EvalExpression

An arithmetic expression evaluator built using .NET

Supports:

• Integers, decimal numbers
  • 420, 1.23
• Addition, Subtraction, Multiplication, Division, Exponentiation
  • +, -, *, /, ^
• Negative numbers
  • -(2), -2
• Parenthesized expressions
  • 2*(1+3)
• Implicit multiplication
  • -2(3+1)
• Extendability
  • Parser implemented as a recursive descent parser

Usage sample:

• Calculate the result on an expression:

  using EvalExpression.Extensions;
  using @eval = EvalExpression.EvalExpression;
  
  var expression = "-(1-(2.5+3*2)^(4/2))";
  
  var result = @eval
      .Build(expression) // builds the AST
      .Evaluate(); // evaluates the AST
  
  // Will output: Expression '-(1-(2.5+3*2)^(4/2))' resolves to: 71.25
  Console.WriteLine($"Expression '{expression}' resolves to: {result}");

• Convert the AST to JSON:

  using EvalExpression.Extensions;
  using @eval = EvalExpression.EvalExpression;
  
  var result = @eval
      .Build("-(1-(2.5+3*2)^(4/2))")
      .ToJsonString(); // serializes to JSON

Prerequisites:

• .NET 8 SDK
• Visual Studio or other IDE

Getting started:

• Clone this repo git clone https://github.com/dariomrk/eval-expression.git
• The source (/src) is comprised of four projects:
  • Lexer: converts the string expression into tokens
  • Parser: builds an abstract syntax tree
  • Interpreter: evaluates the tree
  • EvalExpression: provides an easy to use API
• The code is tested with unit & integration tests (/test)
  • Run them with dotnet test or using the integrated test explorer of your IDE