https://github.com/ZingBallyhoo/StackXML

Stack based zero-allocation XML serializer and deserializer powered by C# 9 source generators
https://github.com/ZingBallyhoo/StackXML

csharp csharp-sourcegenerator dotnet roslyn source-generation source-generators xml

Last synced: 3 months ago
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Stack based zero-allocation XML serializer and deserializer powered by C# 9 source generators

• Host: GitHub
• URL: https://github.com/ZingBallyhoo/StackXML
• Owner: ZingBallyhoo
• License: mit
• Created: 2020-11-28T16:04:19.000Z (almost 4 years ago)
• Default Branch: master
• Last Pushed: 2022-11-21T18:48:01.000Z (almost 2 years ago)
• Last Synced: 2024-05-12T12:41:15.829Z (6 months ago)
• Topics: csharp, csharp-sourcegenerator, dotnet, roslyn, source-generation, source-generators, xml
• Language: C#
• Homepage:
• Size: 63.5 KB
• Stars: 41
• Watchers: 5
• Forks: 8
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

Awesome Lists containing this project

• RSCG_Examples - StackXML
• csharp-source-generators - StackXML -   Stack based zero-allocation XML serializer and deserializer. (Source Generators / Serialization)

README

        
# StackXML

Stack based zero*-allocation XML serializer and deserializer powered by C# 9 source generators.

## Why

Premature optimisation :)

## Setup

- StackXML targets netstandard2.1 which means back to .NET Core 3.0 is supported, but I would recommend .NET 5

- Add the following to your project to reference the serializer and enable the source generator

```xml

    

    

``` 

- The common entrypoint for deserializing is `XmlReadBuffer.ReadStatic(ReadOnlySpan)`

- The common entrypoint for serializing is `XmlWriteBuffer.SerializeStatic(IXmlSerializable)`

  - This method returns a string, to avoid this allocation you will need create your own instance of XmlWriteBuffer and ensure it is disposed safely like `SerializeStatic` does. The `ToSpan` method returns the char span containing the serialized text

## Features

- Fully structured XML serialization and deserialization with 0 allocations, apart from the output data structure when deserializing. Serialization uses a pooled buffer from `ArrayPool.Shared` that is released when the serializer is disposed.

  - `XmlReadBuffer` handles deserialization

  - `XmlWriteBuffer` handles serialization

  - `XmlCls` maps a type to an element

    - Used for the serializer to know what the element name should be

    - Used by the deserializer to map to IXmlSerializable bodies with no explicit name

  - `XmlField` maps to attributes

  - `XmlBody` maps to child elements

  - `IXmlSerializable` (not actually an interface, see quirks) represents a type that can be read from or written to XML

    - Can be manually added as a base, or the source generator will add it automatically to any type that has XML attributes

- Parsing delimited attributes into typed lists

  - ``

  - `[XmlField("list")] [XmlSplitStr(',')] public List m_list;`

  - Using StrReader and StrWriter, see below

- StrReader and StrWriter classes, for reading and writing (comma usually) delimited strings with 0 allocations.

  - Can be used in a fully structured way by adding `StrField` attributes to fields on a `ref partial struct` (not compatible with XmlSplitStr, maybe future consideration)

- Agnostic logging through [LibLog](https://github.com/damianh/LibLog)

## Quirks

- Invalid data between elements is ignored

  - `anything here is completely missed`

- Spaces between attributes is not required by the deserializer

  - e.g `` 

- XmlSerializer must be disposed otherwise the pooled buffer will be leaked.

  - XmlSerializer.SerializeStatic gives of an example of how this should be done in a safe way

- Data types can only be classes, not structs.

  - All types must inherit from IXmlSerializable (either manually or added by the source generator) which is actually an abstract class and not an interface

  - Using structs would be possible but I don't think its worth the box

- Types from another assembly can't be used as a field/body. Needs fixing

- All elements in the data to parse must be defined in the type in one way or another, otherwise an exception will be thrown.

