perf: clippy::missing_const_for_fn (#974)

Cargo.toml

@@ -65,6 +65,7 @@ serde_json = "1.0.109"
 unsafe_code = "forbid"
 [lints.clippy]
 explicit_iter_loop = "warn"
+missing_const_for_fn = "warn"
 needless_for_each = "warn"
 semicolon_if_nothing_returned = "warn"
 

src/backend/crossterm.rs

@@ -97,7 +97,7 @@ where
     /// # use ratatui::prelude::*;
     /// let backend = CrosstermBackend::new(stdout());
     /// ```
-    pub fn new(writer: W) -> CrosstermBackend<W> {
+    pub const fn new(writer: W) -> CrosstermBackend<W> {
         CrosstermBackend { writer }
     }
 }

src/backend/termion.rs

@@ -82,7 +82,7 @@ where
     /// # use ratatui::prelude::*;
     /// let backend = TermionBackend::new(stdout());
     /// ```
-    pub fn new(writer: W) -> TermionBackend<W> {
+    pub const fn new(writer: W) -> TermionBackend<W> {
         TermionBackend { writer }
     }
 }

src/backend/termwiz.rs

@@ -93,14 +93,16 @@ impl TermwizBackend {
     }
 
     /// Creates a new Termwiz backend instance with the given buffered terminal.
-    pub fn with_buffered_terminal(instance: BufferedTerminal<SystemTerminal>) -> TermwizBackend {
+    pub const fn with_buffered_terminal(
+        instance: BufferedTerminal<SystemTerminal>,
+    ) -> TermwizBackend {
         TermwizBackend {
             buffered_terminal: instance,
         }
     }
 
     /// Returns a reference to the buffered terminal used by the backend.
-    pub fn buffered_terminal(&self) -> &BufferedTerminal<SystemTerminal> {
+    pub const fn buffered_terminal(&self) -> &BufferedTerminal<SystemTerminal> {
         &self.buffered_terminal
     }
 

src/backend/test.rs

@@ -84,7 +84,7 @@ impl TestBackend {
     }
 
     /// Returns a reference to the internal buffer of the TestBackend.
-    pub fn buffer(&self) -> &Buffer {
+    pub const fn buffer(&self) -> &Buffer {
         &self.buffer
     }
 

src/buffer/buffer.rs

@@ -92,7 +92,7 @@ impl Buffer {
     }
 
     /// Returns the area covered by this buffer
-    pub fn area(&self) -> &Rect {
+    pub const fn area(&self) -> &Rect {
         &self.area
     }
 

src/terminal/frame.rs

@@ -49,7 +49,7 @@ impl Frame<'_> {
     /// If your app listens for a resize event from the backend, it should ignore the values from
     /// the event for any calculations that are used to render the current frame and use this value
     /// instead as this is the size of the buffer that is used to render the current frame.
-    pub fn size(&self) -> Rect {
+    pub const fn size(&self) -> Rect {
         self.viewport_area
     }
 
@@ -193,7 +193,7 @@ impl Frame<'_> {
     /// let current_count = frame.count();
     /// println!("Current frame count: {}", current_count);
     /// ```
-    pub fn count(&self) -> usize {
+    pub const fn count(&self) -> usize {
         self.count
     }
 }

src/terminal/terminal.rs

@@ -172,7 +172,7 @@ where
     }
 
     /// Gets the backend
-    pub fn backend(&self) -> &B {
+    pub const fn backend(&self) -> &B {
         &self.backend
     }
 

src/text/masked.rs

@@ -36,7 +36,7 @@ impl<'a> Masked<'a> {
     }
 
     /// The character to use for masking.
-    pub fn mask_char(&self) -> char {
+    pub const fn mask_char(&self) -> char {
         self.mask_char
     }
 

src/widgets/barchart.rs

@@ -163,7 +163,7 @@ impl<'a> BarChart<'a> {
     /// // f b b
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn max(mut self, max: u64) -> BarChart<'a> {
+    pub const fn max(mut self, max: u64) -> BarChart<'a> {
         self.max = Some(max);
         self
     }
@@ -213,7 +213,7 @@ impl<'a> BarChart<'a> {
     /// // f   b
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn bar_gap(mut self, gap: u16) -> BarChart<'a> {
+    pub const fn bar_gap(mut self, gap: u16) -> BarChart<'a> {
         self.bar_gap = gap;
         self
     }
@@ -222,7 +222,7 @@ impl<'a> BarChart<'a> {
     ///
     /// If not set, the default is [`bar::NINE_LEVELS`](crate::symbols::bar::NINE_LEVELS).
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn bar_set(mut self, bar_set: symbols::bar::Set) -> BarChart<'a> {
+    pub const fn bar_set(mut self, bar_set: symbols::bar::Set) -> BarChart<'a> {
         self.bar_set = bar_set;
         self
     }
@@ -263,7 +263,7 @@ impl<'a> BarChart<'a> {
 
