Add some basic editing facilities

editor-challenge/src/main.rs

@@ -1,195 +1,22 @@
-use crossterm::{
-    event::{self, KeyCode, KeyEvent, KeyModifiers},
-    terminal::{disable_raw_mode, enable_raw_mode},
-};
+mod ui;
+mod state;
+mod types;
+
+use ui::Canvas;
+use crossterm::event::{self, KeyCode, KeyEvent, KeyModifiers};
+use state::AppState;
 use std::{
-    env,
-    fs::File,
-    io::{self, BufRead, BufReader, Read},
-    path::PathBuf,
+    env, io,
     sync::mpsc,
     thread,
     time::{Duration, Instant},
 };
-use tui::{
-    backend::CrosstermBackend,
-    layout::{Alignment, Constraint, Direction, Layout},
-    style::{Color, Style},
-    widgets::{Block, BorderType, Borders, Paragraph},
-    Terminal,
-};
+use tui::{backend::CrosstermBackend, Terminal};
 
-const TITLE: &str = "Text Editor Challenge";
-const COPYRIGHT: &str = "(c) Savanni D'Gerinel - all rights reserved";
+// const TITLE: &str = "Text Editor Challenge";
+// const COPYRIGHT: &str = "(c) Savanni D'Gerinel - all rights reserved";
 const TICK_RATE_MS: u64 = 200;
 
-#[derive(Default)]
-struct Document {
-    rows: Vec<String>
-}
-
-impl Document {
-    fn contents(&self) -> String {
-        self.rows.join("\n")
-    }
-
-    fn row_length(&self, idx: usize) -> usize {
-        self.rows[idx].len()
-    }
-
-    fn row_count(&self) -> usize {
-        self.rows.len()
-    }
-}
-
-#[derive(Default)]
-struct AppState {
-    path: Option<PathBuf>,
-    cursor: Cursor,
-    contents: Document, // Obviously this is bad, but it's also only temporary.
-}
-
-impl AppState {
-    fn open(path: PathBuf) -> Self {
-        let mut file = File::open(path.clone()).unwrap();
-        let mut reader = BufReader::new(file);
-        let contents = reader
-            .lines()
-            .collect::<Result<Vec<String>, std::io::Error>>()
-            .unwrap();
-
-        Self {
-            path: Some(path),
-            cursor: Default::default(),
-            contents: Document{ rows: contents },
-        }
-    }
-
-    fn cursor_up(&mut self) {
-        self.cursor.cursor_up(&self.contents);
-    }
-
-    fn cursor_down(&mut self) {
-        self.cursor.cursor_down(&self.contents);
-    }
-
-    fn cursor_right(&mut self) {
-        self.cursor.cursor_right(&self.contents);
-    }
-
-    fn cursor_left(&mut self) {
-        self.cursor.cursor_left();
-    }
-}
-
-#[derive(Default)]
-struct Cursor {
-    row: usize,
-    column: usize,
-    desired_column: usize,
-}
-
-impl Cursor {
-    fn cursor_up(&mut self, doc: &Document) {
-        if self.row > 0 {
-            self.row -= 1;
-        }
-        self.correct_columns(doc);
-    }
-
-    fn cursor_down(&mut self, doc: &Document) {
-        if self.row < doc.row_count() - 1 {
-            self.row += 1;
-        }
-        self.correct_columns(doc);
-    }
-
-    fn correct_columns(&mut self, doc: &Document) {
-        let row_len = doc.row_length(self.row);
-        if self.desired_column < row_len {
-            self.column = self.desired_column;
-        } else {
-            self.column = row_len;
-        }
-    }
-
-    fn cursor_right(&mut self, doc: &Document) {
-        if self.column < doc.row_length(self.row) {
-            self.column += 1;
-        }
-        self.desired_column = self.column;
-    }
-
-    fn cursor_left(&mut self) {
-        if self.column > 0 {
-            self.column -= 1;
-        }
-        self.desired_column = self.column;
-    }
-
-}
-
-fn render<T>(app_state: &AppState, terminal: &mut Terminal<T>) -> Result<(), anyhow::Error>
-where
-    T: tui::backend::Backend,
-{
-    terminal.draw(|rect| {
-        let size = rect.size();
-        let chunks = Layout::default()
-            .direction(Direction::Vertical)
-            .margin(2)
-            .constraints(
-                [
-                    Constraint::Length(3),
-                    Constraint::Min(2),
-                    Constraint::Length(3),
-                ]
-                .as_ref(),
-            )
-            .split(size);
-
-        let title = Paragraph::new(
-            app_state
-                .path
-                .clone()
-                .map(|path| path.to_string_lossy().to_owned().into())
-                .unwrap_or("No file opened".to_owned()),
-        )
-        .style(Style::default().fg(Color::LightCyan))
-        .alignment(Alignment::Center)
-        .block(
-            Block::default()
-                .borders(Borders::ALL)
-                .style(Style::default().fg(Color::White))
-                .title("Copyright")
-                .border_type(BorderType::Plain),
-        );
-        rect.render_widget(title, chunks[0]);
-
-        let cp = Paragraph::new(COPYRIGHT)
-            .style(Style::default().fg(Color::LightCyan))
-            .alignment(Alignment::Center)
-            .block(
-                Block::default()
-                    .borders(Borders::ALL)
-                    .style(Style::default().fg(Color::White))
-                    .title("Copyright")
-                    .border_type(BorderType::Plain),
-            );
-        rect.render_widget(cp, chunks[2]);
-
-        // TODO: rework scrolling as soon as I have a working cursor
-        let contents = Paragraph::new(app_state.contents.contents()).scroll((0, 0));
-        rect.render_widget(contents, chunks[1]);
-
-        // TODO: keeping track of the index of the top row and subtract that from the cursor row.
-        let row = app_state.cursor.row as u16;
-        let column = app_state.cursor.column as u16;
-        rect.set_cursor(chunks[1].x + column, chunks[1].y + row);
-    })?;
-    Ok(())
-}
-
 #[derive(Debug)]
 enum Event<I> {
     Input(I),
@@ -209,45 +36,30 @@ fn handle_input(tx: mpsc::Sender<Event<KeyEvent>>, tick_rate: Duration) {
             }
         }
 
