fix handling empty files

src/action.rs

@@ -139,7 +139,9 @@ impl App {
 	}
 	
 	const fn replace(&mut self) {
-		self.partial_action = Some(PartialAction::Replace);
+		if !self.contents.is_empty() {
+			self.partial_action = Some(PartialAction::Replace);
+		}
 	}
 	
 	const fn space(&mut self) {
@@ -156,7 +158,7 @@ impl App {
 	}
 	
 	const fn move_byte_down(&mut self) {
-		if self.contents.len() - 1 - self.cursor.head >= BYTES_PER_LINE {
+		if self.max_contents_index() - self.cursor.head >= BYTES_PER_LINE {
 			self.cursor.head += BYTES_PER_LINE;
 			self.cursor.collapse();
 			
@@ -174,7 +176,7 @@ impl App {
 	}
 	
 	const fn move_byte_right(&mut self) {
-		if self.contents.len() - 1 - self.cursor.head >= 1 {
+		if self.max_contents_index() - self.cursor.head >= 1 {
 			self.cursor.head += 1;
 			self.cursor.collapse();
 			
@@ -190,7 +192,7 @@ impl App {
 	}
 	
 	const fn extend_byte_down(&mut self) {
-		if self.contents.len() - 1 - self.cursor.head >= BYTES_PER_LINE {
+		if self.max_contents_index() - self.cursor.head >= BYTES_PER_LINE {
 			self.cursor.head += BYTES_PER_LINE;
 			self.clamp_screen_to_cursor();
 		}
@@ -204,7 +206,7 @@ impl App {
 	}
 	
 	const fn extend_byte_right(&mut self) {
-		if self.contents.len() - 1 - self.cursor.head >= 1 {
+		if self.max_contents_index() - self.cursor.head >= 1 {
 			self.cursor.head += 1;
 			self.clamp_screen_to_cursor();
 		}
@@ -235,6 +237,8 @@ impl App {
 	}
 	
 	fn scroll_down(&mut self) {
+		if self.contents.len() <= 5 * BYTES_PER_LINE { return; }
+		
 		self.scroll_position = min(
 			self.scroll_position + BYTES_PER_LINE,
 			self.contents.len() - (5 * BYTES_PER_LINE)
@@ -248,6 +252,8 @@ impl App {
 	}
 	
 	fn page_cursor_half_down(&mut self) {
+		if self.contents.len() <= 5 * BYTES_PER_LINE { return; }
+		
 		let head_offset = self.cursor.head - self.scroll_position;
 		let tail_offset = self.cursor.tail - self.scroll_position;
 		
@@ -256,8 +262,8 @@ impl App {
 			self.contents.len() - (5 * BYTES_PER_LINE)
 		);
 		
-		self.cursor.head = (self.scroll_position + head_offset).min(self.contents.len() - 1);
+		self.cursor.head = (self.scroll_position + head_offset).min(self.max_contents_index());
-		self.cursor.tail = (self.scroll_position + tail_offset).min(self.contents.len() - 1);
+		self.cursor.tail = (self.scroll_position + tail_offset).min(self.max_contents_index());
 	}
 	
 	fn page_cursor_half_up(&mut self) {
@@ -268,11 +274,13 @@ impl App {
 			(self.screen_size() / 2).next_multiple_of(BYTES_PER_LINE)
 		);
 		
-		self.cursor.head = (self.scroll_position + head_offset).min(self.contents.len() - 1);
+		self.cursor.head = (self.scroll_position + head_offset).min(self.max_contents_index());
-		self.cursor.tail = (self.scroll_position + tail_offset).min(self.contents.len() - 1);
+		self.cursor.tail = (self.scroll_position + tail_offset).min(self.max_contents_index());
 	}
 	
 	fn page_down(&mut self) {
+		if self.contents.len() <= 5 * BYTES_PER_LINE { return; }
+		
 		self.scroll_position = min(
 			self.scroll_position + self.screen_size(),
 			self.contents.len() - (5 * BYTES_PER_LINE)
@@ -288,12 +296,12 @@ impl App {
 	}
 	
 	fn move_next_word_start(&mut self) {
-		self.cursor.move_to_next_word(self.contents.len() - 1);
+		self.cursor.move_to_next_word(self.max_contents_index());
 		self.clamp_screen_to_cursor();
 	}
 	
 	fn move_next_word_end(&mut self) {
-		self.cursor.move_to_next_end(self.contents.len() - 1);
+		self.cursor.move_to_next_end(self.max_contents_index());
 		self.clamp_screen_to_cursor();
 	}
 	
