r3bl_rs_utils

This library provides utility functions:

1. Thread safe asynchronous Redux library (uses tokio to run subscribers and middleware in parallel). The reducer functions are run single threaded.
2. Functions to unwrap deeply nested objects inspired by Kotlin scope functions.
3. Non binary tree data structure inspired by memory arenas, that is thread safe and supports parallel tree walking.
4. Capabilities to make it easier to build TUIs (Text User Interface apps) in Rust.
5. And more.

💡 To learn more about this library, please read how it was built on developerlife.com.

• You can also read all the Rust content on developerlife.com here.
• The equivalent of this library is available for TypeScript and is called r3bl-ts-utils.

Usage

Please add the following to your Cargo.toml file:

[dependencies]
r3bl_rs_utils = "0.6.7"

redux

Store is a thread safe asynchronous Redux library that uses tokio to run subscribers and middleware in parallel. The reducer functions are run single threaded. Here's an example of how to use it. Let's say we have the following action enum, and state struct.

/// Action enum.
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub enum Action {
  Add(i32, i32),
  AddPop(i32),
  Clear,
  MiddlewareCreateClearAction,
}

/// State.
#[derive(Clone, Default, PartialEq, Debug, Hash)]
pub struct State {
  pub stack: Vec<i32>,
}

Here's an example of the reducer function.

// Reducer function (pure).
let reducer_fn = |state: &State, action: &Action| match action {
  Action::Add(a, b) => {
    let sum = a + b;
    State { stack: vec![sum] }
  }
  Action::AddPop(a) => {
    let sum = a + state.stack[0];
    State { stack: vec![sum] }
  }
  Action::Clear => State { stack: vec![] },
  _ => state.clone(),
};

Here's an example of an async subscriber function (which are run in parallel after an action is dispatched). The following example uses a lambda that captures a shared object. This is a pretty common pattern that you might encounter when creating subscribers that share state in your enclosing block or scope.

// This shared object is used to collect results from the subscriber function & test it later.
let shared_object = Arc::new(Mutex::new(Vec::<i32>::new()));
// This subscriber function is curried to capture a reference to the shared object.
let subscriber_fn = with(shared_object.clone(), |it| {
  let curried_fn = move |state: State| {
    let mut stack = it.lock().unwrap();
    stack.push(state.stack[0]);
  };
  curried_fn
});

Here are two types of async middleware functions. One that returns an action (which will get dispatched once this middleware returns), and another that doesn't return anything (like a logger middleware that just dumps the current action to the console). Note that both these functions share the shared_object reference from above.

// This middleware function is curried to capture a reference to the shared object.
let mw_returns_none = with(shared_object.clone(), |it| {
  let curried_fn = move |action: Action| {
    let mut stack = it.lock().unwrap();
    match action {
      Action::Add(_, _) => stack.push(-1),
      Action::AddPop(_) => stack.push(-2),
      Action::Clear => stack.push(-3),
      _ => {}
    }
    None
  };
  curried_fn
});

// This middleware function is curried to capture a reference to the shared object.
let mw_returns_action = with(shared_object.clone(), |it| {
  let curried_fn = move |action: Action| {
    let mut stack = it.lock().unwrap();
    match action {
      Action::MiddlewareCreateClearAction => stack.push(-4),
      _ => {}
    }
    Some(Action::Clear)
  };
  curried_fn
});

Here's how you can setup a store with the above reducer, middleware, and subscriber functions.

// Setup store.
let mut store = Store::<State, Action>::new();
store
  .add_reducer(ReducerFnWrapper::new(reducer_fn))
  .await
  .add_subscriber(SafeSubscriberFnWrapper::new(subscriber_fn))
  .await
  .add_middleware(SafeMiddlewareFnWrapper::new(mw_returns_none))
  .await;

Finally here's an example of how to dispatch an action in a test. You can dispatch actions asynchronously using dispatch_spawn() which is "fire and forget" meaning that the caller won't block or wait for the dispatch_spawn() to return. Then you can dispatch actions synchronously if that's what you would like using dispatch().

// Test reducer and subscriber by dispatching Add and AddPop actions asynchronously.
store.dispatch_spawn(Action::Add(10, 10)).await;
store.dispatch(&Action::Add(1, 2)).await;
assert_eq!(shared_object.lock().unwrap().pop(), Some(3));
store.dispatch(&Action::AddPop(1)).await;
assert_eq!(shared_object.lock().unwrap().pop(), Some(21));
store.clear_subscribers().await;

// Test async middleware: mw_returns_action.
shared_object.lock().unwrap().clear();
store
  .add_middleware(SafeMiddlewareFnWrapper::new(mw_returns_action))
  .dispatch(&Action::MiddlewareCreateClearAction)
  .await;
assert_eq!(store.get_state().stack.len(), 0);
assert_eq!(shared_object.lock().unwrap().pop(), Some(-4));

tree_memory_arena (non-binary tree data structure)

[Arena] and [MTArena] types are the implementation of a non-binary tree data structure that is inspired by memory arenas.

Here's a simple example of how to use the [Arena] type:

use r3bl_rs_utils::{
  tree_memory_arena::{Arena, HasId, MTArena, ResultUidList},
  utils::{style_primary, style_prompt},
};

let mut arena = Arena::<usize>::new();
let node_1_value = 42 as usize;
let node_1_id = arena.add_new_node(node_1_value, None);
println!("{} {:#?}", style_primary("node_1_id"), node_1_id);
assert_eq!(node_1_id, 0);

Here's how you get weak and strong references from the arena (tree), and tree walk:

use r3bl_rs_utils::{
  tree_memory_arena::{Arena, HasId, MTArena, ResultUidList},
  utils::{style_primary, style_prompt},
};

let mut arena = Arena::<usize>::new();
let node_1_value = 42 as usize;
let node_1_id = arena.add_new_node(node_1_value, None);

{
  assert!(arena.get_node_arc(&node_1_id).is_some());
  let node_1_ref = dbg!(arena.get_node_arc(&node_1_id).unwrap());
  let node_1_ref_weak = arena.get_node_arc_weak(&node_1_id).unwrap();
  assert_eq!(node_1_ref.read().unwrap().payload, node_1_value);
  assert_eq!(
    node_1_ref_weak.upgrade().unwrap().read().unwrap().payload,
    42
  );
}

{
  let node_id_dne = 200 as usize;
  assert!(arena.get_node_arc(&node_id_dne).is_none());
}

{
  let node_1_id = 0 as usize;
  let node_list = dbg!(arena.tree_walk_dfs(&node_1_id).unwrap());
  assert_eq!(node_list.len(), 1);
  assert_eq!(node_list, vec![0]);
}

Here's an example of how to use the [MTArena] type:

use std::{
  sync::Arc,
  thread::{self, JoinHandle},
};

use r3bl_rs_utils::{
  tree_memory_arena::{Arena, HasId, MTArena, ResultUidList},
  utils::{style_primary, style_prompt},
};

type ThreadResult = Vec<usize>;
type Handles = Vec<JoinHandle<ThreadResult>>;

let mut handles: Handles = Vec::new();
let arena = MTArena::<String>::new();

// Thread 1 - add root. Spawn and wait (since the 2 threads below need the root).
{
  let arena_arc = arena.get_arena_arc();
  let thread = thread::spawn(move || {
    let mut arena_write = arena_arc.write().unwrap();
    let root = arena_write.add_new_node("foo".to_string(), None);
    vec![root]
  });
  thread.join().unwrap();
}

// Perform tree walking in parallel. Note the lambda does capture many enclosing variable context.
{
  let arena_arc = arena.get_arena_arc();
  let fn_arc = Arc::new(move |uid, payload| {
    println!(
      "{} {} {} Arena weak_count:{} strong_count:{}",
      style_primary("walker_fn - closure"),
      uid,
      payload,
      Arc::weak_count(&arena_arc),
      Arc::weak_count(&arena_arc)
    );
  });

  // Walk tree w/ a new thread using arc to lambda.
  {
    let thread_handle: JoinHandle<ResultUidList> =
      arena.tree_walk_parallel(&0, fn_arc.clone());

    let result_node_list = thread_handle.join().unwrap();
    println!("{:#?}", result_node_list);
  }

  // Walk tree w/ a new thread using arc to lambda.
  {
    let thread_handle: JoinHandle<ResultUidList> =
      arena.tree_walk_parallel(&1, fn_arc.clone());

    let result_node_list = thread_handle.join().unwrap();
    println!("{:#?}", result_node_list);
  }
}

📜 There are more complex ways of using [Arena] and [MTArena]. Please look at these extensive integration tests that put them thru their paces here.

utils

LazyMemoValues

This struct allows users to create a lazy hash map. A function must be provided that computes the values when they are first requested. These values are cached for the lifetime this struct. Here's an example.

use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
use r3bl_rs_utils::utils::LazyMemoValues;

// These are copied in the closure below.
let arc_atomic_count = AtomicUsize::new(0);
let mut a_variable = 123;
let mut a_flag = false;

let mut generate_value_fn = LazyMemoValues::new(|it| {
  arc_atomic_count.fetch_add(1, SeqCst);
  a_variable = 12;
  a_flag = true;
  a_variable + it
});

assert_eq!(arc_atomic_count.load(SeqCst), 0);
assert_eq!(generate_value_fn.get_ref(&1), &13);
assert_eq!(arc_atomic_count.load(SeqCst), 1);
assert_eq!(generate_value_fn.get_ref(&1), &13); // Won't regenerate the value.
assert_eq!(arc_atomic_count.load(SeqCst), 1); // Doesn't change.

tty

This module contains a set of functions to make it easier to work with terminals.

The following is an example of how to use is_stdin_piped():

fn run(args: Vec<String>) -> Result<(), Box<dyn Error>> {
  match is_stdin_piped() {
    true => piped_grep(PipedGrepOptionsBuilder::parse(args)?)?,
    false => grep(GrepOptionsBuilder::parse(args)?)?,
  }
  Ok(())
}

The following is an example of how to use readline():

use r3bl_rs_utils::utils::{
  print_header, readline, style_dimmed, style_error, style_primary, style_prompt,
};

fn make_a_guess() -> String {
  println!("{}", Blue.paint("Please input your guess."));
  let (bytes_read, guess) = readline();
  println!(
    "{} {}, {} {}",
    style_dimmed("#bytes read:"),
    style_primary(&bytes_read.to_string()),
    style_dimmed("You guessed:"),
    style_primary(&guess)
  );
  guess
}

Here's a list of functions available in this module:

• readline_with_prompt()
• print_prompt()
• readline()
• is_tty()
• is_stdout_piped()
• is_stdin_piped()

safe_unwrap

Functions that make it easy to unwrap a value safely. These functions are provided to improve the ergonomics of using wrapped values in Rust. Examples of wrapped values are <Arc<RwLock<T>>, and <Option>. These functions are inspired by Kotlin scope functions & TypeScript expression based language library which can be found here on r3bl-ts-utils.

Here are some examples.

use r3bl_rs_utils::utils::{
  call_if_some, unwrap_arc_read_lock_and_call, unwrap_arc_write_lock_and_call, with_mut,
};
use r3bl_rs_utils::utils::{ReadGuarded, WriteGuarded};
use r3bl_rs_utils::{
  arena_types::HasId, ArenaMap, FilterFn, NodeRef, ResultUidList, WeakNodeRef,
};

if let Some(parent_id) = parent_id_opt {
  let parent_node_arc_opt = self.get_node_arc(parent_id);
  call_if_some(&parent_node_arc_opt, &|parent_node_arc| {
    unwrap_arc_write_lock_and_call(&parent_node_arc, &mut |parent_node| {
      parent_node.children.push(new_node_id);
    });
  });
}

Here's a list of functions that are provided:

• call_if_some()
• call_if_none()
• call_if_ok()
• call_if_err()
• with()
• with_mut()
• unwrap_arc_write_lock_and_call()
• unwrap_arc_read_lock_and_call()

Here's a list of type aliases provided for better readability:

• ReadGuarded<T>
• WriteGuarded<T>

color_text

ANSI colorized text https://github.com/ogham/rust-ansi-term helper methods. Here's an example.

use r3bl_rs_utils::utils::{
  print_header, readline, style_dimmed, style_error, style_primary, style_prompt,
};

fn make_a_guess() -> String {
  println!("{}", Blue.paint("Please input your guess."));
  let (bytes_read, guess) = readline();
  println!(
    "{} {}, {} {}",
    style_dimmed("#bytes read:"),
    style_primary(&bytes_read.to_string()),
    style_dimmed("You guessed:"),
    style_primary(&guess)
  );
  guess
}

Here's a list of functions available in this module:

• print_header()
• style_prompt()
• style_primary()
• style_dimmed()
• style_error()

tui (experimental)

🚧 WIP - This is an experimental module that isn’t ready yet. It is the first step towards creating a TUI library that can be used to create sophisticated TUI applications. This is similar to Ink library for Node.js & TypeScript (that uses React and Yoga). Or kinda like tui built atop crossterm (and not termion).

Stability

🧑‍🔬 This library is in early development.

1. There are extensive integration tests for code that is production ready.
2. Everything else is marked experimental in the source.

Please report any issues to the issue tracker. And if you have any feature requests, feel free to add them there too 👍.