Merge branch 'main' into project

Optimizations 1

Cargo.lock

@@ -201,6 +201,12 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
 
+[[package]]
+name = "either"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "11157ac094ffbdde99aa67b23417ebdd801842852b500e395a45a9c0aac03e4a"
+
 [[package]]
 name = "encode_unicode"
 version = "0.3.6"
@@ -213,6 +219,16 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
 
+[[package]]
+name = "errno"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a258e46cdc063eb8519c00b9fc845fc47bcfca4130e2f08e88665ceda8474245"
+dependencies = [
+ "libc",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "filetime"
 version = "0.2.23"
@@ -360,6 +376,12 @@ version = "0.2.153"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c198f91728a82281a64e1f4f9eeb25d82cb32a5de251c6bd1b5154d63a8e7bd"
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "01cda141df6706de531b6c46c3a33ecca755538219bd484262fa09410c13539c"
+
 [[package]]
 name = "log"
 version = "0.4.21"
@@ -527,6 +549,19 @@ version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c08c74e62047bb2de4ff487b251e4a92e24f48745648451635cec7d591162d9f"
 
+[[package]]
+name = "rustix"
+version = "0.38.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "65e04861e65f21776e67888bfbea442b3642beaa0138fdb1dd7a84a52dffdb89"
+dependencies = [
+ "bitflags 2.4.2",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "rustlings"
 version = "5.6.1"
@@ -536,14 +571,15 @@ dependencies = [
  "clap",
  "console",
  "glob",
- "home",
  "indicatif",
  "notify-debouncer-mini",
  "predicates",
- "regex",
  "serde",
  "serde_json",
- "toml",
+ "shlex",
+ "toml_edit",
+ "which",
+ "winnow",
 ]
 
 [[package]]
@@ -601,6 +637,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "shlex"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
+
 [[package]]
 name = "strsim"
 version = "0.11.0"
@@ -624,18 +666,6 @@ version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3369f5ac52d5eb6ab48c6b4ffdc8efbcad6b89c765749064ba298f2c68a16a76"
 
-[[package]]
-name = "toml"
-version = "0.8.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a9aad4a3066010876e8dcf5a8a06e70a558751117a145c6ce2b82c2e2054290"
-dependencies = [
- "serde",
- "serde_spanned",
- "toml_datetime",
- "toml_edit",
-]
-
 [[package]]
 name = "toml_datetime"
 version = "0.6.5"
@@ -647,9 +677,9 @@ dependencies = [
 
 [[package]]
 name = "toml_edit"
-version = "0.22.6"
+version = "0.22.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2c1b5fd4128cc8d3e0cb74d4ed9a9cc7c7284becd4df68f5f940e1ad123606f6"
+checksum = "8e40bb779c5187258fd7aad0eb68cb8706a0a81fa712fbea808ab43c4b8374c4"
 dependencies = [
  "indexmap",
  "serde",
@@ -701,6 +731,18 @@ version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
+[[package]]
+name = "which"
+version = "6.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8211e4f58a2b2805adfbefbc07bab82958fc91e3836339b1ab7ae32465dce0d7"
+dependencies = [
+ "either",
+ "home",
+ "rustix",
+ "winsafe",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
@@ -872,3 +914,9 @@ checksum = "dffa400e67ed5a4dd237983829e66475f0a4a26938c4b04c21baede6262215b8"
 dependencies = [
  "memchr",
 ]
+
+[[package]]
+name = "winsafe"
+version = "0.0.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d135d17ab770252ad95e9a872d365cf3090e3be864a34ab46f48555993efc904"

Cargo.toml

@@ -12,13 +12,14 @@ edition = "2021"
 anyhow = "1.0.81"
 clap = { version = "4.5.2", features = ["derive"] }
 console = "0.15.8"
-home = "0.5.9"
 indicatif = "0.17.8"
 notify-debouncer-mini = "0.4.1"
-regex = "1.10.3"
 serde_json = "1.0.114"
 serde = { version = "1.0.197", features = ["derive"] }
-toml = "0.8.10"
+shlex = "1.3.0"
+toml_edit = { version = "0.22.9", default-features = false, features = ["parse", "serde"] }
+which = "6.0.1"
+winnow = "0.6.5"
 
