WIP

crates/items_2/src/binning/timeweight/timeweight_events.rs

@@ -407,8 +407,6 @@ where
                     {
                         // TODO push bin to output.
                         let res = b.agg.result_and_reset_for_new_bin();
-                        let cnt = b.cnt;
-                        b.cnt = 0;
                         self.out.push_back(
                             b.active_beg,
                             b.active_end,
@@ -426,6 +424,7 @@ where
                     b.active_beg = ts1;
                     b.active_end = ts1.add_dt_nano(b.active_len);
                     b.filled_until = ts1;
+                    b.cnt = 0;
                     self.inner_a.minmax = Some((lst.clone(), lst.clone()));
                 } else {
                     self.inner_a.inner_b.fill_until(ts, LstRef(lst));

crates/items_2/src/binning/valuetype.rs

@@ -3,6 +3,7 @@ use super::binnedvaluetype::BinnedNumericValue;
 use super::container_events::Container;
 use super::container_events::EventValueType;
 use crate::vecpreview::PreviewRange;
+use core::fmt;
 use netpod::DtNano;
 use netpod::EnumVariant;
 use serde::Deserialize;
@@ -16,8 +17,12 @@ pub struct EnumVariantContainer {
 }
 
 impl PreviewRange for EnumVariantContainer {
-    fn preview(&self) -> &dyn core::fmt::Debug {
-        todo!()
+    fn preview<'a>(&'a self) -> Box<dyn fmt::Debug + 'a> {
+        let ret = crate::vecpreview::PreviewCell {
+            a: self.ixs.front(),
+            b: self.ixs.back(),
+        };
+        Box::new(ret)
     }
 }
 

crates/items_2/src/vecpreview.rs

@@ -1,13 +1,38 @@
 use core::fmt;
 use std::collections::VecDeque;
 
-pub trait PreviewRange {
-    fn preview(&self) -> &dyn fmt::Debug;
+pub struct PreviewCell<'a, T> {
+    pub a: Option<&'a T>,
+    pub b: Option<&'a T>,
 }
 
-impl<T> PreviewRange for VecDeque<T> {
-    fn preview(&self) -> &dyn fmt::Debug {
-        todo!()
+impl<'a, T> fmt::Debug for PreviewCell<'a, T>
+where
+    T: fmt::Debug,
+{
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match (self.a.as_ref(), self.b.as_ref()) {
+            (Some(a), Some(b)) => write!(fmt, "{:?} .. {:?}", a, b),
+            (Some(a), None) => write!(fmt, "{:?}", a),
+            _ => write!(fmt, "(empty)"),
+        }
+    }
+}
+
+pub trait PreviewRange {
+    fn preview<'a>(&'a self) -> Box<dyn fmt::Debug + 'a>;
+}
+
+impl<T> PreviewRange for VecDeque<T>
+where
+    T: fmt::Debug,
+{
+    fn preview<'a>(&'a self) -> Box<dyn fmt::Debug + 'a> {
+        let ret = PreviewCell {
+            a: self.front(),
+            b: if self.len() <= 1 { None } else { self.back() },
+        };
+        Box::new(ret)
     }
 }