handle line wrapping with wide characters + combining characters

4 files changed, 67 insertions, 2 deletions

diff --git a/src/row.rs b/src/row.rs
index 8f96c27..a0d44a4 100644
--- a/src/row.rs
+++ b/src/row.rs
@@ -191,8 +191,30 @@ impl Row {
                         prev_attrs = *attrs;
                     }
 
-                    contents.extend(cell.contents().as_bytes());
                     prev_pos.col += if cell.is_wide() { 2 } else { 1 };
+                    if prev_pos.col >= self.cols()
+                        && !self.wrapped
+                        && cell.is_wide()
+                        && cell.contents().chars().count() > 1
+                    {
+                        // alternately, we could backspace enough to overwrite
+                        // the second to last character, then ICH and rewrite
+                        // the second to last character and then reposition,
+                        // but that's a lot more complicated and not sure if
+                        // it's worth it for this much of an edge case
+                        let cell_contents = cell.contents();
+                        let mut chars = cell_contents.chars();
+                        let base = chars.next().unwrap();
+                        let mut bytes = [0; 4];
+                        contents.extend(base.encode_utf8(&mut bytes).bytes());
+                        crate::term::Backspace::default().write_buf(contents);
+                        for c in chars {
+                            contents
+                                .extend(c.encode_utf8(&mut bytes).bytes());
+                        }
+                    } else {
+                        contents.extend(cell.contents().as_bytes());
+                    }
                 } else if erase.is_none() {
                     erase = Some((pos.col, attrs));
                 }
@@ -216,6 +238,7 @@ impl Row {
     // while it's true that most of the logic in this is identical to
     // write_contents_formatted, i can't figure out how to break out the
     // common parts without making things noticeably slower.
+    #[allow(clippy::too_many_lines)]
     pub fn write_contents_diff(
         &self,
         contents: &mut Vec<u8>,
@@ -312,8 +335,31 @@ impl Row {
                         prev_attrs = *attrs;
                     }
 
-                    contents.extend(cell.contents().as_bytes());
                     prev_pos.col += if cell.is_wide() { 2 } else { 1 };
+                    if prev_pos.col >= self.cols()
+                        && !self.wrapped
+                        && cell.is_wide()
+                        && cell.contents().chars().count() > 1
+                    {
+                        // alternately, we could backspace enough to overwrite
+                        // the second to last character, then ICH and rewrite
+                        // the second to last character and then reposition,
+                        // but that's a lot more complicated and not sure if
+                        // it's worth it for this much of an edge case
+                        let cell_contents = cell.contents();
+                        let mut chars = cell_contents.chars();
+                        let base = chars.next().unwrap();
+                        let mut bytes = [0; 4];
+                        contents.extend(base.encode_utf8(&mut bytes).bytes());
+                        crate::term::Backspace::default().write_buf(contents);
+                        prev_pos.col -= 1;
+                        for c in chars {
+                            contents
+                                .extend(c.encode_utf8(&mut bytes).bytes());
+                        }
+                    } else {
+                        contents.extend(cell.contents().as_bytes());
+                    }
                 } else if erase.is_none() {
                     erase = Some((pos.col, attrs));
                 }
diff --git a/tests/data/fixtures/combining.in b/tests/data/fixtures/combining.in
index b9c62ca..5f62920 100644
--- a/tests/data/fixtures/combining.in
+++ b/tests/data/fixtures/combining.in
@@ -11,3 +11,4 @@ a
 \u{0301}
 \x1b[H\x1b[Jａ\u{0301}
 \x1b[H\x1b[J\x1b[2C\u{0301}
+\x1b[H\x1b[J\x1b[1;79Hａ\x08\u{301}
diff --git a/tests/data/fixtures/combining/14.json b/tests/data/fixtures/combining/14.json
new file mode 100644
index 0000000..bdc1fe2
--- /dev/null
+++ b/tests/data/fixtures/combining/14.json
@@ -0,0 +1,17 @@
+{
+  "contents": "                                                                              ａ́",
+  "cells": {
+    "0,78": {
+      "contents": "ａ́",
+      "is_wide": true
+    },
+    "0,79": {
+      "contents": "",
+      "is_wide_continuation": true
+    }
+  },
+  "cursor_position": [
+    0,
+    79
+  ]
+}
\ No newline at end of file
diff --git a/tests/data/fixtures/combining/14.typescript b/tests/data/fixtures/combining/14.typescript
new file mode 100644
index 0000000..513bc90
--- /dev/null
+++ b/tests/data/fixtures/combining/14.typescript
@@ -0,0 +1 @@
+ａ́
\ No newline at end of file