use assert_cmd::prelude::*;
use glob::glob;
use predicates::boolean::PredicateBooleanExt;
use std::fs::File;
use std::io::Read;
use std::process::Command;
#[test]
fn runs_without_arguments() {
    let mut cmd = Command::cargo_bin("rustlings").unwrap();
    cmd.assert().success();
}
#[test]
fn fails_when_in_wrong_dir() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .current_dir("tests/")
        .assert()
        .code(1);
}
#[test]
fn verify_all_success() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .arg("verify")
        .current_dir("tests/fixture/success")
        .assert()
        .success();
}
#[test]
fn verify_fails_if_some_fails() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .arg("verify")
        .current_dir("tests/fixture/failure")
        .assert()
        .code(1);
}
#[test]
fn run_single_compile_success() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "compSuccess"])
        .current_dir("tests/fixture/success/")
        .assert()
        .success();
}
#[test]
fn run_single_compile_failure() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "compFailure"])
        .current_dir("tests/fixture/failure/")
        .assert()
        .code(1);
}
#[test]
fn run_single_test_success() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "testSuccess"])
        .current_dir("tests/fixture/success/")
        .assert()
        .success();
}
#[test]
fn run_single_test_failure() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "testFailure"])
        .current_dir("tests/fixture/failure/")
        .assert()
        .code(1);
}
#[test]
fn run_single_test_not_passed() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "testNotPassed.rs"])
        .current_dir("tests/fixture/failure/")
        .assert()
        .code(1);
}
#[test]
fn run_single_test_no_filename() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .arg("run")
        .current_dir("tests/fixture/")
        .assert()
        .code(1);
}
#[test]
fn run_single_test_no_exercise() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "compNoExercise.rs"])
        .current_dir("tests/fixture/failure")
        .assert()
        .code(1);
}
#[test]
fn get_hint_for_single_test() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["hint", "testFailure"])
        .current_dir("tests/fixture/failure")
        .assert()
        .code(0)
        .stdout("Hello!\n");
}
#[test]
fn all_exercises_require_confirmation() {
    for exercise in glob("exercises/**/*.rs").unwrap() {
        let path = exercise.unwrap();
        let source = {
            let mut file = File::open(&path).unwrap();
            let mut s = String::new();
            file.read_to_string(&mut s).unwrap();
            s
        };
        source
            .matches("// I AM NOT DONE")
            .next()
            .unwrap_or_else(|| {
                panic!(
                    "There should be an `I AM NOT DONE` annotation in {:?}",
                    path
                )
            });
    }
}
#[test]
fn run_compile_exercise_does_not_prompt() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "pending_exercise"])
        .current_dir("tests/fixture/state")
        .assert()
        .code(0)
        .stdout(predicates::str::contains("I AM NOT DONE").not());
}
#[test]
fn run_test_exercise_does_not_prompt() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "pending_test_exercise"])
        .current_dir("tests/fixture/state")
        .assert()
        .code(0)
        .stdout(predicates::str::contains("I AM NOT DONE").not());
}
#[test]
fn run_single_test_success_with_output() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["--nocapture", "run", "testSuccess"])
        .current_dir("tests/fixture/success/")
        .assert()
        .code(0)
        .stdout(predicates::str::contains("THIS TEST TOO SHALL PAS"));
}
#[test]
fn run_single_test_success_without_output() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["run", "testSuccess"])
        .current_dir("tests/fixture/success/")
        .assert()
        .code(0)
        .stdout(predicates::str::contains("THIS TEST TOO SHALL PAS").not());
}
#[test]
fn run_rustlings_list() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["list"])
        .current_dir("tests/fixture/success")
        .assert()
        .success();
}
#[test]
fn run_rustlings_list_no_pending() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["list"])
        .current_dir("tests/fixture/success")
        .assert()
        .success()
        .stdout(predicates::str::contains("Pending").not());
}
#[test]
fn run_rustlings_list_both_done_and_pending() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["list"])
        .current_dir("tests/fixture/state")
        .assert()
        .success()
        .stdout(predicates::str::contains("Done").and(predicates::str::contains("Pending")));
}
#[test]
fn run_rustlings_list_without_pending() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["list", "--solved"])
        .current_dir("tests/fixture/state")
        .assert()
        .success()
        .stdout(predicates::str::contains("Pending").not());
}
#[test]
fn run_rustlings_list_without_done() {
    Command::cargo_bin("rustlings")
        .unwrap()
        .args(&["list", "--unsolved"])
        .current_dir("tests/fixture/state")
        .assert()
        .success()
        .stdout(predicates::str::contains("Done").not());
}

#[test]
fn passing() {
    println!("THIS TEST TOO SHALL PASS");
    assert!(true);
}

[[exercises]]
name = "compSuccess"
path = "compSuccess.rs"
mode = "compile"
hint = """"""
[[exercises]]
name = "testSuccess"
path = "testSuccess.rs"
mode = "test"
hint = """"""

fn main() {
}

// I AM NOT DONE
#[test]
fn it_works() {}

// fake_exercise
// I AM NOT DONE
fn main() {
}

[[exercises]]
name = "pending_exercise"
path = "pending_exercise.rs"
mode = "compile"
hint = """"""
[[exercises]]
name = "pending_test_exercise"
path = "pending_test_exercise.rs"
mode = "test"
hint = """"""
[[exercises]]
name = "finished_exercise"
path = "finished_exercise.rs"
mode = "compile"
hint = """"""

// fake_exercise
fn main() {
}

#[test]
fn not_passing() {
    assert!(false);
}

#[test]
fn passing() {
    asset!(true);
}

[[exercises]]
name = "compFailure"
path = "compFailure.rs"
mode = "compile"
hint = ""
[[exercises]]
name = "testFailure"
path = "testFailure.rs"
mode = "test"
hint = "Hello!"

fn main() {
}

fn main() {
    let
}

use crate::exercise::{CompiledExercise, Exercise, Mode, State};
use console::style;
use indicatif::ProgressBar;
use std::env;
// Verify that the provided container of Exercise objects
// can be compiled and run without any failures.
// Any such failures will be reported to the end user.
// If the Exercise being verified is a test, the verbose boolean
// determines whether or not the test harness outputs are displayed.
pub fn verify<'a>(
    start_at: impl IntoIterator<Item = &'a Exercise>,
    verbose: bool,
) -> Result<(), &'a Exercise> {
    for exercise in start_at {
        let compile_result = match exercise.mode {
            Mode::Test => compile_and_test(&exercise, RunMode::Interactive, verbose),
            Mode::Compile => compile_and_run_interactively(&exercise),
            Mode::Clippy => compile_only(&exercise),
        };
        if !compile_result.unwrap_or(false) {
            return Err(exercise);
        }
    }
    Ok(())
}
enum RunMode {
    Interactive,
    NonInteractive,
}
// Compile and run the resulting test harness of the given Exercise
pub fn test(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
    compile_and_test(exercise, RunMode::NonInteractive, verbose)?;
    Ok(())
}
// Invoke the rust compiler without running the resulting binary
fn compile_only(exercise: &Exercise) -> Result<bool, ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
    progress_bar.enable_steady_tick(100);
    let _ = compile(&exercise, &progress_bar)?;
    progress_bar.finish_and_clear();
    success!("Successfully compiled {}!", exercise);
    Ok(prompt_for_completion(&exercise, None))
}
// Compile the given Exercise and run the resulting binary in an interactive mode
fn compile_and_run_interactively(exercise: &Exercise) -> Result<bool, ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
    progress_bar.enable_steady_tick(100);
    let compilation = compile(&exercise, &progress_bar)?;
    progress_bar.set_message(format!("Running {}...", exercise).as_str());
    let result = compilation.run();
    progress_bar.finish_and_clear();
    let output = match result {
        Ok(output) => output,
        Err(output) => {
            warn!("Ran {} with errors", exercise);
            println!("{}", output.stdout);
            println!("{}", output.stderr);
            return Err(());
        }
    };
    success!("Successfully ran {}!", exercise);
    Ok(prompt_for_completion(&exercise, Some(output.stdout)))
}
// Compile the given Exercise as a test harness and display
// the output if verbose is set to true
fn compile_and_test(exercise: &Exercise, run_mode: RunMode, verbose: bool) -> Result<bool, ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Testing {}...", exercise).as_str());
    progress_bar.enable_steady_tick(100);
    let compilation = compile(exercise, &progress_bar)?;
    let result = compilation.run();
    progress_bar.finish_and_clear();
    match result {
        Ok(output) => {
            if verbose {
                println!("{}", output.stdout);
            }
            success!("Successfully tested {}", &exercise);
            if let RunMode::Interactive = run_mode {
                Ok(prompt_for_completion(&exercise, None))
            } else {
                Ok(true)
            }
        }
        Err(output) => {
            warn!(
                "Testing of {} failed! Please try again. Here's the output:",
                exercise
            );
            println!("{}", output.stdout);
            Err(())
        }
    }
}
// Compile the given Exercise and return an object with information
// about the state of the compilation
fn compile<'a, 'b>(
    exercise: &'a Exercise,
    progress_bar: &'b ProgressBar,
) -> Result<CompiledExercise<'a>, ()> {
    let compilation_result = exercise.compile();
    match compilation_result {
        Ok(compilation) => Ok(compilation),
        Err(output) => {
            progress_bar.finish_and_clear();
            warn!(
                "Compiling of {} failed! Please try again. Here's the output:",
                exercise
            );
            println!("{}", output.stderr);
            Err(())
        }
    }
}
fn prompt_for_completion(exercise: &Exercise, prompt_output: Option<String>) -> bool {
    let context = match exercise.state() {
        State::Done => return true,
        State::Pending(context) => context,
    };
    let no_emoji = env::var("NO_EMOJI").is_ok();
    let clippy_success_msg = if no_emoji {
        "The code is compiling, and Clippy is happy!"
    } else {
        "The code is compiling, and 📎 Clippy 📎 is happy!"
    };
    let success_msg = match exercise.mode {
        Mode::Compile => "The code is compiling!",
        Mode::Test => "The code is compiling, and the tests pass!",
        Mode::Clippy => clippy_success_msg,
    };
    println!();
    if no_emoji {
        println!("~*~ {} ~*~", success_msg)
    } else {
        println!("🎉 🎉  {} 🎉 🎉", success_msg)
    }
    println!();
    if let Some(output) = prompt_output {
        println!("Output:");
        println!("{}", separator());
        println!("{}", output);
        println!("{}", separator());
        println!();
    }
    println!("You can keep working on this exercise,");
    println!(
        "or jump into the next one by removing the {} comment:",
        style("`I AM NOT DONE`").bold()
    );
    println!();
    for context_line in context {
        let formatted_line = if context_line.important {
            format!("{}", style(context_line.line).bold())
        } else {
            context_line.line.to_string()
        };
        println!(
            "{:>2} {}  {}",
            style(context_line.number).blue().bold(),
            style("|").blue(),
            formatted_line
        );
    }
    false
}
fn separator() -> console::StyledObject<&'static str> {
    style("====================").bold()
}

macro_rules! warn {
    ($fmt:literal, $ex:expr) => {{
        use console::{style, Emoji};
        use std::env;
        let formatstr = format!($fmt, $ex);
        if env::var("NO_EMOJI").is_ok() {
            println!("{} {}", style("!").red(), style(formatstr).red());
        } else {
            println!(
                "{} {}",
                style(Emoji("⚠️ ", "!")).red(),
                style(formatstr).red()
            );
        }
    }};
}
macro_rules! success {
    ($fmt:literal, $ex:expr) => {{
        use console::{style, Emoji};
        use std::env;
        let formatstr = format!($fmt, $ex);
        if env::var("NO_EMOJI").is_ok() {
            println!("{} {}", style("✓").green(), style(formatstr).green());
        } else {
            println!(
                "{} {}",
                style(Emoji("✅", "✓")).green(),
                style(formatstr).green()
            );
        }
    }};
}

use crate::exercise::{Exercise, Mode};
use crate::verify::test;
use indicatif::ProgressBar;
// Invoke the rust compiler on the path of the given exercise,
// and run the ensuing binary.
// The verbose argument helps determine whether or not to show
// the output from the test harnesses (if the mode of the exercise is test)
pub fn run(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
    match exercise.mode {
        Mode::Test => test(exercise, verbose)?,
        Mode::Compile => compile_and_run(exercise)?,
        Mode::Clippy => compile_and_run(exercise)?,
    }
    Ok(())
}
// Invoke the rust compiler on the path of the given exercise
// and run the ensuing binary.
// This is strictly for non-test binaries, so output is displayed
fn compile_and_run(exercise: &Exercise) -> Result<(), ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
    progress_bar.enable_steady_tick(100);
    let compilation_result = exercise.compile();
    let compilation = match compilation_result {
        Ok(compilation) => compilation,
        Err(output) => {
            progress_bar.finish_and_clear();
            warn!(
                "Compilation of {} failed!, Compiler error message:\n",
                exercise
            );
            println!("{}", output.stderr);
            return Err(());
        }
    };
    progress_bar.set_message(format!("Running {}...", exercise).as_str());
    let result = compilation.run();
    progress_bar.finish_and_clear();
    match result {
        Ok(output) => {
            println!("{}", output.stdout);
            success!("Successfully ran {}", exercise);
            Ok(())
        }
        Err(output) => {
            println!("{}", output.stdout);
            println!("{}", output.stderr);
            warn!("Ran {} with errors", exercise);
            Err(())
        }
    }
}

