Line::as_str() -> Cow<str>

Previously this would create a new String because it had to, but
with the clustered storage we may be able to simply reference the
existing string as a str reference, so allow for that.

mux/src/pane.rs

@@ -447,6 +447,7 @@ impl_downcast!(Pane);
 mod test {
     use super::*;
     use k9::snapshot;
+    use std::borrow::Cow;
     use termwiz::surface::SEQ_ZERO;
 
     struct FakePane {
@@ -577,7 +578,7 @@ mod test {
         let width = 20;
         let physical_lines = physical_lines_from_text(text, width);
 
-        fn text_from_lines(lines: &[Line]) -> Vec<String> {
+        fn text_from_lines(lines: &[Line]) -> Vec<Cow<str>> {
             lines.iter().map(|l| l.as_str()).collect::<Vec<_>>()
         }
 
@@ -603,7 +604,7 @@ mod test {
             lines: physical_lines,
         };
 
-        fn summarize_logical_lines(lines: &[LogicalLine]) -> Vec<(StableRowIndex, String)> {
+        fn summarize_logical_lines(lines: &[LogicalLine]) -> Vec<(StableRowIndex, Cow<str>)> {
             lines
                 .iter()
                 .map(|l| (l.first_row, l.logical.as_str()))

termwiz/src/surface/line.rs

@@ -7,6 +7,7 @@ use bitflags::bitflags;
 use fixedbitset::FixedBitSet;
 #[cfg(feature = "use_serde")]
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use std::borrow::Cow;
 use std::ops::Range;
 use std::sync::Arc;
 use unicode_segmentation::UnicodeSegmentation;
@@ -497,7 +498,7 @@ impl Line {
         // use this as an opportunity to rebuild HAS_HYPERLINK, skip matching
         // cells with existing non-implicit hyperlinks, and avoid matching
         // text with zero-width cells.
-        let line = self.as_str();
+        let line = self.as_str().into_owned();
         self.bits |= LineBits::SCANNED_IMPLICIT_HYPERLINKS;
         self.bits &= !LineBits::HAS_IMPLICIT_HYPERLINKS;
 
@@ -541,12 +542,17 @@ impl Line {
     }
 
     /// Recompose line into the corresponding utf8 string.
-    pub fn as_str(&self) -> String {
-        let mut s = String::new();
-        for cell in self.visible_cells() {
-            s.push_str(cell.str());
+    pub fn as_str(&self) -> Cow<str> {
+        match &self.cells {
+            CellStorage::V(_) => {
+                let mut s = String::new();
+                for cell in self.visible_cells() {
+                    s.push_str(cell.str());
+                }
+                Cow::Owned(s)
+            }
+            CellStorage::C(cl) => Cow::Borrowed(&cl.text),
         }
-        s
     }
 
     pub fn split_off(&mut self, idx: usize, seqno: SequenceNo) -> Self {