automerge/rust/automerge/src/query/keys.rs

54 lines
1.4 KiB
Rust

use crate::op_tree::OpTreeInternal;
use crate::types::Key;
use std::fmt::Debug;
#[derive(Debug)]
pub(crate) struct Keys<'a> {
index: usize,
last_key: Option<Key>,
index_back: usize,
last_key_back: Option<Key>,
op_tree: &'a OpTreeInternal,
}
impl<'a> Keys<'a> {
pub(crate) fn new(op_tree: &'a OpTreeInternal) -> Self {
Self {
index: 0,
last_key: None,
index_back: op_tree.len(),
last_key_back: None,
op_tree,
}
}
}
impl<'a> Iterator for Keys<'a> {
type Item = Key;
fn next(&mut self) -> Option<Self::Item> {
for i in self.index..self.index_back {
let op = self.op_tree.get(i)?;
self.index += 1;
if Some(op.elemid_or_key()) != self.last_key && op.visible() {
self.last_key = Some(op.elemid_or_key());
return Some(op.elemid_or_key());
}
}
None
}
}
impl<'a> DoubleEndedIterator for Keys<'a> {
fn next_back(&mut self) -> Option<Self::Item> {
for i in (self.index..self.index_back).rev() {
let op = self.op_tree.get(i)?;
self.index_back -= 1;
if Some(op.elemid_or_key()) != self.last_key_back && op.visible() {
self.last_key_back = Some(op.elemid_or_key());
return Some(op.elemid_or_key());
}
}
None
}
}