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Fix and simplify WriteAllTextAsync implementation #55

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Merged
rameel merged 1 commit into from
Mar 21, 2026
Merged

Fix and simplify WriteAllTextAsync implementation #55

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35 changes: 3 additions & 32 deletions src/Ramstack.FileSystem.Abstractions/VirtualFileExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -263,7 +263,7 @@ static void Error_EndOfStream() =>
/// A <see cref="ValueTask"/> representing the asynchronous operation.
/// </returns>
public static ValueTask WriteAllTextAsync(this VirtualFile file, string contents, CancellationToken cancellationToken = default) =>
WriteAllTextAsync(file, contents.AsMemory(), Utf8NoBom, cancellationToken);
WriteAllTextAsync(file, contents.AsMemory(), encoding: null, cancellationToken);

/// <summary>
/// Asynchronously writes the specified string to the current file. If the file already exists, it is truncated and overwritten.
Expand Down Expand Up @@ -302,38 +302,9 @@ public static ValueTask WriteAllTextAsync(this VirtualFile file, ReadOnlyMemory<
/// </returns>
public static async ValueTask WriteAllTextAsync(this VirtualFile file, ReadOnlyMemory<char> contents, Encoding? encoding, CancellationToken cancellationToken = default)
{
const int ChunkSize = 8192;

if (contents.IsEmpty)
return;

encoding ??= Utf8NoBom;
var stream = await file.OpenWriteAsync(cancellationToken).ConfigureAwait(false);

var preamble = encoding.GetPreamble();
if (preamble.Length != 0)
stream.Write(preamble.AsSpan());

var bytes = ArrayPool<byte>.Shared.Rent(
encoding.GetMaxCharCount(Math.Min(ChunkSize, contents.Length)));

try
{
var encoder = encoding.GetEncoder();
while (contents.Length != 0)
{
var data = contents[..Math.Min(ChunkSize, contents.Length)];
contents = contents[data.Length..];

var encoded = encoder.GetBytes(data.Span, bytes.AsSpan(), flush: contents.IsEmpty);
await stream.WriteAsync(bytes.AsMemory(0, encoded), cancellationToken).ConfigureAwait(false);
}
}
finally
{
await stream.DisposeAsync().ConfigureAwait(false);
ArrayPool<byte>.Shared.Return(bytes);
}
await using var writer = new StreamWriter(stream, encoding!);
await writer.WriteAsync(contents, cancellationToken).ConfigureAwait(false);
}

/// <summary>
Expand Down
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