@@ -303,12 +311,12 @@ impl App {
 	}
 	
 	fn extend_next_word_start(&mut self) {
-		self.cursor.extend_to_next_word(self.contents.len() - 1);
+		self.cursor.extend_to_next_word(self.max_contents_index());
 		self.clamp_screen_to_cursor();
 	}
 	
 	fn extend_next_word_end(&mut self) {
-		self.cursor.extend_to_next_end(self.contents.len() - 1);
+		self.cursor.extend_to_next_end(self.max_contents_index());
 		self.clamp_screen_to_cursor();
 	}
 	
@@ -331,7 +339,7 @@ impl App {
 		{
 			self.cursor.head = min(
 				self.cursor.head + BYTES_PER_LINE,
-				self.contents.len() - 1
+				self.max_contents_index()
 			);
 		} else {
 			self.cursor.tail -= self.cursor.tail % BYTES_PER_LINE;
@@ -346,7 +354,7 @@ impl App {
 		
 		if self.cursor.head.is_multiple_of(BYTES_PER_LINE) &&
 		   (self.cursor.tail % BYTES_PER_LINE == BYTES_PER_LINE - 1 ||
-		    self.cursor.tail == self.contents.len() - 1)
+		    self.cursor.tail == self.max_contents_index())
 		{
 			self.cursor.head = self.cursor.head.saturating_sub(BYTES_PER_LINE);
 		} else {
@@ -356,12 +364,14 @@ impl App {
 	}
 	
 	fn delete(&mut self) {
-		self.execute_and_add(
+		if !self.contents.is_empty() {
-			EditAction::Delete {
+			self.execute_and_add(
-				cursor: self.cursor,
+				EditAction::Delete {
-				old_data: self.contents[self.cursor.range()].into()
+					cursor: self.cursor,
-			}
+					old_data: self.contents[self.cursor.range()].into()
-		);
+				}
+			);
+		}
 		
 		if self.mode == Mode::Select {
 			self.mode = Mode::Normal;
@@ -369,7 +379,7 @@ impl App {
 	}
 	
 	fn undo(&mut self) {
-		if self.time_traveling == Some(0) || self.edit_history.is_empty() { return }
+		if self.time_traveling == Some(0) || self.edit_history.is_empty() { return; }
 		
 		let current_date = self.time_traveling
 			.map_or(self.edit_history.len() - 1, |date| date - 1);
@@ -387,7 +397,7 @@ impl App {
 	}
 	
 	fn redo(&mut self) {
-		let Some(previous_date) = self.time_traveling else { return };
+		let Some(previous_date) = self.time_traveling else { return; };
 		
 		let current_date = previous_date + 1;
 		

src/app/mod.rs

@@ -183,10 +183,15 @@ impl App {
 			false
 		}
 	}
+	
+	// returns 0 if empty
+	pub const fn max_contents_index(&self) -> usize {
+		self.contents.len().saturating_sub(1)
+	}
 }
 
 fn nybble_from_hex(hex: char) -> Option<u8> {
-	if !hex.is_ascii() { return None }
+	if !hex.is_ascii() { return None; }
 	
 	match hex {
 		'0'..='9' => Some(u8::try_from(hex).unwrap() - u8::try_from('0').unwrap()),

src/app/widget.rs

@@ -33,6 +33,10 @@ impl Widget for &App {
 		let hex_area = Rect::new(area.x, area.y, area.width, area.height - 1);
 		hex_text.render(hex_area, buf);
 		
