fix(text): preserve departure selections and scope Escape dismissal

2026-09-12 22:34:16 -07:00
parent 3412d4f369
commit 7f2947d651
6 changed files with 649 additions and 25 deletions
@@ -0,0 +1,295 @@
+//! Effective selected-byte ranges for a committed departure from a source view.
+//!
+//! Iced's `Cursor` omits cosmic-text's Word/Line selection kind. Saving its raw
+//! endpoints can therefore save an empty range for a visibly selected word/line.
+//! Capture only after navigation admission and destination validation succeed,
+//! immediately before replacing/leaving the live editor. Never use this to inspect
+//! pending queries, failed/no-op navigation, or restore focus to the same editor.
+use iced::advanced::{graphics, text};
+use iced::widget::text_editor::{Action, Content, Cursor, Motion, Position};
+
+/// Capture the effective range for restoration on fresh Content via `move_to`.
+///
+/// A nonempty selection is collapsed to its start in the departing Content; text
+/// is not edited. The returned Normal range preserves selected bytes and typing
+/// replacement, not Word/Line gesture-extension mode or an interior click point.
+/// Unequal raw endpoint direction is preserved; coincident Word/Line endpoints
+/// canonically restore with the active cursor at the effective end.
+///
+/// The renderer constraint is intentional: the inspected Iced graphics editor
+/// collapses any selection to its effective start for `Move(Left)`, and its copied
+/// selection joins editor lines with LF regardless of physical CRLF/LF endings.
+/// Only the selected text is temporarily copied; retained state is one Cursor.
+pub fn capture<R>(content: &mut Content<R>) -> Cursor
+where
+    R: text::Renderer<Editor = graphics::text::Editor>,
+{
+    let original = content.cursor();
+    let Some(selected) = content.selection().filter(|selected| !selected.is_empty()) else {
+        // Moving an unselected caret Left would be a user-visible navigation.
+        return original;
+    };
+    let active_start = original.selection.is_some_and(|anchor| {
+        (original.position.line, original.position.column) < (anchor.line, anchor.column)
+    });
+    content.perform(Action::Move(Motion::Left));
+    let start = content.cursor().position;
+    let end = match selected.rsplit_once('\n') {
+        Some((prefix, suffix)) => Position {
+            line: start.line + prefix.bytes().filter(|byte| *byte == b'\n').count() + 1,
+            column: suffix.len(),
+        },
+        None => Position {
+            line: start.line,
+            column: start.column + selected.len(),
+        },
+    };
+    // These sums describe an existing selection in this same allocated buffer;
+    // neither can exceed its line count / existing UTF-8 line length. A checked
+    // error after collapsing would leave a failed departure with lost selection.
+    debug_assert!(content.cursor().selection.is_none());
+    debug_assert!(start.line < content.line_count() && end.line < content.line_count());
+    debug_assert!((start.line, start.column) < (end.line, end.column));
+    Cursor {
+        position: if active_start { start } else { end },
+        selection: Some(if active_start { end } else { start }),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use iced::widget::text_editor::Edit;
+    use std::sync::Arc;
+
+    type EditorContent = Content<iced::Renderer>;
+
+    fn at(line: usize, column: usize) -> Position {
+        Position { line, column }
+    }
+
+    fn range(start: Position, end: Position, active_start: bool) -> Cursor {
+        Cursor {
+            position: if active_start { start } else { end },
+            selection: Some(if active_start { end } else { start }),
+        }
+    }
+
+    fn caret(content: &mut EditorContent, position: Position) {
+        content.move_to(Cursor {
+            position,
+            selection: None,
+        });
+    }
+
+    fn roundtrip(
+        source: &str,
+        prepare: impl Fn(&mut EditorContent),
+        selected: &str,
+        expected: Cursor,
+        lossy_raw: bool,
+    ) {
+        let mut departing = EditorContent::with_text(source);
+        prepare(&mut departing);
+        assert_eq!(departing.text(), source);
+        assert_eq!(departing.selection().as_deref(), Some(selected));
+        let raw = departing.cursor();
+
+        // Independent direct-typing control retains the original semantic mode.
