ParserObjects

ParserObjects is a library for object-based parsers, combinators, parsing utilities and abstractions. See the Documentation for more details on usage.

Install-Package ParserObjects

See the Test Suite Examples for some examples of usage.

Project Goals

This project has several goals:

1. To enable composing of parsers from smaller building blocks
2. To enable crafting of parsers using a variety of techniques and algorithms, whichever is the best fit for your project
3. To use streaming input from a variety of sources, instead of reading data into fixed memory buffers
4. To be generic as much as possible, supporting common string-parsing algorithms but also being extensible to any structured input type
5. Using good interface design to encourage proper use and good code style
6. To provide an easy on-ramp for people who need to parse data, but are not experts in parsing theory

Sequences and Parsers

An ISequence is similar to an IEnumerable or IEnumerator in concept, though with a focus on supporting parsing operations. Sequences allow you to GetNext() items one at a time, to Peek() at items without consuming them, and rewind the sequence to a previous location. There are many ways to create a sequence:

using static ParserObjects.Sequences;

// Turn an existing IReadOnlyList<T> into an ISequence<T>
var sequence = FromList(myList);

// Get a character sequence from a string
var sequence = FromString("...");

// Get a character sequence from a file or stream
var sequence = FromCharacterFile("fileName.txt");
var sequence = FromCharacterStream(myStream);

An IParser is an object that attempts to match a pattern in an input sequence. If the pattern is matched, the items will be consumed by the parser and a result will be returned. If the parser cannot match at the beginning of the input sequence, it returns a failure and no items are consumed. There are several dozen types of parsers in the library, which can be found by including these lines in your file:

using static ParserObjects.Parsers;
using static ParserObjects.Parsers<char>;

Once you have a parser, you can pass it an input sequence to obtain a parse result:

var result = parser.Parse(sequence);

The ParserObjects library provides many small parsers and parser combinators that can be built up into parsers for large and complex grammars. In addition, ParserObjects provides several pre-made parsers for specialty parsing needs. Please see the Documentation for more information, and the Test Suite Examples for real-world usage patterns.

Contributing

We welcome contributions including code, feedback, bug reports and suggestions.

Current Status

ParserObjects library is currently in active development. Version 6 is available on Nuget and is preferred over all previous versions.