# ebnf

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> A successor bnf parsing library of bnf parsing library, for parsing Extended Backus–Naur form context-free grammars

The code is available on [GitHub](https://github.com/ChAoSUnItY/ebnf)

## Disclaimer:
There are various variants of EBNF, which uses somewhat different syntactic conventions. This library 
takes [EBNF Evaluator](https://mdkrajnak.github.io/ebnftest/)'s example code as standard, which has 
almost most syntactic conventions on Wikipedia's page.

## What does a valid EBNF grammar looks like?

The following example is taken from EBNF Evaluator:

```ebnf
filter ::= ( first ' ' )? ( number '~ ' )? ( number '-' number ) ( ' ' number '~' )? ( ' hz' )? ( ' b' )? ( ' i' )? ( ' a' )?;
first  ::= #'[a-za-z][a-za-z0-9_+]*';
number ::= digits ( ( '.' | ',' ) digits? )?;
digits ::= #'[0-9]+';
```

## How to use this library?

```rust
extern crate ebnf;

fn main() {
    let source = r"
        filter ::= ( first ' ' )? ( number '~ ' )? ( number '-' number ) ( ' ' number '~' )? ( ' hz' )? ( ' b' )? ( ' i' )? ( ' a' )?;
        first  ::= #'[a-za-z][a-za-z0-9_+]*';
        number ::= digits ( ( '.' | ',' ) digits? )?;
        digits ::= #'[0-9]+';
    ";

    let result = ebnf::get_grammar(source);
}
```