use crate::exercise::{Exercise, ExerciseList};
use crate::run::run;
use crate::verify::verify;
use argh::FromArgs;
use console::Emoji;
use notify::DebouncedEvent;
use notify::{RecommendedWatcher, RecursiveMode, Watcher};
use std::ffi::OsStr;
use std::fs;
use std::io::{self, prelude::*};
use std::path::Path;
use std::process::{Command, Stdio};
use std::sync::mpsc::channel;
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;
#[macro_use]
mod ui;
mod exercise;
mod run;
mod verify;
// In sync with crate version
const VERSION: &str = "4.5.0";
#[derive(FromArgs, PartialEq, Debug)]
/// Rustlings is a collection of small exercises to get you used to writing and reading Rust code
struct Args {
    /// show outputs from the test exercises
    #[argh(switch)]
    nocapture: bool,
    /// show the executable version
    #[argh(switch, short = 'v')]
    version: bool,
    #[argh(subcommand)]
    nested: Option<Subcommands>,
}
#[derive(FromArgs, PartialEq, Debug)]
#[argh(subcommand)]
enum Subcommands {
    Verify(VerifyArgs),
    Watch(WatchArgs),
    Run(RunArgs),
    Hint(HintArgs),
    List(ListArgs),
}
#[derive(FromArgs, PartialEq, Debug)]
#[argh(subcommand, name = "verify")]
/// Verifies all exercises according to the recommended order
struct VerifyArgs {}
#[derive(FromArgs, PartialEq, Debug)]
#[argh(subcommand, name = "watch")]
/// Reruns `verify` when files were edited
struct WatchArgs {}
#[derive(FromArgs, PartialEq, Debug)]
#[argh(subcommand, name = "run")]
/// Runs/Tests a single exercise
struct RunArgs {
    #[argh(positional)]
    /// the name of the exercise
    name: String,
}
#[derive(FromArgs, PartialEq, Debug)]
#[argh(subcommand, name = "hint")]
/// Returns a hint for the given exercise
struct HintArgs {
    #[argh(positional)]
    /// the name of the exercise
    name: String,
}
#[derive(FromArgs, PartialEq, Debug)]
#[argh(subcommand, name = "list")]
/// Lists the exercises available in Rustlings
struct ListArgs {
    #[argh(switch, short = 'p')]
    /// show only the paths of the exercises
    paths: bool,
    #[argh(switch, short = 'n')]
    /// show only the names of the exercises
    names: bool,
    #[argh(option, short = 'f')]
    /// provide a string to match exercise names
    /// comma separated patterns are acceptable
    filter: Option<String>,
    #[argh(switch, short = 'u')]
    /// display only exercises not yet solved
    unsolved: bool,
    #[argh(switch, short = 's')]
    /// display only exercises that have been solved
    solved: bool,
}
fn main() {
    let args: Args = argh::from_env();
    if args.version {
        println!("v{}", VERSION);
        std::process::exit(0);
    }
    if args.nested.is_none() {
        println!();
        println!(r#"       welcome to...                      "#);
        println!(r#"                 _   _ _                  "#);
        println!(r#"  _ __ _   _ ___| |_| (_)_ __   __ _ ___  "#);
        println!(r#" | '__| | | / __| __| | | '_ \ / _` / __| "#);
        println!(r#" | |  | |_| \__ \ |_| | | | | | (_| \__ \ "#);
        println!(r#" |_|   \__,_|___/\__|_|_|_| |_|\__, |___/ "#);
        println!(r#"                               |___/      "#);
        println!();
    }
    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() {
        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 verbose = args.nocapture;
    let command = args.nested.unwrap_or_else(|| {
        let text = fs::read_to_string("default_out.txt").unwrap();
        println!("{}", text);
        std::process::exit(0);
    });
    match command {
        Subcommands::List(subargs) => {
            if !subargs.paths && !subargs.names {
                println!("{:<17}\t{:<46}\t{:<7}", "Name", "Path", "Status");
            }
            let mut exercises_done: u16 = 0;
            let filters = subargs.filter.clone().unwrap_or_default().to_lowercase();
            exercises.iter().for_each(|e| {
                let fname = format!("{}", e.path.display());
                let filter_cond = filters
                    .split(',')
                    .filter(|f| !f.trim().is_empty())
                    .any(|f| e.name.contains(&f) || fname.contains(&f));
                let status = if e.looks_done() {
                    exercises_done += 1;
                    "Done"
                } else {
                    "Pending"
                };
                let solve_cond = {
                    (e.looks_done() && subargs.solved)
                        || (!e.looks_done() && subargs.unsolved)
                        || (!subargs.solved && !subargs.unsolved)
                };
                if solve_cond && (filter_cond || subargs.filter.is_none()) {
                    let line = if subargs.paths {
                        format!("{}\n", fname)
                    } else if subargs.names {
                        format!("{}\n", e.name)
                    } else {
                        format!("{:<17}\t{:<46}\t{:<7}\n", e.name, fname, status)
                    };
                    // Somehow using println! leads to the binary panicking
                    // when its output is piped.
                    // So, we're handling a Broken Pipe error and exiting with 0 anyway
                    let stdout = std::io::stdout();
                    {
                        let mut handle = stdout.lock();
                        handle.write_all(line.as_bytes()).unwrap_or_else(|e| {
                            match e.kind() {
                                std::io::ErrorKind::BrokenPipe => std::process::exit(0),
                                _ => std::process::exit(1),
                            };
                        });
                    }
                }
            });
            let percentage_progress = exercises_done as f32 / exercises.len() as f32 * 100.0;
            println!(
                "Progress: You completed {} / {} exercises ({:.2} %).",
                exercises_done,
                exercises.len(),
                percentage_progress
            );
            std::process::exit(0);
        }
        Subcommands::Run(subargs) => {
            let exercise = find_exercise(&subargs.name, &exercises);
            run(&exercise, verbose).unwrap_or_else(|_| std::process::exit(1));
        }
        Subcommands::Hint(subargs) => {
            let exercise = find_exercise(&subargs.name, &exercises);
            println!("{}", exercise.hint);
        }
        Subcommands::Verify(_subargs) => {
            verify(&exercises, verbose).unwrap_or_else(|_| std::process::exit(1));
        }
        Subcommands::Watch(_subargs) => {
            if let Err(e) = watch(&exercises, verbose) {
                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);
            }
            println!(
                "{emoji} All exercises completed! {emoji}",
                emoji = Emoji("🎉", "★")
            );
            println!();
            println!("+----------------------------------------------------+");
            println!("|          You made it to the Fe-nish line!          |");
            println!("+--------------------------  ------------------------+");
            println!("                          \\/                         ");
            println!("     ▒▒          ▒▒▒▒▒▒▒▒      ▒▒▒▒▒▒▒▒          ▒▒   ");
            println!("   ▒▒▒▒  ▒▒    ▒▒        ▒▒  ▒▒        ▒▒    ▒▒  ▒▒▒▒ ");
            println!("   ▒▒▒▒  ▒▒  ▒▒            ▒▒            ▒▒  ▒▒  ▒▒▒▒ ");
            println!(" ░░▒▒▒▒░░▒▒  ▒▒            ▒▒            ▒▒  ▒▒░░▒▒▒▒ ");
            println!("   ▓▓▓▓▓▓▓▓  ▓▓      ▓▓██  ▓▓  ▓▓██      ▓▓  ▓▓▓▓▓▓▓▓ ");
            println!("     ▒▒▒▒    ▒▒      ████  ▒▒  ████      ▒▒░░  ▒▒▒▒   ");
            println!("       ▒▒  ▒▒▒▒▒▒        ▒▒▒▒▒▒        ▒▒▒▒▒▒  ▒▒     ");
            println!("         ▒▒▒▒▒▒▒▒▒▒▓▓▓▓▓▓▒▒▒▒▒▒▒▒▓▓▒▒▓▓▒▒▒▒▒▒▒▒       ");
            println!("           ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒         ");
            println!("             ▒▒▒▒▒▒▒▒▒▒██▒▒▒▒▒▒██▒▒▒▒▒▒▒▒▒▒           ");
            println!("           ▒▒  ▒▒▒▒▒▒▒▒▒▒██████▒▒▒▒▒▒▒▒▒▒  ▒▒         ");
            println!("         ▒▒    ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒    ▒▒       ");
            println!("       ▒▒    ▒▒    ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒    ▒▒    ▒▒     ");
            println!("       ▒▒  ▒▒    ▒▒                  ▒▒    ▒▒  ▒▒     ");
            println!("           ▒▒  ▒▒                      ▒▒  ▒▒         ");
            println!();
            println!("We hope you enjoyed learning about the various aspects of Rust!");
            println!(
                "If you noticed any issues, please don't hesitate to report them to our repo."
            );
            println!("You can also contribute your own exercises to help the greater community!");
            println!();
            println!("Before reporting an issue or contributing, please read our guidelines:");
            println!("https://github.com/rust-lang/rustlings/blob/main/CONTRIBUTING.md");
        }
    }
}
fn spawn_watch_shell(failed_exercise_hint: &Arc<Mutex<Option<String>>>) {
    let failed_exercise_hint = Arc::clone(failed_exercise_hint);
    println!("Type 'hint' or open the corresponding README.md file to get help or type 'clear' to clear the screen.");
    thread::spawn(move || loop {
        let mut input = String::new();
        match io::stdin().read_line(&mut input) {
            Ok(_) => {
                let input = input.trim();
                if input.eq("hint") {
                    if let Some(hint) = &*failed_exercise_hint.lock().unwrap() {
                        println!("{}", hint);
                    }
                } else if input.eq("clear") {
                    println!("\x1B[2J\x1B[1;1H");
                } else {
                    println!("unknown command: {}", input);
                }
            }
            Err(error) => println!("error reading command: {}", error),
        }
    });
}
fn find_exercise<'a>(name: &str, exercises: &'a [Exercise]) -> &'a Exercise {
    if name.eq("next") {
        exercises
            .iter()
            .find(|e| !e.looks_done())
            .unwrap_or_else(|| {
                println!("🎉 Congratulations! You have done all the exercises!");
                println!("🔚 There are no more exercises to do next!");
                std::process::exit(1)
            })
    } else {
        exercises
            .iter()
            .find(|e| e.name == name)
            .unwrap_or_else(|| {
                println!("No exercise found for '{}'!", name);
                std::process::exit(1)
            })
    }
}
fn watch(exercises: &[Exercise], verbose: bool) -> notify::Result<()> {
    /* Clears the terminal with an ANSI escape code.
    Works in UNIX and newer Windows terminals. */
    fn clear_screen() {
        println!("\x1Bc");
    }
    let (tx, rx) = channel();
    let mut watcher: RecommendedWatcher = Watcher::new(tx, Duration::from_secs(2))?;
    watcher.watch(Path::new("./exercises"), RecursiveMode::Recursive)?;
    clear_screen();
    let to_owned_hint = |t: &Exercise| t.hint.to_owned();
    let failed_exercise_hint = match verify(exercises.iter(), verbose) {
        Ok(_) => return Ok(()),
        Err(exercise) => Arc::new(Mutex::new(Some(to_owned_hint(exercise)))),
    };
    spawn_watch_shell(&failed_exercise_hint);
    loop {
        match rx.recv() {
            Ok(event) => match event {
                DebouncedEvent::Create(b) | DebouncedEvent::Chmod(b) | DebouncedEvent::Write(b) => {
                    if b.extension() == Some(OsStr::new("rs")) && b.exists() {
                        let filepath = b.as_path().canonicalize().unwrap();
                        let pending_exercises = exercises
                            .iter()
                            .skip_while(|e| !filepath.ends_with(&e.path))
                            // .filter(|e| filepath.ends_with(&e.path))
                            .chain(
                                exercises
                                    .iter()
                                    .filter(|e| !e.looks_done() && !filepath.ends_with(&e.path)),
                            );
                        clear_screen();
                        match verify(pending_exercises, verbose) {
                            Ok(_) => return Ok(()),
                            Err(exercise) => {
                                let mut failed_exercise_hint = failed_exercise_hint.lock().unwrap();
                                *failed_exercise_hint = Some(to_owned_hint(exercise));
                            }
                        }
                    }
                }
                _ => {}
            },
            Err(e) => println!("watch error: {:?}", e),
        }
    }
}
fn rustc_exists() -> bool {
    Command::new("rustc")
        .args(&["--version"])
        .stdout(Stdio::null())
        .spawn()
        .and_then(|mut child| child.wait())
        .map(|status| status.success())
        .unwrap_or(false)
}

