ZString

Zero Allocation StringBuilder for .NET Core and Unity.

Struct StringBuilder to avoid allocation of builder itself
Rent write buffer from ThreadStatic or ArrayPool
All append methods are generics(Append<T>(T value)) and write to buffer directly instead of concatenate value.ToString
T1~T16 AppendFormat(AppendFormat<T1,...,T16>(string format, T1 arg1, ..., T16 arg16) avoids boxing of struct argument
Also T1~T16 Concat(Concat<T1,...,T16>(T1 arg1, ..., T16 arg16)) avoid boxing and value.ToString allocation
Convenient ZString.Format/Concat/Join methods can replace instead of String.Format/Concat/Join
Can build both Utf16(Span<char>) and Utf8(Span<byte>) directly
Can use inner buffer to avoid allocate final string
Integrated with Unity TextMeshPro to avoid string allocation

This graph compares following codes.

"x:" + x + " y:" + y + " z:" + z
ZString.Concat("x:", x, " y:", y, " z:", z)
string.Format("x:{0} y:{1} z:{2}", x, y, z)
ZString.Format("x:{0} y:{1} z:{2}", x, y, z)
new StringBuilder(), Append(), .ToString()
ZString.CreateStringBuilder(), Append(), .ToString()

"x:" + x + " y:" + y + " z:" + z is converted to String.Concat(new []{ "x:", x.ToString(), " y:", y.ToString(), " z:", z.ToString() }) by C# compiler. It has each .ToString allocation and params array allocation. string.Format calls String.Format(string, object, object, object) so each arguments causes int -> object boxing.

All ZString methods only allocate final string. Also, ZString has enabled to access inner buffer so if output target has stringless api(like Unity TextMeshPro's SetCharArray), you can achieve completely zero allocation.

The blog post of detailed explanation by author: medium@neuecc/ZString

Related project for loggin using with ZString, Cysharp/ZLogger - Zero Allocation Text/Strcutured Logger.

Getting Started
Reference
Unity
Advanced Tips
License

Getting Started

For .NET Core, use NuGet.

PM> Install-Package ZString

For Unity, check the releases page, download ZString.Unity.unitypackage.

using Cysharp.Text; // namespace

async void Example(int x, int y, int z)
{
    // same as x + y + z
    _ = ZString.Concat(x, y, z);

    // also can use numeric format strings
    _ = ZString.Format("x:{0}, y:{1:000}, z:{2:P}",x, y, z);

    _ = ZString.Join(',', x, y, z);

    // for Unity, direct write(avoid string allocation completely) to TextMeshPro
    tmp.SetTextFormat("Position: {0}, {1}, {2}", x, y, z);

    // create StringBuilder
    using(var sb = ZString.CreateStringBuilder())
    {
        sb.Append("foo");
        sb.AppendLine(42);
        sb.AppendFormat("{0} {1:.###}", "bar", 123.456789);

        // and build final string
        var str = sb.ToString();

        // for Unity, direct write to TextMeshPro
        tmp.SetText(sb);

        // write to destination buffer
        sb.TryCopyTo(dest, out var written);
    }

    // prepare format, return value should store to field(like RegexOptions.Compile)
    var prepared = ZString.PrepareUtf16<int, int>("x:{0}, y:{1:000}");
    _ = prepared.Format(10, 20);

    // C# 8.0, Using declarations
    // create Utf8 StringBuilder that build Utf8 directly to avoid encoding
    using var sb2 = ZString.CreateUtf8StringBuilder();

    sb2.AppendFormat("foo:{0} bar:{1}", x, y);

    // directly write to steam or dest to avoid allocation
    await sb2.WriteToAsync(stream);
    sb2.CopyTo(bufferWritter);
    sb2.TryCopyTo(dest, out var written);
}

Reference

static class ZString

struct Utf16ValueStringBuilder : IBufferWriter<char>, IDisposable

struct Utf8ValueStringBuilder : IBufferWriter<byte>, IDisposable

ZString

Install / Use

README

ZString

Table of Contents

Getting Started

Reference