     /// Set the gap between [`BarGroup`].
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn group_gap(mut self, gap: u16) -> BarChart<'a> {
+    pub const fn group_gap(mut self, gap: u16) -> BarChart<'a> {
         self.group_gap = gap;
         self
     }
@@ -300,7 +300,7 @@ impl<'a> BarChart<'a> {
     /// █bar██
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn direction(mut self, direction: Direction) -> BarChart<'a> {
+    pub const fn direction(mut self, direction: Direction) -> BarChart<'a> {
         self.direction = direction;
         self
     }

src/widgets/barchart/bar.rs

@@ -50,7 +50,7 @@ impl<'a> Bar<'a> {
     /// [`Bar::value_style`] to style the value.  
     /// [`Bar::text_value`] to set the displayed value.
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn value(mut self, value: u64) -> Bar<'a> {
+    pub const fn value(mut self, value: u64) -> Bar<'a> {
         self.value = value;
         self
     }

src/widgets/block.rs

@@ -1107,7 +1107,7 @@ mod tests {
     }
 
     #[test]
-    fn border_type_can_be_const() {
+    const fn border_type_can_be_const() {
         const _PLAIN: border::Set = BorderType::border_symbols(BorderType::Plain);
     }
 
@@ -1130,7 +1130,7 @@ mod tests {
     }
 
     #[test]
-    fn block_can_be_const() {
+    const fn block_can_be_const() {
         const _DEFAULT_STYLE: Style = Style::new();
         const _DEFAULT_PADDING: Padding = Padding::uniform(1);
         const _DEFAULT_BLOCK: Block = Block::new()

src/widgets/block/padding.rs

@@ -186,7 +186,7 @@ mod tests {
     }
 
     #[test]
-    fn can_be_const() {
+    const fn can_be_const() {
         const _PADDING: Padding = Padding::new(1, 1, 1, 1);
         const _UNI_PADDING: Padding = Padding::uniform(1);
         const _NO_PADDING: Padding = Padding::zero();

src/widgets/block/title.rs

@@ -97,14 +97,14 @@ impl<'a> Title<'a> {
 
     /// Set the title alignment.
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn alignment(mut self, alignment: Alignment) -> Title<'a> {
+    pub const fn alignment(mut self, alignment: Alignment) -> Title<'a> {
         self.alignment = Some(alignment);
         self
     }
 
     /// Set the title position.
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn position(mut self, position: Position) -> Title<'a> {
+    pub const fn position(mut self, position: Position) -> Title<'a> {
         self.position = Some(position);
         self
     }

src/widgets/canvas.rs

@@ -671,7 +671,7 @@ where
     ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn x_bounds(mut self, bounds: [f64; 2]) -> Canvas<'a, F> {
+    pub const fn x_bounds(mut self, bounds: [f64; 2]) -> Canvas<'a, F> {
         self.x_bounds = bounds;
         self
     }
@@ -683,7 +683,7 @@ where
     ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn y_bounds(mut self, bounds: [f64; 2]) -> Canvas<'a, F> {
+    pub const fn y_bounds(mut self, bounds: [f64; 2]) -> Canvas<'a, F> {
         self.y_bounds = bounds;
         self
     }
@@ -701,7 +701,7 @@ where
     ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn background_color(mut self, color: Color) -> Canvas<'a, F> {
+    pub const fn background_color(mut self, color: Color) -> Canvas<'a, F> {
         self.background_color = color;
         self
     }
@@ -744,7 +744,7 @@ where
     ///     .marker(symbols::Marker::Block)
     ///     .paint(|ctx| {});
     /// ```
-    pub fn marker(mut self, marker: symbols::Marker) -> Canvas<'a, F> {
+    pub const fn marker(mut self, marker: symbols::Marker) -> Canvas<'a, F> {
         self.marker = marker;
         self
     }

src/widgets/chart.rs

@@ -70,7 +70,7 @@ impl<'a> Axis<'a> {
     ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn bounds(mut self, bounds: [f64; 2]) -> Axis<'a> {
+    pub const fn bounds(mut self, bounds: [f64; 2]) -> Axis<'a> {
         self.bounds = bounds;
         self
     }
@@ -133,7 +133,7 @@ impl<'a> Axis<'a> {
     ///
     /// On the X axis, this parameter only affects the first label.
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn labels_alignment(mut self, alignment: Alignment) -> Axis<'a> {
+    pub const fn labels_alignment(mut self, alignment: Alignment) -> Axis<'a> {
         self.labels_alignment = alignment;
         self
     }
@@ -341,7 +341,7 @@ impl<'a> Dataset<'a> {
     ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn data(mut self, data: &'a [(f64, f64)]) -> Dataset<'a> {
+    pub const fn data(mut self, data: &'a [(f64, f64)]) -> Dataset<'a> {
         self.data = data;
         self
     }
@@ -356,7 +356,7 @@ impl<'a> Dataset<'a> {
     ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn marker(mut self, marker: symbols::Marker) -> Dataset<'a> {
+    pub const fn marker(mut self, marker: symbols::Marker) -> Dataset<'a> {
         self.marker = marker;
         self
     }
@@ -369,7 +369,7 @@ impl<'a> Dataset<'a> {
     ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn graph_type(mut self, graph_type: GraphType) -> Dataset<'a> {
+    pub const fn graph_type(mut self, graph_type: GraphType) -> Dataset<'a> {
         self.graph_type = graph_type;
         self
     }
@@ -648,7 +648,10 @@ impl<'a> Chart<'a> {
     /// let chart = Chart::new(vec![]).hidden_legend_constraints(constraints);
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn hidden_legend_constraints(mut self, constraints: (Constraint, Constraint)) -> Chart<'a> {
+    pub const fn hidden_legend_constraints(
+        mut self,
+        constraints: (Constraint, Constraint),
+    ) -> Chart<'a> {
         self.hidden_legend_constraints = constraints;
         self
     }
@@ -683,7 +686,7 @@ impl<'a> Chart<'a> {
     /// let chart = Chart::new(vec![]).legend_position(None);
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn legend_position(mut self, position: Option<LegendPosition>) -> Chart<'a> {
+    pub const fn legend_position(mut self, position: Option<LegendPosition>) -> Chart<'a> {
         self.legend_position = position;
         self
     }