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::path::PathBuf;
use std::process::{self, Command};
const RUSTC_COLOR_ARGS: &[&str] = &["--color", "always"];
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/clippy/Cargo.toml";
// Get a temporary file name that is hopefully unique
#[inline]
fn temp_file() -> String {
    let thread_id: String = format!("{:?}", std::thread::current().id())
        .chars()
        .filter(|c| c.is_alphanumeric())
        .collect();
    format!("./temp_{}_{}", process::id(), thread_id)
}
// The mode of the exercise.
#[derive(Deserialize, Copy, Clone, Debug)]
#[serde(rename_all = "lowercase")]
pub enum Mode {
    // Indicates that the exercise should be compiled as a binary
    Compile,
    // Indicates that the exercise should be compiled as a test harness
    Test,
    // Indicates that the exercise should be linted with clippy
    Clippy,
}
#[derive(Deserialize)]
pub struct ExerciseList {
    pub exercises: Vec<Exercise>,
}
// A representation of a rustlings exercise.
// This is deserialized from the accompanying info.toml file
#[derive(Deserialize, Debug)]
pub struct Exercise {
    // Name of the exercise
    pub name: String,
    // The path to the file containing the exercise's source code
    pub path: PathBuf,
    // The mode of the exercise (Test, Compile, or Clippy)
    pub mode: Mode,
    // The hint text associated with the exercise
    pub hint: String,
}
// An enum to track of the state of an Exercise.
// An Exercise can be either Done or Pending
#[derive(PartialEq, Debug)]
pub enum State {
    // The state of the exercise once it's been completed
    Done,
    // The state of the exercise while it's not completed yet
    Pending(Vec<ContextLine>),
}
// The context information of a pending exercise
#[derive(PartialEq, Debug)]
pub struct ContextLine {
    // The source code that is still pending completion
    pub line: String,
    // The line number of the source code still pending completion
    pub number: usize,
    // Whether or not this is important
    pub important: bool,
}
// The result of compiling an exercise
pub struct CompiledExercise<'a> {
    exercise: &'a Exercise,
    _handle: FileHandle,
}
impl<'a> CompiledExercise<'a> {
    // Run the compiled exercise
    pub fn run(&self) -> Result<ExerciseOutput, ExerciseOutput> {
        self.exercise.run()
    }
}
// A representation of an already executed binary
#[derive(Debug)]
pub struct ExerciseOutput {
    // The textual contents of the standard output of the binary
    pub stdout: String,
    // The textual contents of the standard error of the binary
    pub stderr: String,
}
struct FileHandle;
impl Drop for FileHandle {
    fn drop(&mut self) {
        clean();
    }
}
impl Exercise {
    pub fn compile(&self) -> Result<CompiledExercise, ExerciseOutput> {
        let cmd = match self.mode {
            Mode::Compile => Command::new("rustc")
                .args(&[self.path.to_str().unwrap(), "-o", &temp_file()])
                .args(RUSTC_COLOR_ARGS)
                .output(),
            Mode::Test => Command::new("rustc")
                .args(&["--test", self.path.to_str().unwrap(), "-o", &temp_file()])
                .args(RUSTC_COLOR_ARGS)
                .output(),
            Mode::Clippy => {
                let cargo_toml = format!(
                    r#"[package]
name = "{}"
version = "0.0.1"
edition = "2018"
[[bin]]
name = "{}"
path = "{}.rs""#,
                    self.name, self.name, self.name
                );
                let cargo_toml_error_msg = if env::var("NO_EMOJI").is_ok() {
                    "Failed to write Clippy Cargo.toml file."
                } else {
                    "Failed to write 📎 Clippy 📎 Cargo.toml file."
                };
                fs::write(CLIPPY_CARGO_TOML_PATH, cargo_toml).expect(cargo_toml_error_msg);
                // To support the ability to run the clipy exercises, build
                // an executable, in addition to running clippy. With a
                // compilation failure, this would silently fail. But we expect
                // clippy to reflect the same failure while compiling later.
                Command::new("rustc")
                    .args(&[self.path.to_str().unwrap(), "-o", &temp_file()])
                    .args(RUSTC_COLOR_ARGS)
                    .output()
                    .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
                // This is already fixed on Clippy's master branch. See this issue to track merging into Cargo:
                // https://github.com/rust-lang/rust-clippy/issues/3837
                Command::new("cargo")
                    .args(&["clean", "--manifest-path", CLIPPY_CARGO_TOML_PATH])
                    .args(RUSTC_COLOR_ARGS)
                    .output()
                    .expect("Failed to run 'cargo clean'");
                Command::new("cargo")
                    .args(&["clippy", "--manifest-path", CLIPPY_CARGO_TOML_PATH])
                    .args(RUSTC_COLOR_ARGS)
                    .args(&["--", "-D", "warnings"])
                    .output()
            }
        }
        .expect("Failed to run 'compile' command.");
        if cmd.status.success() {
            Ok(CompiledExercise {
                exercise: &self,
                _handle: FileHandle,
            })
        } else {
            clean();
            Err(ExerciseOutput {
                stdout: String::from_utf8_lossy(&cmd.stdout).to_string(),
                stderr: String::from_utf8_lossy(&cmd.stderr).to_string(),
            })
        }
    }
    fn run(&self) -> Result<ExerciseOutput, ExerciseOutput> {
        let arg = match self.mode {
            Mode::Test => "--show-output",
            _ => "",
        };
        let cmd = Command::new(&temp_file())
            .arg(arg)
            .output()
            .expect("Failed to run 'run' command");
        let output = ExerciseOutput {
            stdout: String::from_utf8_lossy(&cmd.stdout).to_string(),
            stderr: String::from_utf8_lossy(&cmd.stderr).to_string(),
        };
        if cmd.status.success() {
            Ok(output)
        } else {
            Err(output)
        }
    }
    pub fn state(&self) -> State {
        let mut source_file =
            File::open(&self.path).expect("We were unable to open the exercise file!");
        let source = {
            let mut s = String::new();
            source_file
                .read_to_string(&mut s)
                .expect("We were unable to read the exercise file!");
            s
        };
        let re = Regex::new(I_AM_DONE_REGEX).unwrap();
        if !re.is_match(&source) {
            return State::Done;
        }
        let matched_line_index = source
            .lines()
            .enumerate()
            .filter_map(|(i, line)| if re.is_match(line) { Some(i) } else { None })
            .next()
            .expect("This should not happen at all");
        let min_line = ((matched_line_index as i32) - (CONTEXT as i32)).max(0) as usize;
        let max_line = matched_line_index + CONTEXT;
        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();
        State::Pending(context)
    }
    // Check that the exercise looks to be solved using self.state()
    // This is not the best way to check since
    // the user can just remove the "I AM NOT DONE" string from the file
    // without actually having solved anything.
    // The only other way to truly check this would to compile and run
    // the exercise; which would be both costly and counterintuitive
    pub fn looks_done(&self) -> bool {
        self.state() == State::Done
    }
}
impl Display for Exercise {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        write!(f, "{}", self.path.to_str().unwrap())
    }
}
#[inline]
fn clean() {
    let _ignored = remove_file(&temp_file());
}
#[cfg(test)]
mod test {
    use super::*;
    use std::path::Path;
    #[test]
    fn test_clean() {
        File::create(&temp_file()).unwrap();
        let exercise = Exercise {
            name: String::from("example"),
            path: PathBuf::from("tests/fixture/state/pending_exercise.rs"),
            mode: Mode::Compile,
            hint: String::from(""),
        };
        let compiled = exercise.compile().unwrap();
        drop(compiled);
        assert!(!Path::new(&temp_file()).exists());
    }
    #[test]
    fn test_pending_state() {
        let exercise = Exercise {
            name: "pending_exercise".into(),
            path: PathBuf::from("tests/fixture/state/pending_exercise.rs"),
            mode: Mode::Compile,
            hint: String::new(),
        };
        let state = exercise.state();
        let expected = vec![
            ContextLine {
                line: "// fake_exercise".to_string(),
                number: 1,
                important: false,
            },
            ContextLine {
                line: "".to_string(),
                number: 2,
                important: false,
            },
            ContextLine {
                line: "// I AM NOT DONE".to_string(),
                number: 3,
                important: true,
            },
            ContextLine {
                line: "".to_string(),
                number: 4,
                important: false,
            },
            ContextLine {
                line: "fn main() {".to_string(),
                number: 5,
                important: false,
            },
        ];
        assert_eq!(state, State::Pending(expected));
    }
    #[test]
    fn test_finished_exercise() {
        let exercise = Exercise {
            name: "finished_exercise".into(),
            path: PathBuf::from("tests/fixture/state/finished_exercise.rs"),
            mode: Mode::Compile,
            hint: String::new(),
        };
        assert_eq!(exercise.state(), State::Done);
    }
    #[test]
    fn test_exercise_with_output() {
        let exercise = Exercise {
            name: "exercise_with_output".into(),
            path: PathBuf::from("tests/fixture/success/testSuccess.rs"),
            mode: Mode::Test,
            hint: String::new(),
        };
        let out = exercise.compile().unwrap().run().unwrap();
        assert!(out.stdout.contains("THIS TEST TOO SHALL PASS"));
    }
}

#!/usr/bin/env bash
echo "Let's get you set up with Rustlings!"
echo "Checking requirements..."
if [ -x "$(command -v git)" ]
then
    echo "SUCCESS: Git is installed"
else
    echo "ERROR: Git does not seem to be installed."
    echo "Please download Git using your package manager or over https://git-scm.com/!"
    exit 1
fi
if [ -x "$(command -v rustc)" ]
then
    echo "SUCCESS: Rust is installed"
else
    echo "ERROR: Rust does not seem to be installed."
    echo "Please download Rust using https://rustup.rs!"
    exit 1
fi
if [ -x "$(command -v cargo)" ]
then
    echo "SUCCESS: Cargo is installed"
else
    echo "ERROR: Cargo does not seem to be installed."
    echo "Please download Rust and Cargo using https://rustup.rs!"
    exit 1
fi
# Look up python installations, starting with 3 with a fallback of 2
if [ -x "$(command -v python3)" ]
then
    PY="$(command -v python3)"
elif [ -x "$(command -v python)" ]
then
    PY="$(command -v python)"
elif [ -x "$(command -v python2)" ]
then
    PY="$(command -v python2)"
else
    echo "ERROR: No working python installation was found"
    echo "Please install python and add it to the PATH variable"
    exit 1
fi
# Function that compares two versions strings v1 and v2 given in arguments (e.g 1.31 and 1.33.0).
# Returns 1 if v1 > v2, 0 if v1 == v2, 2 if v1 < v2.
function vercomp() {
    if [[ $1 == $2 ]]
    then
        return 0
    fi
    v1=( ${1//./ } )
    v2=( ${2//./ } )
    len1=${#v1[@]}
    len2=${#v2[@]}
    max_len=$len1
    if [[ $max_len -lt $len2 ]]
    then
        max_len=$len2
    fi
    for i in `seq 0 $max_len`
    do
        # Fill empty fields with zeros in v1
        if [ -z "${v1[$i]}" ]
        then
            v1[$i]=0
        fi
        # And in v2
        if [ -z "${v2[$i]}" ]
        then
            v2[$i]=0
        fi
        if [ ${v1[$i]} -gt ${v2[$i]} ]
        then
            return 1
        fi
        if [ ${v1[$i]} -lt ${v2[$i]} ]
        then
            return 2
        fi
    done
    return 0
}
RustVersion=$(rustc --version | cut -d " " -f 2)
MinRustVersion=1.39
vercomp $RustVersion $MinRustVersion
if [ $? -eq 2 ]
then
    echo "ERROR: Rust version is too old: $RustVersion - needs at least $MinRustVersion"
    echo "Please update Rust with 'rustup update'"
    exit 1
else
    echo "SUCCESS: Rust is up to date"
fi
Path=${1:-rustlings/}
echo "Cloning Rustlings at $Path..."
git clone -q https://github.com/rust-lang/rustlings $Path
cd $Path
Version=$(curl -s https://api.github.com/repos/rust-lang/rustlings/releases/latest | ${PY} -c "import json,sys;obj=json.load(sys.stdin);print(obj['tag_name']);")
CargoBin="${CARGO_HOME:-$HOME/.cargo}/bin"
if [[ -z ${Version} ]]
then
    echo "The latest tag version could not be fetched remotely."
    echo "Using the local git repository..."
    Version=$(ls -tr .git/refs/tags/ | tail -1)
    if [[ -z ${Version}  ]]
    then
        echo "No valid tag version found"
        echo "Rustlings will be installed using the main branch"
        Version="main"
    else
        Version="tags/${Version}"
    fi
else
    Version="tags/${Version}"
fi
echo "Checking out version $Version..."
git checkout -q ${Version}
echo "Installing the 'rustlings' executable..."
cargo install --force --path .
if ! [ -x "$(command -v rustlings)" ]
then
    echo "WARNING: Please check that you have '$CargoBin' in your PATH environment variable!"
fi
# Checking whether Clippy is installed.
# Due to a bug in Cargo, this must be done with Rustup: https://github.com/rust-lang/rustup/issues/1514
Clippy=$(rustup component list | grep "clippy" | grep "installed")
if [ -z "$Clippy" ]
then
    echo "Installing the 'cargo-clippy' executable..."
    rustup component add clippy
fi
echo "All done! Run 'rustlings' to get started."

