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396 lines (350 loc) · 9.83 KB
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use std::fmt;
use std::ops::{Index, IndexMut};
use std::slice;
use std::vec;
use crate::Dimension;
/// A multi-dimensional array.
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Array<T> {
dims: Vec<Dimension>,
data: Vec<T>,
}
impl<T: fmt::Display> fmt::Display for Array<T> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
if self.dims.iter().any(|dim| dim.lower_bound != 1) {
for dim in &self.dims {
write!(
fmt,
"[{}:{}]",
dim.lower_bound,
dim.lower_bound + dim.len - 1
)?;
}
write!(fmt, "=")?;
}
fmt_helper(0, &self.dims, &mut self.data.iter(), fmt)
}
}
fn fmt_helper<'a, T, I>(
depth: usize,
dims: &[Dimension],
data: &mut I,
fmt: &mut fmt::Formatter<'_>,
) -> fmt::Result
where
I: Iterator<Item = &'a T>,
T: 'a + fmt::Display,
{
if dims.len() == 0 {
return write!(fmt, "{{}}");
}
if depth == dims.len() {
return write!(fmt, "{}", data.next().unwrap());
}
write!(fmt, "{{")?;
for i in 0..dims[depth].len {
if i != 0 {
write!(fmt, ",")?;
}
fmt_helper(depth + 1, dims, data, fmt)?;
}
write!(fmt, "}}")
}
impl<T> Array<T> {
/// Creates a new `Array` from its underlying components.
///
/// The data array should be provided in the higher-dimensional equivalent
/// of row-major order.
///
/// # Panics
///
/// Panics if the number of elements provided does not match the number of
/// elements specified by the dimensions.
pub fn from_parts(data: Vec<T>, dimensions: Vec<Dimension>) -> Array<T> {
assert!(
(data.is_empty() && dimensions.is_empty())
|| data.len() as i32 == dimensions.iter().fold(1, |acc, i| acc * i.len),
"size mismatch"
);
Array {
dims: dimensions,
data,
}
}
/// Creates a new one-dimensional array.
pub fn from_vec(data: Vec<T>, lower_bound: i32) -> Array<T> {
Array {
dims: vec![Dimension {
len: data.len() as i32,
lower_bound,
}],
data,
}
}
/// Wraps this array in a new dimension of size 1.
///
/// For example, the one dimensional array `[1, 2]` would turn into the
/// two-dimensional array `[[1, 2]]`.
pub fn wrap(&mut self, lower_bound: i32) {
self.dims.insert(
0,
Dimension {
len: 1,
lower_bound,
},
);
}
/// Consumes another array, appending it to the top level dimension of this
/// array.
///
/// The dimensions of the other array must be the same as the dimensions
/// of this array with the first dimension removed. This includes lower
/// bounds as well as lengths.
///
/// For example, if `[3, 4]` is pushed onto `[[1, 2]]`, the result is
/// `[[1, 2], [3, 4]]`.
///
/// # Panics
///
/// Panics if the dimensions of the two arrays do not match.
pub fn push(&mut self, other: Array<T>) {
assert!(
self.dims.len() - 1 == other.dims.len(),
"cannot append differently shaped arrays"
);
for (dim1, dim2) in self.dims.iter().skip(1).zip(other.dims.iter()) {
assert!(dim1 == dim2, "cannot append differently shaped arrays");
}
self.dims[0].len += 1;
self.data.extend(other.data);
}
/// Returns the dimensions of this array.
pub fn dimensions(&self) -> &[Dimension] {
&self.dims
}
fn shift_idx(&self, indices: &[i32]) -> i32 {
assert_eq!(self.dims.len(), indices.len());
self.dims
.iter()
.zip(indices.iter().cloned())
.rev()
.fold((0, 1), |(acc, stride), (dim, idx)| {
let shifted = dim.shift(idx);
(acc + shifted * stride, dim.len * stride)
})
.0
}
/// Returns an iterator over references to the elements of the array in the
/// higher-dimensional equivalent of row-major order.
pub fn iter(&self) -> Iter<'_, T> {
Iter {
inner: self.data.iter(),
}
}
/// Returns an iterator over mutable references to the elements of the
/// array in the higher-dimensional equivalent of row-major order.
pub fn iter_mut(&mut self) -> IterMut<'_, T> {
IterMut {
inner: self.data.iter_mut(),
}
}
/// Returns the underlying data vector for this Array in the
/// higher-dimensional equivalent of row-major order.
pub fn into_inner(self) -> Vec<T> {
self.data
}
}
/// A trait implemented by types that can index into an `Array`.
pub trait ArrayIndex {
/// Calculates the index into the `Array`'s underlying storage specified
/// by the value of `self`.
