Introduce `Cursor::seek_start` to compute `VersionedOffset` once

Antonio Scandurra created 4 years ago

Change summary

zed/src/editor/buffer.rs   | 14 ++++++--------
zed/src/sum_tree.rs        | 12 ------------
zed/src/sum_tree/cursor.rs |  4 ++++
3 files changed, 10 insertions(+), 20 deletions(-)

Detailed changes

zed/src/editor/buffer.rs

@@ -1679,9 +1679,7 @@ impl Buffer {
                 bias,
                 version,
             } => {
-                let mut cursor = self
-                    .fragments
-                    .cursor::<VersionedOffset, (VersionedOffset, usize)>();
+                let mut cursor = self.fragments.cursor::<VersionedOffset, usize>();
                 cursor.seek(
                     &VersionedOffset::Offset(*offset),
                     *bias,
@@ -1689,12 +1687,12 @@ impl Buffer {
                 );
                 let fragment = cursor.item().unwrap();
                 let overshoot = if fragment.visible {
-                    offset - cursor.start().0.offset()
+                    offset - cursor.seek_start().offset()
                 } else {
                     0
                 };
 
-                self.text_summary_for_range(0..cursor.start().1 + overshoot)
+                self.text_summary_for_range(0..cursor.start() + overshoot)
             }
         }
     }
@@ -1713,14 +1711,14 @@ impl Buffer {
             } => {
                 let mut cursor = self
                     .fragments
-                    .cursor::<VersionedOffset, (VersionedOffset, FragmentTextSummary)>();
+                    .cursor::<VersionedOffset, FragmentTextSummary>();
                 cursor.seek(
                     &VersionedOffset::Offset(*offset),
                     *bias,
                     &Some(version.clone()),
                 );
-                let overshoot = offset - cursor.start().0.offset();
-                let summary = cursor.start().1;
+                let overshoot = offset - cursor.seek_start().offset();
+                let summary = cursor.start();
                 summary.visible + summary.deleted + overshoot
             }
         }

zed/src/sum_tree.rs

@@ -37,18 +37,6 @@ impl<'a, T: Summary> Dimension<'a, T> for () {
     fn add_summary(&mut self, _: &'a T, _: &T::Context) {}
 }
 
-impl<'a, S, D1, D2> Dimension<'a, S> for (D1, D2)
-where
-    S: Summary,
-    D1: Dimension<'a, S>,
-    D2: Dimension<'a, S>,
-{
-    fn add_summary(&mut self, summary: &'a S, cx: &S::Context) {
-        self.0.add_summary(summary, cx);
-        self.1.add_summary(summary, cx);
-    }
-}
-
 pub trait SeekDimension<'a, T: Summary>: Dimension<'a, T> {
     fn cmp(&self, other: &Self, cx: &T::Context) -> Ordering;
 }

zed/src/sum_tree/cursor.rs

@@ -45,6 +45,10 @@ where
         self.sum_dimension = U::default();
     }
 
+    pub fn seek_start(&self) -> &S {
+        &self.seek_dimension
+    }
+
     pub fn start(&self) -> &U {
         &self.sum_dimension
     }