Merge branch 'main' into performance

1 files changed, 71 insertions, 73 deletions

diff --git a/src/main.rs b/src/main.rs
index f646fdc..a513e71 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,11 +6,12 @@ use clap::{Parser, Subcommand};
 use console::Emoji;
 use notify_debouncer_mini::notify::{self, RecursiveMode};
 use notify_debouncer_mini::{new_debouncer, DebouncedEventKind};
+use shlex::Shlex;
 use std::ffi::OsStr;
 use std::fs;
 use std::io::{self, prelude::*};
 use std::path::Path;
-use std::process::{Command, Stdio};
+use std::process::Command;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::mpsc::{channel, RecvTimeoutError};
 use std::sync::{Arc, Mutex};
@@ -91,24 +92,25 @@ fn main() {
         println!("\n{WELCOME}\n");
     }
 
-    if !Path::new("info.toml").exists() {
-        println!(
-            "{} must be run from the rustlings directory",
-            std::env::current_exe().unwrap().to_str().unwrap()
-        );
-        println!("Try `cd rustlings/`!");
-        std::process::exit(1);
-    }
-
-    if !rustc_exists() {
+    if which::which("rustc").is_err() {
         println!("We cannot find `rustc`.");
         println!("Try running `rustc --version` to diagnose your problem.");
         println!("For instructions on how to install Rust, check the README.");
         std::process::exit(1);
     }
 
-    let toml_str = &fs::read_to_string("info.toml").unwrap();
-    let exercises = toml::from_str::<ExerciseList>(toml_str).unwrap().exercises;
+    let info_file = fs::read_to_string("info.toml").unwrap_or_else(|e| {
+        match e.kind() {
+            io::ErrorKind::NotFound => println!(
+                "The program must be run from the rustlings directory\nTry `cd rustlings/`!",
+            ),
+            _ => println!("Failed to read the info.toml file: {e}"),
+        }
+        std::process::exit(1);
+    });
+    let exercises = toml_edit::de::from_str::<ExerciseList>(&info_file)
+        .unwrap()
+        .exercises;
     let verbose = args.nocapture;
 
     let command = args.command.unwrap_or_else(|| {
@@ -230,16 +232,13 @@ fn main() {
                 println!("Failed to write rust-project.json to disk for rust-analyzer");
             } else {
                 println!("Successfully generated rust-project.json");
-                println!("rust-analyzer will now parse exercises, restart your language server or editor")
+                println!("rust-analyzer will now parse exercises, restart your language server or editor");
             }
         }
 
         Subcommands::Watch { success_hints } => match watch(&exercises, verbose, success_hints) {
             Err(e) => {
-                println!(
-                    "Error: Could not watch your progress. Error message was {:?}.",
-                    e
-                );
+                println!("Error: Could not watch your progress. Error message was {e:?}.");
                 println!("Most likely you've run out of disk space or your 'inotify limit' has been reached.");
                 std::process::exit(1);
             }
@@ -259,53 +258,55 @@ fn main() {
 }
 
 fn spawn_watch_shell(
-    failed_exercise_hint: &Arc<Mutex<Option<String>>>,
+    failed_exercise_hint: Arc<Mutex<Option<String>>>,
     should_quit: Arc<AtomicBool>,
 ) {
-    let failed_exercise_hint = Arc::clone(failed_exercise_hint);
     println!("Welcome to watch mode! You can type 'help' to get an overview of the commands you can use here.");
-    thread::spawn(move || loop {
-        let mut input = String::new();
-        match io::stdin().read_line(&mut input) {
-            Ok(_) => {
-                let input = input.trim();
-                if input == "hint" {
-                    if let Some(hint) = &*failed_exercise_hint.lock().unwrap() {
-                        println!("{hint}");
-                    }
-                } else if input == "clear" {
-                    println!("\x1B[2J\x1B[1;1H");
-                } else if input.eq("quit") {
-                    should_quit.store(true, Ordering::SeqCst);
-                    println!("Bye!");
-                } else if input.eq("help") {
-                    println!("Commands available to you in watch mode:");
-                    println!("  hint   - prints the current exercise's hint");
-                    println!("  clear  - clears the screen");
-                    println!("  quit   - quits watch mode");
-                    println!("  !<cmd> - executes a command, like `!rustc --explain E0381`");
-                    println!("  help   - displays this help message");
-                    println!();
-                    println!("Watch mode automatically re-evaluates the current exercise");
-                    println!("when you edit a file's contents.")
-                } else if let Some(cmd) = input.strip_prefix('!') {
-                    let parts: Vec<&str> = cmd.split_whitespace().collect();
-                    if parts.is_empty() {
-                        println!("no command provided");
-                    } else if let Err(e) = Command::new(parts[0]).args(&parts[1..]).status() {
-                        println!("failed to execute command `{}`: {}", cmd, e);
-                    }
-                } else {
-                    println!("unknown command: {input}");
+
+    thread::spawn(move || {
+        let mut input = String::with_capacity(32);
+        let mut stdin = io::stdin().lock();
+
+        loop {
+            // Recycle input buffer.
+            input.clear();
+
+            if let Err(e) = stdin.read_line(&mut input) {
+                println!("error reading command: {e}");
+            }
+
+            let input = input.trim();
+            if input == "hint" {
+                if let Some(hint) = &*failed_exercise_hint.lock().unwrap() {
+                    println!("{hint}");
+                }
+            } else if input == "clear" {
+                println!("\x1B[2J\x1B[1;1H");
+            } else if input == "quit" {
+                should_quit.store(true, Ordering::SeqCst);
+                println!("Bye!");
+            } else if input == "help" {
+                println!("{WATCH_MODE_HELP_MESSAGE}");
+            } else if let Some(cmd) = input.strip_prefix('!') {
+                let mut parts = Shlex::new(cmd);
+
+                let Some(program) = parts.next() else {
+                    println!("no command provided");
+                    continue;
+                };
+
+                if let Err(e) = Command::new(program).args(parts).status() {
+                    println!("failed to execute command `{cmd}`: {e}");
                 }
+            } else {
+                println!("unknown command: {input}\n{WATCH_MODE_HELP_MESSAGE}");
             }
-            Err(error) => println!("error reading command: {error}"),
         }
     });
 }
 
