https://github.com/bushero/pevac

A parser combinator library around the System.Text.Json.Utf8JsonReader class
https://github.com/bushero/pevac

csharp dotnet5 json parser parser-combinators system-text-json

Last synced: 5 months ago
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A parser combinator library around the System.Text.Json.Utf8JsonReader class

• Host: GitHub
• URL: https://github.com/bushero/pevac
• Owner: BusHero
• License: mit
• Created: 2021-08-30T21:04:42.000Z (almost 5 years ago)
• Default Branch: main
• Last Pushed: 2024-09-05T13:51:52.000Z (almost 2 years ago)
• Last Synced: 2025-08-01T04:21:28.384Z (11 months ago)
• Topics: csharp, dotnet5, json, parser, parser-combinators, system-text-json
• Language: C#
• Homepage:
• Size: 118 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# Pevac ![Some other name that doesn't matter](https://github.com/BusHero/Pevac/actions/workflows/build.yaml/badge.svg)

Pevac is a simple, lightweight library for constructing functional, forward only parsers that use [Utf8JsonReader](https://docs.microsoft.com/en-us/dotnet/api/system.text.json.utf8jsonreader) struct as the source of tokens. Parsers can then be used to simplify constuction of custom deserializers for the [System.Text.Json](https://docs.microsoft.com/en-us/dotnet/api/system.text.json). 

It is heavely inspired by the [Sprache](https://github.com/sprache/Sprache) parser combinator library! 

## Motivation

The scope of the project is to simplify building cusom deserializers for the [System.Text.Json](https://docs.microsoft.com/en-us/dotnet/api/system.text.json) by providing the posibility of building functional parsers that can consume an instance of [Utf8JsonReader](https://docs.microsoft.com/en-us/dotnet/api/system.text.json.utf8jsonreader) struct.

It is impossible to use the [Utf8JsonReader](https://docs.microsoft.com/en-us/dotnet/api/system.text.json.utf8jsonreader) with any existing parser combinator library because of the limitation imposed on the struct.

* [Utf8JsonReader](https://docs.microsoft.com/en-us/dotnet/api/system.text.json.utf8jsonreader) cannot be specified as a generic parameter.

* All the interaction with the [Utf8JsonReader](https://docs.microsoft.com/en-us/dotnet/api/system.text.json.utf8jsonreader) struct should be through a reference.

## Usage

Unlike most parser-building frameworks, you use [Pevac](#pevac) directly from your program code, and don't need to set up any build-time code generation tasks. [Pevac](#pevac) itself is a single tiny assembly.

[Pevac](#pevac) provides a number of build-in functions that can make bigger parsers from smaller once, often callable via Linq query comprehensions:

```csharp

Parser parser = from _ in Parser.StartObject

                     from propertyName in Parser.PropertyName

                     from value in Parser.String

                     from __ in Parser.EndObject

                     select new Foo(propertyName, value)

var json = "{ \"foo\" : \"bar\" }";

var bytes = Encoding.UTF8.GetBytes(foo);

var reader = new Utf8JsonReader(bytes);

var foo = parser.Parse(reader, default);

Assert.AreEqual(new Foo("foo", "bar"), foo);

```

## Credits

[![](https://avatars1.githubusercontent.com/u/1999078?v=3&s=200)](https://github.com/sprache/Sprache)