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// run-pass
// If `Index` used an associated type for its output, this test would
// work more smoothly.
use std::ops::Index;
struct Mat<T> { data: Vec<T>, cols: usize, }
impl<T> Mat<T> {
fn new(data: Vec<T>, cols: usize) -> Mat<T> {
Mat { data: data, cols: cols }
}
fn row<'a>(&'a self, row: usize) -> Row<&'a Mat<T>> {
Row { mat: self, row: row, }
}
}
impl<T> Index<(usize, usize)> for Mat<T> {
type Output = T;
fn index<'a>(&'a self, (row, col): (usize, usize)) -> &'a T {
&self.data[row * self.cols + col]
}
}
impl<'a, T> Index<(usize, usize)> for &'a Mat<T> {
type Output = T;
fn index<'b>(&'b self, index: (usize, usize)) -> &'b T {
(*self).index(index)
}
}
struct Row<M> { mat: M, row: usize, }
impl<T, M: Index<(usize, usize), Output=T>> Index<usize> for Row<M> {
type Output = T;
fn index<'a>(&'a self, col: usize) -> &'a T {
&self.mat[(self.row, col)]
}
}
fn main() {
let m = Mat::new(vec![1, 2, 3, 4, 5, 6], 3);
let r = m.row(1);
assert_eq!(r.index(2), &6);
assert_eq!(r[2], 6);
assert_eq!(r[2], 6);
assert_eq!(6, r[2]);
let e = r[2];
assert_eq!(e, 6);
let e: usize = r[2];
assert_eq!(e, 6);
}
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