src/widgets/gauge.rs

@@ -147,7 +147,7 @@ impl<'a> Gauge<'a> {
     /// [unicode block characters](https://en.wikipedia.org/wiki/Block_Elements).
     /// This is useful to display a higher precision bar (8 extra fractional parts per cell).
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn use_unicode(mut self, unicode: bool) -> Gauge<'a> {
+    pub const fn use_unicode(mut self, unicode: bool) -> Gauge<'a> {
         self.use_unicode = unicode;
         self
     }
@@ -307,7 +307,7 @@ impl<'a> LineGauge<'a> {
     /// [`NORMAL`](symbols::line::NORMAL), [`DOUBLE`](symbols::line::DOUBLE) and
     /// [`THICK`](symbols::line::THICK).
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn line_set(mut self, set: symbols::line::Set) -> Self {
+    pub const fn line_set(mut self, set: symbols::line::Set) -> Self {
         self.line_set = set;
         self
     }

src/widgets/list.rs

@@ -62,7 +62,7 @@ impl ListState {
     /// let state = ListState::default().with_offset(1);
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn with_offset(mut self, offset: usize) -> Self {
+    pub const fn with_offset(mut self, offset: usize) -> Self {
         self.offset = offset;
         self
     }
@@ -78,7 +78,7 @@ impl ListState {
     /// let state = ListState::default().with_selected(Some(1));
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn with_selected(mut self, selected: Option<usize>) -> Self {
+    pub const fn with_selected(mut self, selected: Option<usize>) -> Self {
         self.selected = selected;
         self
     }
@@ -92,7 +92,7 @@ impl ListState {
     /// let state = ListState::default();
     /// assert_eq!(state.offset(), 0);
     /// ```
-    pub fn offset(&self) -> usize {
+    pub const fn offset(&self) -> usize {
         self.offset
     }
 
@@ -120,7 +120,7 @@ impl ListState {
     /// let state = TableState::default();
     /// assert_eq!(state.selected(), None);
     /// ```
-    pub fn selected(&self) -> Option<usize> {
+    pub const fn selected(&self) -> Option<usize> {
         self.selected
     }
 
@@ -594,7 +594,7 @@ impl<'a> List<'a> {
     /// let list = List::new(items).highlight_symbol(">>");
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn highlight_symbol(mut self, highlight_symbol: &'a str) -> List<'a> {
+    pub const fn highlight_symbol(mut self, highlight_symbol: &'a str) -> List<'a> {
         self.highlight_symbol = Some(highlight_symbol);
         self
     }
@@ -629,7 +629,7 @@ impl<'a> List<'a> {
     ///
     /// This is a fluent setter method which must be chained or used as it consumes self
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn repeat_highlight_symbol(mut self, repeat: bool) -> List<'a> {
+    pub const fn repeat_highlight_symbol(mut self, repeat: bool) -> List<'a> {
         self.repeat_highlight_symbol = repeat;
         self
     }
@@ -660,7 +660,7 @@ impl<'a> List<'a> {
     /// let list = List::new(items).highlight_spacing(HighlightSpacing::Always);
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn highlight_spacing(mut self, value: HighlightSpacing) -> Self {
+    pub const fn highlight_spacing(mut self, value: HighlightSpacing) -> Self {
         self.highlight_spacing = value;
         self
     }
@@ -682,7 +682,7 @@ impl<'a> List<'a> {
     /// let list = List::new(items).direction(ListDirection::BottomToTop);
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn direction(mut self, direction: ListDirection) -> List<'a> {
+    pub const fn direction(mut self, direction: ListDirection) -> List<'a> {
         self.direction = direction;
         self
     }
@@ -701,7 +701,7 @@ impl<'a> List<'a> {
     /// let list = List::new(items).scroll_padding(1);
     /// ```
     #[must_use = "method moves the value of self and returns the modified value"]
-    pub fn scroll_padding(mut self, padding: usize) -> List<'a> {
+    pub const fn scroll_padding(mut self, padding: usize) -> List<'a> {
         self.scroll_padding = padding;
         self
     }