Table of Contents

Intro

NCalc is a mathematical expression evaluator in .NET. NCalc can parse any expression and evaluate the result, including static or dynamic parameters and custom functions.

Project Description

NCalc is a mathematical expression evaluator in .NET. NCalc can parse any expression and evaluate the result, including static or dynamic parameters and custom functions.

Table of Contents

  • Language: Core language reference for operators, values, functions, and parameters.
  • Evaluation: Behavioral rules and options for expression execution.
  • Runtime: Execution-focused topics like async, caching, cancellation, and logging.
  • Extensibility: Lambda compilation, dependency injection, overrides, and plugins.
  • Project: Architecture, benchmarks, changelog, and release process.

Functionalities

Simple Expressions

var expression = new Expression("2 + 3 * 5");
Debug.Assert(17 == expression.Evaluate());

.NET Data Types

Debug.Assert(123456 == new Expression("123456").Evaluate()); // integers
Debug.Assert(new DateTime(2001, 01, 01) == new Expression("#01/01/2001#").Evaluate()); // datetime
Debug.Assert(123.456 == new Expression("123.456").Evaluate()); // floating point numbers
Debug.Assert(true == new Expression("true").Evaluate()); // booleans
Debug.Assert("azerty" == new Expression("'azerty'").Evaluate()); // strings

Mathematical functional from System.Math**

Debug.Assert(0 == new Expression("Sin(0)").Evaluate());
Debug.Assert(2 == new Expression("Sqrt(4)").Evaluate());
Debug.Assert(0 == new Expression("Tan(0)").Evaluate());

Custom Functions

var expression = new Expression("SecretOperation(3, 6)");
expression.Functions["SecretOperation"] = (args) => {
    return (int)args[0].Evaluate() + (int)args[1].Evaluate();
};

Debug.Assert(9 == expression.Evaluate());

Unicode Characters

Debug.Assert("経済協力開発機構" == new Expression("'経済協力開発機構'").Evaluate());
Debug.Assert("Hello" == new Expression(@"'\u0048\u0065\u006C\u006C\u006F'").Evaluate());
Debug.Assert("だ" == new Expression(@"'\u3060'").Evaluate());
Debug.Assert("\u0100" == new Expression(@"'\u0100'").Evaluate());

Parameters - Static and Dynamic

var expression = new Expression("Round(Pow([Pi], 2) + Pow([Pi2], 2) + [X], 2)");

expression.Parameters["Pi2"] = new Expression("Pi * [Pi]");
expression.Parameters["X"] = 10;

expression.DynamicParameters["Pi"] = _ => {
    Console.WriteLine("I'm evaluating π!");
    return 3.14;
};

Debug.Assert(117.07 == expression.Evaluate());

Lambda Expressions

var expression = new Expression("1 + 2");
Func<int> function = expression.ToLambda<int>();
Debug.Assert(function()); //3

Expression Serialization

To convert an expression tree back to NCalc source text, use ToExpressionString(bool, CancellationToken). This method delegates to SerializationVisitor. In older versions it was possible using ToString(), but it's not a good practice as documented at Microsoft docs.

using NCalc;

var expression = new Expression("1 + 2");
var expressionText = expression.ToExpressionString();
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