#!/usr/bin/env pwsh
#Requires -Version 5
param($path = "$pwd/rustlings")
Write-Host "Let's get you set up with Rustlings!"
Write-Host "Checking requirements..."
if (Get-Command git -ErrorAction SilentlyContinue) {
    Write-Host "SUCCESS: Git is installed"
} else {
    Write-Host "WARNING: Git does not seem to be installed."
    Write-Host "Please download Git using your package manager or over https://git-scm.com/!"
    exit 1
}
if (Get-Command rustc -ErrorAction SilentlyContinue) {
    Write-Host "SUCCESS:  Rust is installed"
} else {
    Write-Host "WARNING: Rust does not seem to be installed."
    Write-Host "Please download Rust using https://rustup.rs!"
    exit 1
}
if (Get-Command cargo -ErrorAction SilentlyContinue) {
    Write-Host "SUCCESS: Cargo is installed"
} else {
    Write-Host "WARNING: Cargo does not seem to be installed."
    Write-Host "Please download Rust and Cargo using https://rustup.rs!"
    exit 1
}
# Function that compares two versions strings v1 and v2 given in arguments (e.g 1.31 and 1.33.0).
# Returns 1 if v1 > v2, 0 if v1 == v2, 2 if v1 < v2.
function vercomp($v1, $v2) {
    if ($v1 -eq $v2) {
       return 0
    }
    $v1 = $v1.Replace(".", "0")
    $v2 = $v2.Replace(".", "0")
    if ($v1.Length -gt $v2.Length) {
        $v2 = $v2.PadRight($v1.Length, "0")
    } else {
        $v1 = $v1.PadRight($v2.Length, "0")
    }
    if ($v1 -gt $v2) {
        return 1
    } else {
        return 2
    }
}
$rustVersion = $(rustc --version).Split(" ")[1]
$minRustVersion = "1.39"
if ((vercomp $rustVersion $minRustVersion) -eq 2) {
    Write-Host "WARNING: Rust version is too old: $rustVersion - needs at least $minRustVersion"
    Write-Host "Please update Rust with 'rustup update'"
    exit 1
} else {
    Write-Host "SUCCESS: Rust is up to date"
}
Write-Host "Cloning Rustlings at $path"
git clone -q https://github.com/rust-lang/rustlings $path
if (!($LASTEXITCODE -eq 0)) {
    exit 1
}
# UseBasicParsing is deprecated, pwsh 6 or above will automatically use it,
# but anyone running pwsh 5 will have to pass the argument.
$version = Invoke-WebRequest -UseBasicParsing https://api.github.com/repos/rust-lang/rustlings/releases/latest `
    | ConvertFrom-Json | Select-Object -ExpandProperty tag_name
Write-Host "Checking out version $version..."
Set-Location $path
git checkout -q tags/$version
Write-Host "Installing the 'rustlings' executable..."
cargo install --force --path .
if (!(Get-Command rustlings -ErrorAction SilentlyContinue)) {
    Write-Host "WARNING: Please check that you have '~/.cargo/bin' in your PATH environment variable!"
}
# Checking whether Clippy is installed.
# Due to a bug in Cargo, this must be done with Rustup: https://github.com/rust-lang/rustup/issues/1514
$clippy = (rustup component list | Select-String "clippy" | Select-String "installed") | Out-String
if (!$clippy) {
    Write-Host "Installing the 'cargo-clippy' executable..."
    rustup component add clippy
}
Write-Host "All done! Run 'rustlings' to get started."

