add TextWriter WriteAsync and Write for StringBuilder

Author: SimonCropp

contributing.md

@@ -189,10 +189,12 @@ Example:
 // <auto-generated />
 #pragma warning disable
 
-#if FeatureMemory && (NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0)
+#if FeatureMemory
 
 namespace Polyfills;
+
 using System;
+using System.Text;
 using System.Buffers;
 using System.IO;
 using System.Runtime.InteropServices;
@@ -202,6 +204,56 @@ using System.Threading.Tasks;
 
 static partial class Polyfill
 {
+#if !NETCOREAPP3_0_OR_GREATER
+    /// <summary>
+    /// Equivalent to Write(stringBuilder.ToString()) however it uses the
+    /// StringBuilder.GetChunks() method to avoid creating the intermediate string
+    /// </summary>
+    /// <param name="value">The string (as a StringBuilder) to write to the stream</param>
+    [Link("https://learn.microsoft.com/en-us/dotnet/api/system.io.textwriter.write#system-io-textwriter-write(system-text-stringbuilder)")]
+    public static void Write(this TextWriter target, StringBuilder? value)
+    {
+        if (value != null)
+        {
+            foreach (ReadOnlyMemory<char> chunk in value.GetChunks())
+            {
+                target.Write(chunk.Span);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Equivalent to WriteAsync(stringBuilder.ToString()) however it uses the
+    /// StringBuilder.GetChunks() method to avoid creating the intermediate string
+    /// </summary>
+    /// <param name="value">The string (as a StringBuilder) to write to the stream</param>
+    /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
+    [Link("https://learn.microsoft.com/en-us/dotnet/api/system.io.textwriter.writeasync#system-io-textwriter-writeasync(system-readonlymemory((system-char))-system-threading-cancellationtoken)")]
+    public static Task WriteAsync(this TextWriter target, StringBuilder? value, CancellationToken cancellationToken = default)
+    {
+        if (cancellationToken.IsCancellationRequested)
+        {
+            return Task.FromCanceled(cancellationToken);
+        }
+
+        if (value == null)
+        {
+            return Task.CompletedTask;
+        }
+
+        return WriteAsyncCore(value, cancellationToken);
+
+        async Task WriteAsyncCore(StringBuilder builder, CancellationToken cancel)
+        {
+            foreach (ReadOnlyMemory<char> chunk in builder.GetChunks())
+            {
+                await target.WriteAsync(chunk, cancel).ConfigureAwait(false);
+            }
+        }
+    }
+#endif
+
+#if NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0
 #if FeatureValueTask
 
     /// <summary>
@@ -303,10 +355,11 @@ static partial class Polyfill
             pool.Return(array);
         }
     }
+#endif
 }
 #endif
 ```
-<sup><a href='/src/Polyfill/Polyfill_TextWriter.cs#L1-L119' title='Snippet source file'>snippet source</a> | <a href='#snippet-Polyfill_TextWriter.cs' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/Polyfill/Polyfill_TextWriter.cs#L1-L172' title='Snippet source file'>snippet source</a> | <a href='#snippet-Polyfill_TextWriter.cs' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 

src/Consume/Consume.cs

@@ -482,6 +482,17 @@ void NonGenericTaskCompletionSource()
     }
 
 #if FeatureMemory
+    async Task TextWriter()
+    {
+        TextWriter target = new StringWriter();
+        target.Write(new StringBuilder());
+        target.WriteAsync(new StringBuilder());
+        target.WriteLine("a".AsSpan());
+        await target.WriteLineAsync("a".AsMemory());
+        target.Write("a".AsSpan());
+        await target.WriteAsync("a".AsMemory());
+    }
+
     void RandomNextBytesSpan()
     {
         var random = new Random();

src/Polyfill/Polyfill_TextWriter.cs

@@ -1,10 +1,12 @@
 // <auto-generated />
 #pragma warning disable
 
-#if FeatureMemory && (NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0)
+#if FeatureMemory
 
 namespace Polyfills;
+
 using System;
+using System.Text;
 using System.Buffers;
 using System.IO;
 using System.Runtime.InteropServices;
@@ -14,6 +16,56 @@ namespace Polyfills;
 
 static partial class Polyfill
 {
+#if !NETCOREAPP3_0_OR_GREATER
+    /// <summary>
+    /// Equivalent to Write(stringBuilder.ToString()) however it uses the
+    /// StringBuilder.GetChunks() method to avoid creating the intermediate string
+    /// </summary>
+    /// <param name="value">The string (as a StringBuilder) to write to the stream</param>
+    [Link("https://learn.microsoft.com/en-us/dotnet/api/system.io.textwriter.write#system-io-textwriter-write(system-text-stringbuilder)")]
+    public static void Write(this TextWriter target, StringBuilder? value)
+    {
+        if (value != null)
+        {
+            foreach (ReadOnlyMemory<char> chunk in value.GetChunks())
+            {
+                target.Write(chunk.Span);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Equivalent to WriteAsync(stringBuilder.ToString()) however it uses the
+    /// StringBuilder.GetChunks() method to avoid creating the intermediate string
+    /// </summary>
+    /// <param name="value">The string (as a StringBuilder) to write to the stream</param>
+    /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
+    [Link("https://learn.microsoft.com/en-us/dotnet/api/system.io.textwriter.writeasync#system-io-textwriter-writeasync(system-readonlymemory((system-char))-system-threading-cancellationtoken)")]
+    public static Task WriteAsync(this TextWriter target, StringBuilder? value, CancellationToken cancellationToken = default)
+    {
+        if (cancellationToken.IsCancellationRequested)
+        {
+            return Task.FromCanceled(cancellationToken);
+        }
+
+        if (value == null)
+        {
+            return Task.CompletedTask;
+        }
+
+        return WriteAsyncCore(value, cancellationToken);
+
+        async Task WriteAsyncCore(StringBuilder builder, CancellationToken cancel)
+        {
+            foreach (ReadOnlyMemory<char> chunk in builder.GetChunks())
+            {
+                await target.WriteAsync(chunk, cancel).ConfigureAwait(false);
+            }
+        }
+    }
+#endif
+
+#if NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0
 #if FeatureValueTask
 
     /// <summary>
@@ -115,5 +167,6 @@ public static void WriteLine(
             pool.Return(array);
         }
     }
+#endif
 }
 #endif

src/Tests/PolyfillTests_TextWriter.cs

@@ -11,6 +11,28 @@ public async Task TextWriterWriteSpan()
         Assert.AreEqual("value", s);
     }
 
+    [Test]
+    public async Task TextWriterWriteStringBuilder()
+    {
+        using var stream = new MemoryStream();
+        using var writer = new StreamWriter(stream);
+        writer.Write(new StringBuilder("value"));
+        await writer.FlushAsync();
+        var s = Encoding.UTF8.GetString(stream.ToArray());
+        Assert.AreEqual("value", s);
+    }
+
+    [Test]
+    public async Task TextWriterWriteStringBuilderAsync()
+    {
+        using var stream = new MemoryStream();
+        using var writer = new StreamWriter(stream);
+        await writer.WriteAsync(new StringBuilder("value"));
+        await writer.FlushAsync();
+        var s = Encoding.UTF8.GetString(stream.ToArray());
+        Assert.AreEqual("value", s);
+    }
+
     [Test]
     public async Task TextWriterWriteLineSpan()
     {