 [[bin]]
 name = "rustlings"

src/exercise.rs

@@ -1,19 +1,33 @@
-use regex::Regex;
 use serde::Deserialize;
-use std::env;
 use std::fmt::{self, Display, Formatter};
 use std::fs::{self, remove_file, File};
-use std::io::Read;
+use std::io::{self, BufRead, BufReader};
 use std::path::PathBuf;
-use std::process::{self, Command};
+use std::process::{self, exit, Command, Stdio};
+use std::{array, env, mem};
+use winnow::ascii::{space0, Caseless};
+use winnow::combinator::opt;
+use winnow::Parser;
 
 const RUSTC_COLOR_ARGS: &[&str] = &["--color", "always"];
 const RUSTC_EDITION_ARGS: &[&str] = &["--edition", "2021"];
 const RUSTC_NO_DEBUG_ARGS: &[&str] = &["-C", "strip=debuginfo"];
-const I_AM_DONE_REGEX: &str = r"(?m)^\s*///?\s*I\s+AM\s+NOT\s+DONE";
 const CONTEXT: usize = 2;
 const CLIPPY_CARGO_TOML_PATH: &str = "./exercises/22_clippy/Cargo.toml";
 
+// Checks if the line contains the "I AM NOT DONE" comment.
+fn contains_not_done_comment(input: &str) -> bool {
+    (
+        space0::<_, ()>,
+        "//",
+        opt('/'),
+        space0,
+        Caseless("I AM NOT DONE"),
+    )
+        .parse_next(&mut &*input)
+        .is_ok()
+}
+
 // Get a temporary file name that is hopefully unique
 #[inline]
 fn temp_file() -> String {
@@ -58,7 +72,7 @@ pub struct Exercise {
 
 // An enum to track of the state of an Exercise.
 // An Exercise can be either Done or Pending
-#[derive(PartialEq, Debug)]
+#[derive(PartialEq, Eq, Debug)]
 pub enum State {
     // The state of the exercise once it's been completed
     Done,
@@ -67,7 +81,7 @@ pub enum State {
 }
 
 // The context information of a pending exercise
-#[derive(PartialEq, Debug)]
+#[derive(PartialEq, Eq, Debug)]
 pub struct ContextLine {
     // The source code that is still pending completion
     pub line: String,
@@ -148,7 +162,10 @@ path = "{}.rs""#,
                     .args(RUSTC_COLOR_ARGS)
                     .args(RUSTC_EDITION_ARGS)
                     .args(RUSTC_NO_DEBUG_ARGS)
-                    .output()
+                    .stdin(Stdio::null())
+                    .stdout(Stdio::null())
+                    .stderr(Stdio::null())
+                    .status()
                     .expect("Failed to compile!");
                 // Due to an issue with Clippy, a cargo clean is required to catch all lints.
                 // See https://github.com/rust-lang/rust-clippy/issues/2604
@@ -157,7 +174,10 @@ path = "{}.rs""#,
                 Command::new("cargo")
                     .args(["clean", "--manifest-path", CLIPPY_CARGO_TOML_PATH])
                     .args(RUSTC_COLOR_ARGS)
-                    .output()
+                    .stdin(Stdio::null())
+                    .stdout(Stdio::null())
+                    .stderr(Stdio::null())
+                    .status()
                     .expect("Failed to run 'cargo clean'");
                 Command::new("cargo")
                     .args(["clippy", "--manifest-path", CLIPPY_CARGO_TOML_PATH])
@@ -205,51 +225,101 @@ path = "{}.rs""#,
     }
 
     pub fn state(&self) -> State {
-        let mut source_file = File::open(&self.path).unwrap_or_else(|e| {
-            panic!(
-                "We were unable to open the exercise file {}! {e}",
-                self.path.display()
-            )
+        let source_file = File::open(&self.path).unwrap_or_else(|e| {
+            println!(
+                "Failed to open the exercise file {}: {e}",
+                self.path.display(),
+            );
+            exit(1);
         });
+        let mut source_reader = BufReader::new(source_file);
 