# VARIABLES
[[exercises]]
name = "variables1"
path = "exercises/variables/variables1.rs"
mode = "compile"
hint = """
Hint: The declaration on line 12 is missing a keyword that is needed in Rust
to create a new variable binding."""
[[exercises]]
name = "variables2"
path = "exercises/variables/variables2.rs"
mode = "compile"
hint = """
The compiler message is saying that Rust cannot infer the type that the
variable binding `x` has with what is given here.
What happens if you annotate line 7 with a type annotation?
What if you give x a value?
What if you do both?
What type should x be, anyway?
What if x is the same type as 10? What if it's a different type?"""
[[exercises]]
name = "variables3"
path = "exercises/variables/variables3.rs"
mode = "compile"
hint = """
In Rust, variable bindings are immutable by default. But here we're trying
to reassign a different value to x! There's a keyword we can use to make
a variable binding mutable instead."""
[[exercises]]
name = "variables4"
path = "exercises/variables/variables4.rs"
mode = "compile"
hint = """
Oops! In this exercise, we have a variable binding that we've created on
line 7, and we're trying to use it on line 8, but we haven't given it a
value. We can't print out something that isn't there; try giving x a value!
This is an error that can cause bugs that's very easy to make in any
programming language -- thankfully the Rust compiler has caught this for us!"""
[[exercises]]
name = "variables5"
path = "exercises/variables/variables5.rs"
mode = "compile"
hint = """
In variables3 we already learned how to make an immutable variable mutable
using a special keyword. Unfortunately this doesn't help us much in this exercise
because we want to assign a different typed value to an existing variable. Sometimes
you may also like to reuse existing variable names because you are just converting
values to different types like in this exercise.
Fortunately Rust has a powerful solution to this problem: 'Shadowing'!
You can read more about 'Shadowing' in the book's section 'Variables and Mutability':
https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#shadowing
Try to solve this exercise afterwards using this technique."""
[[exercises]]
name = "variables6"
path = "exercises/variables/variables6.rs"
mode = "compile"
hint = """
We know about variables and mutability, but there is another important type of
variable available; constants.
Constants are always immutable and they are declared with keyword 'const' rather
than keyword 'let'.
Constants types must also always be annotated.
Read more about constants under 'Differences Between Variables and Constants' in the book's section 'Variables and Mutability':
https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#differences-between-variables-and-constants
"""
# FUNCTIONS
[[exercises]]
name = "functions1"
path = "exercises/functions/functions1.rs"
mode = "compile"
hint = """
This main function is calling a function that it expects to exist, but the
function doesn't exist. It expects this function to have the name `call_me`.
It expects this function to not take any arguments and not return a value.
Sounds a lot like `main`, doesn't it?"""
[[exercises]]
name = "functions2"
path = "exercises/functions/functions2.rs"
mode = "compile"
hint = """
Rust requires that all parts of a function's signature have type annotations,
but `call_me` is missing the type annotation of `num`."""
[[exercises]]
name = "functions3"
path = "exercises/functions/functions3.rs"
mode = "compile"
hint = """
This time, the function *declaration* is okay, but there's something wrong
with the place where we're calling the function."""
[[exercises]]
name = "functions4"
path = "exercises/functions/functions4.rs"
mode = "compile"
hint = """
The error message points to line 14 and says it expects a type after the
`->`. This is where the function's return type should be-- take a look at
the `is_even` function for an example!"""
[[exercises]]
name = "functions5"
path = "exercises/functions/functions5.rs"
mode = "compile"
hint = """
This is a really common error that can be fixed by removing one character.
It happens because Rust distinguishes between expressions and statements: expressions return
a value based on its operand, and statements simply return a () type which behaves just like `void` in C/C++ language.
We want to return a value of `i32` type from the `square` function, but it is returning a `()` type...
They are not the same. There are two solutions:
1. Add a `return` ahead of `num * num;`
2. remove `;`, make it to be `num * num`"""
# IF
[[exercises]]
name = "if1"
path = "exercises/if/if1.rs"
mode = "test"
hint = """
It's possible to do this in one line if you would like!
Some similar examples from other languages:
- In C(++) this would be: `a > b ? a : b`
- In Python this would be:  `a if a > b else b`
Remember in Rust that:
- the `if` condition does not need to be surrounded by parentheses
- `if`/`else` conditionals are expressions
- Each condition is followed by a `{}` block."""
[[exercises]]
name = "if2"
path = "exercises/if/if2.rs"
mode = "test"
hint = """
For that first compiler error, it's important in Rust that each conditional
block return the same type! To get the tests passing, you will need a couple
conditions checking different input values."""
# TEST 1
[[exercises]]
name = "quiz1"
path = "exercises/quiz1.rs"
mode = "test"
hint = "No hints this time ;)"
# MOVE SEMANTICS
[[exercises]]
name = "move_semantics1"
path = "exercises/move_semantics/move_semantics1.rs"
mode = "compile"
hint = """
So you've got the "cannot borrow immutable local variable `vec1` as mutable" error on line 13,
right? The fix for this is going to be adding one keyword, and the addition is NOT on line 13
where the error is."""
[[exercises]]
name = "move_semantics2"
path = "exercises/move_semantics/move_semantics2.rs"
mode = "compile"
hint = """
So `vec0` is being *moved* into the function `fill_vec` when we call it on
line 10, which means it gets dropped at the end of `fill_vec`, which means we
can't use `vec0` again on line 13 (or anywhere else in `main` after the
`fill_vec` call for that matter). We could fix this in a few ways, try them
all!
1. Make another, separate version of the data that's in `vec0` and pass that
   to `fill_vec` instead.
2. Make `fill_vec` borrow its argument instead of taking ownership of it,
   and then copy the data within the function in order to return an owned
   `Vec<i32>`
3. Make `fill_vec` *mutably* borrow its argument (which will need to be
   mutable), modify it directly, then not return anything. Then you can get rid
   of `vec1` entirely -- note that this will change what gets printed by the
   first `println!`"""
[[exercises]]
name = "move_semantics3"
path = "exercises/move_semantics/move_semantics3.rs"
mode = "compile"
hint = """
The difference between this one and the previous ones is that the first line
of `fn fill_vec` that had `let mut vec = vec;` is no longer there. You can,
instead of adding that line back, add `mut` in one place that will change
an existing binding to be a mutable binding instead of an immutable one :)"""
[[exercises]]
name = "move_semantics4"
path = "exercises/move_semantics/move_semantics4.rs"
mode = "compile"
hint = """
Stop reading whenever you feel like you have enough direction :) Or try
doing one step and then fixing the compiler errors that result!
So the end goal is to:
   - get rid of the first line in main that creates the new vector
   - so then `vec0` doesn't exist, so we can't pass it to `fill_vec`
   - we don't want to pass anything to `fill_vec`, so its signature should
     reflect that it does not take any arguments
   - since we're not creating a new vec in `main` anymore, we need to create
     a new vec in `fill_vec`, similarly to the way we did in `main`"""
[[exercises]]
name = "move_semantics5"
path = "exercises/move_semantics/move_semantics5.rs"
mode = "compile"
hint = """
Carefully reason about the range in which each mutable reference is in
vogue. Does it help to update the value of referent (x) immediately after
the mutable reference is taken? Read more about 'Mutable References'
in the book's section References and Borrowing':
https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html#mutable-references.
Additional hint:
If you can't add, change, or remove any statements in `main()`, can you
reorder them in a way that lets the program compile?"""
# PRIMITIVE TYPES
[[exercises]]
name = "primitive_types1"
path = "exercises/primitive_types/primitive_types1.rs"
mode = "compile"
hint = "No hints this time ;)"
[[exercises]]
name = "primitive_types2"
path = "exercises/primitive_types/primitive_types2.rs"
mode = "compile"
hint = "No hints this time ;)"
[[exercises]]
name = "primitive_types3"
path = "exercises/primitive_types/primitive_types3.rs"
mode = "compile"
hint = """
There's a shorthand to initialize Arrays with a certain size that does not
require you to type in 100 items (but you certainly can if you want!).
For example, you can do:
let array = ["Are we there yet?"; 10];
Bonus: what are some other things you could have that would return true
for `a.len() >= 100`?"""
[[exercises]]
name = "primitive_types4"
path = "exercises/primitive_types/primitive_types4.rs"
mode = "test"
hint = """
Take a look at the Understanding Ownership -> Slices -> Other Slices section of the book:
https://doc.rust-lang.org/book/ch04-03-slices.html
and use the starting and ending indices of the items in the Array
that you want to end up in the slice.
If you're curious why the first argument of `assert_eq!` does not
have an ampersand for a reference since the second argument is a
reference, take a look at the Deref coercions section of the book:
https://doc.rust-lang.org/book/ch15-02-deref.html"""
[[exercises]]
name = "primitive_types5"
path = "exercises/primitive_types/primitive_types5.rs"
mode = "compile"
hint = """
Take a look at the Data Types -> The Tuple Type section of the book:
https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
Particularly the part about destructuring (second to last example in the section).
You'll need to make a pattern to bind `name` and `age` to the appropriate parts
of the tuple. You can do it!!"""
[[exercises]]
name = "primitive_types6"
path = "exercises/primitive_types/primitive_types6.rs"
mode = "test"
hint = """
While you could use a destructuring `let` for the tuple here, try
indexing into it instead, as explained in the last example of the
Data Types -> The Tuple Type section of the book:
https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
Now you have another tool in your toolbox!"""
# STRUCTS
[[exercises]]
name = "structs1"
path = "exercises/structs/structs1.rs"
mode = "test"
hint = """
Rust has more than one type of struct. Three actually, all variants are used to package related data together.
There are normal (or classic) structs. These are named collections of related data stored in fields.
Tuple structs are basically just named tuples.
Finally, Unit structs. These don't have any fields and are useful for generics.
In this exercise you need to complete and implement one of each kind.
Read more about structs in The Book: https://doc.rust-lang.org/book/ch05-01-defining-structs.html"""
[[exercises]]
name = "structs2"
path = "exercises/structs/structs2.rs"
mode = "test"
hint = """
Creating instances of structs is easy, all you need to do is assign some values to its fields.
There are however some shortcuts that can be taken when instantiating structs.
Have a look in The Book, to find out more: https://doc.rust-lang.org/stable/book/ch05-01-defining-structs.html#creating-instances-from-other-instances-with-struct-update-syntax"""
[[exercises]]
name = "structs3"
path = "exercises/structs/structs3.rs"
mode = "test"
hint = """
The new method needs to panic if the weight is physically impossible :), how do we do that in Rust?
For is_international: What makes a package international? Seems related to the places it goes through right?
For calculate_transport_fees: Bigger is more expensive usually, we don't have size, but something may fit the bill here :)
Have a look in The Book, to find out more about method implementations: https://doc.rust-lang.org/book/ch05-03-method-syntax.html"""
# ENUMS
[[exercises]]
name = "enums1"
path = "exercises/enums/enums1.rs"
mode = "compile"
hint = """
Hint: The declaration of the enumeration type has not been defined yet."""
[[exercises]]
name = "enums2"
path = "exercises/enums/enums2.rs"
mode = "compile"
hint = """
Hint: you can create enumerations that have different variants with different types
such as no data, anonymous structs, a single string, tuples, ...etc"""
[[exercises]]
name = "enums3"
path = "exercises/enums/enums3.rs"
mode = "test"
hint = "No hints this time ;)"
# MODULES
[[exercises]]
name = "modules1"
path = "exercises/modules/modules1.rs"
mode = "compile"
hint = """
Everything is private in Rust by default-- but there's a keyword we can use
to make something public! The compiler error should point to the thing that
needs to be public."""
[[exercises]]
name = "modules2"
path = "exercises/modules/modules2.rs"
mode = "compile"
hint = """
The delicious_snacks module is trying to present an external
interface (the `fruit` and `veggie` constants) that is different than
its internal structure (the `fruits` and `veggies` modules and
associated constants). It's almost there except for one keyword missing for
each constant."""
# COLLECTIONS
[[exercises]]
name = "vec1"
path = "exercises/collections/vec1.rs"
mode = "test"
hint = """
In Rust, there are two ways to define a Vector.
1. One way is to use the `Vec::new()` function to create a new vector
  and fill it with the `push()` method.
2. The second way, which is simpler is to use the `vec![]` macro and
  define your elements inside the square brackets.
Check this chapter: https://doc.rust-lang.org/stable/book/ch08-01-vectors.html
of the Rust book to learn more.
"""
[[exercises]]
name = "vec2"
path = "exercises/collections/vec2.rs"
mode = "test"
hint = """
Hint 1: `i` is each element from the Vec as they are being iterated.
  Can you try multiplying this?
Hint 2: Check the suggestion from the compiler error ;)
"""
[[exercises]]
name = "hashmap1"
path = "exercises/collections/hashmap1.rs"
mode = "test"
hint = """
Hint 1: Take a look at the return type of the function to figure out
  the type for the `basket`.
Hint 2: Number of fruits should be at least 5. And you have to put
  at least three different types of fruits.
"""
[[exercises]]
name = "hashmap2"
path = "exercises/collections/hashmap2.rs"
mode = "test"
hint = """
Use the `entry()` and `or_insert()` methods of `HashMap` to achieve this.
Learn more at https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
"""
# STRINGS
[[exercises]]
name = "strings1"
path = "exercises/strings/strings1.rs"
mode = "compile"
hint = """
The `current_favorite_color` function is currently returning a string slice with the `'static`
lifetime. We know this because the data of the string lives in our code itself -- it doesn't
come from a file or user input or another program -- so it will live as long as our program
lives. But it is still a string slice. There's one way to create a `String` by converting a
string slice covered in the Strings chapter of the book, and another way that uses the `From`
trait."""
[[exercises]]
name = "strings2"
path = "exercises/strings/strings2.rs"
mode = "compile"
hint = """
Yes, it would be really easy to fix this by just changing the value bound to `word` to be a
string slice instead of a `String`, wouldn't it?? There is a way to add one character to line
9, though, that will coerce the `String` into a string slice."""
# TEST 2
[[exercises]]
name = "quiz2"
path = "exercises/quiz2.rs"
mode = "compile"
hint = "No hints this time ;)"
# ERROR HANDLING
[[exercises]]
name = "errors1"
path = "exercises/error_handling/errors1.rs"
mode = "test"
hint = """
`Err` is one of the variants of `Result`, so what the 2nd test is saying
is that `generate_nametag_text` should return a `Result` instead of an
`Option`.
To make this change, you'll need to:
   - update the return type in the function signature to be a Result<String, String> that
     could be the variants `Ok(String)` and `Err(String)`
   - change the body of the function to return `Ok(stuff)` where it currently
     returns `Some(stuff)`
   - change the body of the function to return `Err(error message)` where it
     currently returns `None`
   - change the first test to expect `Ok(stuff)` where it currently expects
     `Some(stuff)`."""
[[exercises]]
name = "errors2"
path = "exercises/error_handling/errors2.rs"
mode = "test"
hint = """
One way to handle this is using a `match` statement on
`item_quantity.parse::<i32>()` where the cases are `Ok(something)` and
`Err(something)`. This pattern is very common in Rust, though, so there's
a `?` operator that does pretty much what you would make that match statement
do for you! Take a look at this section of the Error Handling chapter:
https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors-the--operator
and give it a try!"""
[[exercises]]
name = "errors3"
path = "exercises/error_handling/errors3.rs"
mode = "compile"
hint = """
If other functions can return a `Result`, why shouldn't `main`?"""
[[exercises]]
name = "errors4"
path = "exercises/error_handling/errors4.rs"
mode = "test"
hint = """
`PositiveNonzeroInteger::new` is always creating a new instance and returning an `Ok` result.
It should be doing some checking, returning an `Err` result if those checks fail, and only
returning an `Ok` result if those checks determine that everything is... okay :)"""
[[exercises]]
name = "errors5"
path = "exercises/error_handling/errors5.rs"
mode = "compile"
hint = """
Hint: There are two different possible `Result` types produced within
`main()`, which are propagated using `?` operators. How do we declare a
return type from `main()` that allows both?
Another hint: under the hood, the `?` operator calls `From::from`
on the error value to convert it to a boxed trait object, a
`Box<dyn error::Error>`, which is polymorphic-- that means that lots of
different kinds of errors can be returned from the same function because
all errors act the same since they all implement the `error::Error` trait.
Check out this section of the book:
https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors-the--operator
This exercise uses some concepts that we won't get to until later in the
course, like `Box` and the `From` trait. It's not important to understand
them in detail right now, but you can read ahead if you like.
Read more about boxing errors:
https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/boxing_errors.html
Read more about using the `?` operator with boxed errors:
https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reenter_question_mark.html
"""
[[exercises]]
name = "errors6"
path = "exercises/error_handling/errors6.rs"
mode = "test"
hint = """
This exercise uses a completed version of `PositiveNonzeroInteger` from
errors4.
Below the line that TODO asks you to change, there is an example of using
the `map_err()` method on a `Result` to transform one type of error into
another. Try using something similar on the `Result` from `parse()`. You
might use the `?` operator to return early from the function, or you might
use a `match` expression, or maybe there's another way!
You can create another function inside `impl ParsePosNonzeroError` to use
with `map_err()`.
Read more about `map_err()` in the `std::result` documentation:
https://doc.rust-lang.org/std/result/enum.Result.html#method.map_err"""
# Generics
[[exercises]]
name = "generics1"
path = "exercises/generics/generics1.rs"
mode = "compile"
hint = """
Vectors in rust make use of generics to create dynamically sized arrays of any type.
You need to tell the compiler what type we are pushing onto this vector."""
[[exercises]]
name = "generics2"
path = "exercises/generics/generics2.rs"
mode = "test"
hint = """
Currently we are wrapping only values of type 'u32'.
Maybe we could update the explicit references to this data type somehow?
If you are still stuck https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-method-definitions
"""
[[exercises]]
name = "generics3"
path = "exercises/generics/generics3.rs"
mode = "test"
hint = """
To find the best solution to this challenge you're going to need to think back to your
knowledge of traits, specifically Trait Bound Syntax -  you may also need this: "use std::fmt::Display;"
This is definitely harder than the last two exercises! You need to think about not only making the
ReportCard struct generic, but also the correct property - you will need to change the implementation
of the struct slightly too...you can do it!
"""
# OPTIONS
[[exercises]]
name = "option1"
path = "exercises/option/option1.rs"
mode = "compile"
hint = """
Hint 1: Check out some functions of Option:
is_some
is_none
unwrap
and:
pattern matching
Hint 2: There are no sensible defaults for the value of an Array; the values need to be filled before use.
"""
[[exercises]]
name = "option2"
path = "exercises/option/option2.rs"
mode = "compile"
hint = """
check out:
https://doc.rust-lang.org/rust-by-example/flow_control/if_let.html
https://doc.rust-lang.org/rust-by-example/flow_control/while_let.html
Remember that Options can be stacked in if let and while let.
For example: Some(Some(variable)) = variable2
Also see Option::flatten
"""
[[exercises]]
name = "option3"
path = "exercises/option/option3.rs"
mode = "compile"
hint = """
The compiler says a partial move happened in the `match`
statement. How can this be avoided? The compiler shows the correction
needed. After making the correction as suggested by the compiler, do
read: https://doc.rust-lang.org/std/keyword.ref.html"""
# TRAITS
[[exercises]]
name = "traits1"
path = "exercises/traits/traits1.rs"
mode = "test"
hint = """
A discussion about Traits in Rust can be found at:
https://doc.rust-lang.org/book/ch10-02-traits.html
"""
[[exercises]]
name = "traits2"
path = "exercises/traits/traits2.rs"
mode = "test"
hint = """
Notice how the trait takes ownership of 'self',and returns `Self'.
Try mutating the incoming string vector.
Vectors provide suitable methods for adding an element at the end. See
the documentation at: https://doc.rust-lang.org/std/vec/struct.Vec.html"""
# TESTS
[[exercises]]
name = "tests1"
path = "exercises/tests/tests1.rs"
mode = "test"
hint = """
You don't even need to write any code to test -- you can just test values and run that, even
though you wouldn't do that in real life :) `assert!` is a macro that needs an argument.
Depending on the value of the argument, `assert!` will do nothing (in which case the test will
pass) or `assert!` will panic (in which case the test will fail). So try giving different values
to `assert!` and see which ones compile, which ones pass, and which ones fail :)"""
[[exercises]]
name = "tests2"
path = "exercises/tests/tests2.rs"
mode = "test"
hint = """
Like the previous exercise, you don't need to write any code to get this test to compile and
run. `assert_eq!` is a macro that takes two arguments and compares them. Try giving it two
values that are equal! Try giving it two arguments that are different! Try giving it two values
that are of different types! Try switching which argument comes first and which comes second!"""
[[exercises]]
name = "tests3"
path = "exercises/tests/tests3.rs"
mode = "test"
hint = """
You can call a function right where you're passing arguments to `assert!` -- so you could do
something like `assert!(having_fun())`. If you want to check that you indeed get false, you
can negate the result of what you're doing using `!`, like `assert!(!having_fun())`."""
# TEST 3
[[exercises]]
name = "quiz3"
path = "exercises/quiz3.rs"
mode = "test"
hint = "No hints this time ;)"
# STANDARD LIBRARY TYPES
[[exercises]]
name = "box1"
path = "exercises/standard_library_types/box1.rs"
mode = "test"
hint = """
Step 1
The compiler's message should help: since we cannot store the value of the actual type
when working with recursive types, we need to store a reference (pointer) to its value.
We should, therefore, place our `List` inside a `Box`. More details in the book here:
https://doc.rust-lang.org/book/ch15-01-box.html#enabling-recursive-types-with-boxes
Step 2
Creating an empty list should be fairly straightforward (hint: peek at the assertions).
For a non-empty list keep in mind that we want to use our Cons "list builder".
Although the current list is one of integers (i32), feel free to change the definition
and try other types!
"""
[[exercises]]
name = "arc1"
path = "exercises/standard_library_types/arc1.rs"
mode = "compile"
hint = """
Make `shared_numbers` be an `Arc` from the numbers vector. Then, in order
to avoid creating a copy of `numbers`, you'll need to create `child_numbers`
inside the loop but still in the main thread.
`child_numbers` should be a clone of the Arc of the numbers instead of a
thread-local copy of the numbers.
This is a simple exercise if you understand the underlying concepts, but if this
is too much of a struggle, consider reading through all of Chapter 16 in the book:
https://doc.rust-lang.org/stable/book/ch16-00-concurrency.html
"""
[[exercises]]
name = "iterators1"
path = "exercises/standard_library_types/iterators1.rs"
mode = "compile"
hint = """
Step 1:
We need to apply something to the collection `my_fav_fruits` before we start to go through
it. What could that be? Take a look at the struct definition for a vector for inspiration:
https://doc.rust-lang.org/std/vec/struct.Vec.html.
Step 2 & step 2.1:
Very similar to the lines above and below. You've got this!
Step 3:
An iterator goes through all elements in a collection, but what if we've run out of
elements? What should we expect here? If you're stuck, take a look at
https://doc.rust-lang.org/std/iter/trait.Iterator.html for some ideas.
"""
[[exercises]]
name = "iterators2"
path = "exercises/standard_library_types/iterators2.rs"
mode = "test"
hint = """
Step 1
The variable `first` is a `char`. It needs to be capitalized and added to the
remaining characters in `c` in order to return the correct `String`.
The remaining characters in `c` can be viewed as a string slice using the
`as_str` method.
The documentation for `char` contains many useful methods.
https://doc.rust-lang.org/std/primitive.char.html
Step 2
Create an iterator from the slice. Transform the iterated values by applying
the `capitalize_first` function. Remember to collect the iterator.
Step 3.
This is surprising similar to the previous solution. Collect is very powerful
and very general. Rust just needs to know the desired type."""
[[exercises]]
name = "iterators3"
path = "exercises/standard_library_types/iterators3.rs"
mode = "test"
hint = """
The divide function needs to return the correct error when even division is not
possible.
The division_results variable needs to be collected into a collection type.
The result_with_list function needs to return a single Result where the success
case is a vector of integers and the failure case is a DivisionError.
The list_of_results function needs to return a vector of results.
See https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.collect for how 
the `FromIterator` trait is used in `collect()`."""
[[exercises]]
name = "iterators4"
path = "exercises/standard_library_types/iterators4.rs"
mode = "test"
hint = """
In an imperative language, you might write a for loop that updates
a mutable variable. Or, you might write code utilizing recursion
and a match clause. In Rust you can take another functional
approach, computing the factorial elegantly with ranges and iterators."""
[[exercises]]
name = "iterators5"
path = "exercises/standard_library_types/iterators5.rs"
mode = "test"
hint = """
The documentation for the std::iter::Iterator trait contains numerous methods
that would be helpful here.
Return 0 from count_collection_iterator to make the code compile in order to
test count_iterator.
The collection variable in count_collection_iterator is a slice of HashMaps. It
needs to be converted into an iterator in order to use the iterator methods.
The fold method can be useful in the count_collection_iterator function.
For a further challenge, consult the documentation for Iterator to find
a different method that could make your code more compact than using fold."""
# THREADS
[[exercises]]
name = "threads1"
path = "exercises/threads/threads1.rs"
mode = "compile"
hint = """
`Arc` is an Atomic Reference Counted pointer that allows safe, shared access
to **immutable** data. But we want to *change* the number of `jobs_completed`
so we'll need to also use another type that will only allow one thread to
mutate the data at a time. Take a look at this section of the book:
https://doc.rust-lang.org/book/ch16-03-shared-state.html#atomic-reference-counting-with-arct
and keep reading if you'd like more hints :)
Do you now have an `Arc` `Mutex` `JobStatus` at the beginning of main? Like:
`let status = Arc::new(Mutex::new(JobStatus { jobs_completed: 0 }));`
Similar to the code in the example in the book that happens after the text
that says "We can use Arc<T> to fix this.". If not, give that a try! If you
do and would like more hints, keep reading!!
Make sure neither of your threads are holding onto the lock of the mutex
while they are sleeping, since this will prevent the other thread from
being allowed to get the lock. Locks are automatically released when
they go out of scope.
Ok, so, real talk, this was actually tricky for *me* to do too. And
I could see a lot of different problems you might run into, so at this
point I'm not sure which one you've hit :)
Please open an issue if you're still running into a problem that
these hints are not helping you with, or if you've looked at the sample
answers and don't understand why they work and yours doesn't.
If you've learned from the sample solutions, I encourage you to come
back to this exercise and try it again in a few days to reinforce
what you've learned :)"""
# MACROS
[[exercises]]
name = "macros1"
path = "exercises/macros/macros1.rs"
mode = "compile"
hint = """
When you call a macro, you need to add something special compared to a
regular function call. If you're stuck, take a look at what's inside
`my_macro`."""
[[exercises]]
name = "macros2"
path = "exercises/macros/macros2.rs"
mode = "compile"
hint = """
Macros don't quite play by the same rules as the rest of Rust, in terms of
what's available where.
Unlike other things in Rust, the order of "where you define a macro" versus
"where you use it" actually matters."""
[[exercises]]
name = "macros3"
path = "exercises/macros/macros3.rs"
mode = "compile"
hint = """
In order to use a macro outside of its module, you need to do something
special to the module to lift the macro out into its parent.
The same trick also works on "extern crate" statements for crates that have
exported macros, if you've seen any of those around."""
[[exercises]]
name = "macros4"
path = "exercises/macros/macros4.rs"
mode = "compile"
hint = """
You only need to add a single character to make this compile.
The way macros are written, it wants to see something between each
"macro arm", so it can separate them."""
# TEST 4
[[exercises]]
name = "quiz4"
path = "exercises/quiz4.rs"
mode = "test"
hint = "No hints this time ;)"
#  CLIPPY
[[exercises]]
name = "clippy1"
path = "exercises/clippy/clippy1.rs"
mode = "clippy"
hint = """
Not every floating point value can be represented exactly in binary values in
memory. Take a look at the description of 
https://doc.rust-lang.org/stable/std/primitive.f32.html
When using the binary compare operators with floating points you won't compare
the floating point values but the binary representation in memory. This is 
usually not what you would like to do. 
See the suggestions of the clippy warning in compile output and use the
machine epsilon value...
https://doc.rust-lang.org/stable/std/primitive.f32.html#associatedconstant.EPSILON"""
[[exercises]]
name = "clippy2"
path = "exercises/clippy/clippy2.rs"
mode = "clippy"
hint = """
`for` loops over Option values are more clearly expressed as an `if let`"""
# TYPE CONVERSIONS
[[exercises]]
name = "using_as"
path = "exercises/conversions/using_as.rs"
mode = "test"
hint = """
Use the `as` operator to cast one of the operands in the last line of the
`average` function into the expected return type."""
[[exercises]]
name = "from_into"
path = "exercises/conversions/from_into.rs"
mode = "test"
hint = """
Follow the steps provided right before the `From` implementation"""
[[exercises]]
name = "try_from_into"
path = "exercises/conversions/try_from_into.rs"
mode = "test"
hint = """
Follow the steps provided right before the `TryFrom` implementation.
You can also use the example at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
You might want to look back at the exercise errors5 (or its hints) to remind
yourself about how `Box<dyn Error>` works.
If you're trying to return a string as an error, note that neither `str`
nor `String` implements `error::Error`. However, there is an implementation
of `From<&str>` for `Box<dyn Error>`. This means you can use `.into()` or
the `?` operator to convert your string into the correct error type.
If you're having trouble with using the `?` operator to convert an error string,
recall that `?` works to convert `Err(something)` into the appropriate error
type for returning from the function."""
[[exercises]]
name = "as_ref_mut"
path = "exercises/conversions/as_ref_mut.rs"
mode = "test"
hint = """
Add AsRef<str> as a trait bound to the functions."""
[[exercises]]
name = "from_str"
path = "exercises/conversions/from_str.rs"
mode = "test"
hint = """
The implementation of FromStr should return an Ok with a Person object,
or an Err with an error if the string is not valid.
This is almost like the `try_from_into` exercise.
If you're having trouble with returning the correct error type, see the
hints for try_from_into."""