-        if last_tick.elapsed() >= tick_rate {
-            if let Ok(_) = tx.send(Event::Tick) {
+        if last_tick.elapsed() >= tick_rate && tx.send(Event::Tick).is_ok() {
             last_tick = Instant::now();
         }
     }
-    }
 }
 
 fn app_loop<T>(
     mut app_state: AppState,
-    terminal: &mut Terminal<T>,
+    mut screen: Canvas<T>,
     rx: mpsc::Receiver<Event<KeyEvent>>,
 ) -> Result<(), anyhow::Error>
 where
     T: tui::backend::Backend,
 {
     loop {
-        render(&app_state, terminal)?;
+        screen.render(&app_state)?;
 
-        let event = rx.recv()?;
-
-        match event {
-            Event::Input(KeyEvent { code, modifiers })
-                if code == KeyCode::Char('x') && modifiers == KeyModifiers::CONTROL =>
+        match rx.recv()? {
+            Event::Input(event)
+                if event.code == KeyCode::Char('x') && event.modifiers == KeyModifiers::CONTROL =>
             {
                 break;
             }
-            Event::Input(KeyEvent { code, .. }) if code == KeyCode::Down => {
-                app_state.cursor_down();
-            }
-            Event::Input(KeyEvent { code, .. }) if code == KeyCode::Up => {
-                app_state.cursor_up();
-            }
-            Event::Input(KeyEvent { code, .. }) if code == KeyCode::Right => {
-                app_state.cursor_right();
-            }
-            Event::Input(KeyEvent { code, .. }) if code == KeyCode::Left => {
-                app_state.cursor_left();
-            }
+            Event::Input(event) => app_state.handle_event(event),
             _ => {}
         }
     }
@@ -271,17 +83,14 @@ fn main() -> Result<(), anyhow::Error> {
         handle_input(tx, tick_rate);
     });
 
-    enable_raw_mode()?;
-
     let stdout = io::stdout();
     let backend = CrosstermBackend::new(stdout);
     let mut terminal = Terminal::new(backend)?;
-    let _ = terminal.clear()?;
+    terminal.clear()?;
 
-    let result = app_loop(app_state, &mut terminal, rx);
+    let screen = Canvas::new(terminal);
 
