sequence filter
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2 changed files with 155 additions and 0 deletions
154
nested/src/sequence/filter.rs
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154
nested/src/sequence/filter.rs
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use {
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std::sync::Arc,
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std::sync::RwLock,
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crate::{
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sequence::{SequenceView},
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core::{
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Observer, ObserverExt, ObserverBroadcast,
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View, ViewPort, OuterViewPort
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}
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}
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};
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//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
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impl<V: SequenceView + ?Sized + 'static> OuterViewPort<V>
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{
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pub fn filter<
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P: Fn(&V::Item) -> bool + Send + Sync + 'static
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>(&self, pred: P) -> OuterViewPort<dyn SequenceView<Item = V::Item>> {
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let port = ViewPort::new();
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let filter = Arc::new(RwLock::new(
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Filter {
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src_view: None,
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pred,
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old_preds: RwLock::new(Vec::new()),
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cast: port.inner().get_broadcast()
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}
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));
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self.add_observer(filter.clone());
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port.inner().set_view(Some(filter));
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port.into_outer()
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}
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}
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//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
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struct Filter<SrcView, P>
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where SrcView: SequenceView + ?Sized + 'static,
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P: Fn(&SrcView::Item) -> bool + Send + Sync + 'static
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{
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src_view: Option<Arc<SrcView>>,
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pred: P,
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old_preds: RwLock<Vec<bool>>,
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cast: Arc<RwLock<ObserverBroadcast<dyn SequenceView<Item = SrcView::Item>>>>
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}
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impl<SrcView, P> Filter<SrcView, P>
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where SrcView: SequenceView + ?Sized + 'static,
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P: Fn(&SrcView::Item) -> bool + Send + Sync + 'static
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{
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fn get_offset(&self, idx: usize) -> usize {
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if let Some(v) = self.src_view.clone() {
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let mut i = 0;
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let mut j = 0;
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let mut offset = 0;
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while let (Some(x), true) = (v.get(&i), j <= idx) {
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if (self.pred)(&x) {
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j += 1;
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} else {
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offset += 1;
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}
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i+=1;
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}
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offset
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} else {
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0
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}
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}
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}
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//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
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impl<SrcView, P> View for Filter<SrcView, P>
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where SrcView: SequenceView + ?Sized + 'static,
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P: Fn(&SrcView::Item) -> bool + Send + Sync + 'static
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{
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type Msg = usize;
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}
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impl<SrcView, P> SequenceView for Filter<SrcView, P>
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where SrcView: SequenceView + ?Sized + 'static,
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P: Fn(&SrcView::Item) -> bool + Send + Sync + 'static
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{
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type Item = SrcView::Item;
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fn len(&self) -> Option<usize> {
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if let Some(src_len) = self.src_view.len() {
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Some(src_len - self.get_offset(src_len) )
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} else {
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None
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}
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}
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fn get(&self, idx: &usize) -> Option<Self::Item> {
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self.src_view.get(&( idx + self.get_offset(*idx) ))
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}
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}
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//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
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impl<SrcView, P> Observer<SrcView> for Filter<SrcView, P>
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where SrcView: SequenceView + ?Sized + 'static,
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P: Fn(&SrcView::Item) -> bool + Send + Sync + 'static
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{
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fn reset(&mut self, new_src: Option<Arc<SrcView>>) {
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let old_len = self.len();
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self.src_view = new_src;
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self.old_preds = RwLock::new(Vec::new());
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let new_len = self.len();
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if let Some(len) = old_len { self.cast.notify_each(0 .. len); }
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if let Some(len) = new_len { self.cast.notify_each(0 .. len); }
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}
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fn notify(&self, idx: &usize) {
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let l = self.len().unwrap_or(0)+1;
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let np =
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if let Some(x) = self.src_view.get(idx) {
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(self.pred)(&x)
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} else {
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false
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};
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let mut opds = self.old_preds.write().unwrap();
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opds.resize_with(1+*idx, || false);
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let op = opds.get(*idx).cloned().unwrap_or(false);
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*opds.get_mut(*idx).unwrap() = np;
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drop(opds);
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let i =
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(0 .. *idx)
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.map(
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|j|
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if let Some(x) = self.src_view.get(&j) {
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if (self.pred)(&x) { 1 } else { 0 }
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} else {
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0
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}
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)
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.sum();
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if np != op {
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self.cast.notify_each(i .. l);
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} else {
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self.cast.notify(&i);
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}
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}
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}
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@ -2,6 +2,7 @@
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pub mod seq2idx;
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pub mod vec_buffer;
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pub mod map;
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pub mod filter;
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pub mod flatten;
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pub use {
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