Add ability to select and cut text in the input buffer (#689)

* Add ability to select and cut text in the input buffer

* Add visual selection effect

* Add SelectMoveWord<Left/Right> command on Shift + Ctrl + Arrow

* Add ability to delete selection with EditCommands 'Delete' and 'Backspace'

* Make selection an option on every move EditCommand

* Add display text for optional 'select' parameter to move EditCommands

src/core_editor/editor.rs

@@ -9,9 +9,9 @@ use crate::{core_editor::get_default_clipboard, EditCommand};
 pub struct Editor {
     line_buffer: LineBuffer,
     cut_buffer: Box<dyn Clipboard>,
-
     edit_stack: EditStack<LineBuffer>,
     last_undo_behavior: UndoBehavior,
+    selection_anchor: Option<usize>,
 }
 
 impl Default for Editor {
@@ -21,6 +21,7 @@ impl Default for Editor {
             cut_buffer: Box::new(get_default_clipboard()),
             edit_stack: EditStack::new(),
             last_undo_behavior: UndoBehavior::CreateUndoPoint,
+            selection_anchor: None,
         }
     }
 }
@@ -40,28 +41,32 @@ impl Editor {
 
     pub(crate) fn run_edit_command(&mut self, command: &EditCommand) {
         match command {
-            EditCommand::MoveToStart => self.line_buffer.move_to_start(),
-            EditCommand::MoveToLineStart => self.line_buffer.move_to_line_start(),
-            EditCommand::MoveToEnd => self.line_buffer.move_to_end(),
-            EditCommand::MoveToLineEnd => self.line_buffer.move_to_line_end(),
-            EditCommand::MoveToPosition(pos) => self.line_buffer.set_insertion_point(*pos),
-            EditCommand::MoveLeft => self.line_buffer.move_left(),
-            EditCommand::MoveRight => self.line_buffer.move_right(),
-            EditCommand::MoveWordLeft => self.line_buffer.move_word_left(),
-            EditCommand::MoveBigWordLeft => self.line_buffer.move_big_word_left(),
-            EditCommand::MoveWordRight => self.line_buffer.move_word_right(),
-            EditCommand::MoveWordRightStart => self.line_buffer.move_word_right_start(),
-            EditCommand::MoveBigWordRightStart => self.line_buffer.move_big_word_right_start(),
-            EditCommand::MoveWordRightEnd => self.line_buffer.move_word_right_end(),
-            EditCommand::MoveBigWordRightEnd => self.line_buffer.move_big_word_right_end(),
-            EditCommand::InsertChar(c) => self.line_buffer.insert_char(*c),
+            EditCommand::MoveToStart { select } => self.move_to_start(*select),
+            EditCommand::MoveToLineStart { select } => self.move_to_line_start(*select),
+            EditCommand::MoveToEnd { select } => self.move_to_end(*select),
+            EditCommand::MoveToLineEnd { select } => self.move_to_line_end(*select),
+            EditCommand::MoveToPosition { position, select } => {
+                self.move_to_position(*position, *select)
+            }
+            EditCommand::MoveLeft { select } => self.move_left(*select),
+            EditCommand::MoveRight { select } => self.move_right(*select),
+            EditCommand::MoveWordLeft { select } => self.move_word_left(*select),
+            EditCommand::MoveBigWordLeft { select } => self.move_big_word_left(*select),
+            EditCommand::MoveWordRight { select } => self.move_word_right(*select),
+            EditCommand::MoveWordRightStart { select } => self.move_word_right_start(*select),
+            EditCommand::MoveBigWordRightStart { select } => {
+                self.move_big_word_right_start(*select)
+            }
+            EditCommand::MoveWordRightEnd { select } => self.move_word_right_end(*select),
+            EditCommand::MoveBigWordRightEnd { select } => self.move_big_word_right_end(*select),
+            EditCommand::InsertChar(c) => self.insert_char(*c),
             EditCommand::Complete => {}
-            EditCommand::InsertString(str) => self.line_buffer.insert_str(str),
-            EditCommand::InsertNewline => self.line_buffer.insert_newline(),
+            EditCommand::InsertString(str) => self.insert_str(str),
+            EditCommand::InsertNewline => self.insert_newline(),
             EditCommand::ReplaceChar(chr) => self.replace_char(*chr),
             EditCommand::ReplaceChars(n_chars, str) => self.replace_chars(*n_chars, str),
-            EditCommand::Backspace => self.line_buffer.delete_left_grapheme(),
-            EditCommand::Delete => self.line_buffer.delete_right_grapheme(),
+            EditCommand::Backspace => self.backspace(),
+            EditCommand::Delete => self.delete(),
             EditCommand::CutChar => self.cut_char(),
             EditCommand::BackspaceWord => self.line_buffer.delete_word_left(),
             EditCommand::DeleteWord => self.line_buffer.delete_word_right(),
@@ -90,16 +95,31 @@ impl Editor {
             EditCommand::Redo => self.redo(),
             EditCommand::CutRightUntil(c) => self.cut_right_until_char(*c, false, true),
             EditCommand::CutRightBefore(c) => self.cut_right_until_char(*c, true, true),
-            EditCommand::MoveRightUntil(c) => self.move_right_until_char(*c, false, true),
-            EditCommand::MoveRightBefore(c) => self.move_right_until_char(*c, true, true),
+            EditCommand::MoveRightUntil { c, select } => {
+                self.move_right_until_char(*c, false, true, *select)
+            }
+            EditCommand::MoveRightBefore { c, select } => {
+                self.move_right_until_char(*c, true, true, *select)
+            }
             EditCommand::CutLeftUntil(c) => self.cut_left_until_char(*c, false, true),
             EditCommand::CutLeftBefore(c) => self.cut_left_until_char(*c, true, true),
-            EditCommand::MoveLeftUntil(c) => self.move_left_until_char(*c, false, true),
-            EditCommand::MoveLeftBefore(c) => self.move_left_until_char(*c, true, true),
+            EditCommand::MoveLeftUntil { c, select } => {
+                self.move_left_until_char(*c, false, true, *select)
+            }
+            EditCommand::MoveLeftBefore { c, select } => {
+                self.move_left_until_char(*c, true, true, *select)
+            }
+            EditCommand::SelectAll => self.select_all(),
+            EditCommand::CutSelection => self.cut_selection(),
+            EditCommand::CopySelection => self.copy_selection(),
         }
+        if !matches!(command.edit_type(), EditType::MoveCursor { select: true }) {
+            self.selection_anchor = None;
+        }
+        if let EditType::MoveCursor { select: true } = command.edit_type() {}
 
