Sprache is a simple, lightweight library for constructing parsers directly in C# code.
It doesn't compete with "industrial strength" language workbenches - it fits somewhere in between regular expressions and a full-featured toolset like ANTLR.
Unlike most parser-building frameworks, you use Sprache directly from your program code, and don't need to set up any build-time code generation tasks. Sprache itself is a single tiny assembly.
A simple parser might parse a sequence of characters:
// Parse any number of capital 'A's in a row
var parseA = Parse.Char('A').AtLeastOnce();
Sprache provides a number of built-in functions that can make bigger parsers from smaller ones, often callable via Linq query comprehensions:
Parser<string> identifier =
from leading in Parse.WhiteSpace.Many()
from first in Parse.Letter.Once()
from rest in Parse.LetterOrDigit.Many()
from trailing in Parse.WhiteSpace.Many()
select new string(first.Concat(rest).ToArray());
var id = identifier.Parse(" abc123 ");
Assert.AreEqual("abc123", id);
The best place to start is this introductory article.
Examples included with the source demonstrate:
- Parsing XML directly to a Document object
- Parsing numeric expressions to System.Linq.Expression objects
- Parsing comma-separated (CSV) 'files' into lists of strings
Parser combinators are covered extensively on the web. The original paper describing the monadic implementation by Graham Hutton and Eric Meijer is very readable. Sprache grew out of some exercises in Hutton's Haskell book.
Sprache itself draws on some great C# tutorials: