# rb_tree
This crate contains an implementation of the Red Black tree data structure and several data structures that are built on top of this implementation. The data structures currently include RBTree, RBMap, and RBQueue

### RBTree
This data structure can be used as a set and has methods to support its use as a set. Methods specific to this data structure include set operations such as union, difference etc. Values are stored in their `PartialOrd` ordering.

### RBMap
This data structure provides an interface for using the RBTree as a map. Values in the map are ordered by their keys' `PartialOrd` ordering.

### RBQueue
This data structure allows the use of the underlying Red-Black tree as a priority queue. A comparison function is provided on instantiation (either with `RBQueue::new(Fn(&T, &T) -> std::cmp::Ordering)` or `rbqueue_c_new!(Fn(&T, &T) -> i8)`) which is used to order the entries.

Examples:
```
use rb_tree::RBTree;

// uses an rbtree to sort data
fn sort<T: PartialOrd>(to_order: Vec<T>) -> Vec<T> {
    let mut tree = RBTree::new();
    let mut ordered = Vec::new();
    for v in to_order {
        tree.insert(v);
    }
    while let Some(v) = tree.pop() {
        ordered.push(v);
    }
    ordered
}

fn main() {
    let eg1 = vec!(3, 6, 1, 2, 0, 4, -1, 5, 10, 11, -13);
    assert_eq!(sort(eg1), vec!(-13, -1, 0, 1, 2, 3, 4, 5, 6, 10, 11));

    let eg2 = vec!("Is", "this", "the", "real", "life");
    assert_eq!(sort(eg2), vec!("Is", "life", "real", "the", "this"))
}
```

```
use rb_tree::RBMap;

fn main() {
    let mut squares = RBMap::new();
    for i in 0..10 {
        squares.insert(i, i);
    }

    squares.values_mut().for_each(|v| *v = (*v as f64).powi(2) as u32);

    for i in 0..10 {
        assert_eq!(*squares.get(&i).unwrap(), (i as f64).powi(2) as u32);
    }
}
```

```
#[macro_use(rbqueue_c_new)]
extern crate rb_tree;

use rb_tree::RBQueue;

fn main() {
    
    // use the default comarator
    let mut q1 = RBQueue::new(|l: &i64, r| {
        l.cmp(r)
    });

    // compare in the reverse order
    let mut q2 = rbqueue_c_new!(|l: &i64, r| (r - l));

    q1.insert(1);
    q1.insert(2);
    q1.insert(3);
    q2.insert(1);
    q2.insert(2);
    q2.insert(3);

    assert_eq!(q1.ordered(), [&1, &2, &3]);
    assert_eq!(q2.ordered(), [&3, &2, &1]);
}
```