ArithmeticString

The tool lib of converting string into an formula, and calculate the answer.

Quick Start

using ArithmeticString.Compiling;

class Programe{
	static void Main(string[] args){
		string formula = "x + 1";
		Equation<float> equation = FloatCompile.Compile(formula);
		
		// result = 2
		Console.WriteLine(equation.PutVariable("x", 1).Solve());
	}
}

Environment

Framework: .NET Core 3.1

Tutorial

Element of Formula

• Constant

  Constant is the basic element of the formula. It must be declare as numeric characters such as 1, 2.1, ...etc.

   var formula = "x";
   var equation = FloatCompile.Compile(formula);
   
   // result = 1
   Console.WriteLine(equation.Solve());

• Variable

  Variable is detected if it's not declare as other type. After compiled the formula, we may put the variable by specific value.

   var formula = "x + 1";
   var equation = FloatCompile.Compile(formula);
   
   // result = 2
   Console.WriteLine(equation.PutVariable("x", 1).Solve());

• Operator

  Operator will calculate the left and right element of the formula. And it will follow the priority of the operator (like * = / > +, -) by default. Also, you may customize your operator and priority (see #Advance Usage).

   var formula = "1 + 2 * 3";
   var equation = FloatCompile.Compile(formula);
   
   // result = 7
   Console.WriteLine(equation.Solve());

• Function

  We can define a function if the whole formula is too long or the sub-formula is be used frequently. Define a function of the sub-formula is an efficient measure.

   var script = "square(x) = x * x; 1 + squre(3);";
   var equation = FloatCompile.Compile(formula);
   
   // result = 10
   Console.WriteLine(equation.Solve());

• Decorator

  Use the decorator to modified the result of sub-formula such as Negative.

   var formula = "1 + -2";
   var equation = FloatCompile.Compile(formula);
   
   // result = -1
   Console.WriteLine(equation.Solve());

Advanced Usage

• Custom Define Compiler

  Define custom operator by implementing IOperator<T> interface, and call the InstallOperator<T> method to install the operator with specific operator symble.

   using ArithmeticString.Compiling.Operators.Float;
   
   void Example(){
   	var compiler = new Compile<float>(new FloatParser());
   	var compiler.InstallOperator<PlusOperator>("+");
   	
   	var formula = "1 + 2";
   	var equation = compiler.Compile(formula);
   	
   	// result = 3
   	Console.WriteLine(equation.Solve());
   }
   
   class PlusOperator : IOperator<float>
   {
       public float Calculate(float x, float y)
       {
           return x + y;
       }
   }

• Function with unspecific length parameter

  If we need to define a function with unspecific parameter, we may call InstallFunc and pass the function into it.

   using ArithmeticString.Compiling.Operators.Float;
   
   void Example(){
   	var compiler = new Compile<float>(new FloatParser());
   	var compiler.InstallFunc("Sigma", Sigma);
   	
   	var formula = "Sigma(1, 2, 3)";
   	var equation = compiler.Compile(formula);
   	
   	// result = 6
   	Console.WriteLine(equation.Solve());
   }
   
   float Sigma(float[] args){
   	float sum = 0;
   	foreach(var arg in args){
   		sum += arg;
   	}
   	return sum;
   }

Future Feature

Reference

• Expression Tree (see Wiki)