Improve storage comparison algorithm

Instead of iterating over the raw storage vector because the offsets
don't allow direct comparison, the comparison is now done in chunks.
Based on benchmarking this is a lot more efficient than using split_off
+ append or iterating over the elements of the buffer.

The `history_size` field has also been removed from the storage
structure because it can be easily calculated by substracting the number
of visible lines from the length of the raw storage vector.

1 files changed, 11 insertions, 20 deletions

diff --git a/src/grid/mod.rs b/src/grid/mod.rs
index b6cff604..f3c8ea79 100644
--- a/src/grid/mod.rs
+++ b/src/grid/mod.rs
@@ -52,23 +52,13 @@ impl<T> Deref for Indexed<T> {
 
 impl<T: PartialEq> ::std::cmp::PartialEq for Grid<T> {
     fn eq(&self, other: &Self) -> bool {
-        // Compare raw grid content
-        // TODO: This is pretty inefficient but only used in tests
-        let mut raw_match = true;
-        for i in 0..(self.lines.0 + self.history_size) {
-            for j in 0..self.cols.0 {
-                if self[i][Column(j)] != other[i][Column(j)] {
-                    raw_match = false;
-                    break;
-                }
-            }
-        }
-
         // Compare struct fields and check result of grid comparison
-        self.cols.eq(&other.cols) &&
+        self.raw.eq(&other.raw) &&
+            self.cols.eq(&other.cols) &&
             self.lines.eq(&other.lines) &&
-            self.history_size.eq(&other.history_size) &&
-            raw_match
+            self.display_offset.eq(&other.display_offset) &&
+            self.scroll_limit.eq(&other.scroll_limit) &&
+            self.selection.eq(&other.selection)
     }
 }
 
@@ -102,10 +92,6 @@ pub struct Grid<T> {
     /// Selected region
     #[serde(skip)]
     pub selection: Option<Selection>,
-
-    /// Maximum number of lines in the scrollback history
-    #[serde(default)]
-    history_size: usize,
 }
 
 pub struct GridIterator<'a, T: 'a> {
@@ -150,7 +136,6 @@ impl<T: Copy + Clone> Grid<T> {
             display_offset: 0,
             scroll_limit: 0,
             selection: None,
-            history_size: scrollback,
         }
     }
 
@@ -426,6 +411,12 @@ impl<T> Grid<T> {
         self.scroll_limit = 0;
     }
 
+    /// Total number of lines in the buffer, this includes scrollback + visible lines
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.raw.len()
+    }
+
     pub fn iter_from(&self, point: Point<usize>) -> GridIterator<T> {
         GridIterator {
             grid: self,