matreex 0.42.7

A simple matrix implementation.
Documentation 
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//! Matrix shape representations.

use crate::error::{Error, Result};

#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

/// A struct representing the shape of a matrix.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Debug, Clone, Copy, Default, Hash, PartialEq, Eq)]
pub struct Shape {
    /// The number of rows.
    pub nrows: usize,

    /// The number of columns.
    pub ncols: usize,
}

impl Shape {
    /// Creates a new [`Shape`].
    ///
    /// # Examples
    ///
    /// ```
    /// use matreex::Shape;
    ///
    /// let shape = Shape::new(2, 3);
    /// assert_eq!(shape.nrows, 2);
    /// assert_eq!(shape.ncols, 3);
    /// ```
    #[inline]
    pub fn new(nrows: usize, ncols: usize) -> Self {
        Self { nrows, ncols }
    }

    /// Returns the size.
    ///
    /// # Errors
    ///
    /// - [`Error::SizeOverflow`] if the size exceeds [`usize::MAX`].
    ///
    /// # Examples
    ///
    /// ```
    /// use matreex::{Error, Shape};
    ///
    /// let shape = Shape::new(2, 3);
    /// assert_eq!(shape.size(), Ok(6));
    ///
    /// let shape = Shape::new(2, usize::MAX);
    /// assert_eq!(shape.size(), Err(Error::SizeOverflow));
    /// ```
    #[inline]
    pub fn size(&self) -> Result<usize> {
        AsShape::size(self)
    }

    /// Swaps the numbers of rows and columns.
    ///
    /// # Examples
    ///
    /// ```
    /// use matreex::Shape;
    ///
    /// let mut shape = Shape::new(2, 3);
    /// shape.swap();
    /// assert_eq!(shape, Shape::new(3, 2));
    /// ```
    #[inline]
    pub fn swap(&mut self) -> &mut Self {
        (self.nrows, self.ncols) = (self.ncols, self.nrows);
        self
    }
}

impl From<(usize, usize)> for Shape {
    #[inline]
    fn from(value: (usize, usize)) -> Self {
        let (nrows, ncols) = value;
        Self { nrows, ncols }
    }
}

impl From<[usize; 2]> for Shape {
    #[inline]
    fn from(value: [usize; 2]) -> Self {
        let [nrows, ncols] = value;
        Self { nrows, ncols }
    }
}

/// A trait representing the shape of a matrix.
///
/// # Examples
///
/// ```
/// use matreex::{Matrix, matrix};
/// use matreex::shape::AsShape;
///
/// struct S(usize, usize);
///
/// impl AsShape for S {
///     fn nrows(&self) -> usize {
///         self.0
///     }
///
///     fn ncols(&self) -> usize {
///         self.1
///     }
/// }
///
/// let result = Matrix::from_value(S(2, 3), 0);
/// assert_eq!(result, Ok(matrix![[0, 0, 0], [0, 0, 0]]));
/// ```
pub trait AsShape {
    /// Returns the number of rows.
    fn nrows(&self) -> usize;

    /// Returns the number of columns.
    fn ncols(&self) -> usize;

    /// Returns the size.
    ///
    /// # Errors
    ///
    /// - [`Error::SizeOverflow`] if the size exceeds [`usize::MAX`].
    ///
    /// # Notes
    ///
    /// Overriding the default implementation is not recommended.
    #[inline]
    fn size(&self) -> Result<usize> {
        self.nrows()
            .checked_mul(self.ncols())
            .ok_or(Error::SizeOverflow)
    }
}

impl AsShape for Shape {
    #[inline]
    fn nrows(&self) -> usize {
        self.nrows
    }

    #[inline]
    fn ncols(&self) -> usize {
        self.ncols
    }
}

impl AsShape for (usize, usize) {
    #[inline]
    fn nrows(&self) -> usize {
        self.0
    }

