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