// variables6.rs
// Make me compile! Execute the command `rustlings hint variables6` if you want a hint :)
// I AM NOT DONE
const NUMBER = 3;
fn main() {
    println!("Number {}", NUMBER);
}

// variables5.rs
// Make me compile! Execute the command `rustlings hint variables5` if you want a hint :)
// I AM NOT DONE
fn main() {
    let number = "T-H-R-E-E"; // don't change this line
    println!("Spell a Number : {}", number);
    number = 3;
    println!("Number plus two is : {}", number + 2);
}

// variables4.rs
// Make me compile! Execute the command `rustlings hint variables4` if you want a hint :)
// I AM NOT DONE
fn main() {
    let x: i32;
    println!("Number {}", x);
}

// variables3.rs
// Make me compile! Execute the command `rustlings hint variables3` if you want a hint :)
// I AM NOT DONE
fn main() {
    let x = 3;
    println!("Number {}", x);
    x = 5; // don't change this line
    println!("Number {}", x);
}

// variables2.rs
// Make me compile! Execute the command `rustlings hint variables2` if you want a hint :)
// I AM NOT DONE
fn main() {
    let x;
    if x == 10 {
        println!("Ten!");
    } else {
        println!("Not ten!");
    }
}

// variables1.rs
// Make me compile! Execute the command `rustlings hint variables1` if you want a hint :)
// About this `I AM NOT DONE` thing:
// We sometimes encourage you to keep trying things on a given exercise,
// even after you already figured it out. If you got everything working and
// feel ready for the next exercise, remove the `I AM NOT DONE` comment below.
// I AM NOT DONE
fn main() {
    x = 5;
    println!("x has the value {}", x);
}

# Variables
In Rust, variables are immutable by default.
When a variable is immutable, once a value is bound to a name, you can’t change that value.
You can make them mutable by adding mut in front of the variable name.
## Further information
- [Variables and Mutability](https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html)

// traits2.rs
//
// Your task is to implement the trait
// `AppendBar' for a vector of strings.
//
// To implement this trait, consider for
// a moment what it means to 'append "Bar"'
// to a vector of strings.
//
// No boiler plate code this time,
// you can do this!
// I AM NOT DONE
trait AppendBar {
    fn append_bar(self) -> Self;
}
//TODO: Add your code here
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn is_vec_pop_eq_bar() {
        let mut foo = vec![String::from("Foo")].append_bar();
        assert_eq!(foo.pop().unwrap(), String::from("Bar"));
        assert_eq!(foo.pop().unwrap(), String::from("Foo"));
    }
}

// traits1.rs
// Time to implement some traits!
//
// Your task is to implement the trait
// `AppendBar' for the type `String'.
//
// The trait AppendBar has only one function,
// which appends "Bar" to any object
// implementing this trait.
// I AM NOT DONE
trait AppendBar {
    fn append_bar(self) -> Self;
}
impl AppendBar for String {
    //Add your code here
}
fn main() {
    let s = String::from("Foo");
    let s = s.append_bar();
    println!("s: {}", s);
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn is_FooBar() {
        assert_eq!(String::from("Foo").append_bar(), String::from("FooBar"));
    }
    #[test]
    fn is_BarBar() {
        assert_eq!(
            String::from("").append_bar().append_bar(),
            String::from("BarBar")
        );
    }
}

# Traits
A trait is a collection of methods.
Data types can implement traits. To do so, the methods making up the trait are defined for the data type. For example, the `String` data type implements the `From<&str>` trait. This allows a user to write `String::from("hello")`.
In this way, traits are somewhat similar to Java interfaces and C++ abstract classes.
Some additional common Rust traits include:
- `Clone` (the `clone` method)
- `Display` (which allows formatted display via `{}`)
- `Debug` (which allows formatted display via `{:?}`)
Because traits indicate shared behavior between data types, they are useful when writing generics.
## Further information
- [Traits](https://doc.rust-lang.org/book/ch10-02-traits.html)

// threads1.rs
// Make this compile! Execute `rustlings hint threads1` for hints :)
// The idea is the thread spawned on line 22 is completing jobs while the main thread is
// monitoring progress until 10 jobs are completed. Because of the difference between the
// spawned threads' sleep time, and the waiting threads sleep time, when you see 6 lines
// of "waiting..." and the program ends without timing out when running,
// you've got it :)
// I AM NOT DONE
use std::sync::Arc;
use std::thread;
use std::time::Duration;
struct JobStatus {
    jobs_completed: u32,
}
fn main() {
    let status = Arc::new(JobStatus { jobs_completed: 0 });
    let status_shared = status.clone();
    thread::spawn(move || {
        for _ in 0..10 {
            thread::sleep(Duration::from_millis(250));
            status_shared.jobs_completed += 1;
        }
    });
    while status.jobs_completed < 10 {
        println!("waiting... ");
        thread::sleep(Duration::from_millis(500));
    }
}

# Threads
In most current operating systems, an executed program’s code is run in a process, and the operating system manages multiple processes at once.
Within your program, you can also have independent parts that run simultaneously. The features that run these independent parts are called threads.
## Further information
- [Dining Philosophers example](https://doc.rust-lang.org/1.4.0/book/dining-philosophers.html)
- [Using Threads to Run Code Simultaneously](https://doc.rust-lang.org/book/ch16-01-threads.html)

// tests3.rs
// This test isn't testing our function -- make it do that in such a way that
// the test passes. Then write a second test that tests whether we get the result
// we expect to get when we call `is_even(5)`.
// Execute `rustlings hint tests3` for hints :)
// I AM NOT DONE
pub fn is_even(num: i32) -> bool {
    num % 2 == 0
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn is_true_when_even() {
        assert!();
    }
    #[test]
    fn is_false_when_odd() {
        assert!();
    }
}

// tests2.rs
// This test has a problem with it -- make the test compile! Make the test
// pass! Make the test fail! Execute `rustlings hint tests2` for hints :)
// I AM NOT DONE
#[cfg(test)]
mod tests {
    #[test]
    fn you_can_assert_eq() {
        assert_eq!();
    }
}

// tests1.rs
// Tests are important to ensure that your code does what you think it should do.
// Tests can be run on this file with the following command:
// rustlings run tests1
// This test has a problem with it -- make the test compile! Make the test
// pass! Make the test fail! Execute `rustlings hint tests1` for hints :)
// I AM NOT DONE
#[cfg(test)]
mod tests {
    #[test]
    fn you_can_assert() {
        assert!();
    }
}

