
SetFlagToAddListSeparatorBeforeNextItem();
_tokenType = JsonTokenType.Number;
}
private void WriteNumberValueMinimized(float value)
{
int maxRequired = JsonConstants.MaximumFormatSingleLength + 1; // Optionally, 1 list separator
if (_memory.Length - BytesPending < maxRequired)
{
Grow(maxRequired);
}
Span<byte> output = _memory.Span;
if (_currentDepth < 0)
{
output[BytesPending++] = JsonConstants.ListSeparator;
}
bool result = TryFormatSingle(value, output.Slice(BytesPending), out int bytesWritten);
Debug.Assert(result);
BytesPending += bytesWritten;
}
private void WriteNumberValueIndented(float value)
{
int indent = Indentation;
Debug.Assert(indent <= 2 * _options.MaxDepth);
int maxRequired = indent + JsonConstants.MaximumFormatSingleLength + 1 + s_newLineLength; // Optionally, 1 list separator and 1-2 bytes for new line
if (_memory.Length - BytesPending < maxRequired)
{
Grow(maxRequired);
}
Span<byte> output = _memory.Span;
if (_currentDepth < 0)
{
output[BytesPending++] = JsonConstants.ListSeparator;
}
if (_tokenType != JsonTokenType.PropertyName)
{
if (_tokenType != JsonTokenType.None)
{
WriteNewLine(output);
}
JsonWriterHelper.WriteIndentation(output.Slice(BytesPending), indent);
BytesPending += indent;
}
bool result = TryFormatSingle(value, output.Slice(BytesPending), out int bytesWritten);
Debug.Assert(result);
BytesPending += bytesWritten;
}
private static bool TryFormatSingle(float value, Span<byte> destination, out int bytesWritten)
{
// Frameworks that are not .NET Core 3.0 or higher do not produce roundtrippable strings by
// default. Further, the Utf8Formatter on older frameworks does not support taking a precision
// specifier for 'G' nor does it represent other formats such as 'R'. As such, we duplicate
// the .NET Core 3.0 logic of forwarding to the UTF16 formatter and transcoding it back to UTF8,
// with some additional changes to remove dependencies on Span APIs which don't exist downlevel.
#if NETCOREAPP
return Utf8Formatter.TryFormat(value, destination, out bytesWritten);
#else
string utf16Text = value.ToString(JsonConstants.SingleFormatString, CultureInfo.InvariantCulture);
// Copy the value to the destination, if it's large enough.
if (utf16Text.Length > destination.Length)
{
bytesWritten = 0;
return false;
}
try
{
byte[] bytes = Encoding.UTF8.GetBytes(utf16Text);
if (bytes.Length > destination.Length)
{
bytesWritten = 0;
return false;
}
bytes.CopyTo(destination);
bytesWritten = bytes.Length;
return true;
}
catch
{
bytesWritten = 0;
return false;
}
#endif
}
internal void WriteNumberValueAsString(float value)
{
Span<byte> utf8Number = stackalloc byte[JsonConstants.MaximumFormatSingleLength];
bool result = TryFormatSingle(value, utf8Number, out int bytesWritten);
Debug.Assert(result);
WriteNumberValueAsStringUnescaped(utf8Number.Slice(0, bytesWritten));
}
internal void WriteFloatingPointConstant(float value)
{
if (float.IsNaN(value))
{
WriteNumberValueAsStringUnescaped(JsonConstants.NaNValue);
}
else if (float.IsPositiveInfinity(value))
{
WriteNumberValueAsStringUnescaped(JsonConstants.PositiveInfinityValue);
}
else if (float.IsNegativeInfinity(value))
{
WriteNumberValueAsStringUnescaped(JsonConstants.NegativeInfinityValue);
}
else
{
WriteNumberValue(value);
}
}
}
}