  - The deserializer relies on complete parsing and has no way of skipping elements

- Comments within a primitive type body will cause the parser to crash (future consideration...)

  - `hi`

- Null strings are currently output exactly the same as empty strings... might need changing

- The source generator emits a parameterless constructor on all XML types that initializes `List` bodies to an empty list

  - Trying to serialize a null list currently crashes the serializer....

- When decoding XML text an extra allocation of the input string is required

  - WebUtility.HtmlDecode does not provide an overload taking a span, but the method taking a string turns it into a span anyway.. hmm

  - The decode is avoided where possible

- Would be nice to be able to use [ValueStringBuilder](https://github.com/dotnet/runtime/blob/master/src/libraries/Common/src/System/Text/ValueStringBuilder.cs). See https://github.com/dotnet/runtime/issues/25587

## Performance

Very simple benchmark, loading a single element and getting the string value of its attribute `attribute`

``` ini

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.17134.1845 (1803/April2018Update/Redstone4)

Intel Core i5-6600K CPU 3.50GHz (Skylake), 1 CPU, 4 logical and 4 physical cores

.NET Core SDK=5.0.100

  [Host]     : .NET Core 5.0.0 (CoreCLR 5.0.20.51904, CoreFX 5.0.20.51904), X64 RyuJIT

  DefaultJob : .NET Core 5.0.0 (CoreC CoreCLRLR 5.0.20.51904, CoreFX 5.0.20.51904), X64 RyuJIT

```

|        Method |         Mean |      Error |     StdDev |  Ratio | RatioSD |  Gen 0 | Gen 1 | Gen 2 | Allocated |

|-------------- |-------------:|-----------:|-----------:|-------:|--------:|-------:|------:|------:|----------:|

|    ReadBuffer |     95.81 ns |   0.983 ns |   0.872 ns |   1.00 |    0.00 | 0.0178 |     - |     - |      56 B |

|    XmlReader  |  1,866.22 ns |  37.250 ns |  79.383 ns |  19.57 |    0.87 | 3.3216 |     - |     - |   10424 B |

|    XDocument  |  2,286.97 ns |  45.784 ns | 124.560 ns |  24.48 |    1.16 | 3.4313 |     - |     - |   10776 B |

|   XmlDocument |  2,869.48 ns |  44.058 ns |  39.057 ns |  29.96 |    0.60 | 3.9196 |     - |     - |   12328 B |

| XmlSerializer | 10,386.07 ns | 152.481 ns | 142.631 ns | 108.44 |    1.49 | 4.7150 |     - |     - |   14882 B |

## Example data classes

### Simple Attribute

```xml

```

```csharp

[XmlCls("test"))]

public partial class Test

{

    [XmlField("attribute")]

    public string m_attribute;

}

```

### Text body

```xml

    

```

CData can be configured by setting `cdataMode` for serializing and deserializing

```xml

    Hello world

```

```csharp

[XmlCls("test2"))]

public partial class Test2

{

    [XmlBody("name")]

    public string m_name;

}

```

### Lists

```xml

    

    

    

    

```

```csharp

[XmlCls("listItem"))]

public partial class ListItem

{

    [XmlField("name")]

    public string m_name;

    

    [XmlField("age")]

    public int m_age; // could also be byte, uint etc

}

[XmlCls("container")]

public partial class ListContainer

{

    [XmlBody()]

    public List m_items; // no explicit name, is taken from XmlCls

}

```

### Delimited attributes

```xml

    

    cool

    awesome

    fresh

```

```csharp

[XmlCls("musicTrack"))]

public partial class MusicTrack

{

    [XmlField("id")]

    public int m_id;

    

    [XmlBody("n")]

    public string m_name;

    

    [XmlField("artists"), XmlSplitStr(',')]

    public List m_artists;

    

    [XmlBody("tags")]

    public List m_tags;

}

```