# Tests
Going out of order from the book to cover tests -- many of the following exercises will ask you to make tests pass!
## Further information
- [Writing Tests](https://doc.rust-lang.org/book/ch11-01-writing-tests.html)

// structs3.rs
// Structs contain data, but can also have logic. In this exercise we have
// defined the Package struct and we want to test some logic attached to it.
// Make the code compile and the tests pass!
// If you have issues execute `rustlings hint structs3`
// I AM NOT DONE
#[derive(Debug)]
struct Package {
    sender_country: String,
    recipient_country: String,
    weight_in_grams: i32,
}
impl Package {
    fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
        if weight_in_grams <= 0 {
            // Something goes here...
        } else {
            return Package {
                sender_country,
                recipient_country,
                weight_in_grams,
            };
        }
    }
    fn is_international(&self) -> ??? {
        // Something goes here...
    }
    fn get_fees(&self, cents_per_gram: i32) -> ??? {
        // Something goes here...
    }
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    #[should_panic]
    fn fail_creating_weightless_package() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Austria");
        Package::new(sender_country, recipient_country, -2210);
    }
    #[test]
    fn create_international_package() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Russia");
        let package = Package::new(sender_country, recipient_country, 1200);
        assert!(package.is_international());
    }
    #[test]
    fn create_local_package() {
        let sender_country = String::from("Canada");
        let recipient_country = sender_country.clone();
        let package = Package::new(sender_country, recipient_country, 1200);
        assert!(!package.is_international());
    }
    #[test]
    fn calculate_transport_fees() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Spain");
        let cents_per_gram = ???;
        let package = Package::new(sender_country, recipient_country, 1500);
        assert_eq!(package.get_fees(cents_per_gram), 4500);
    }
}

// structs2.rs
// Address all the TODOs to make the tests pass!
// I AM NOT DONE
#[derive(Debug)]
struct Order {
    name: String,
    year: u32,
    made_by_phone: bool,
    made_by_mobile: bool,
    made_by_email: bool,
    item_number: u32,
    count: u32,
}
fn create_order_template() -> Order {
    Order {
        name: String::from("Bob"),
        year: 2019,
        made_by_phone: false,
        made_by_mobile: false,
        made_by_email: true,
        item_number: 123,
        count: 0,
    }
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn your_order() {
        let order_template = create_order_template();
        // TODO: Create your own order using the update syntax and template above!
        // let your_order =
        assert_eq!(your_order.name, "Hacker in Rust");
        assert_eq!(your_order.year, order_template.year);
        assert_eq!(your_order.made_by_phone, order_template.made_by_phone);
        assert_eq!(your_order.made_by_mobile, order_template.made_by_mobile);
        assert_eq!(your_order.made_by_email, order_template.made_by_email);
        assert_eq!(your_order.item_number, order_template.item_number);
        assert_eq!(your_order.count, 1);
    }
}

// structs1.rs
// Address all the TODOs to make the tests pass!
// I AM NOT DONE
struct ColorClassicStruct {
    // TODO: Something goes here
}
struct ColorTupleStruct(/* TODO: Something goes here */);
#[derive(Debug)]
struct UnitStruct;
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn classic_c_structs() {
        // TODO: Instantiate a classic c struct!
        // let green =
        assert_eq!(green.name, "green");
        assert_eq!(green.hex, "#00FF00");
    }
    #[test]
    fn tuple_structs() {
        // TODO: Instantiate a tuple struct!
        // let green =
        assert_eq!(green.0, "green");
        assert_eq!(green.1, "#00FF00");
    }
    #[test]
    fn unit_structs() {
        // TODO: Instantiate a unit struct!
        // let unit_struct =
        let message = format!("{:?}s are fun!", unit_struct);
        assert_eq!(message, "UnitStructs are fun!");
    }
}

# Structs
Rust has three struct types: a classic C struct, a tuple struct, and a unit struct.
## Further information
- [Structures](https://doc.rust-lang.org/book/ch05-01-defining-structs.html)
- [Method Syntax](https://doc.rust-lang.org/book/ch05-03-method-syntax.html)

// strings2.rs
// Make me compile without changing the function signature!
// Execute `rustlings hint strings2` for hints :)
// I AM NOT DONE
fn main() {
    let word = String::from("green"); // Try not changing this line :)
    if is_a_color_word(word) {
        println!("That is a color word I know!");
    } else {
        println!("That is not a color word I know.");
    }
}
fn is_a_color_word(attempt: &str) -> bool {
    attempt == "green" || attempt == "blue" || attempt == "red"
}

// strings1.rs
// Make me compile without changing the function signature!
// Execute `rustlings hint strings1` for hints ;)
// I AM NOT DONE
fn main() {
    let answer = current_favorite_color();
    println!("My current favorite color is {}", answer);
}
fn current_favorite_color() -> String {
    "blue"
}

# Strings
Rust has two string types, a string slice (`&str`) and an owned string (`String`).
We're not going to dictate when you should use which one, but we'll show you how
to identify and create them, as well as use them.
## Further information
- [Strings](https://doc.rust-lang.org/book/ch08-02-strings.html)

// iterators5.rs
// Let's define a simple model to track Rustlings exercise progress. Progress
// will be modelled using a hash map. The name of the exercise is the key and
// the progress is the value. Two counting functions were created to count the
// number of exercises with a given progress. These counting functions use
// imperative style for loops. Recreate this counting functionality using
// iterators. Only the two iterator methods (count_iterator and
// count_collection_iterator) need to be modified.
// Execute `rustlings hint iterators5` for hints.
//
// Make the code compile and the tests pass.
// I AM NOT DONE
use std::collections::HashMap;
#[derive(Clone, Copy, PartialEq, Eq)]
enum Progress {
    None,
    Some,
    Complete,
}
fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
    let mut count = 0;
    for val in map.values() {
        if val == &value {
            count += 1;
        }
    }
    count
}
fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
    // map is a hashmap with String keys and Progress values.
    // map = { "variables1": Complete, "from_str": None, ... }
}
fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
    let mut count = 0;
    for map in collection {
        for val in map.values() {
            if val == &value {
                count += 1;
            }
        }
    }
    count
}
fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
    // collection is a slice of hashmaps.
    // collection = [{ "variables1": Complete, "from_str": None, ... },
    //     { "variables2": Complete, ... }, ... ]
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn count_complete() {
        let map = get_map();
        assert_eq!(3, count_iterator(&map, Progress::Complete));
    }
    #[test]
    fn count_equals_for() {
        let map = get_map();
        assert_eq!(
            count_for(&map, Progress::Complete),
            count_iterator(&map, Progress::Complete)
        );
    }
    #[test]
    fn count_collection_complete() {
        let collection = get_vec_map();
        assert_eq!(
            6,
            count_collection_iterator(&collection, Progress::Complete)
        );
    }
    #[test]
    fn count_collection_equals_for() {
        let collection = get_vec_map();
        assert_eq!(
            count_collection_for(&collection, Progress::Complete),
            count_collection_iterator(&collection, Progress::Complete)
        );
    }
    fn get_map() -> HashMap<String, Progress> {
        use Progress::*;
        let mut map = HashMap::new();
        map.insert(String::from("variables1"), Complete);
        map.insert(String::from("functions1"), Complete);
        map.insert(String::from("hashmap1"), Complete);
        map.insert(String::from("arc1"), Some);
        map.insert(String::from("as_ref_mut"), None);
        map.insert(String::from("from_str"), None);
        map
    }
    fn get_vec_map() -> Vec<HashMap<String, Progress>> {
        use Progress::*;
        let map = get_map();
        let mut other = HashMap::new();
        other.insert(String::from("variables2"), Complete);
        other.insert(String::from("functions2"), Complete);
        other.insert(String::from("if1"), Complete);
        other.insert(String::from("from_into"), None);
        other.insert(String::from("try_from_into"), None);
        vec![map, other]
    }
}

// iterators4.rs
// I AM NOT DONE
pub fn factorial(num: u64) -> u64 {
    // Complete this function to return the factorial of num
    // Do not use:
    // - return
    // Try not to use:
    // - imperative style loops (for, while)
    // - additional variables
    // For an extra challenge, don't use:
    // - recursion
    // Execute `rustlings hint iterators4` for hints.
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn factorial_of_1() {
        assert_eq!(1, factorial(1));
    }
    #[test]
    fn factorial_of_2() {
        assert_eq!(2, factorial(2));
    }
    #[test]
    fn factorial_of_4() {
        assert_eq!(24, factorial(4));
    }
}

// iterators3.rs
// This is a bigger exercise than most of the others! You can do it!
// Here is your mission, should you choose to accept it:
// 1. Complete the divide function to get the first four tests to pass.
// 2. Get the remaining tests to pass by completing the result_with_list and
//    list_of_results functions.
// Execute `rustlings hint iterators3` to get some hints!
// I AM NOT DONE
#[derive(Debug, PartialEq, Eq)]
pub enum DivisionError {
    NotDivisible(NotDivisibleError),
    DivideByZero,
}
#[derive(Debug, PartialEq, Eq)]
pub struct NotDivisibleError {
    dividend: i32,
    divisor: i32,
}
// Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
// Otherwise, return a suitable error.
pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {}
// Complete the function and return a value of the correct type so the test passes.
// Desired output: Ok([1, 11, 1426, 3])
fn result_with_list() -> () {
    let numbers = vec![27, 297, 38502, 81];
    let division_results = numbers.into_iter().map(|n| divide(n, 27));
}
// Complete the function and return a value of the correct type so the test passes.
// Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
fn list_of_results() -> () {
    let numbers = vec![27, 297, 38502, 81];
    let division_results = numbers.into_iter().map(|n| divide(n, 27));
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_success() {
        assert_eq!(divide(81, 9), Ok(9));
    }
    #[test]
    fn test_not_divisible() {
        assert_eq!(
            divide(81, 6),
            Err(DivisionError::NotDivisible(NotDivisibleError {
                dividend: 81,
                divisor: 6
            }))
        );
    }
    #[test]
    fn test_divide_by_0() {
        assert_eq!(divide(81, 0), Err(DivisionError::DivideByZero));
    }
    #[test]
    fn test_divide_0_by_something() {
        assert_eq!(divide(0, 81), Ok(0));
    }
    #[test]
    fn test_result_with_list() {
        assert_eq!(format!("{:?}", result_with_list()), "Ok([1, 11, 1426, 3])");
    }
    #[test]
    fn test_list_of_results() {
        assert_eq!(
            format!("{:?}", list_of_results()),
            "[Ok(1), Ok(11), Ok(1426), Ok(3)]"
        );
    }
}

// iterators2.rs
// In this exercise, you'll learn some of the unique advantages that iterators
// can offer. Follow the steps to complete the exercise.
// As always, there are hints if you execute `rustlings hint iterators2`!
// I AM NOT DONE
// Step 1.
// Complete the `capitalize_first` function.
// "hello" -> "Hello"
pub fn capitalize_first(input: &str) -> String {
    let mut c = input.chars();
    match c.next() {
        None => String::new(),
        Some(first) => ???,
    }
}
// Step 2.
// Apply the `capitalize_first` function to a slice of string slices.
// Return a vector of strings.
// ["hello", "world"] -> ["Hello", "World"]
pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
    vec![]
}
// Step 3.
// Apply the `capitalize_first` function again to a slice of string slices.
// Return a single string.
// ["hello", " ", "world"] -> "Hello World"
pub fn capitalize_words_string(words: &[&str]) -> String {
    String::new()
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_success() {
        assert_eq!(capitalize_first("hello"), "Hello");
    }
    #[test]
    fn test_empty() {
        assert_eq!(capitalize_first(""), "");
    }
    #[test]
    fn test_iterate_string_vec() {
        let words = vec!["hello", "world"];
        assert_eq!(capitalize_words_vector(&words), ["Hello", "World"]);
    }
    #[test]
    fn test_iterate_into_string() {
        let words = vec!["hello", " ", "world"];
        assert_eq!(capitalize_words_string(&words), "Hello World");
    }
}

// iterators1.rs
//
//  Make me compile by filling in the `???`s
//
// When performing operations on elements within a collection, iterators are essential.
// This module helps you get familiar with the structure of using an iterator and
// how to go through elements within an iterable collection.
//
// Execute `rustlings hint iterators1` for hints :D
// I AM NOT DONE
fn main () {
    let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
    let mut my_iterable_fav_fruits = ???;   // TODO: Step 1
    assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2
    assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2.1
    assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 3
}

