ksteensig / sharp-comb

A monadic parser combinator library implemented in C#

Sharp Comb - Monadic Parser Combinator

Sharp Comb is a monadic parser combinator library implemented in C#.

It's bundled as a library in the src folder. While in the samples folder an extremely simple example can be found.

Example

The parser library can be used through the LINQ comprehension or fluent syntax.

In this example this simple class represents an addition.

public class Addition
{
    int x;
    int y;
    public Addition(int x, int y)
    {
        this.x = x;
        this.y = y;
    }
    public void Evaluate()
    {
        Console.WriteLine(x + y);
    }
}

Then the following two parsers are implemented.

The first one Number is used to parse a number. So it returns a Parser<int>.

public static Parser<int> Number =
            from x in Parser.Integer.Text()
            select int.Parse(x);

The next one Addition is used to parse an Addition. It uses the Number parser to parse the numbers for the Addition.

public static Parser<Addition> Addition =
            from x  in Number
            from s1 in Parser.Char(' ').Many()
            from op in Parser.Char('+')
            from s2 in Parser.Char(' ').Many()
            from y  in Number.EndOfInput()
            select new Addition(x, y);

The parsing is lazily evaluated, so it's only evaluated when required.

To use the parser you need to use the public static Result<T> TryParse<T>(this Parser<T> p, string input) method which takes a parser and a string as input.