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use super::super::{
ast::{Alt, Call, Cat, Epsilon, Fix, Literal, Parameter, Variable},
visit::{Mapper, Visitable},
};
#[derive(Clone, Copy, Debug, Default)]
pub struct ShallowVars {
depth: usize,
}
impl Mapper for ShallowVars {
type Out = ();
fn map_epsilon(&mut self, _: &mut Epsilon) -> Self::Out {}
fn map_literal(&mut self, _: &mut Literal) -> Self::Out {}
fn map_cat(&mut self, cat: &mut Cat) -> Self::Out {
cat.first_mut().map(self);
cat.second_mut().map(self);
}
fn map_alt(&mut self, alt: &mut Alt) -> Self::Out {
alt.left_mut().map(self);
alt.right_mut().map(self);
}
fn map_fix(&mut self, fix: &mut Fix) -> Self::Out {
self.depth += 1;
fix.inner_mut().map(self);
self.depth -= 1;
}
fn map_variable(&mut self, bind: &mut Variable) -> Self::Out {
if bind.index() > self.depth {
*bind.index_mut() -= 1;
}
}
fn map_parameter(&mut self, _param: &mut Parameter) -> Self::Out {}
fn map_call(&mut self, call: &mut Call) -> Self::Out {
for arg in call.args_mut() {
arg.map(self);
}
}
}
|