         let new_undo_behavior = match (command, command.edit_type()) {
-            (_, EditType::MoveCursor) => UndoBehavior::MoveCursor,
+            (_, EditType::MoveCursor { .. }) => UndoBehavior::MoveCursor,
             (EditCommand::InsertChar(c), EditType::EditText) => UndoBehavior::InsertCharacter(*c),
             (EditCommand::Delete, EditType::EditText) => {
                 let deleted_char = self.edit_stack.current().grapheme_right().chars().next();
@@ -112,8 +132,21 @@ impl Editor {
             (_, EditType::UndoRedo) => UndoBehavior::UndoRedo,
             (_, _) => UndoBehavior::CreateUndoPoint,
         };
+
         self.update_undo_state(new_undo_behavior);
     }
+    fn update_selection_anchor(&mut self, select: bool) {
+        self.selection_anchor = if select {
+            self.selection_anchor
+                .or_else(|| Some(self.insertion_point()))
+        } else {
+            None
+        };
+    }
+    fn move_to_position(&mut self, position: usize, select: bool) {
+        self.update_selection_anchor(select);
+        self.line_buffer.set_insertion_point(position)
+    }
 
     pub(crate) fn move_line_up(&mut self) {
         self.line_buffer.move_line_up();
@@ -170,25 +203,24 @@ impl Editor {
         self.edit_stack.reset();
     }
 
