| use std::ops::{Index, IndexMut}; |
| |
| struct Foo { |
| x: isize, |
| y: isize, |
| } |
| |
| impl<'a> Index<&'a String> for Foo { |
| type Output = isize; |
| |
| fn index(&self, z: &String) -> &isize { |
| if *z == "x" { |
| &self.x |
| } else { |
| &self.y |
| } |
| } |
| } |
| |
| impl<'a> IndexMut<&'a String> for Foo { |
| fn index_mut(&mut self, z: &String) -> &mut isize { |
| if *z == "x" { |
| &mut self.x |
| } else { |
| &mut self.y |
| } |
| } |
| } |
| |
| struct Bar { |
| x: isize, |
| } |
| |
| impl Index<isize> for Bar { |
| type Output = isize; |
| |
| fn index<'a>(&'a self, z: isize) -> &'a isize { |
| &self.x |
| } |
| } |
| |
| fn main() { |
| let mut f = Foo { |
| x: 1, |
| y: 2, |
| }; |
| let mut s = "hello".to_string(); |
| let rs = &mut s; |
| println!("{}", f[&s]); |
| //~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable |
| f[&s] = 10; |
| //~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable |
| let s = Bar { |
| x: 1, |
| }; |
| s[2] = 20; |
| //~^ ERROR cannot assign to data in an index of `Bar` |
| drop(rs); |
| } |