input: Fix some Rope method call will crash. (#1213)

Author: huacnlee

crates/ui/src/input/rope_ext.rs

@@ -1,23 +1,40 @@
 pub(crate) trait RopeExt {
     /// Get the index of (line, column) (0-based) from the byte offset (0-based).
     /// If the offset is out of bounds, return the last line and column.
+    ///
+    /// If the `offset` is out of bounds, it returns (0, 0).
     fn line_column(&self, byte_offset: usize) -> (usize, usize);
     /// Get the byte offset (0-based) from the line, column (0-based).
+    ///
+    /// Return the last line, if line is out of bounds.
+    /// Return the end column of line, if the column is out of bounds.
     fn line_column_to_byte(&self, line_ix: usize, column_ix: usize) -> usize;
 }
 
 impl RopeExt for ropey::Rope {
     fn line_column(&self, offset: usize) -> (usize, usize) {
-        let line_ix = self.byte_to_line(offset);
-        let line_offset = offset.saturating_sub(self.line_to_byte(line_ix));
+        let Ok(line_ix) = self.try_byte_to_line(offset) else {
+            return (0, 0);
+        };
+
         let line = self.line(line_ix);
-        let column_ix = line.byte_to_char(line_offset);
+        let line_start_byte = self.line_to_byte(line_ix);
+        let line_offset = offset.saturating_sub(line_start_byte);
+
+        let column_ix = line
+            .try_byte_to_char(line_offset)
+            .unwrap_or(line.len_chars());
 
         (line_ix, column_ix)
     }
 
     fn line_column_to_byte(&self, line_ix: usize, column_ix: usize) -> usize {
+        let line_ix = self.len_lines().saturating_sub(1).min(line_ix);
         let line = self.line(line_ix);
-        self.line_to_byte(line_ix) + line.char_to_byte(column_ix)
+
+        self.line_to_byte(line_ix)
+            + line
+                .try_char_to_byte(column_ix)
+                .unwrap_or(line.len_bytes().saturating_sub(1))
     }
 }

crates/ui/src/input/state.rs

@@ -565,10 +565,18 @@ impl InputState {
         let offset = self.cursor().offset;
         let was_preferred_column = self.preferred_column;
 
-        let line_ix = self.text.byte_to_line(offset);
+        let Ok(line_ix) = self.text.try_byte_to_line(offset) else {
+            return;
+        };
+
         let new_line_ix = line_ix.saturating_add_signed(move_lines);
-        let line = self.text.line(new_line_ix);
-        let line_start_offset = self.text.line_to_byte(new_line_ix);
+        let Some(line) = self.text.get_line(new_line_ix) else {
+            return;
+        };
+        let Ok(line_start_offset) = self.text.try_line_to_byte(new_line_ix) else {
+            return;
+        };
+
         let new_column = self
             .preferred_column
             .unwrap_or_default()