// box1.rs
//
// At compile time, Rust needs to know how much space a type takes up. This becomes problematic
// for recursive types, where a value can have as part of itself another value of the same type.
// To get around the issue, we can use a `Box` - a smart pointer used to store data on the heap,
// which also allows us to wrap a recursive type.
//
// The recursive type we're implementing in this exercise is the `cons list` - a data structure
// frequently found in functional programming languages. Each item in a cons list contains two
// elements: the value of the current item and the next item. The last item is a value called `Nil`.
//
// Step 1: use a `Box` in the enum definition to make the code compile
// Step 2: create both empty and non-empty cons lists by replacing `unimplemented!()`
//
// Note: the tests should not be changed
//
// Execute `rustlings hint box1` for hints :)
// I AM NOT DONE
#[derive(PartialEq, Debug)]
pub enum List {
    Cons(i32, List),
    Nil,
}
fn main() {
    println!("This is an empty cons list: {:?}", create_empty_list());
    println!(
        "This is a non-empty cons list: {:?}",
        create_non_empty_list()
    );
}
pub fn create_empty_list() -> List {
    unimplemented!()
}
pub fn create_non_empty_list() -> List {
    unimplemented!()
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_create_empty_list() {
        assert_eq!(List::Nil, create_empty_list())
    }
    #[test]
    fn test_create_non_empty_list() {
        assert_ne!(create_empty_list(), create_non_empty_list())
    }
}

// arc1.rs
// In this exercise, we are given a Vec of u32 called "numbers" with values ranging
// from 0 to 99 -- [ 0, 1, 2, ..., 98, 99 ]
// We would like to use this set of numbers within 8 different threads simultaneously.
// Each thread is going to get the sum of every eighth value, with an offset.
// The first thread (offset 0), will sum 0, 8, 16, ...
// The second thread (offset 1), will sum 1, 9, 17, ...
// The third thread (offset 2), will sum 2, 10, 18, ...
// ...
// The eighth thread (offset 7), will sum 7, 15, 23, ...
// Because we are using threads, our values need to be thread-safe.  Therefore,
// we are using Arc.  We need to make a change in each of the two TODOs.
// Make this code compile by filling in a value for `shared_numbers` where the
// first TODO comment is, and create an initial binding for `child_numbers`
// where the second TODO comment is. Try not to create any copies of the `numbers` Vec!
// Execute `rustlings hint arc1` for hints :)
// I AM NOT DONE
#![forbid(unused_imports)] // Do not change this, (or the next) line.
use std::sync::Arc;
use std::thread;
fn main() {
    let numbers: Vec<_> = (0..100u32).collect();
    let shared_numbers = // TODO
    let mut joinhandles = Vec::new();
    for offset in 0..8 {
        let child_numbers = // TODO
        joinhandles.push(thread::spawn(move || {
            let mut i = offset;
            let mut sum = 0;
            while i < child_numbers.len() {
                sum += child_numbers[i];
                i += 8;
            }
            println!("Sum of offset {} is {}", offset, sum);
        }));
    }
    for handle in joinhandles.into_iter() {
        handle.join().unwrap();
    }
}

# Standard library types
This section will teach you about Box, Shared-State Concurrency and Iterators.
## Further information
- [Using Box to Point to Data on the Heap](https://doc.rust-lang.org/book/ch15-01-box.html)
- [Shared-State Concurrency](https://doc.rust-lang.org/book/ch16-03-shared-state.html)
- [Iterator](https://doc.rust-lang.org/book/ch13-02-iterators.html)
- [Iterator documentation](https://doc.rust-lang.org/stable/std/iter/)

// quiz4.rs
// This quiz covers the sections:
// - Modules
// - Macros
// Write a macro that passes the quiz! No hints this time, you can do it!
// I AM NOT DONE
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_my_macro_world() {
        assert_eq!(my_macro!("world!"), "Hello world!");
    }
    #[test]
    fn test_my_macro_goodbye() {
        assert_eq!(my_macro!("goodbye!"), "Hello goodbye!");
    }
}

// quiz3.rs
// This is a quiz for the following sections:
// - Tests
// This quiz isn't testing our function -- make it do that in such a way that
// the test passes. Then write a second test that tests that we get the result
// we expect to get when we call `times_two` with a negative number.
// No hints, you can do this :)
// I AM NOT DONE
pub fn times_two(num: i32) -> i32 {
    num * 2
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn returns_twice_of_positive_numbers() {
        assert_eq!(times_two(4), ???);
    }
    #[test]
    fn returns_twice_of_negative_numbers() {
        // TODO replace unimplemented!() with an assert for `times_two(-4)`
        unimplemented!()
    }
}

// quiz2.rs
// This is a quiz for the following sections:
// - Strings
// Ok, here are a bunch of values-- some are `String`s, some are `&str`s. Your
// task is to call one of these two functions on each value depending on what
// you think each value is. That is, add either `string_slice` or `string`
// before the parentheses on each line. If you're right, it will compile!
// I AM NOT DONE
fn string_slice(arg: &str) {
    println!("{}", arg);
}
fn string(arg: String) {
    println!("{}", arg);
}
fn main() {
    ???("blue");
    ???("red".to_string());
    ???(String::from("hi"));
    ???("rust is fun!".to_owned());
    ???("nice weather".into());
    ???(format!("Interpolation {}", "Station"));
    ???(&String::from("abc")[0..1]);
    ???("  hello there ".trim());
    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
}

// quiz1.rs
// This is a quiz for the following sections:
// - Variables
// - Functions
// Mary is buying apples. One apple usually costs 2 Rustbucks, but if you buy
// more than 40 at once, each apple only costs 1! Write a function that calculates
// the price of an order of apples given the quantity bought. No hints this time!
// I AM NOT DONE
// Put your function here!
// fn ..... {
// Don't modify this function!
#[test]
fn verify_test() {
    let price1 = calculate_apple_price(35);
    let price2 = calculate_apple_price(40);
    let price3 = calculate_apple_price(65);
    assert_eq!(70, price1);
    assert_eq!(80, price2);
    assert_eq!(65, price3);
}

// primitive_types6.rs
// Use a tuple index to access the second element of `numbers`.
// You can put the expression for the second element where ??? is so that the test passes.
// Execute `rustlings hint primitive_types6` for hints!
// I AM NOT DONE
#[test]
fn indexing_tuple() {
    let numbers = (1, 2, 3);
    // Replace below ??? with the tuple indexing syntax.
    let second = ???;
    assert_eq!(2, second,
        "This is not the 2nd number in the tuple!")
}

// primitive_types5.rs
// Destructure the `cat` tuple so that the println will work.
// Execute `rustlings hint primitive_types5` for hints!
// I AM NOT DONE
fn main() {
    let cat = ("Furry McFurson", 3.5);
    let /* your pattern here */ = cat;
    println!("{} is {} years old.", name, age);
}

// primitive_types4.rs
// Get a slice out of Array a where the ??? is so that the test passes.
// Execute `rustlings hint primitive_types4` for hints!!
// I AM NOT DONE
#[test]
fn slice_out_of_array() {
    let a = [1, 2, 3, 4, 5];
    let nice_slice = ???
    assert_eq!([2, 3, 4], nice_slice)
}

// primitive_types3.rs
// Create an array with at least 100 elements in it where the ??? is.
// Execute `rustlings hint primitive_types3` for hints!
// I AM NOT DONE
fn main() {
    let a = ???
    if a.len() >= 100 {
        println!("Wow, that's a big array!");
    } else {
        println!("Meh, I eat arrays like that for breakfast.");
    }
}

// primitive_types2.rs
// Fill in the rest of the line that has code missing!
// No hints, there's no tricks, just get used to typing these :)
// I AM NOT DONE
fn main() {
    // Characters (`char`)
    let my_first_initial = 'C';
    if my_first_initial.is_alphabetic() {
        println!("Alphabetical!");
    } else if my_first_initial.is_numeric() {
        println!("Numerical!");
    } else {
        println!("Neither alphabetic nor numeric!");
    }
    let // Finish this line like the example! What's your favorite character?
    // Try a letter, try a number, try a special character, try a character
    // from a different language than your own, try an emoji!
    if your_character.is_alphabetic() {
        println!("Alphabetical!");
    } else if your_character.is_numeric() {
        println!("Numerical!");
    } else {
        println!("Neither alphabetic nor numeric!");
    }
}

// primitive_types1.rs
// Fill in the rest of the line that has code missing!
// No hints, there's no tricks, just get used to typing these :)
// I AM NOT DONE
fn main() {
    // Booleans (`bool`)
    let is_morning = true;
    if is_morning {
        println!("Good morning!");
    }
    let // Finish the rest of this line like the example! Or make it be false!
    if is_evening {
        println!("Good evening!");
    }
}

# Primitive Types
Rust has a couple of basic types that are directly implemented into the
compiler. In this section, we'll go through the most important ones.
## Further information
- [Data Types](https://doc.rust-lang.org/stable/book/ch03-02-data-types.html)
- [The Slice Type](https://doc.rust-lang.org/stable/book/ch04-03-slices.html)

// option3.rs
// Make me compile! Execute `rustlings hint option3` for hints
// I AM NOT DONE
struct Point {
    x: i32,
    y: i32,
}
fn main() {
    let y: Option<Point> = Some(Point { x: 100, y: 200 });
    match y {
        Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y),
        _ => println!("no match"),
    }
    y; // Fix without deleting this line.
}

// option2.rs
// Make me compile! Execute `rustlings hint option2` for hints
// I AM NOT DONE
fn main() {
    let optional_word = Some(String::from("rustlings"));
    // TODO: Make this an if let statement whose value is "Some" type
    word = optional_word {
        println!("The word is: {}", word);
    } else {
        println!("The optional word doesn't contain anything");
    }
    let mut optional_integers_vec: Vec<Option<i8>> = Vec::new();
    for x in 1..10 {
        optional_integers_vec.push(Some(x));
    }
    // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>
    // You can stack `Option<T>`'s into while let and if let
    integer = optional_integers_vec.pop() {
        println!("current value: {}", integer);
    }
}

// option1.rs
// Make me compile! Execute `rustlings hint option1` for hints
// I AM NOT DONE
// you can modify anything EXCEPT for this function's sig
fn print_number(maybe_number: Option<u16>) {
    println!("printing: {}", maybe_number.unwrap());
}
fn main() {
    print_number(13);
    print_number(99);
    let mut numbers: [Option<u16>; 5];
    for iter in 0..5 {
        let number_to_add: u16 = {
            ((iter * 1235) + 2) / (4 * 16)
        };
        numbers[iter as usize] = number_to_add;
    }
}

# Option
Type Option represents an optional value: every Option is either Some and contains a value, or None, and does not. 
Option types are very common in Rust code, as they have a number of uses:
- Initial values
- Return values for functions that are not defined over their entire input range (partial functions)
- Return value for otherwise reporting simple errors, where None is returned on error
- Optional struct fields
- Struct fields that can be loaned or "taken"
- Optional function arguments
- Nullable pointers
- Swapping things out of difficult situations
## Further Information
- [Option Enum Format](https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-enum-definitions)
- [Option Module Documentation](https://doc.rust-lang.org/std/option/)
- [Option Enum Documentation](https://doc.rust-lang.org/std/option/enum.Option.html)

// move_semantics5.rs
// Make me compile without adding, removing, or changing any of the
// lines in `main()`.
// Execute `rustlings hint move_semantics5` for hints :)
// I AM NOT DONE
fn main() {
    let mut x = 100;
    let y = &mut x;
    let z = &mut *y;
    *y += 100;
    *z += 1000;
    assert_eq!(x, 1200);
}

// move_semantics4.rs
// Refactor this code so that instead of having `vec0` and creating the vector
// in `fn main`, we create it within `fn fill_vec` and transfer the
// freshly created vector from fill_vec to its caller.
// Execute `rustlings hint move_semantics4` for hints!
// I AM NOT DONE
fn main() {
    let vec0 = Vec::new();
    let mut vec1 = fill_vec(vec0);
    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
    vec1.push(88);
    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}
// `fill_vec()` no longer takes `vec: Vec<i32>` as argument
fn fill_vec() -> Vec<i32> {
    let mut vec = vec;
    vec.push(22);
    vec.push(44);
    vec.push(66);
    vec
}

// move_semantics3.rs
// Make me compile without adding new lines-- just changing existing lines!
// (no lines with multiple semicolons necessary!)
// Execute `rustlings hint move_semantics3` for hints :)
// I AM NOT DONE
fn main() {
    let vec0 = Vec::new();
    let mut vec1 = fill_vec(vec0);
    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
    vec1.push(88);
    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}
fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
    vec.push(22);
    vec.push(44);
    vec.push(66);
    vec
}

// move_semantics2.rs
// Make me compile without changing line 13!
// Execute `rustlings hint move_semantics2` for hints :)
// I AM NOT DONE
fn main() {
    let vec0 = Vec::new();
    let mut vec1 = fill_vec(vec0);
    // Do not change the following line!
    println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
    vec1.push(88);
    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}
fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
    let mut vec = vec;
    vec.push(22);
    vec.push(44);
    vec.push(66);
    vec
}

// move_semantics1.rs
// Make me compile! Execute `rustlings hint move_semantics1` for hints :)
// I AM NOT DONE
fn main() {
    let vec0 = Vec::new();
    let vec1 = fill_vec(vec0);
    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
    vec1.push(88);
    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}
fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
    let mut vec = vec;
    vec.push(22);
    vec.push(44);
    vec.push(66);
    vec
}

# Move Semantics
These exercises are adapted from [pnkfelix](https://github.com/pnkfelix)'s [Rust Tutorial](https://pnkfelix.github.io/rust-examples-icfp2014/) -- Thank you Felix!!!
## Further information
For this section, the book links are especially important.
- [Ownership](https://doc.rust-lang.org/book/ch04-01-what-is-ownership.html)
- [Reference and borrowing](https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html)