1 unstable release
Uses old Rust 2015
0.0.1 | Mar 14, 2015 |
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#14 in #descent
5KB
109 lines
Regex Parser
This is a recursive descent parser written in Rust for regular expresssions. Given a regular expression as input, it outputs an AST. It follows this very simple LL(1) grammar:
<regex> ::= <term> '|' <regex>
| <term>
<term> ::= { <factor> }
<factor> ::= <base> { '*' }
<base> ::= <char>
| '(' <regex> ')'
Usage
let mut p = RegExParser::new("((a|b*)|a*)|aab".to_string());
let res = Ok(Or(
Box::new(Sequence(vec![Box::new(Or(
Box::new(Sequence(
vec![Box::new(Or(Box::new(Sequence(vec![Box::new(Terminal('a'))])),
Box::new(Sequence(
vec![Box::new(Repetition(Box::new(Terminal('b'))))]))))])),
Box::new(Sequence(vec![Box::new(Repetition(Box::new(Terminal('a'))))]))))])),
Box::new(Sequence(vec![Box::new(Terminal('a')), Box::new(Terminal('a')),
Box::new(Terminal('b'))]))));
assert_eq!(p.parse(), res);