just/variables.rs

29 lines
706 B
Rust

use crate::common::*;
pub struct Variables<'a> {
stack: Vec<&'a Expression<'a>>,
}
impl<'a> Iterator for Variables<'a> {
type Item = &'a Token<'a>;
fn next(&mut self) -> Option<&'a Token<'a>> {
match self.stack.pop() {
None
| Some(Expression::String { .. })
| Some(Expression::Backtick { .. })
| Some(Expression::Call { .. }) => None,
Some(Expression::Variable { token, .. }) => Some(token),
Some(Expression::Concatination { lhs, rhs }) => {
self.stack.push(lhs);
self.stack.push(rhs);
self.next()
}
Some(Expression::Group { expression }) => {
self.stack.push(expression);
self.next()
}
}
}
}