    #[inline]
    fn ncols(&self) -> usize {
        self.1
    }
}

impl AsShape for [usize; 2] {
    #[inline]
    fn nrows(&self) -> usize {
        self[0]
    }

    #[inline]
    fn ncols(&self) -> usize {
        self[1]
    }
}

impl<S> AsShape for &S
where
    S: AsShape,
{
    #[inline]
    fn nrows(&self) -> usize {
        (*self).nrows()
    }

    #[inline]
    fn ncols(&self) -> usize {
        (*self).ncols()
    }
}

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

    #[test]
    fn test_shape_new() {
        let shape = Shape::new(2, 3);
        assert_eq!(shape, Shape { nrows: 2, ncols: 3 });

        let shape: Shape = Shape::new(3, 2);
        assert_eq!(shape, Shape { nrows: 3, ncols: 2 });
    }

    #[test]
    fn test_shape_size() {
        let shape = Shape::new(2, 3);
        assert_eq!(shape.size(), Ok(6));

        let shape = Shape::new(2, usize::MAX);
        assert_eq!(shape.size(), Err(Error::SizeOverflow));

        let shape = Shape::new(usize::MAX, 3);
        assert_eq!(shape.size(), Err(Error::SizeOverflow));
    }

    #[test]
    fn test_shape_swap() {
        let mut shape = Shape::new(2, 3);
        shape.swap();
        assert_eq!(shape, Shape::new(3, 2));

        let mut shape = Shape::new(3, 2);
        shape.swap();
        assert_eq!(shape, Shape::new(2, 3));
    }

    #[test]
    fn test_as_shape_nrows() {
        let shape = Shape::new(2, 3);
        assert_eq!(AsShape::nrows(&shape), 2);

        let shape = Shape::new(3, 2);
        assert_eq!(AsShape::nrows(&shape), 3);

        let shape = (2, 3);
        assert_eq!(AsShape::nrows(&shape), 2);

        let shape = (3, 2);
        assert_eq!(AsShape::nrows(&shape), 3);

        let shape = [2, 3];
        assert_eq!(AsShape::nrows(&shape), 2);

        let shape = [3, 2];
        assert_eq!(AsShape::nrows(&shape), 3);
    }

    #[test]
    fn test_as_shape_ncols() {
        let shape = Shape::new(2, 3);
        assert_eq!(AsShape::ncols(&shape), 3);

        let shape = Shape::new(3, 2);
        assert_eq!(AsShape::ncols(&shape), 2);

        let shape = (2, 3);
        assert_eq!(AsShape::ncols(&shape), 3);

        let shape = (3, 2);
        assert_eq!(AsShape::ncols(&shape), 2);

        let shape = [2, 3];
        assert_eq!(AsShape::ncols(&shape), 3);

        let shape = [3, 2];
        assert_eq!(AsShape::ncols(&shape), 2);
    }

    #[test]
    fn test_as_shape_size() {
        let shape = Shape::new(2, 3);
        assert_eq!(AsShape::size(&shape), Ok(6));

        let shape = Shape::new(2, usize::MAX);
        assert_eq!(AsShape::size(&shape), Err(Error::SizeOverflow));

        let shape = Shape::new(usize::MAX, 3);
        assert_eq!(shape.size(), Err(Error::SizeOverflow));

        let shape = (2, 3);
        assert_eq!(AsShape::size(&shape), Ok(6));

        let shape = (2, usize::MAX);
        assert_eq!(AsShape::size(&shape), Err(Error::SizeOverflow));

        let shape = (usize::MAX, 3);
        assert_eq!(shape.size(), Err(Error::SizeOverflow));

        let shape = [2, 3];
        assert_eq!(AsShape::size(&shape), Ok(6));

        let shape = [2, usize::MAX];
        assert_eq!(AsShape::size(&shape), Err(Error::SizeOverflow));

        let shape = [usize::MAX, 3];
        assert_eq!(shape.size(), Err(Error::SizeOverflow));
    }
}