-    disable_raw_mode()?;
-    terminal.show_cursor()?;
+    let result = app_loop(app_state, screen, rx);
 
     result?;
 

editor-challenge/src/state.rs

@@ -0,0 +1,75 @@
+use crossterm::event::{KeyCode, KeyEvent};
+
+use crate::types::{Cursor, Document};
+use std::{fs::File, io::{BufRead, BufReader}, path::PathBuf};
+
+#[derive(Default)]
+pub struct AppState {
+    pub path: Option<PathBuf>,
+    pub cursor: Cursor,
+    pub contents: Document, // Obviously this is bad, but it's also only temporary.
+}
+
+impl AppState {
+    pub fn open(path: PathBuf) -> Self {
+        let file = File::open(path.clone()).unwrap();
+        let reader = BufReader::new(file);
+        let contents = reader
+            .lines()
+            .collect::<Result<Vec<String>, std::io::Error>>()
+            .unwrap();
+
+        Self {
+            path: Some(path),
+            cursor: Default::default(),
+            contents: Document::new(contents),
+        }
+    }
+
+    pub fn cursor_up(&mut self) {
+        self.cursor.cursor_up(&self.contents);
+    }
+
+    pub fn cursor_down(&mut self) {
+        self.cursor.cursor_down(&self.contents);
+    }
+
+    pub fn cursor_right(&mut self) {
+        self.cursor.cursor_right(&self.contents);
+    }
+
+    pub fn cursor_left(&mut self) {
+        self.cursor.cursor_left();
+    }
+
+    pub fn handle_event(&mut self, event: KeyEvent) {
+    let KeyEvent { code, .. }: KeyEvent = event;
+    match code {
+        KeyCode::Down => {
+            self.cursor_down();
+        }
+        KeyCode::Up => {
+            self.cursor_up();
+        }
+        KeyCode::Right => {
+            self.cursor_right();
+        }
+        KeyCode::Left => {
+            self.cursor_left();
+        }
+        KeyCode::Backspace => {
+            self.contents.backspace(&mut self.cursor);
+        }
+        KeyCode::Delete => {
+            self.contents.delete_at(&mut self.cursor);
+        }
+        KeyCode::Enter => {
+            self.contents.new_line(&mut self.cursor);
+        }
+        KeyCode::Char(c) => {
+            self.contents.insert_at(&mut self.cursor, c);
+        }
+        _ => {}
+    };
+    }
+}

editor-challenge/src/types.rs

@@ -0,0 +1,116 @@
+
+// TODO: I'm increasingly feeling that cursors are per-document, not per-application. So I think I
+// want to move the cursor into here, and then rendering requires asking for the cursor for the
+// current document.
+#[derive(Default)]
+pub struct Document {
+    rows: Vec<String>
+}
+
+impl Document {
+    pub fn new(contents: Vec<String>) -> Self {
+        if contents.len() > (u16::MAX.into()) {
+            panic!("Document row count exceeds u16::MAX. The current scrolling code cannot handle that.");
+        }
+        Self{
+            rows: contents
+        }
+    }
+
+    pub fn contents(&self) -> String {
+        self.rows.join("\n")
+    }
+
+    pub fn row_length(&self, idx: usize) -> usize {
+        self.rows[idx].len()
+    }
+
+    pub fn row_count(&self) -> usize {
+        self.rows.len()
+    }
+
+    pub fn insert_at(&mut self, cursor: &mut Cursor, c: char){
+        let (row, column) = cursor.addr();
+
+        self.rows[row].insert(column, c);
+        cursor.cursor_right(self);
+    }
+
+    pub fn backspace(&mut self, cursor: &mut Cursor) {
+        let (row, column) = cursor.addr();
+        if cursor.column > 0 {
+            let _ = self.rows[row].remove(column - 1);
+            cursor.cursor_left();
+        }
+    }
+
+    pub fn delete_at(&mut self, cursor: &mut Cursor) {
+        let (row, column) = cursor.addr();
+        if cursor.column < self.rows[row].len() {
+            self.rows[row].remove(column);
+            cursor.correct_columns(self);
+        }
+    }
+
+    pub fn new_line(&mut self, cursor: &mut Cursor) {
+        // when doing a newline, take everything to the right of the cursor from the current line
+        // and move it to the next line.
+        let (row, _) = cursor.addr();
+
+        self.rows.insert(row, String::new());
+        cursor.cursor_down(&self);
+    }
+}
+
+#[derive(Default)]
+pub struct Cursor {
+    row: usize,
+    column: usize,
+    desired_column: usize,
+}
+
+impl Cursor {
+    pub fn addr(&self) -> (usize, usize) {
+        (self.row, self.column)
+    }
+
+    pub fn cursor_up(&mut self, doc: &Document) {
+        if self.row > 0 {
+            self.row -= 1;
+        }
+        self.correct_columns(doc);
+    }
+
+    pub fn cursor_down(&mut self, doc: &Document) {
+        if self.row < doc.row_count() - 1 {
+            self.row += 1;
+        }
+        self.correct_columns(doc);
+    }
+
+    pub fn correct_columns(&mut self, doc: &Document) {
+        let row_len = doc.row_length(self.row);
+        if self.desired_column < row_len {
+            self.column = self.desired_column;
+        } else {
+            self.column = row_len;
+        }
+    }
+
+    pub fn cursor_right(&mut self, doc: &Document) {
+        if self.column < doc.row_length(self.row) {
+            self.column += 1;
+        }
+        self.desired_column = self.column;
+    }
+
+    pub fn cursor_left(&mut self) {
+        if self.column > 0 {
+            self.column -= 1;
+        }
+        self.desired_column = self.column;
+    }
+
+}
+
+