///
/// # Panics
///
/// Panics if the value of `self` does not correspond to an in-bounds
/// element of the `Array`.
fn index<T>(&self, array: &Array<T>) -> i32;
}
impl<'a> ArrayIndex for &'a [i32] {
fn index<T>(&self, array: &Array<T>) -> i32 {
array.shift_idx(*self)
}
}
impl ArrayIndex for i32 {
fn index<T>(&self, array: &Array<T>) -> i32 {
let slice: &[i32] = &[*self];
ArrayIndex::index(&slice, array)
}
}
macro_rules! tuple_impl {
($($name:ident : $t:ty),+) => {
impl ArrayIndex for ($($t,)+) {
fn index<T>(&self, array: &Array<T>) -> i32 {
let ($($name,)+) = *self;
let slice: &[i32] = &[$($name),+];
ArrayIndex::index(&slice, array)
}
}
}
}
tuple_impl!(a: i32);
tuple_impl!(a: i32, b: i32);
tuple_impl!(a: i32, b: i32, c: i32);
tuple_impl!(a: i32, b: i32, c: i32, d: i32);
tuple_impl!(a: i32, b: i32, c: i32, d: i32, e: i32);
tuple_impl!(a: i32, b: i32, c: i32, d: i32, e: i32, f: i32);
tuple_impl!(a: i32, b: i32, c: i32, d: i32, e: i32, f: i32, g: i32);
tuple_impl!(
a: i32,
b: i32,
c: i32,
d: i32,
e: i32,
f: i32,
g: i32,
h: i32
);
tuple_impl!(
a: i32,
b: i32,
c: i32,
d: i32,
e: i32,
f: i32,
g: i32,
h: i32,
i: i32
);
/// Indexes into the `Array`, retrieving a reference to the contained
/// value.
///
/// Since `Array`s can be multi-dimensional, the `Index` trait is
/// implemented for a variety of index types. In the most generic case, a
/// `&[i32]` can be used. In addition, a bare `i32` as well as tuples
/// of up to 10 `i32` values may be used for convenience.
///
/// # Panics
///
/// Panics if the index does not correspond to an in-bounds element of the
/// `Array`.
///
/// # Examples
///
/// ```rust
/// # use postgres_array::Array;
/// let mut array = Array::from_vec(vec![0i32, 1, 2, 3], 0);
/// assert_eq!(2, array[2]);
///
/// array.wrap(0);
/// array.push(Array::from_vec(vec![4, 5, 6, 7], 0));
///
/// assert_eq!(6, array[(1, 2)]);
/// ```
impl<T, I: ArrayIndex> Index<I> for Array<T> {
type Output = T;
fn index(&self, idx: I) -> &T {
let idx = idx.index(self);
&self.data[idx as usize]
}
}
impl<T, I: ArrayIndex> IndexMut<I> for Array<T> {
fn index_mut(&mut self, idx: I) -> &mut T {
let idx = idx.index(self);
&mut self.data[idx as usize]
}
}
impl<'a, T: 'a> IntoIterator for &'a Array<T> {
type Item = &'a T;
type IntoIter = Iter<'a, T>;
fn into_iter(self) -> Iter<'a, T> {
self.iter()
}
}
impl<'a, T: 'a> IntoIterator for &'a mut Array<T> {
type Item = &'a mut T;
type IntoIter = IterMut<'a, T>;
fn into_iter(self) -> IterMut<'a, T> {
self.iter_mut()
}
}
impl<T> IntoIterator for Array<T> {
type Item = T;
type IntoIter = IntoIter<T>;
fn into_iter(self) -> IntoIter<T> {
IntoIter {
inner: self.data.into_iter(),
}
}
}
/// An iterator over references to values of an `Array` in the
/// higher-dimensional equivalent of row-major order.
pub struct Iter<'a, T> {
inner: slice::Iter<'a, T>,
}
impl<'a, T: 'a> Iterator for Iter<'a, T> {
type Item = &'a T;
fn next(&mut self) -> Option<&'a T> {
self.inner.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
impl<'a, T: 'a> DoubleEndedIterator for Iter<'a, T> {
fn next_back(&mut self) -> Option<&'a T> {
self.inner.next_back()
}
}
impl<'a, T: 'a> ExactSizeIterator for Iter<'a, T> {
fn len(&self) -> usize {
self.inner.len()
}
}
/// An iterator over mutable references to values of an `Array` in the
/// higher-dimensional equivalent of row-major order.
pub struct IterMut<'a, T> {
inner: slice::IterMut<'a, T>,
}
impl<'a, T: 'a> Iterator for IterMut<'a, T> {
type Item = &'a mut T;
fn next(&mut self) -> Option<&'a mut T> {
self.inner.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
impl<'a, T: 'a> DoubleEndedIterator for IterMut<'a, T> {
fn next_back(&mut self) -> Option<&'a mut T> {
self.inner.next_back()
}
}
impl<'a, T: 'a> ExactSizeIterator for IterMut<'a, T> {
fn len(&self) -> usize {
self.inner.len()
}
}
/// An iterator over values of an `Array` in the higher-dimensional
/// equivalent of row-major order.
pub struct IntoIter<T> {
inner: vec::IntoIter<T>,
}
impl<T> Iterator for IntoIter<T> {
type Item = T;
fn next(&mut self) -> Option<T> {
self.inner.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
impl<T> DoubleEndedIterator for IntoIter<T> {
fn next_back(&mut self) -> Option<T> {
self.inner.next_back()
}
}
impl<T> ExactSizeIterator for IntoIter<T> {
fn len(&self) -> usize {
self.inner.len()
}
}
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