-    pub(crate) fn move_to_start(&mut self, undo_behavior: UndoBehavior) {
+    pub(crate) fn move_to_start(&mut self, select: bool) {
+        self.update_selection_anchor(select);
         self.line_buffer.move_to_start();
-        self.update_undo_state(undo_behavior);
     }
 
-    pub(crate) fn move_to_end(&mut self, undo_behavior: UndoBehavior) {
+    pub(crate) fn move_to_end(&mut self, select: bool) {
+        self.update_selection_anchor(select);
         self.line_buffer.move_to_end();
-        self.update_undo_state(undo_behavior);
     }
 
-    #[allow(dead_code)]
-    pub(crate) fn move_to_line_start(&mut self, undo_behavior: UndoBehavior) {
+    pub(crate) fn move_to_line_start(&mut self, select: bool) {
+        self.update_selection_anchor(select);
         self.line_buffer.move_to_line_start();
-        self.update_undo_state(undo_behavior);
     }
 
-    pub(crate) fn move_to_line_end(&mut self, undo_behavior: UndoBehavior) {
+    pub(crate) fn move_to_line_end(&mut self, select: bool) {
+        self.update_selection_anchor(select);
         self.line_buffer.move_to_line_end();
-        self.update_undo_state(undo_behavior);
     }
 
     fn undo(&mut self) {
@@ -201,7 +233,7 @@ impl Editor {
         self.line_buffer = val.clone();
     }
 
-    fn update_undo_state(&mut self, undo_behavior: UndoBehavior) {
+    pub(crate) fn update_undo_state(&mut self, undo_behavior: UndoBehavior) {
         if matches!(undo_behavior, UndoBehavior::UndoRedo) {
             self.last_undo_behavior = UndoBehavior::UndoRedo;
             return;
@@ -357,6 +389,7 @@ impl Editor {
     }
 
     fn insert_cut_buffer_before(&mut self) {
+        self.delete_selection();
         match self.cut_buffer.get() {
             (content, ClipboardMode::Normal) => {
                 self.line_buffer.insert_str(&content);
@@ -375,6 +408,7 @@ impl Editor {
     }
 
     fn insert_cut_buffer_after(&mut self) {
+        self.delete_selection();
         match self.cut_buffer.get() {
             (content, ClipboardMode::Normal) => {
                 self.line_buffer.move_right();
@@ -393,15 +427,29 @@ impl Editor {
         }
     }
 
-    fn move_right_until_char(&mut self, c: char, before_char: bool, current_line: bool) {
+    fn move_right_until_char(
+        &mut self,
+        c: char,
+        before_char: bool,
+        current_line: bool,
+        select: bool,
+    ) {
+        self.update_selection_anchor(select);
         if before_char {
             self.line_buffer.move_right_before(c, current_line);
         } else {
             self.line_buffer.move_right_until(c, current_line);
         }
     }
 
-    fn move_left_until_char(&mut self, c: char, before_char: bool, current_line: bool) {
+    fn move_left_until_char(
+        &mut self,
+        c: char,
+        before_char: bool,
+        current_line: bool,
+        select: bool,
+    ) {
+        self.update_selection_anchor(select);
         if before_char {
             self.line_buffer.move_left_before(c, current_line);
         } else {
@@ -462,6 +510,115 @@ impl Editor {
 
