Fix unsafe arithmetics and casts

src/editor.rs

@@ -60,10 +60,14 @@ impl Editor {
     }
     fn draw_welcome_message() -> Result<(), Error> {
         let mut welcome_message = format!("{NAME} editor -- version {VERSION}");
-        let width = Terminal::size()?.width as usize;
+        let width = Terminal::size()?.width;
         let len = welcome_message.len();
-        let padding = (width - len) / 2;
-        let spaces = " ".repeat(padding - 1);
+        // we allow this since we don't care if our welcome message is put _exactly_ in the middle.
+        // it's allowed to be a bit to the left or right.
+        #[allow(clippy::integer_division)]
+        let padding = (width.saturating_sub(len)) / 2;
+
+        let spaces = " ".repeat(padding.saturating_sub(1));
         welcome_message = format!("~{spaces}{welcome_message}");
         welcome_message.truncate(width);
         Terminal::print(welcome_message)?;
@@ -77,12 +81,15 @@ impl Editor {
         let Size { height, .. } = Terminal::size()?;
         for current_row in 0..height {
             Terminal::clear_line()?;
+            // we allow this since we don't care if our welcome message is put _exactly_ in the middle.
+            // it's allowed to be a bit up or down
+            #[allow(clippy::integer_division)]
             if current_row == height / 3 {
                 Self::draw_welcome_message()?;
             } else {
                 Self::draw_empty_row()?;
             }
-            if current_row + 1 < height {
+            if current_row.saturating_add(1) < height {
                 Terminal::print("\r\n")?;
             }
         }

src/editor/terminal.rs

@@ -1,20 +1,26 @@
+use core::fmt::Display;
 use crossterm::cursor::{Hide, MoveTo, Show};
 use crossterm::style::Print;
 use crossterm::terminal::{disable_raw_mode, enable_raw_mode, size, Clear, ClearType};
 use crossterm::{queue, Command};
 use std::io::{stdout, Error, Write};
-use core::fmt::Display;
 
 #[derive(Copy, Clone)]
 pub struct Size {
-    pub height: u16,
-    pub width: u16,
+    pub height: usize,
+    pub width: usize,
 }
 #[derive(Copy, Clone)]
 pub struct Position {
-    pub x: u16,
-    pub y: u16,
+    pub x: usize,
+    pub y: usize,
 }
+/// Represents the Terminal.
+/// Edge Case for platforms where `usize` < `u16`:
+/// Regardless of the actual size of the Terminal, this representation
+/// only spans over at most `usize::MAX` or `u16::size` rows/columns, whichever is smaller.
+/// Each size returned truncates to min(`usize::MAX`, `u16::MAX`)
+/// And should you attempt to set the cursor out of these bounds, it will also be truncated.
 pub struct Terminal;
 
 impl Terminal {
@@ -38,8 +44,13 @@ impl Terminal {
         Self::queue_command(Clear(ClearType::CurrentLine))?;
         Ok(())
     }
+    /// Moves the cursor to the given Position.
+    /// # Arguments
+    /// * `Position` - the  `Position`to move the cursor to. Will be truncated to `u16::MAX` if bigger.
     pub fn move_cursor_to(position: Position) -> Result<(), Error> {
-        Self::queue_command(MoveTo(position.x, position.y))?;
+        // clippy::as_conversions: See doc above
+        #[allow(clippy::as_conversions, clippy::cast_possible_truncation)]
+        Self::queue_command(MoveTo(position.x as u16, position.y as u16))?;
         Ok(())
     }
     pub fn hide_cursor() -> Result<(), Error> {
@@ -54,16 +65,26 @@ impl Terminal {
         Self::queue_command(Print(string))?;
         Ok(())
     }
+
+    /// Returns the current size of this Terminal.
+    /// Edge Case for systems with `usize` < `u16`:
+    /// * A `Size` representing the terminal size. Any coordinate `z` truncated to `usize` if `usize` < `z` < `u16`
     pub fn size() -> Result<Size, Error> {
-        let (width, height) = size()?;
+        let (width_u16, height_u16) = size()?;
+        // clippy::as_conversions: See doc above
+        #[allow(clippy::as_conversions)]
+        let height = height_u16 as usize;
+        // clippy::as_conversions: See doc above
+        #[allow(clippy::as_conversions)]
+        let width = width_u16 as usize;
         Ok(Size { height, width })
     }
     pub fn execute() -> Result<(), Error> {
         stdout().flush()?;
         Ok(())
     }
 
-    fn queue_command<T:Command>(command: T) -> Result<(), Error> {
+    fn queue_command<T: Command>(command: T) -> Result<(), Error> {
         queue!(stdout(), command)?;
         Ok(())
     }

src/main.rs

@@ -1,4 +1,4 @@
-#![warn(clippy::all, clippy::pedantic, clippy::print_stdout)]
+#![warn(clippy::all, clippy::pedantic, clippy::print_stdout, clippy::arithmetic_side_effects, clippy::as_conversions, clippy::integer_division)]
 mod editor;
 use editor::Editor;