-        let source = {
-            let mut s = String::new();
-            source_file.read_to_string(&mut s).unwrap_or_else(|e| {
-                panic!(
-                    "We were unable to read the exercise file {}! {e}",
-                    self.path.display()
-                )
-            });
-            s
+        // Read the next line into `buf` without the newline at the end.
+        let mut read_line = |buf: &mut String| -> io::Result<_> {
+            let n = source_reader.read_line(buf)?;
+            if buf.ends_with('\n') {
+                buf.pop();
+                if buf.ends_with('\r') {
+                    buf.pop();
+                }
+            }
+            Ok(n)
         };
 
-        let re = Regex::new(I_AM_DONE_REGEX).unwrap();
+        let mut current_line_number: usize = 1;
+        // Keep the last `CONTEXT` lines while iterating over the file lines.
+        let mut prev_lines: [_; CONTEXT] = array::from_fn(|_| String::with_capacity(256));
+        let mut line = String::with_capacity(256);
 
-        if !re.is_match(&source) {
+        loop {
+            let n = read_line(&mut line).unwrap_or_else(|e| {
+                println!(
+                    "Failed to read the exercise file {}: {e}",
+                    self.path.display(),
+                );
+                exit(1);
+            });
+
+            // Reached the end of the file and didn't find the comment.
+            if n == 0 {
                 return State::Done;
             }
 
-        let matched_line_index = source
-            .lines()
+            if contains_not_done_comment(&line) {
+                let mut context = Vec::with_capacity(2 * CONTEXT + 1);
+                // Previous lines.
+                for (ind, prev_line) in prev_lines
+                    .into_iter()
+                    .take(current_line_number - 1)
                     .enumerate()
-            .find_map(|(i, line)| if re.is_match(line) { Some(i) } else { None })
-            .expect("This should not happen at all");
+                    .rev()
+                {
+                    context.push(ContextLine {
+                        line: prev_line,
+                        number: current_line_number - 1 - ind,
+                        important: false,
+                    });
+                }
 
-        let min_line = ((matched_line_index as i32) - (CONTEXT as i32)).max(0) as usize;
-        let max_line = matched_line_index + CONTEXT;
+                // Current line.
+                context.push(ContextLine {
+                    line,
+                    number: current_line_number,
+                    important: true,
+                });
 
-        let context = source
-            .lines()
-            .enumerate()
-            .filter(|&(i, _)| i >= min_line && i <= max_line)
-            .map(|(i, line)| ContextLine {
-                line: line.to_string(),
-                number: i + 1,
-                important: i == matched_line_index,
-            })
-            .collect();
+                // Next lines.
+                for ind in 0..CONTEXT {
+                    let mut next_line = String::with_capacity(256);
+                    let Ok(n) = read_line(&mut next_line) else {
+                        // If an error occurs, just ignore the next lines.
+                        break;
+                    };
 
-        State::Pending(context)
+                    // Reached the end of the file.
+                    if n == 0 {
+                        break;
+                    }
+
+                    context.push(ContextLine {
+                        line: next_line,
+                        number: current_line_number + 1 + ind,
+                        important: false,
+                    });
+                }
+
+                return State::Pending(context);
+            }
+
+            current_line_number += 1;
+            // Add the current line as a previous line and shift the older lines by one.
+            for prev_line in &mut prev_lines {
+                mem::swap(&mut line, prev_line);
+            }
+            // The current line now contains the oldest previous line.
+            // Recycle it for reading the next line.
+            line.clear();
+        }
     }
 
