gridit 0.1.0

2D grid library utilizing the fun of iterators
Documentation 
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use super::{Positions, PositionsEnumerator};

pub struct GridIter<'a, T> {
    pub(crate) grid_iter: std::slice::Iter<'a, T>,
    pub(crate) width: usize,
}

impl<'a, T> Iterator for GridIter<'a, T> {
    type Item = &'a T;
    fn next(&mut self) -> Option<Self::Item> {
        self.grid_iter.next()
    }
}

impl<'a, T: 'static> PositionsEnumerator for GridIter<'a, T> {
    fn grid_positions(self) -> Positions<GridIter<'a, T>> {
        Positions {
            inner: self,
            prev_position: None,
            next_pos: |inner, prev_pos| {
                let (px, py) = match prev_pos {
                    Some(xy) => xy.into(),
                    None => return (0, 0).into(),
                };
                let (x, y) = match px == (inner.width - 1) {
                    true => (0, py + 1),   // go one row down and reset x to 0
                    false => (px + 1, py), // keep moving x forward
                };
                (x, y).into()
            },
        }
    }
}

pub struct GridIterMut<'a, T> {
    pub(crate) grid_iter: std::slice::IterMut<'a, T>,
    pub(crate) width: usize,
}

impl<'a, T> Iterator for GridIterMut<'a, T> {
    type Item = &'a mut T;
    fn next(&mut self) -> Option<Self::Item> {
        self.grid_iter.next()
    }
}

impl<'a, T: 'static> PositionsEnumerator for GridIterMut<'a, T> {
    fn grid_positions(self) -> Positions<Self> {
        Positions {
            inner: self,
            prev_position: None,
            next_pos: |inner, prev_pos| {
                let (px, py) = match prev_pos {
                    Some(xy) => xy.into(),
                    None => return (0, 0).into(),
                };
                let (x, y) = match px == (inner.width - 1) {
                    true => (0, py + 1),   // go one row down and reset x to 0
                    false => (px + 1, py), // keep moving x forward
                };
                (x, y).into()
            },
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::Grid;

    #[test]
    fn grid_iter() {
        let grid = Grid {
            width: 3,
            height: 1,
            items: vec![0, 1, 2],
        };
        let mut grid_iter = grid.iter();
        assert_eq!(grid_iter.next(), Some(&0));
        assert_eq!(grid_iter.next(), Some(&1));
        assert_eq!(grid_iter.next(), Some(&2));
        assert_eq!(grid_iter.next(), None);
    }

    #[test]
    fn grid_iter_positions() {
        let grid = Grid::new(2, 2, 9usize);
        let mut iter = grid.iter().grid_positions();

        assert_eq!(iter.next(), Some(((0, 0).into(), &9)));
        assert_eq!(iter.next(), Some(((1, 0).into(), &9)));
        assert_eq!(iter.next(), Some(((0, 1).into(), &9)));
        assert_eq!(iter.next(), Some(((1, 1).into(), &9)));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn grid_iter_mut() {
        let mut grid = Grid {
            width: 3,
            height: 1,
            items: vec![0, 1, 2],
        };

        let mut grid_iter = grid.iter_mut();
        assert_eq!(grid_iter.next(), Some(&mut 0));
        assert_eq!(grid_iter.next(), Some(&mut 1));
        assert_eq!(grid_iter.next(), Some(&mut 2));
        assert_eq!(grid_iter.next(), None);
    }

    #[test]
    fn grid_iter_mut_positions() {
        let mut grid = Grid::new(2, 2, 9usize);
        let mut iter = grid.iter_mut().grid_positions();

        assert_eq!(iter.next(), Some(((0, 0).into(), &mut 9)));
        assert_eq!(iter.next(), Some(((1, 0).into(), &mut 9)));
        assert_eq!(iter.next(), Some(((0, 1).into(), &mut 9)));
        assert_eq!(iter.next(), Some(((1, 1).into(), &mut 9)));
        assert_eq!(iter.next(), None);
    }
}