+        let replacement = Action::Edit(Edit::Paste(Arc::new("替🚀".into())));
+        let mut direct = EditorContent::with_text(source);
+        prepare(&mut direct);
+        direct.perform(replacement.clone());
+
+        let captured = capture(&mut departing);
+        assert_eq!(captured, expected);
+        assert_eq!(
+            departing.text(),
+            source,
+            "capture cannot edit physical source bytes"
+        );
+        assert!(departing.cursor().selection.is_none());
+        let mut restored = EditorContent::with_text(source);
+        restored.move_to(captured);
+        assert_eq!(restored.selection().as_deref(), Some(selected));
+        assert_eq!(restored.text(), source);
+        restored.perform(replacement);
+        assert_eq!(
+            restored.text(),
+            direct.text(),
+            "restored range must replace exactly the original selected bytes"
+        );
+        assert_eq!(restored.cursor(), direct.cursor());
+        if lossy_raw {
+            let mut old = EditorContent::with_text(source);
+            old.move_to(raw);
+            assert_ne!(
+                old.selection().as_deref(),
+                Some(selected),
+                "negative control must discriminate raw cursor storage"
+            );
+        } else {
+            assert_eq!(
+                captured, raw,
+                "ordinary directional ranges are already canonical"
+            );
+        }
+    }
+
+    #[test]
+    fn unicode_normal_ranges_preserve_forward_and_reverse_direction() {
+        let source = "先 αβ 救助 🚀 tail\r\n";
+        for active_start in [false, true] {
+            let expected = range(
+                at(0, "先 ".len()),
+                at(0, "先 αβ 救助 🚀".len()),
+                active_start,
+            );
+            roundtrip(
+                source,
+                |content| content.move_to(expected),
+                "αβ 救助 🚀",
+                expected,
+                false,
+            );
+        }
+    }
+
+    #[test]
+    fn repeated_unicode_words_capture_the_selected_occurrence_without_searching() {
+        let source = "éclair éclair éclair\r\n";
+        let start = "éclair ".len();
+        roundtrip(
+            source,
+            |content| {
+                caret(content, at(0, start + "écl".len()));
+                content.perform(Action::SelectWord);
+            },
+            "éclair",
+            range(at(0, start), at(0, start + "éclair".len()), false),
+            true,
+        );
+    }
+
+    #[test]
+    fn line_selection_expands_past_its_interior_unicode_caret() {
+        let source = "first\r\n救助 🚀 tail\r\nlast";
+        roundtrip(
+            source,
+            |content| {
+                caret(content, at(1, "救助 ".len()));
+                content.perform(Action::SelectLine);
+            },
+            "救助 🚀 tail",
+            range(at(1, 0), at(1, "救助 🚀 tail".len()), false),
+            true,
+        );
+    }
+
+    #[test]
+    fn multiline_ranges_use_copied_lf_and_utf8_columns_for_physical_crlf_and_mixed_endings() {
+        for source in ["pré α\r\n中 🚀\r\nfin Ω", "pré α\n中 🚀\r\nfin Ω"] {
+            for active_start in [false, true] {
+                let expected = range(at(0, "pré ".len()), at(2, "fin ".len()), active_start);
+                roundtrip(
+                    source,
+                    |content| content.move_to(expected),
+                    "α\n中 🚀\nfin ",
+                    expected,
+                    false,
+                );
+            }
+        }
+    }
+
+    #[test]
+    fn expanded_word_and_line_modes_capture_multiline_ranges_in_both_directions() {
+        let source = "one alpha\r\ntwo beta\nthree gamma";
+        for line in [false, true] {
+            for reverse in [false, true] {
+                let (start, end, selected) = match (line, reverse) {
+                    (false, false) => (at(0, 4), at(2, 11), "alpha\ntwo beta\nthree gamma"),
+                    (false, true) => (at(0, 0), at(2, 11), "one alpha\ntwo beta\nthree gamma"),
+                    (true, _) => (at(0, 0), at(2, 11), "one alpha\ntwo beta\nthree gamma"),
+                };
+                roundtrip(
+                    source,
+                    |content| {
+                        caret(content, if reverse { at(2, 8) } else { at(0, 6) });
+                        content.perform(if line {
+                            Action::SelectLine
+                        } else {
+                            Action::SelectWord
+                        });
+                        // Iced preserves existing Word/Line mode for Select motions.
+                        content.perform(Action::Select(if reverse {
+                            Motion::DocumentStart
+                        } else {
+                            Motion::DocumentEnd
+                        }));
+                    },
+                    selected,
+                    range(start, end, reverse),
+                    true,
+                );
+            }
+        }
+    }
+
+    #[test]
+    fn trailing_newline_selection_restores_endpoint_on_the_empty_last_line() {
+        let source = "雨\r\n🚀\r\n";
+        let expected = range(at(0, 0), at(2, 0), false);
+        roundtrip(
+            source,
+            |content| content.perform(Action::SelectAll),
+            "雨\n🚀\n",
+            expected,
+            false,
+        );
+    }
+
+    #[test]
+    fn absent_and_empty_selection_do_not_move_the_departing_caret() {
+        for source in ["", "\r\n", "alpha\r\n\r\ntail"] {
+            for empty_selection in [false, true] {
+                let mut content = EditorContent::with_text(source);
+                let position = if source.starts_with("alpha") {
+                    at(1, 0)
+                } else {
+                    at(0, 0)
+                };
+                caret(&mut content, position);
+                if empty_selection {
+                    content.perform(Action::SelectLine);
+                    assert_eq!(content.selection().as_deref(), Some(""));
+                } else {
+                    assert!(content.selection().is_none());
+                }
+                let raw = content.cursor();
+                let selected = content.selection();
+                assert_eq!(capture(&mut content), raw);
+                assert_eq!(content.cursor(), raw);
+                assert_eq!(content.selection(), selected);
+                assert_eq!(content.text(), source);
+            }
+        }
+        for empty_normal in [false, true] {
+            let mut content = EditorContent::with_text("éclair");
+            let position = at(0, "écl".len());
+            content.move_to(Cursor {
+                position,
+                selection: empty_normal.then_some(position),
+            });
+            let raw = content.cursor();
+            let selected = content.selection();
+            assert_eq!(capture(&mut content), raw);
+            assert_eq!(
+                content.cursor(),
+                raw,
+                "an unselected interior caret must not move left"
+            );
+            assert_eq!(content.selection(), selected);
+        }
+    }
+}