     // Check that the exercise looks to be solved using self.state()
@@ -375,4 +445,20 @@ mod test {
         let out = exercise.compile().unwrap().run().unwrap();
         assert!(out.stdout.contains("THIS TEST TOO SHALL PASS"));
     }
+
+    #[test]
+    fn test_not_done() {
+        assert!(contains_not_done_comment("// I AM NOT DONE"));
+        assert!(contains_not_done_comment("/// I AM NOT DONE"));
+        assert!(contains_not_done_comment("//  I AM NOT DONE"));
+        assert!(contains_not_done_comment("///  I AM NOT DONE"));
+        assert!(contains_not_done_comment("// I AM NOT DONE "));
+        assert!(contains_not_done_comment("// I AM NOT DONE!"));
+        assert!(contains_not_done_comment("// I am not done"));
+        assert!(contains_not_done_comment("// i am NOT done"));
+
+        assert!(!contains_not_done_comment("I AM NOT DONE"));
+        assert!(!contains_not_done_comment("// NOT DONE"));
+        assert!(!contains_not_done_comment("DONE"));
+    }
 }

src/main.rs

@@ -7,11 +7,12 @@ 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};
@@ -92,24 +93,25 @@ fn main() -> Result<()> {
         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(|| {
@@ -129,31 +131,43 @@ fn main() -> Result<()> {
                 println!("{:<17}\t{:<46}\t{:<7}", "Name", "Path", "Status");
             }
             let mut exercises_done: u16 = 0;
-            let filters = filter.clone().unwrap_or_default().to_lowercase();
-            exercises.iter().for_each(|e| {
-                let fname = format!("{}", e.path.display());
-                let filter_cond = filters
+            let lowercase_filter = filter
+                .as_ref()
+                .map(|s| s.to_lowercase())
+                .unwrap_or_default();
+            let filters = lowercase_filter
                 .split(',')
-                    .filter(|f| !f.trim().is_empty())
-                    .any(|f| e.name.contains(f) || fname.contains(f));
-                let status = if e.looks_done() {
+                .filter_map(|f| {
+                    let f = f.trim();
+                    if f.is_empty() {
+                        None
+                    } else {
+                        Some(f)
+                    }
+                })
+                .collect::<Vec<_>>();
+
+            for exercise in &exercises {
+                let fname = exercise.path.to_string_lossy();
+                let filter_cond = filters
+                    .iter()
+                    .any(|f| exercise.name.contains(f) || fname.contains(f));
+                let looks_done = exercise.looks_done();
+                let status = if looks_done {
                     exercises_done += 1;
                     "Done"
                 } else {
                     "Pending"
                 };
-                let solve_cond = {
-                    (e.looks_done() && solved)
-                        || (!e.looks_done() && unsolved)
-                        || (!solved && !unsolved)
-                };
+                let solve_cond =
+                    (looks_done && solved) || (!looks_done && unsolved) || (!solved && !unsolved);
                 if solve_cond && (filter_cond || filter.is_none()) {
                     let line = if paths {
                         format!("{fname}\n")
                     } else if names {
-                        format!("{}\n", e.name)
+                        format!("{}\n", exercise.name)
                     } else {
-                        format!("{:<17}\t{fname:<46}\t{status:<7}\n", e.name)
+                        format!("{:<17}\t{fname:<46}\t{status:<7}\n", exercise.name)
                     };
                     // Somehow using println! leads to the binary panicking
                     // when its output is piped.
@@ -169,7 +183,8 @@ fn main() -> Result<()> {
                         });
                     }
                 }
-            });
+            }
+
             let percentage_progress = exercises_done as f32 / exercises.len() as f32 * 100.0;
             println!(
                 "Progress: You completed {} / {} exercises ({:.1} %).",
@@ -208,16 +223,13 @@ fn main() -> Result<()> {
                 println!("Failed to write rust-project.json to disk for rust-analyzer: {e}");
             } 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);
             }
@@ -239,15 +251,23 @@ fn main() -> Result<()> {
 }
 
