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use proc_macro2::Span;
use super::super::{
ast::{Alt, Call, Cat, Epsilon, Fix, Literal, Parameter, Variable},
visit::{Visitable, Visitor},
};
#[derive(Clone, Copy, Debug)]
pub struct Spanning;
impl Visitor for Spanning {
type Out = Option<Span>;
fn visit_epsilon(&mut self, eps: &Epsilon) -> Self::Out {
eps.map(|e| e.span)
}
fn visit_literal(&mut self, lit: &Literal) -> Self::Out {
lit.span()
}
fn visit_cat(&mut self, cat: &Cat) -> Self::Out {
let fst = cat.first().visit(self);
let snd = cat.second().visit(self);
match (fst, snd) {
(None, snd) => snd,
(Some(fst), None) => Some(fst),
(Some(fst), Some(snd)) => fst.join(snd),
}
}
fn visit_alt(&mut self, alt: &Alt) -> Self::Out {
let left = alt.left().visit(self);
let right = alt.right().visit(self);
match (left, right) {
(None, right) => right,
(Some(left), None) => Some(left),
(Some(left), Some(right)) => left.join(right),
}
}
fn visit_fix(&mut self, fix: &Fix) -> Self::Out {
fix.span()
}
fn visit_variable(&mut self, var: &Variable) -> Self::Out {
var.name().span()
}
fn visit_parameter(&mut self, param: &Parameter) -> Self::Out {
param.name().span()
}
fn visit_call(&mut self, call: &Call) -> Self::Out {
call.span()
}
}
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