StringBuilder serialization support

Author: lucasteles

src/Backdash/Serialization/BinaryBufferReader.cs

@@ -3,6 +3,7 @@
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Text;
 using Backdash.Core;
 using Backdash.Data;
 using Backdash.Network;
@@ -75,6 +76,15 @@ Span<T> GetListSpan<T>(in List<T> values, in IObjectPool<T> pool) where T : clas
         return CollectionsMarshal.AsSpan(values);
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    ReadOnlySpan<T> AllocSpan<T>(int size) where T : struct
+    {
+        var span = CurrentBuffer[..(size * Unsafe.SizeOf<T>())];
+        Advance(size);
+        return MemoryMarshal.Cast<byte, T>(span);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
     void ReadSpan<T>(in Span<T> data) where T : struct => Read(MemoryMarshal.AsBytes(data));
 
     /// <summary>Reads single <see cref="byte"/> from buffer.</summary>
@@ -450,6 +460,17 @@ public void Read<T>(in List<T> values, IObjectPool<T> pool) where T : class, IBi
     public void Read<T>(List<T> values) where T : class, IBinarySerializable, new() =>
         Read(GetListSpan(in values, in DefaultObjectPool<T>.Instance));
 
+    /// <summary>
+    /// Reads a StringBuilder into <paramref name="values"/> from buffer.
+    /// </summary>
+    public void Read(in StringBuilder values)
+    {
+        var size = ReadInt32();
+        var chars = AllocSpan<char>(size);
+        values.Clear();
+        values.Append(chars);
+    }
+
     /// <inheritdoc cref="ReadByte()"/>
     public void Read(ref byte value) => value = ReadByte();
 

src/Backdash/Serialization/BinaryBufferWriter.cs

@@ -4,6 +4,7 @@
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Text;
 using Backdash.Core;
 using Backdash.Network;
 
@@ -51,6 +52,15 @@ Span<T> AllocSpan<T>(in ReadOnlySpan<T> value) where T : unmanaged
         return result;
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    Span<T> AllocSpan<T>(int size) where T : unmanaged
+    {
+        var sizeBytes = Unsafe.SizeOf<T>() * size;
+        var result = MemoryMarshal.Cast<byte, T>(buffer.GetSpan(sizeBytes));
+        Advance(sizeBytes);
+        return result;
+    }
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     Span<T> GetListSpan<T>(in List<T> values)
     {
@@ -525,6 +535,14 @@ public void Write<T>(in T[] values) where T : IBinarySerializable =>
     /// <typeparam name="T">A type that implements <see cref="IBinarySerializable"/>.</typeparam>
     public void Write<T>(in List<T> values) where T : IBinarySerializable => Write<T>(GetListSpan(in values));
 
+    /// <summary>Writes an <see cref="StringBuilder"/> <paramref name="value"/> into buffer.</summary>
+    public void Write(in StringBuilder value)
+    {
+        var len = value.Length;
+        Write(len);
+        value.CopyTo(0, AllocSpan<char>(len), len);
+    }
+
     /// <summary>Writes an unmanaged struct into buffer.</summary>
     public void WriteStruct<T>(in T value) where T : unmanaged => Write(Mem.AsBytes(in value));
 
@@ -547,7 +565,21 @@ public void WriteStruct<T>(in T? value) where T : unmanaged
     }
 
     /// <summary>Writes an <see cref="string"/> <paramref name="value"/> into buffer.</summary>
-    public void WriteString(in string value) => Write(value.AsSpan());
+    public void WriteString(in string value, int size)
+    {
+        var chars = value.AsSpan();
+        if (chars.Length >= size)
+        {
+            Write(chars[..size]);
+        }
+        else
+        {
+            Write(chars);
+            Span<char> nullChars = stackalloc char[size - chars.Length];
+            nullChars.Fill(' ');
+            Write(nullChars);
+        }
+    }
 
     /// <summary>Writes an <see cref="string"/> <paramref name="value"/> into buffer as UTF8.</summary>
     public void WriteUtf8String(in ReadOnlySpan<char> value)

tests/Backdash.Tests/Specs/Unit/Serialization/BinaryBufferReadWriteSpanTests.cs

@@ -1,5 +1,6 @@
 using System.Buffers;
 using System.Runtime.CompilerServices;
+using System.Text;
 using Backdash.Network;
 using Backdash.Serialization;
 using Backdash.Tests.TestUtils;
@@ -225,18 +226,33 @@ public bool SpanOfUtf8Bytes(NonEmptyString input, Endianness endianness)
     }
 
     [PropertyTest]
-    public bool String(NonEmptyString input, Endianness endianness)
+    public bool String(NonEmptyString input, PositiveInt stringSize)
     {
         var value = input.Item;
+        var size = stringSize.Item;
 
-        var size = Setup(value.ToCharArray(), endianness, out var writer);
-        writer.WriteString(value);
+        Setup(Endianness.LittleEndian, out var writer);
+        writer.WriteString(value, size);
         var reader = GetReader(writer);
 
-        var result = reader.ReadString(value.Length);
+        var result = reader.ReadString(size);
 
-        reader.ReadCount.Should().Be(size);
-        return string.Equals(value, result);
+        if (value.Length > size)
+            value = value[..size];
+
+        return string.Equals(value.Trim(), result.Trim());
+    }
+
+    [PropertyTest]
+    public bool StringBuilder(StringBuilder value, StringBuilder read)
+    {
+        Setup(Endianness.LittleEndian, out var writer);
+        writer.Write(in value);
+
+        var reader = GetReader(writer);
+        reader.Read(in read);
+
+        return string.Equals(value.ToString(), read.ToString());
     }
 
     [PropertyTest]
@@ -457,6 +473,16 @@ out BinaryBufferWriter writer
         return size;
     }
 
+    static void Setup(
+        Endianness endianness,
+        out BinaryBufferWriter writer
+    )
+    {
+        readOffset = 0;
+        ArrayBufferWriter<byte> buffer = new();
+        writer = new(buffer, endianness);
+    }
+
     static BinaryBufferReader GetReader(in BinaryBufferWriter writer)
     {
         var buffer = (ArrayBufferWriter<byte>)writer.Buffer;

tests/Backdash.Tests/TestUtils/TestGenerators.cs

@@ -1,5 +1,6 @@
 using System.Drawing;
 using System.Numerics;
+using System.Text;
 using Backdash.Core;
 using Backdash.Data;
 using Backdash.Network.Messages;
@@ -77,6 +78,11 @@ from y in Generate<int>()
         select new Point(x, y)
     );
 
+    public static Arbitrary<StringBuilder> StringBuilderGenerator() => Arb.From(
+        from s in Generate<string>()
+        select new StringBuilder(s)
+    );
+
     public static Arbitrary<SimpleStructData> SimpleStructDataGenerator(
         Arbitrary<Point> pointGenerator
     ) =>