https://github.com/diasbruno/cl-bnf

A simple BNF parser.
https://github.com/diasbruno/cl-bnf

ast bnf common-lisp parser

Last synced: about 2 months ago
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A simple BNF parser.

• Host: GitHub
• URL: https://github.com/diasbruno/cl-bnf
• Owner: diasbruno
• License: mit
• Created: 2018-05-07T05:28:26.000Z (almost 7 years ago)
• Default Branch: development
• Last Pushed: 2023-11-15T18:37:08.000Z (about 1 year ago)
• Last Synced: 2024-12-09T01:35:28.694Z (about 2 months ago)
• Topics: ast, bnf, common-lisp, parser
• Language: Common Lisp
• Homepage:
• Size: 38.1 KB
• Stars: 10
• Watchers: 4
• Forks: 1
• Open Issues: 2
• Metadata Files:
  • Readme: readme.md
  • License: license

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README

        
# cl-bnf

[![CI](https://github.com/diasbruno/cl-bnf/actions/workflows/ci.yml/badge.svg)](https://github.com/diasbruno/cl-bnf/actions/workflows/ci.yml)

A simple BNF.

`(:char . #\a)`     matches the given char.

`(:string . "abc")` matches the given string.

`(:and exp ...)`    all expressions must match.

`(:or exp ...)`     returns the first expression that matches.

`(:* . exp)`        collect all strings matches the expression, if any.

`(:? . exp)`        optional match.

`#'some-function`   execute the function with the current char. must return boolean.

`and` can also be written in a form of sequence `rule-c := rule-a rule-b`.

`or` can also be written using `:/`, for example: `rule-c := rule-a :/ rule-b`.

## rules & grammars

You can define a single rule using `define-rule`

```lisp

(cl-bnf:define-rule word (:* . #'alpha-char-p) :call #'stringify)

```

...or using the `define-grammar`

```lisp

(cl-bnf:define-grammar (abc . parser)

   abc := #\a #\b #\c

   cba := "cba"

   abc-cba := abc :/ cba

   parser := abc-cba)

(abc "abc") ;; (#\a #\b #\c)

(abc "cba") ;; "cba"

```

#### transformations

- `:call` apply a function to the results using `funcall`.

- `:apply` apply a function to the results using `apply`.

- `:tag` return a cons like `(cons TAG RESULTS)`.

- If none where specified, it return all matches.

## License

This project is released under the MIT License.

See `license`.