editor-challenge/src/ui.rs

@@ -0,0 +1,91 @@
+use crossterm::terminal::{disable_raw_mode, enable_raw_mode};
+use tui::{layout::{Alignment, Constraint, Direction, Layout}, style::{Color, Style}, widgets::{Block, BorderType, Borders, Paragraph}, Terminal};
+
+use crate::state::AppState;
+
+pub struct Canvas<T: tui::backend::Backend> {
+    top_row: usize,
+    terminal: Terminal<T>,
+}
+
+impl<T: tui::backend::Backend> Canvas<T> {
+    pub fn new(terminal: Terminal<T>) -> Self {
+        enable_raw_mode().unwrap();
+        Self {
+            top_row: 0,
+            terminal
+        }
+    }
+
+    pub fn render(&mut self, app_state: &AppState) -> Result<(), anyhow::Error>
+    {
+        self.terminal.draw(|rect| {
+            let size = rect.size();
+            let chunks = Layout::default()
+                .direction(Direction::Vertical)
+                .margin(2)
+                .constraints(
+                    [
+                        Constraint::Min(2),
+                        Constraint::Length(3),
+                        // Constraint::Length(3),
+                    ]
+                    .as_ref(),
+                )
+                .split(size);
+
+            let title = Paragraph::new(
+                app_state
+                    .path
+                    .clone()
+                    .map(|path| path.to_string_lossy().into_owned())
+                    .unwrap_or("No file opened".to_owned()),
+            )
+            .style(Style::default().fg(Color::LightCyan))
+            .alignment(Alignment::Center)
+            .block(
+                Block::default()
+                    .borders(Borders::ALL)
+                    .style(Style::default().fg(Color::White))
+                    .border_type(BorderType::Plain),
+            );
+            rect.render_widget(title, chunks[1]);
+
+            /*
+            let cp = Paragraph::new(COPYRIGHT)
+                .style(Style::default().fg(Color::LightCyan))
+                .alignment(Alignment::Center)
+                .block(
+                    Block::default()
+                        .borders(Borders::ALL)
+                        .style(Style::default().fg(Color::White))
+                        .title("Copyright")
+                        .border_type(BorderType::Plain),
+                );
+            rect.render_widget(cp, chunks[2]);
+            */
+
+            let (row, column) = app_state.cursor.addr();
+            if row == self.top_row && row >= 1 {
+                self.top_row -= 1;
+            } else if row - self.top_row == (chunks[0].height - 1).into() {
+                self.top_row += 1;
+            }
+
+            let contents = Paragraph::new(app_state.contents.contents()).scroll((self.top_row as u16, 0));
+            rect.render_widget(contents, chunks[0]);
+
+            rect.set_cursor(chunks[0].x + column as u16, chunks[0].y + (row - self.top_row) as u16);
+        })?;
+        Ok(())
+    }
+}
+
+impl<T: tui::backend::Backend> Drop for Canvas<T> {
+    fn drop(&mut self) {
+        let _ = disable_raw_mode();
+        let _ = self.terminal.show_cursor();
+    }
+}
+
+