67 lines
2 KiB
Rust
67 lines
2 KiB
Rust
use crate::query::{QueryResult, TreeQuery, VisWindow};
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use crate::types::{Clock, ElemId, ListEncoding, Op};
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use std::fmt::Debug;
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#[derive(Debug, Clone, PartialEq)]
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pub(crate) struct NthAt {
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clock: Clock,
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target: usize,
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seen: usize,
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encoding: ListEncoding,
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last_seen: Option<ElemId>,
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window: VisWindow,
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pub(crate) ops: Vec<Op>,
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pub(crate) ops_pos: Vec<usize>,
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pub(crate) pos: usize,
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}
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impl NthAt {
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pub(crate) fn new(target: usize, clock: Clock, encoding: ListEncoding) -> Self {
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NthAt {
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clock,
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target,
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seen: 0,
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encoding,
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last_seen: None,
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ops: vec![],
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ops_pos: vec![],
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pos: 0,
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window: Default::default(),
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}
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}
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}
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impl<'a> TreeQuery<'a> for NthAt {
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fn query_element(&mut self, element: &'a Op) -> QueryResult {
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if element.insert {
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if self.seen > self.target {
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return QueryResult::Finish;
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};
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self.last_seen = None
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}
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let visible = self.window.visible_at(element, self.pos, &self.clock);
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if visible && self.last_seen.is_none() {
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self.seen += element.width(self.encoding);
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self.last_seen = element.elemid()
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}
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if self.seen > self.target && visible {
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for (vpos, vop) in self.window.seen_op(element, self.pos) {
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if vop.is_counter() {
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// this could be out of order because of inc's - we can find the right place
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// since pos will always be in order
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let pos = self
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.ops_pos
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.binary_search_by(|probe| probe.cmp(&vpos))
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.unwrap_err();
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self.ops.insert(pos, vop);
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self.ops_pos.insert(pos, vpos);
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} else {
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self.ops.push(vop);
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self.ops_pos.push(vpos);
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}
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}
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}
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self.pos += 1;
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QueryResult::Next
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}
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}
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