Add a feature flag for derive_more impls (#970)

This adds a feature flag to allow opting out of the `derive_more`
dependency and derivations added in e063091. `derive_more` brings in
heavy proc macro dependencies and isn't crucial for the core functioning
of crossterm, so it should be possible for a crossterm dependent to opt
out of bringing in the transitive dependency.

Cargo.toml

@@ -21,7 +21,7 @@ path = "src/lib.rs"
 all-features = true
 
 [features]
-default = ["bracketed-paste", "events", "windows"]
+default = ["bracketed-paste", "events", "windows", "derive-more"]
 
 #! ### Default features
 ## Enables triggering [`Event::Paste`](event::Event::Paste) when pasting text into the terminal.
@@ -44,9 +44,12 @@ serde = ["dep:serde", "bitflags/serde"]
 ## Enables raw file descriptor polling / selecting instead of mio.
 use-dev-tty = ["filedescriptor", "rustix/process"]
 
+## Enables `is_*` helper functions for event enums.
+derive-more = ["dep:derive_more"]
+
 [dependencies]
 bitflags = { version = "2.3" }
-derive_more = { version = "1.0.0", features = ["is_variant"] }
+derive_more = { version = "1.0.0", features = ["is_variant"], optional = true }
 document-features = "0.2.10"
 futures-core = { version = "0.3", optional = true, default-features = false }
 parking_lot = "0.12"

README.md

@@ -153,6 +153,7 @@ features = ["event-stream"]
 | `serde`        | (De)serializing of events.                   |
 | `events`        | Reading input/system events (enabled by default) |
 | `filedescriptor` | Use raw filedescriptor for all events rather then mio dependency |
+| `derive-more`  | Adds `is_*` helper functions for event types |
 
 
 To use crossterm as a very thin layer you can disable the `events` feature or use `filedescriptor` feature. 
@@ -170,6 +171,7 @@ This can disable `mio` / `signal-hook` / `signal-hook-mio` dependencies.
 | `winapi`       | Used for low-level windows system calls which ANSI codes can't replace           | windows only                          |
 | `futures-core` | For async stream of events                                                       | only with `event-stream` feature flag |
 | `serde`        | ***ser***ializing and ***de***serializing of events                              | only with `serde` feature flag        |
+| `derive_more`  | Adds `is_*` helper functions for event types                                     | optional (`derive-more` feature), included by default |
 
 ### Other Resources
 

src/event.rs

@@ -126,6 +126,7 @@ pub(crate) mod stream;
 pub(crate) mod sys;
 pub(crate) mod timeout;
 
+#[cfg(feature = "derive-more")]
 use derive_more::derive::IsVariant;
 #[cfg(feature = "event-stream")]
 pub use stream::EventStream;
@@ -543,8 +544,9 @@ impl Command for PopKeyboardEnhancementFlags {
 
 /// Represents an event.
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "derive-more", derive(IsVariant))]
 #[cfg_attr(not(feature = "bracketed-paste"), derive(Copy))]
-#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Hash, IsVariant)]
+#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Hash)]
 pub enum Event {
     /// The terminal gained focus
     FocusGained,
@@ -793,7 +795,8 @@ pub struct MouseEvent {
 /// `MouseEventKind::Up` and `MouseEventKind::Drag` events. `MouseButton::Left`
 /// is returned if we don't know which button was used.
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
-#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash, IsVariant)]
+#[cfg_attr(feature = "derive-more", derive(IsVariant))]
+#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
 pub enum MouseEventKind {
     /// Pressed mouse button. Contains the button that was pressed.
     Down(MouseButton),
@@ -815,7 +818,8 @@ pub enum MouseEventKind {
 
 /// Represents a mouse button.
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
-#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash, IsVariant)]
+#[cfg_attr(feature = "derive-more", derive(IsVariant))]
+#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
 pub enum MouseButton {
     /// Left mouse button.
     Left,
@@ -895,7 +899,8 @@ impl Display for KeyModifiers {
 
 /// Represents a keyboard event kind.
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
-#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash, IsVariant)]
+#[cfg_attr(feature = "derive-more", derive(IsVariant))]
+#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
 pub enum KeyEventKind {
     Press,
     Repeat,
@@ -1002,17 +1007,17 @@ impl KeyEvent {
 
     /// Returns whether the key event is a press event.
     pub fn is_press(&self) -> bool {
-        self.kind.is_press()
+        matches!(self.kind, KeyEventKind::Press)
     }
 
     /// Returns whether the key event is a release event.
     pub fn is_release(&self) -> bool {
-        self.kind.is_release()
+        matches!(self.kind, KeyEventKind::Release)
     }
 
     /// Returns whether the key event is a repeat event.
     pub fn is_repeat(&self) -> bool {
-        self.kind.is_repeat()
+        matches!(self.kind, KeyEventKind::Repeat)
     }
 }
 
@@ -1214,7 +1219,8 @@ impl Display for ModifierKeyCode {
 }
 
 /// Represents a key.
-#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash, IsVariant)]
+#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
+#[cfg_attr(feature = "derive-more", derive(IsVariant))]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub enum KeyCode {
     /// Backspace key (Delete on macOS, Backspace on other platforms).
@@ -1248,12 +1254,12 @@ pub enum KeyCode {
     /// F key.
     ///
     /// `KeyCode::F(1)` represents F1 key, etc.
-    #[is_variant(ignore)]
+    #[cfg_attr(feature = "derive-more", is_variant(ignore))]
     F(u8),
     /// A character.
     ///
     /// `KeyCode::Char('c')` represents `c` character, etc.
-    #[is_variant(ignore)]
+    #[cfg_attr(feature = "derive-more", is_variant(ignore))]
     Char(char),
     /// Null.
     Null,
@@ -1306,7 +1312,7 @@ pub enum KeyCode {
     /// **Note:** these keys can only be read if
     /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
     /// [`PushKeyboardEnhancementFlags`].
-    #[is_variant(ignore)]
+    #[cfg_attr(feature = "derive-more", is_variant(ignore))]
     Media(MediaKeyCode),
     /// A modifier key.
     ///
@@ -1314,7 +1320,7 @@ pub enum KeyCode {
     /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] and
     /// [`KeyboardEnhancementFlags::REPORT_ALL_KEYS_AS_ESCAPE_CODES`] have been enabled with
     /// [`PushKeyboardEnhancementFlags`].
-    #[is_variant(ignore)]
+    #[cfg_attr(feature = "derive-more", is_variant(ignore))]
     Modifier(ModifierKeyCode),
 }
 
@@ -1632,6 +1638,7 @@ mod tests {
         modifiers: KeyModifiers::empty(),
     };
 
+    #[cfg(feature = "derive-more")]
     #[test]
     fn event_is() {
         let event = Event::FocusGained;