SimulationTree.ExpressionMachine 0.3.9

Prefix Reserved

dotnet add package SimulationTree.ExpressionMachine --version 0.3.9

NuGet\Install-Package SimulationTree.ExpressionMachine -Version 0.3.9

This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.

<PackageReference Include="SimulationTree.ExpressionMachine" Version="0.3.9" />

For projects that support PackageReference, copy this XML node into the project file to reference the package.

<PackageVersion Include="SimulationTree.ExpressionMachine" Version="0.3.9" />
                    

                            Directory.Packages.props

<PackageReference Include="SimulationTree.ExpressionMachine" />
                    

                            Project file

For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package.

paket add SimulationTree.ExpressionMachine --version 0.3.9

The NuGet Team does not provide support for this client. Please contact its maintainers for support.

#r "nuget: SimulationTree.ExpressionMachine, 0.3.9"

#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.

#:package SimulationTree.ExpressionMachine@0.3.9

#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package.

#addin nuget:?package=SimulationTree.ExpressionMachine&version=0.3.9
                    

                            Install as a Cake Addin

#tool nuget:?package=SimulationTree.ExpressionMachine&version=0.3.9
                    

                            Install as a Cake Tool

The NuGet Team does not provide support for this client. Please contact its maintainers for support.

Expression Machine

Library for evaluating logic expressions at runtime.

Features

Basic arithmetic operations (addition, subtraction, multiplication, division)
Parentheses for grouping operations
Injectable float variables
Injectable functions accepting one or no input arguments

Example

Below is an example that fills a destination span with coordinates for the points of a circle, with either a radius or a diameter as input. While reusing the same machine instance by modifying its source and variables, and re-evaluating the expression.

public void GetCirclePositions(float radius, Span<Vector2> positions)
{
    using Machine vm = new();
    vm.SetVariable("value", value);
    vm.SetFunction("cos", MathF.Cos);
    vm.SetFunction("sin", MathF.Sin);

    int length = positions.Length;
    for (int i = 0; i < length; i++)
    {
        float t = i * MathF.PI / (length * 0.5f);
        vm.SetVariable("t", t);
        vm.SetSource("cos(t) * radius");
        float x = vm.Evaluate();    
        vm.SetSource("sin(t) * radius");
        float y = vm.Evaluate();
        positions[i] = new Vector2(x, y);
    }
}

Checking for compilation issues

When a text source is assigned to the machine, it returns a compilation result. This result value can be used to check if there were issues. And can do so with the try-do pattern:

if (vm.TrySetSource("5 +", out Exception? exception))
{
    //success
}
else
{
    //error
    throw exception;
}

Contributions and direction

This library is small and isn't mean to substitute things like Lua or other languages within interpreters. Instead, it's more fitting as a base to extend upon and branch away. And it should remain as unmanaged as it is. Without extending it, it's most useful fruit is allowing your code to express different values, all through a single C# variable via different expressions.

Contributions that align with this are welcome.

Product	Compatible and additional computed target framework versions.
.NET	net9.0 is compatible. net9.0-android was computed. net9.0-browser was computed. net9.0-ios was computed. net9.0-maccatalyst was computed. net9.0-macos was computed. net9.0-tvos was computed. net9.0-windows was computed. net10.0 was computed. net10.0-android was computed. net10.0-browser was computed. net10.0-ios was computed. net10.0-maccatalyst was computed. net10.0-macos was computed. net10.0-tvos was computed. net10.0-windows was computed.

Product

.NET

Compatible target framework(s)

Included target framework(s) (in package)

Learn more about Target Frameworks and .NET Standard.

net9.0
- SimulationTree.Collections (>= 0.3.9)
- SimulationTree.Unmanaged.Core (>= 0.3.9)

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version	Downloads	Last Updated
0.3.9	187	9/24/2025