 fn find_exercise<'a>(name: &str, exercises: &'a [Exercise]) -> &'a Exercise {
-    if name.eq("next") {
+    if name == "next" {
         exercises
             .iter()
             .find(|e| !e.looks_done())
@@ -351,7 +352,6 @@ fn watch(
 
     clear_screen();
 
-    let to_owned_hint = |t: &Exercise| t.hint.to_owned();
     let failed_exercise_hint = match verify(
         exercises.iter(),
         (0, exercises.len()),
@@ -359,9 +359,9 @@ fn watch(
         success_hints,
     ) {
         Ok(_) => return Ok(WatchStatus::Finished),
-        Err(exercise) => Arc::new(Mutex::new(Some(to_owned_hint(exercise)))),
+        Err(exercise) => Arc::new(Mutex::new(Some(exercise.hint.clone()))),
     };
-    spawn_watch_shell(&failed_exercise_hint, Arc::clone(&should_quit));
+    spawn_watch_shell(Arc::clone(&failed_exercise_hint), Arc::clone(&should_quit));
     loop {
         match rx.recv_timeout(Duration::from_secs(1)) {
             Ok(event) => match event {
@@ -396,7 +396,7 @@ fn watch(
                                 Err(exercise) => {
                                     let mut failed_exercise_hint =
                                         failed_exercise_hint.lock().unwrap();
-                                    *failed_exercise_hint = Some(to_owned_hint(exercise));
+                                    *failed_exercise_hint = Some(exercise.hint.clone());
                                 }
                             }
                         }
@@ -416,19 +416,7 @@ fn watch(
     }
 }
 
-fn rustc_exists() -> bool {
-    Command::new("rustc")
-        .args(["--version"])
-        .stdout(Stdio::null())
-        .stderr(Stdio::null())
-        .stdin(Stdio::null())
-        .spawn()
-        .and_then(|mut child| child.wait())
-        .map(|status| status.success())
-        .unwrap_or(false)
-}
-
-const DEFAULT_OUT: &str = r#"Thanks for installing Rustlings!
+const DEFAULT_OUT: &str = "Thanks for installing Rustlings!
 
 Is this your first time? Don't worry, Rustlings was made for beginners! We are
 going to teach you a lot of things about Rust, but before we can get
@@ -454,7 +442,7 @@ started, here's a couple of notes about how Rustlings operates:
    autocompletion, run the command `rustlings lsp`.
 
 Got all that? Great! To get started, run `rustlings watch` in order to get the first
-exercise. Make sure to have your editor open!"#;
+exercise. Make sure to have your editor open!";
 
 const FENISH_LINE: &str = "+----------------------------------------------------+
 |          You made it to the Fe-nish line!          |
@@ -490,3 +478,13 @@ const WELCOME: &str = r"       welcome to...
  | |  | |_| \__ \ |_| | | | | | (_| \__ \
  |_|   \__,_|___/\__|_|_|_| |_|\__, |___/
                                |___/";
+
+const WATCH_MODE_HELP_MESSAGE: &str = "Commands available to you in watch mode:
+  hint   - prints the current exercise's hint
+  clear  - clears the screen
+  quit   - quits watch mode
+  !<cmd> - executes a command, like `!rustc --explain E0381`
+  help   - displays this help message
+
+Watch mode automatically re-evaluates the current exercise
+when you edit a file's contents.";