MutString

An alternative to the System.Text.StringBuilder C# class. Modified version of LiteStringBuilder.

Why?

Because System.Text.StringBuilder does a lot of unnecessary memory allocation when appending data and is overall slow with its implementations. It is also not always continuous data but instead spread across in chunks, disallowing the use of Span. MutString is designed for smaller strings that are frequently modified instead of document-sized text.

Possible Improvements

MutString is faster than LiteStringBuilder with major changes to the existing methods. Some of the implementations are based on String's source code. Even with those changes, there are still possibilities for improvement.

Single, Double, Decimal

Floats currently relies on .ToString because it uses Dragon4, which is hard to compete with. .NET does not in the latest version expose any of the methods used to implement it, and has too many dependencies realistically to copy.

Params Append

It currently loops and individually appends each element. This could be improved by allocating enough space before appending.

Trim Character

Trim, TrimStart and TrimEnd is supported for removing empty space. String supports trimming by specified characters which MutString does not support.

Append Join

System.Text.StringBuilder supports appending multiple elements with separators which MutString lacks.

String Comparison

It currently does not support StringComparison for many of its methods which would benefit from it. Implementing StringComparison in a performative way is not easy and would most likely need different algorithms depending on the comparison type.

Performance

Benchmark Test

.NET 7

BenchmarkDotNet v0.13.7, Windows 11 (10.0.22621.2134/22H2/2022Update/SunValley2)
AMD Ryzen 7 7700, 1 CPU, 16 logical and 8 physical cores
.NET SDK 7.0.400
  [Host]     : .NET 7.0.10 (7.0.1023.36312), X64 RyuJIT AVX2
  DefaultJob : .NET 7.0.10 (7.0.1023.36312), X64 RyuJIT AVX2

Method	Mean	Error	StdDev	Gen0	Gen1	Allocated
StringReplace	58.74 ns	0.269 ns	0.239 ns	0.0143	-	240 B
StringPlusOperation	114.86 ns	0.401 ns	0.335 ns	0.0181	-	304 B
StringInterpolation	117.50 ns	0.981 ns	0.819 ns	0.0067	-	112 B
MutStringAppend	131.50 ns	0.499 ns	0.466 ns	0.0143	-	240 B
StringConcat	141.66 ns	1.172 ns	1.096 ns	0.0315	-	528 B
StringJoin	156.69 ns	1.015 ns	0.950 ns	0.0272	-	456 B
MutStringReplace	162.85 ns	0.284 ns	0.237 ns	0.0110	-	184 B
StringBuilderAppend	200.80 ns	1.231 ns	1.152 ns	0.0257	-	432 B
LargeStringPlusOperation	205.03 ns	4.108 ns	5.484 ns	0.4795	-	8024 B
LargeStringConcat	214.53 ns	4.170 ns	4.283 ns	0.4795	-	8024 B
LargeStringBuilderAppend	275.13 ns	4.988 ns	5.122 ns	0.4959	0.0153	8296 B
PrimitiveMutStringAppend	353.22 ns	2.398 ns	2.243 ns	0.0296	-	496 B
LargeMutStringAppend	368.39 ns	7.036 ns	6.582 ns	0.4935	-	8248 B
PrimitiveStringConcat	383.77 ns	2.725 ns	2.549 ns	0.0648	-	1088 B
PrimitiveStringInterpolated	402.43 ns	1.352 ns	1.199 ns	0.0172	-	288 B
PrimitiveStringBuilderAppend	410.15 ns	2.230 ns	2.086 ns	0.0334	-	560 B
PrimitiveStringPlusOperation	427.88 ns	1.576 ns	1.316 ns	0.0515	-	864 B
LargeStringInterpolated	440.49 ns	8.043 ns	7.524 ns	0.4792	-	8024 B
StringBuilderReplace	754.67 ns	15.028 ns	17.306 ns	0.0219	-	368 B

Supported Platforms

• .NET Core 6.0+
• .NET Framework 4.6+
• .NET Standard 1.3+

How to Use it

Install the Nuget package:

    dotnet add package Celezt.Text.MutString --version 2.2.0

Package

Or reference the MutString.dll assembly that matches your app's platform.

Creating MutString

    using Celezt.String;
    
    // Create through instance.
    var ms = new MutString();
    
    // Or through static call (will create a new instance).
    var ms = MutString.Create();
    
    // Can create an instance with buffer pool size.
    var ms = new MutString(500);
    
    // Can create an instance with an initial string value.
    var ms = new MutString("Hello World");
    

Using MutString

    // Retrieve an instance from the pool.
    var ms = MutString.Create();
    
    ms.Append("Cost: ")
      .Append(32.11)
      .Append(" Sent: ")
      .Append(false);
	
    ms[0] = 'A';
    char chr = ms[0];
	
    ms.Span.Fill('B');
    
    // Return instance of string.
    ms.ToString();