https://github.com/ruby-next/paco

Paco is a parser combinator library inspired by Haskell's Parsec and Parsimmon.
https://github.com/ruby-next/paco

Last synced: 3 months ago
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Paco is a parser combinator library inspired by Haskell's Parsec and Parsimmon.

• Host: GitHub
• URL: https://github.com/ruby-next/paco
• Owner: ruby-next
• License: mit
• Created: 2021-12-12T16:47:50.000Z (almost 3 years ago)
• Default Branch: master
• Last Pushed: 2023-12-27T08:07:24.000Z (11 months ago)
• Last Synced: 2024-08-05T18:21:25.201Z (3 months ago)
• Language: Ruby
• Homepage:
• Size: 70.3 KB
• Stars: 22
• Watchers: 4
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE.txt

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README

        
# Paco

[![Gem Version](https://badge.fury.io/rb/paco.svg)](https://rubygems.org/gems/paco)

[![Build](https://github.com/skryukov/paco/workflows/Build/badge.svg)](https://github.com/skryukov/paco/actions)

Paco is a parser combinator library inspired by Haskell's [Parsec] and [Parsimmon].

"But I don't need to write another JSON parser or a new language, why do I need your library then?"

Well, most probably you don't. But I can think of rare cases when you do. Say, you need to write a validation for [git branch names].

You can go with easy-peasy regex:

```ruby

branch_name_regex = /^(?!\/|.*(?:[\/.]\.|\/\/|@{|\\|\.lock$|[\/.]$))[^\040\177 ~^:?*\[]+$/

branch_name_regex.match?("feature/branch-validation")

```

With Paco, you can go with a little more verbose version of that rule:

```ruby

module BranchNameParser

  extend Paco

  class << self

    def parse(input)

      parser.parse(input)

    end

    def parser

      lookahead(none_of("/")).next(valid_chars.join)

    end

    def valid_chars

      any_char.not_followed_by(invalid_sequences).at_least(1)

    end

    

    def invalid_sequences

      alt(invalid_chars, invalid_endings)

    end

    def invalid_chars

      alt(

        string("/."),

        string(".."),

        string("//"),

        string("@{"),

        string("\\\\"),

        one_of("\040\177 ~^:?*\\[")

      )

    end

    def invalid_endings

      seq(

        alt(string(".lock"), one_of("/.")),

        eof

      )

    end

  end

end

BranchNameParser.parse("feature/branch-validation")

```

Easy? Not really, but there is a chance you can read it. 😅

See [API documentation](docs/paco.md), [examples](examples) and [specs](spec) for more info on usage.



## Installation

Add to your `Gemfile`:

```ruby

gem "paco"

```

And then run `bundle install`.

## Development

After checking out the repo, run `bin/setup` to install dependencies. Then, run `bundle exec rspec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run `bundle exec rake install`.

## Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/skryukov/paco.

## Alternatives

- [parslet] - A small (but featureful) PEG based parser library.

- [parsby] — Parser combinator library for Ruby inspired by Haskell's Parsec.

## License

The gem is available as open source under the terms of the [MIT License].

[MIT License]: https://opensource.org/licenses/MIT

[Parsec]: https://github.com/haskell/parsec

[Parsimmon]: https://github.com/jneen/parsimmon

[parslet]: https://github.com/kschiess/parslet

[parsby]: https://github.com/jolmg/parsby

[git branch names]: https://git-scm.com/docs/git-check-ref-format#_description