         self.line_buffer.insert_str(string);
     }
+
+    fn move_left(&mut self, select: bool) {
+        self.update_selection_anchor(select);
+        self.line_buffer.move_left();
+    }
+
+    fn move_right(&mut self, select: bool) {
+        self.update_selection_anchor(select);
+        self.line_buffer.move_right();
+    }
+
+    fn select_all(&mut self) {
+        self.selection_anchor = Some(0);
+        self.line_buffer.move_to_end();
+    }
+
+    fn cut_selection(&mut self) {
+        if let Some((start, end)) = self.get_selection() {
+            let cut_slice = &self.line_buffer.get_buffer()[start..end];
+            self.cut_buffer.set(cut_slice, ClipboardMode::Normal);
+            self.line_buffer.clear_range_safe(start, end);
+            self.selection_anchor = None;
+        }
+    }
+
+    fn copy_selection(&mut self) {
+        if let Some((start, end)) = self.get_selection() {
+            let cut_slice = &self.line_buffer.get_buffer()[start..end];
+            self.cut_buffer.set(cut_slice, ClipboardMode::Normal);
+        }
+    }
+
+    /// If a selection is active returns the selected range, otherwise None.
+    /// The range is guaranteed to be ascending.
+    pub fn get_selection(&self) -> Option<(usize, usize)> {
+        self.selection_anchor.map(|selection_anchor| {
+            if self.insertion_point() > selection_anchor {
+                (selection_anchor, self.insertion_point())
+            } else {
+                (self.insertion_point(), selection_anchor)
+            }
+        })
+    }
+
+    fn delete_selection(&mut self) {
+        if let Some((start, end)) = self.get_selection() {
+            self.line_buffer.clear_range_safe(start, end);
+            self.selection_anchor = None;
+        }
+    }
+
+    fn backspace(&mut self) {
+        if self.selection_anchor.is_some() {
+            self.delete_selection();
+        } else {
+            self.line_buffer.delete_left_grapheme();
+        }
+    }
+
+    fn delete(&mut self) {
+        if self.selection_anchor.is_some() {
+            self.delete_selection();
+        } else {
+            self.line_buffer.delete_right_grapheme();
+        }
+    }
+
+    fn move_word_left(&mut self, select: bool) {
+        self.move_to_position(self.line_buffer.word_left_index(), select);
+    }
+
+    fn move_big_word_left(&mut self, select: bool) {
+        self.move_to_position(self.line_buffer.big_word_left_index(), select);
+    }
+
+    fn move_word_right(&mut self, select: bool) {
+        self.move_to_position(self.line_buffer.word_right_index(), select);
+    }
+
+    fn move_word_right_start(&mut self, select: bool) {
+        self.move_to_position(self.line_buffer.word_right_start_index(), select);
+    }
+
+    fn move_big_word_right_start(&mut self, select: bool) {
+        self.move_to_position(self.line_buffer.big_word_right_start_index(), select);
+    }
+
+    fn move_word_right_end(&mut self, select: bool) {
+        self.move_to_position(self.line_buffer.word_right_end_index(), select);
+    }
+
+    fn move_big_word_right_end(&mut self, select: bool) {
+        self.move_to_position(self.line_buffer.big_word_right_end_index(), select);
+    }
+
+    fn insert_char(&mut self, c: char) {
+        self.delete_selection();
+        self.line_buffer.insert_char(c);
+    }
+
+    fn insert_str(&mut self, str: &str) {
+        self.delete_selection();
+        self.line_buffer.insert_str(str);
+    }
+
+    fn insert_newline(&mut self) {
+        self.delete_selection();
+        self.line_buffer.insert_newline();
+    }
 }
 
 #[cfg(test)]

src/core_editor/line_buffer.rs

@@ -396,6 +396,27 @@ impl LineBuffer {
         self.insertion_point = 0;
     }
 
+    /// Clear all contents between `start` and `end` and change insertion point if necessary.
+    ///
+    /// If the cursor is located between `start` and `end` it is adjusted to `start`.
+    /// If the cursor is located after `end` it is adjusted to stay at its current char boundary.
+    pub fn clear_range_safe(&mut self, start: usize, end: usize) {
+        let (start, end) = if start > end {
+            (end, start)
+        } else {
+            (start, end)
+        };
+        if self.insertion_point <= start {
+            // No action necessary
+        } else if self.insertion_point < end {
+            self.insertion_point = start;
+        } else {
+            // Insertion point after end
+            self.insertion_point -= end - start;
+        }
+        self.clear_range(start..end);
+    }
+
     /// Clear text covered by `range` in the current line
     ///
     /// Safety: Does not change the insertion point/offset and is thus not unicode safe!