Re-add terminal frontend

Cargo.toml

@@ -12,6 +12,7 @@ generational-arena = "0.2"
 crossterm = "0.27.0"
 [dependencies.partial-pretty-printer]
     git = "https://github.com/justinpombrio/partial-pretty-printer"
+    version = "0.3.0"
 [dependencies.no-nonsense-flamegraphs]
     version = "0.2.*"
     git = "https://github.com/justinpombrio/no-nonsense-flamegraphs"

src/frontends/frontend.rs

@@ -0,0 +1,117 @@
+use partial_pretty_printer as ppp;
+use std::fmt;
+use std::time::Duration;
+
+pub use crate::style::ColorTheme;
+
+/// A front end for the editor. It knows how to render a frame and how to
+/// receive keyboard and mouse events.
+pub trait Frontend: Sized + ppp::pane::PrettyWindow {
+    /// Construct a new frontend.
+    fn new(theme: ColorTheme) -> Result<Self, Self::Error>;
+
+    /// Set the color theme. Must not be called between `start_frame()` and `end_frame()`.
+    fn set_color_theme(&mut self, theme: ColorTheme) -> Result<(), Self::Error>;
+
+    /// Block until an event (eg. keypress) occurs, then return it. `None` means that no event
+    /// occurred before the timeout elapsed.
+    fn next_event(&mut self, timeout: Duration) -> Result<Option<Event>, Self::Error>;
+
+    /// Prepare to start modifying a fresh new frame. This must be called before pretty-printing.
+    fn start_frame(&mut self) -> Result<(), Self::Error>;
+
+    /// Show the modified frame to the user. This must be called after pretty-printing.
+    fn end_frame(&mut self) -> Result<(), Self::Error>;
+}
+
+/// An input event.
+pub enum Event {
+    Key(Key),
+    Mouse(MouseEvent),
+    /// The window was resized. Call `.size()` to get the new size.
+    Resize,
+    /// For "bracketed paste", which not all terminal emulators support.
+    Paste(String),
+}
+
+pub struct MouseEvent {
+    /// A character grid position, relative to the window.
+    pub click_pos: ppp::Pos,
+    /// Which mouse button was clicked.
+    pub button: MouseButton,
+}
+
+pub enum MouseButton {
+    Left,
+    Middle,
+    Right,
+}
+
+/// If the key code can be capitalized, then shift is indicated by capitalizing it and _not_
+/// setting the shift modifier.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Key {
+    pub code: KeyCode,
+    pub modifiers: KeyModifiers,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub struct KeyModifiers {
+    pub ctrl: bool,
+    pub alt: bool,
+    /// (See comment about shift on `Key`.)
+    pub shift: bool,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub enum KeyCode {
+    Backspace,
+    Enter,
+    Left,
+    Right,
+    Up,
+    Down,
+    Home,
+    End,
+    PageUp,
+    PageDown,
+    Tab,
+    Delete,
+    Insert,
+    Esc,
+    F(u8),
+    Char(char),
+}
+
+impl fmt::Display for Key {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.modifiers.ctrl {
+            write!(f, "C-");
+        }
+        if self.modifiers.alt {
+            write!(f, "A-");
+        }
+        if self.modifiers.shift {
+            write!(f, "S-");
+        }
+        match self.code {
+            KeyCode::Backspace => write!(f, "bksp"),
+            KeyCode::Enter => write!(f, "enter"),
+            KeyCode::Left => write!(f, "←"),
+            KeyCode::Right => write!(f, "→"),
+            KeyCode::Up => write!(f, "↑"),
+            KeyCode::Down => write!(f, "↓"),
+            KeyCode::Home => write!(f, "home"),
+            KeyCode::End => write!(f, "end"),
+            KeyCode::PageUp => write!(f, "pg_up"),
+            KeyCode::PageDown => write!(f, "pg_dn"),
+            KeyCode::Tab => write!(f, "tab"),
+            KeyCode::Delete => write!(f, "del"),
+            KeyCode::Insert => write!(f, "ins"),
+            KeyCode::Esc => write!(f, "esc"),
+            KeyCode::F(num) => write!(f, "f{}", num),
+            KeyCode::Char(' ') => write!(f, "space"),
+            KeyCode::Char(c) => write!(f, "{}", c),
+        }
+    }
+}

src/frontends/mod.rs

@@ -1 +1,3 @@
+mod frontend;
+mod screen_buf;
 mod terminal;