// Copyright 2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. // If `Index` used an associated type for its output, this test would // work more smoothly. #![feature(old_orphan_check)] use std::ops::Index; struct Mat { data: Vec, cols: uint, } impl Mat { fn new(data: Vec, cols: uint) -> Mat { Mat { data: data, cols: cols } } fn row<'a>(&'a self, row: uint) -> Row<&'a Mat> { Row { mat: self, row: row, } } } impl Index<(uint, uint), T> for Mat { fn index<'a>(&'a self, &(row, col): &(uint, uint)) -> &'a T { &self.data[row * self.cols + col] } } impl<'a, T> Index<(uint, uint), T> for &'a Mat { fn index<'b>(&'b self, index: &(uint, uint)) -> &'b T { (*self).index(index) } } struct Row { mat: M, row: uint, } impl> Index for Row { fn index<'a>(&'a self, col: &uint) -> &'a T { &self.mat[(self.row, *col)] } } fn main() { let m = Mat::new(vec!(1u, 2, 3, 4, 5, 6), 3); let r = m.row(1); assert!(r.index(&2) == &6); assert!(r[2] == 6); assert!(r[2u] == 6u); assert!(6 == r[2]); let e = r[2]; assert!(e == 6); let e: uint = r[2]; assert!(e == 6); }