+		if self.contents.is_empty() {
+			Line::from("empty file").render(area, buf);
+		}
+		
 		let status_line_area = Rect::new(area.x, area.bottom() - 1, area.width, 1);
 		self.render_status_line().render(status_line_area, buf);
 		
@@ -416,14 +420,18 @@ mod extra_statuses {
 	
 	impl App {
 		pub fn render_extra_statuses(&self) -> Line<'_> {
-			#[allow(clippy::cast_precision_loss)]
-			let percentage = self.cursor.head as f64 / (self.contents.len() - 1) as f64 * 100.0;
-			
 			let partial_action = self.partial_action
 				.as_ref()
 				.map_or("", |partial_action| partial_action.label());
 			
-			format!("{partial_action} {percentage:.0}% ").into()
+			if self.contents.is_empty() {
+				format!("{partial_action} ").into()
+			} else {
+				#[allow(clippy::cast_precision_loss)]
+				let percentage = self.cursor.head as f64 / self.max_contents_index() as f64 * 100.0;
+				
+				format!("{partial_action} {percentage:.0}% ").into()
+			}
 		}
 	}
 }

src/cursor.rs

@@ -50,7 +50,7 @@ impl Cursor {
 	}
 	
 	pub fn move_to_next_word(&mut self, max: usize) {
-		if self.head == max { return }
+		if self.head == max { return; }
 		
 		if self.head.is_multiple_of(4) { // at the beginning of a word
 			self.head = (self.head + 4).min(max);
@@ -61,7 +61,7 @@ impl Cursor {
 	}
 	
 	pub fn move_to_next_end(&mut self, max: usize) {
-		if self.head == max { return }
+		if self.head == max { return; }
 		
 		self.collapse();
 		if self.head % 4 == 3 { // at the end of a word
@@ -73,7 +73,7 @@ impl Cursor {
 	}
 	
 	pub const fn move_to_previous_beginning(&mut self) {
-		if self.head == 0 { return }
+		if self.head == 0 { return; }
 		
 		self.collapse();
 		if self.head.is_multiple_of(4) { // at the beginning of a word
@@ -85,7 +85,7 @@ impl Cursor {
 	}
 	
 	pub fn extend_to_next_word(&mut self, max: usize) {
-		if self.head == max { return }
+		if self.head == max { return; }
 		
 		if self.head.is_multiple_of(4) { // at the beginning of a word
 			self.head = (self.head + 4).min(max);
@@ -95,7 +95,7 @@ impl Cursor {
 	}
 	
 	pub fn extend_to_next_end(&mut self, max: usize) {
-		if self.head == max { return }
+		if self.head == max { return; }
 		
 		if self.head % 4 == 3 { // at the end of a word
 			self.head = (self.head + 4).min(max);
@@ -105,7 +105,7 @@ impl Cursor {
 	}
 	
 	pub const fn extend_to_previous_beginning(&mut self) {
-		if self.head == 0 { return }
+		if self.head == 0 { return; }
 		
 		if self.head.is_multiple_of(4) { // at the beginning of a word
 			self.head -= 4;

src/edit_action.rs

@@ -66,7 +66,7 @@ impl App {
 	fn delete_at(&mut self, cursor: Cursor) {
 		self.contents.drain(cursor.range());
 		
-		self.cursor.head = min(min(cursor.head, cursor.tail), self.contents.len() - 1);
+		self.cursor.head = min(min(cursor.head, cursor.tail), self.max_contents_index());
 		self.cursor.collapse();
 	}
 	

src/main.rs

@@ -50,8 +50,7 @@ const CHUNKS_PER_LINE: usize = BYTES_PER_LINE / BYTES_PER_CHUNK;
 // - utf8?
 // - diffing
 
-// TODO: opening empty file crashes (or deleting entire file)
+// TODO: quit should confirm if unsaved changes
-// - cursor is NOT guaranteed to be in-bounds..?
 
 // when AsciiChar is stabilized, use it instead of char everywhere