 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(_) => {
+
+    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() {
@@ -255,37 +275,31 @@ fn spawn_watch_shell(
                 }
             } else if input == "clear" {
                 println!("\x1B[2J\x1B[1;1H");
-                } else if input.eq("quit") {
+            } else if input == "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 input == "help" {
+                println!("{WATCH_MODE_HELP_MESSAGE}");
             } else if let Some(cmd) = input.strip_prefix('!') {
-                    let parts: Vec<&str> = cmd.split_whitespace().collect();
-                    if parts.is_empty() {
+                let mut parts = Shlex::new(cmd);
+
+                let Some(program) = parts.next() else {
                     println!("no command provided");
-                    } else if let Err(e) = Command::new(parts[0]).args(&parts[1..]).status() {
-                        println!("failed to execute command `{}`: {}", cmd, e);
+                    continue;
+                };
+
+                if let Err(e) = Command::new(program).args(parts).status() {
+                    println!("failed to execute command `{cmd}`: {e}");
                 }
             } else {
-                    println!("unknown command: {input}");
+                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())
@@ -331,7 +345,6 @@ 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()),
@@ -339,9 +352,9 @@ 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 {
@@ -376,7 +389,7 @@ 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());
                                 }
                             }
                         }
@@ -396,19 +409,7 @@ 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
@@ -434,7 +435,7 @@ 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!          |
@@ -470,3 +471,13 @@ 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.";

src/run.rs

@@ -21,7 +21,8 @@ pub fn run(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
 // Resets the exercise by stashing the changes.
 pub fn reset(exercise: &Exercise) -> Result<(), ()> {
     let command = Command::new("git")
-        .args(["stash", "--"])
+        .arg("stash")
+        .arg("--")
         .arg(&exercise.path)
         .spawn();
 

src/verify.rs

@@ -24,7 +24,7 @@ pub fn verify<'a>(
             .progress_chars("#>-"),
     );
     bar.set_position(num_done as u64);
-    bar.set_message(format!("({:.1} %)", percentage));
+    bar.set_message(format!("({percentage:.1} %)"));
 
     for exercise in exercises {
         let compile_result = match exercise.mode {
@@ -37,7 +37,7 @@ pub fn verify<'a>(
         }
         percentage += 100.0 / total as f32;
         bar.inc(1);
-        bar.set_message(format!("({:.1} %)", percentage));
+        bar.set_message(format!("({percentage:.1} %)"));
         if bar.position() == total as u64 {
             println!(
                 "Progress: You completed {} / {} exercises ({:.1} %).",
@@ -51,6 +51,7 @@ pub fn verify<'a>(
     Ok(())
 }
 
+#[derive(PartialEq, Eq)]
 enum RunMode {
     Interactive,
     NonInteractive,
@@ -124,7 +125,7 @@ fn compile_and_test(
             if verbose {
                 println!("{}", output.stdout);
             }
-            if let RunMode::Interactive = run_mode {
+            if run_mode == RunMode::Interactive {
                 Ok(prompt_for_completion(exercise, None, success_hints))
             } else {
                 Ok(true)
@@ -191,27 +192,25 @@ fn prompt_for_completion(
         Mode::Test => "The code is compiling, and the tests pass!",
         Mode::Clippy => clippy_success_msg,
     };
-    println!();
+
     if no_emoji {
-        println!("~*~ {success_msg} ~*~")
+        println!("\n~*~ {success_msg} ~*~\n");
     } else {
-        println!("🎉 🎉  {success_msg} 🎉 🎉")
+        println!("\n🎉 🎉  {success_msg} 🎉 🎉\n");
     }
-    println!();
 
     if let Some(output) = prompt_output {
-        println!("Output:");
-        println!("{}", separator());
-        println!("{output}");
-        println!("{}", separator());
-        println!();
+        println!(
+            "Output:\n{separator}\n{output}\n{separator}\n",
+            separator = separator(),
+        );
     }
     if success_hints {
-        println!("Hints:");
-        println!("{}", separator());
-        println!("{}", exercise.hint);
-        println!("{}", separator());
-        println!();
+        println!(
+            "Hints:\n{separator}\n{}\n{separator}\n",
+            exercise.hint,
+            separator = separator(),
+        );
     }
 
     println!("You can keep working on this exercise,");
@@ -224,14 +223,14 @@ fn prompt_for_completion(
         let formatted_line = if context_line.important {
             format!("{}", style(context_line.line).bold())
         } else {
-            context_line.line.to_string()
+            context_line.line
         };
 
         println!(
             "{:>2} {}  {}",
             style(context_line.number).blue().bold(),
             style("|").blue(),
-            formatted_line
+            formatted_line,
         );
     }