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Mathematical expressions evaluator that supports math functions and enumerators, using only `System`.
Mathematical expressions evaluator that supports math and enumerable functions, using only System
,
from the lexer to the parser with no bizarre regex.
dotnet add package Eval.cs
using System;
using Eval;
// csharp prefixes can be omitted and lower cased
Console.WriteLine(Evaluator.Evaluate("-2 + pi - Ceiling(3.2)"));
// Everything is called like functions
Console.WriteLine(Evaluator.Evaluate("IEnumerable.Average(2, 3, 5)"));
Console.WriteLine(Evaluator.Evaluate("pow(-average(2, 3, 5), -5)"));
Console.WriteLine(Evaluator.Evaluate("19e-11 /- 12");
Console.WriteLine(Evaluator.Evaluate("last(4, last(1, 2), 5)");
Console.WriteLine(Evaluator.Evaluate("921.315 * -20.93 % 34.567");
Console.WriteLine(Evaluator.Evaluate(" 9>>3 /+ 1.2");
There are two custom exceptions, catch the rest as general exceptions that have a message
Means that the passed string is not a valid expression
Type | Property | Description |
---|---|---|
string | Src | the expression |
int | Offset | the offset before the error, specialy useful for pointing where the error has happened |
int | Length | the length of the wrong value or function |
string | Message | the cause of the exception, eg: "Closing unexsistent paren" |
Means that the wrong of arguments was passed to a function
Type | Property | Description |
---|---|---|
string | Src | same as InvalidExpressionException |
int | Offset | same as InvalidExpressionException |
int | Length | same as InvalidExpressionException |
string | Message | the message: $"Function () expects Expected arguments but received Received " |
string | Function | name of the failed function |
int | Expected | expected amount of arguments |
int | Received | received amount of arguments |
Should not happen unless there is a logical problem with this evaluator
Throw like an general Exception that has a message
A text based exception
pow() expects 2 arguments but received 3
Math.Pow(1, 2, 3) - 4
^~~~~~~~~~~~~~~~^
using Eval;
using System;
static string ErrorMsg(string message, string src, int offset, int length)
{
if (length < 1)
{
return $"{message}";
}
var marker = new string(' ', offset);
if (length == 1)
{
marker += "^";
}
else if (length == 2)
{
marker += "^^";
}
else if (length > 2)
{
marker += $"^{new('~', length - 2)}^";
}
return $"{message}\n{src}\n{marker}";
}
try
{
var result = Evaluator.Evaluate("Math.Pow(1, 2, 3) - 4");
}
catch (Exception e)
{
Console.WriteLine(
e switch
{
InvalidExpressionException ie => ErrorMsg(ie.Message, ie.Src, ie.Offset, ie.Length),
ArgumentAmountException ae => ErrorMsg(ae.Message, ae.Src, ae.Offset, ae.Length),
_ => e.Message
}
);
}
Generates simple math expressions, does not generate functions and parens.
Code to test the lexer, evaluation and exceptions.
FAQs
Mathematical expressions evaluator that supports math functions and enumerators, using only `System`.
We found that eval.cs demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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