Function

The function class is the entry point for Just Functional it can be constructed in several ways.

//Using the default Configuration:
string fx = "(X*4)^2";

var f1 = new Function(fx);
var evaluationContext = new EvaluationContext(new Dictionary<string, decimal> { ["X"] = 3 });
var result = f1.Evaluate(evaluationContext);

Console.WriteLine(result);//output: 144

//Using the Options Directly:
string fx = "(X*4)^2";

var options = new FunctionOptions(
    evaluatorProvider: new CompiledExpressionEvaluatorFactory(),
    tokensProvider: new DefaultTokensProvider(),
    variablesProvider: null,
    cultureProvider: new CultureProvider()
);

var f2 = new Function(fx, options);
var evaluationContext = new EvaluationContext(new Dictionary<string, decimal> { ["X"] = 3 });
var result = f2.Evaluate(evaluationContext);

Console.WriteLine(result);//output: 144

// Using the Factory:
string fx = "(X*4)^2";

var factory = FunctionFactoryBuilder.ConfigureFactory(options =>
{
    options
        .WithEvaluationContextVariablesProvider()
        .WithDefaultsTokenProvider()
        .WithCompiledEvaluator()
        .WithSystemProvidedCulture();
});

var f3 = factory.Create(fx);
var evaluationContext = new EvaluationContext(new Dictionary<string, decimal> { ["X"] = 3 });
var result = f3.Evaluate(evaluationContext);

Console.WriteLine(result);//output: 144

In the code above f1, f2, f3 are using the same configuration.

Evaluation Context

The EvaluatorContext class is the way you supply values to variables at runtime and is really straight-forward to use.

//Using Constructor:
var context1 = new EvaluationContext(new Dictionary<string, decimal> { ["X"] = 3 });

//Registering variables manually:
var context2 = new EvaluationContext();
context2.RegisterVariable("X", 3);

The code above shows you how you can create a context with “X=3”.

Note that you can create an empty EvaluationContext when you need to evaluate a Function with no variables.

What’s next

You can learn the more about the Operands or go to the docs.