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//! Move across lists of events.
use crate::event::{Event, Kind, Name};
/// Skip from `index`, optionally past `names`.
pub fn opt(events: &[Event], index: usize, names: &[Name]) -> usize {
skip_opt_impl(events, index, names, true)
}
/// Skip from `index`, optionally past `names`, backwards.
pub fn opt_back(events: &[Event], index: usize, names: &[Name]) -> usize {
skip_opt_impl(events, index, names, false)
}
/// Skip from `index` forwards to `names`.
pub fn to(events: &[Event], index: usize, names: &[Name]) -> usize {
to_impl(events, index, names, true)
}
/// Skip from `index` backwards to `names`.
pub fn to_back(events: &[Event], index: usize, names: &[Name]) -> usize {
to_impl(events, index, names, false)
}
/// Skip to something.
fn to_impl(events: &[Event], mut index: usize, names: &[Name], forward: bool) -> usize {
while index < events.len() {
let current = &events[index].name;
if names.contains(current) {
break;
}
index = if forward { index + 1 } else { index - 1 };
}
index
}
/// Skip past things.
fn skip_opt_impl(events: &[Event], mut index: usize, names: &[Name], forward: bool) -> usize {
let mut balance = 0;
let open = if forward { Kind::Enter } else { Kind::Exit };
while index < events.len() {
let current = &events[index].name;
if !names.contains(current) || events[index].kind != open {
break;
}
index = if forward { index + 1 } else { index - 1 };
balance += 1;
loop {
balance = if events[index].kind == open {
balance + 1
} else {
balance - 1
};
if events[index].name == *current && balance == 0 {
index = if forward { index + 1 } else { index - 1 };
break;
}
index = if forward { index + 1 } else { index - 1 };
}
}
index
}
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