A library for parsing Backus–Naur form context-free grammars inspired by the JavaScript library prettybnf
The following grammar from the Wikipedia page on Backus-Naur form exemplifies a compatible grammar after adding ';' characters to indicate the end of each producion.
```text
<name-part> ::= <personal-part> <last-name> <opt-suffix-part> <EOL>
| <personal-part> <name-part>;
<personal-part> ::= <initial> "." | <first-name>;
<street-address> ::= <house-num> <street-name> <opt-apt-num> <EOL>;
<zip-part> ::= <town-name> "," <state-code> <ZIP-code> <EOL>;
Take the following grammar to be input to this library's parse function.
<A> ::= <B> | "C";
<B> ::= "D" | "E";
The output is a Grammar object representing a tree that looks like this:
Grammar {
productions: [
Production {
lhs: Nonterminal(
"A"
),
rhs: [
Expression {
terms: [
Nonterminal(
"B"
)
]
},
Expression {
terms: [
Terminal(
"C"
)
]
}
]
},
Production {
lhs: Nonterminal(
"B"
),
rhs: [
Expression {
terms: [
Terminal(
"D"
)
]
},
Expression {
terms: [
Terminal(
"E"
)
]
}
]
}
]
}
```rust extern crate bnf;
fn main() {
let input =
"
<name-part> ::= <personal-part> <last-name> <opt-suffix-part> <EOL>
| <personal-part> <name-part>;
<personal-part> ::= <initial> \".\" | <first-name>;
<street-address> ::= <house-num> <street-name> <opt-apt-num> <EOL>;
<zip-part> ::= <town-name> \",\" <state-code> <ZIP-code> <EOL>;
<opt-suffix-part> ::= \"Sr.\" | \"Jr.\" | <roman-numeral> | \"\";
<opt-apt-num> ::= <apt-num> | \"\";";
let grammar = bnf::parse(input);
println!("{:#?}", grammar);
} ```