preserve wrapping state when possible

13 files changed, 125 insertions, 0 deletions

diff --git a/src/row.rs b/src/row.rs
index 36d7d34..8f96c27 100644
--- a/src/row.rs
+++ b/src/row.rs
@@ -127,6 +127,14 @@ impl Row {
         let mut prev_was_wide = false;
         let default_cell = crate::cell::Cell::default();
 
+        let first_cell = self.get(start).unwrap();
+        if wrapping && first_cell == &default_cell {
+            contents.push(b' ');
+            crate::term::Backspace::default().write_buf(contents);
+            crate::term::EraseChar::new(1).write_buf(contents);
+            prev_pos = crate::grid::Pos { row, col: 0 };
+        }
+
         let mut erase: Option<(u16, &crate::attrs::Attrs)> = None;
         for (col, cell) in self
             .cells()
@@ -221,6 +229,32 @@ impl Row {
     ) -> (crate::grid::Pos, crate::attrs::Attrs) {
         let mut prev_was_wide = false;
 
+        let first_cell = self.get(start).unwrap();
+        let prev_first_cell = prev.get(start).unwrap();
+        if wrapping
+            && first_cell == prev_first_cell
+            && prev_pos.row + 1 == row
+            && prev_pos.col
+                >= self.cols() - if prev_first_cell.is_wide() { 1 } else { 0 }
+        {
+            let mut cell_contents = prev_first_cell.contents();
+            let need_erase = if cell_contents == "" {
+                cell_contents = " ".to_string();
+                true
+            } else {
+                false
+            };
+            contents.extend(cell_contents.as_bytes());
+            crate::term::Backspace::default().write_buf(contents);
+            if prev_first_cell.is_wide() {
+                crate::term::Backspace::default().write_buf(contents);
+            }
+            if need_erase {
+                crate::term::EraseChar::new(1).write_buf(contents);
+            }
+            prev_pos = crate::grid::Pos { row, col: 0 };
+        }
+
         let mut erase: Option<(u16, &crate::attrs::Attrs)> = None;
         for (col, (cell, prev_cell)) in self
             .cells()
diff --git a/src/term.rs b/src/term.rs
index 5a9fbd6..0a578c1 100644
--- a/src/term.rs
+++ b/src/term.rs
@@ -46,6 +46,16 @@ impl BufWrite for CRLF {
 
 #[derive(Default, Debug)]
 #[must_use = "this struct does nothing unless you call write_buf"]
+pub struct Backspace;
+
+impl BufWrite for Backspace {
+    fn write_buf(&self, buf: &mut Vec<u8>) {
+        buf.extend_from_slice(b"\x08");
+    }
+}
+
+#[derive(Default, Debug)]
+#[must_use = "this struct does nothing unless you call write_buf"]
 pub struct MoveTo {
     row: u16,
     col: u16,
diff --git a/tests/data/fixtures/il_dl.in b/tests/data/fixtures/il_dl.in
index e0a564e..3e159aa 100644
--- a/tests/data/fixtures/il_dl.in
+++ b/tests/data/fixtures/il_dl.in
@@ -10,3 +10,8 @@
 a
 \x1b[L
 bc
+\x1bc\x1b[1;80H
+a
+b
+\x1b[L
+cd
diff --git a/tests/data/fixtures/il_dl/13.json b/tests/data/fixtures/il_dl/13.json
new file mode 100644
index 0000000..5deb58b
--- /dev/null
+++ b/tests/data/fixtures/il_dl/13.json
@@ -0,0 +1,8 @@
+{
+  "contents": "",
+  "cells": {},
+  "cursor_position": [
+    0,
+    79
+  ]
+}
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/13.typescript b/tests/data/fixtures/il_dl/13.typescript
new file mode 100644
index 0000000..fc29e50
--- /dev/null
+++ b/tests/data/fixtures/il_dl/13.typescript
@@ -0,0 +1 @@
+c
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/14.json b/tests/data/fixtures/il_dl/14.json
new file mode 100644
index 0000000..59543cb
--- /dev/null
+++ b/tests/data/fixtures/il_dl/14.json
@@ -0,0 +1,12 @@
+{
+  "contents": "                                                                               a",
+  "cells": {
+    "0,79": {
+      "contents": "a"
+    }
+  },
+  "cursor_position": [
+    0,
+    80
+  ]
+}
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/14.typescript b/tests/data/fixtures/il_dl/14.typescript
new file mode 100644
index 0000000..2e65efe
--- /dev/null
+++ b/tests/data/fixtures/il_dl/14.typescript
@@ -0,0 +1 @@
+a
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/15.json b/tests/data/fixtures/il_dl/15.json
new file mode 100644
index 0000000..a28d5bc
--- /dev/null
+++ b/tests/data/fixtures/il_dl/15.json
@@ -0,0 +1,15 @@
+{
+  "contents": "                                                                               ab",
+  "cells": {
+    "0,79": {
+      "contents": "a"
+    },
+    "1,0": {
+      "contents": "b"
+    }
+  },
+  "cursor_position": [
+    1,
+    1
+  ]
+}
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/15.typescript b/tests/data/fixtures/il_dl/15.typescript
new file mode 100644
index 0000000..63d8dbd
--- /dev/null
+++ b/tests/data/fixtures/il_dl/15.typescript
@@ -0,0 +1 @@
+b
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/16.json b/tests/data/fixtures/il_dl/16.json
new file mode 100644
index 0000000..102c2f1
--- /dev/null
+++ b/tests/data/fixtures/il_dl/16.json
@@ -0,0 +1,15 @@
+{
+  "contents": "                                                                               a\nb",
+  "cells": {
+    "0,79": {
+      "contents": "a"
+    },
+    "2,0": {
+      "contents": "b"
+    }
+  },
+  "cursor_position": [
+    1,
+    1
+  ]
+}
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/16.typescript b/tests/data/fixtures/il_dl/16.typescript
new file mode 100644
index 0000000..a330c08
--- /dev/null
+++ b/tests/data/fixtures/il_dl/16.typescript
@@ -0,0 +1 @@
+
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/17.json b/tests/data/fixtures/il_dl/17.json
new file mode 100644
index 0000000..4b2e900
--- /dev/null
+++ b/tests/data/fixtures/il_dl/17.json
@@ -0,0 +1,21 @@
+{
+  "contents": "                                                                               a cd\nb",
+  "cells": {
+    "0,79": {
+      "contents": "a"
+    },
+    "1,1": {
+      "contents": "c"
+    },
+    "1,2": {
+      "contents": "d"
+    },
+    "2,0": {
+      "contents": "b"
+    }
+  },
+  "cursor_position": [
+    1,
+    3
+  ]
+}
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/17.typescript b/tests/data/fixtures/il_dl/17.typescript
new file mode 100644
index 0000000..25038d7
--- /dev/null
+++ b/tests/data/fixtures/il_dl/17.typescript
@@ -0,0 +1 @@
+cd
\ No newline at end of file