42 lines
1 KiB
Rust
42 lines
1 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 LenAt {
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pub(crate) len: usize,
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clock: Clock,
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pos: usize,
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encoding: ListEncoding,
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last: Option<ElemId>,
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window: VisWindow,
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}
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impl LenAt {
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pub(crate) fn new(clock: Clock, encoding: ListEncoding) -> Self {
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LenAt {
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clock,
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pos: 0,
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len: 0,
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encoding,
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last: None,
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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 LenAt {
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fn query_element(&mut self, op: &'a Op) -> QueryResult {
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if op.insert {
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self.last = None;
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}
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let elem = op.elemid();
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let visible = self.window.visible_at(op, self.pos, &self.clock);
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if elem != self.last && visible {
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self.len += op.width(self.encoding);
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self.last = elem;
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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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