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YACEP : yet another csharp expression parser
YACEP is a small and tiny csharp expression parser, can parse a valid single-line string to an abstract syntax tree. It also provides a simple compiler that can compile an abstract syntax tree to an IEvaluator instance,
IEvaluator instance can be executed as C# delegate.
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Important
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YACEP not supported multi-line expressions and will not be supported in the future. if you need multi-line expressions, my recommendation is IronLanguages |
"x+', '+y".Compile().EvaluateAs<string>(new { x = "hello", y = "world" });
// value is "hello, world"
"x + y".Compile().EvaluateAs<int>(new { x = 1, y = 2 });
// value is 3Why YACEP ?
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I found a very interesting thing when using docker, Casbin. After reading the source code of Casbin, found that Casbin used a very simple DSL to solve a series of authorization problems. You can see it on Casbin's official website. There are many implementations of the language, but the work of the .net platform Casbin-Net has been in the WIP state for long time. After reading the source code of Casbin-Net, I found that the library did not continue to write down because it could not find a good expression parser. So I used a simplified hill climbing algorithm to write a simple implementation.
Features
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Out of the box - Zero-Configuration
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Custom unary operator - support custom a string as an unary operator
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Custom binary operator - support custom a string as a binary operator and set an order for it
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Custom literal - support custom a literal as a value
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Custom function - support custom function
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Conditional expression - like ?: operator in C#
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In expression - evaluates to true if it finds a variable in an array and false otherwise
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Cross platform - build with netstandard2.0
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Small and tiny - the core parser code is only 500+ lines
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Low consumption - use ReadOnlySpan<T> Struct to read string
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High Performance - good performance to access object’s public method, field, property value instance over using C# reflection. Benchmark report
Quick Start
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Create a console application
mkdir yacep-demo cd yacep-demo dotnet new console
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add TupacAmaru.Yacep
dotnet add package TupacAmaru.Yacep
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update Program.cs
cat>Program.cs<<EOF
using TupacAmaru.Yacep.Extensions;
namespace yacep_demo
{
class Program
{
static void Main()
=> System.Console.WriteLine("x+', '+y".Compile().EvaluateAs<string>(new { x = "hello", y = "world" }));
}
}
EOF
If using a windows system, please copy the following to Program.cs
using TupacAmaru.Yacep.Extensions;
namespace yacep_demo
{
class Program
{
static void Main()
=> System.Console.WriteLine("x+', '+y".Compile().EvaluateAs<string>(new { x = "hello", y = "world" }));
}
}-
Run
dotnet run
Seeing the output hello, world means succeeded.
Build
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Clone source code
git clone https://github.com/tupac-amaru/yacep.git
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Run tests Coverlet ReportGenerator
Linux & Mac
cd yacep
./coverage.shLinux & Mac
cd yacep
./benchmark.shWindows
cd yacep
.\benchmark.batThanks
Tool&Library
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xUnit.net: a free, open source, community-focused unit testing tool for the .NET Framework
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BenchmarkDotNet: Powerful .NET library for benchmarking
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Coverlet: Cross platform code coverage for .NET Core
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ReportGenerator: ReportGenerator converts coverage reports generated by OpenCover, dotCover, Visual Studio, NCover, Cobertura, JaCoCo or Clover into human readable reports in various formats.
