src/test/run-pass/unboxed-closures-extern-fn.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Checks that extern fn pointers implement the full range of Fn traits.
  12
  13 use std::ops::{Fn,FnMut,FnOnce};
  14
  15 fn square(x: isize) -> isize { x * x }
  16
  17 fn call_it<F:Fn(isize)->isize>(f: &F, x: isize) -> isize {
  18     f(x)
  19 }
  20
  21 fn call_it_mut<F:FnMut(isize)->isize>(f: &mut F, x: isize) -> isize {
  22     f(x)
  23 }
  24
  25 fn call_it_once<F:FnOnce(isize)->isize>(f: F, x: isize) -> isize {
  26     f(x)
  27 }
  28
  29 fn main() {
  30     let x = call_it(&square, 22);
  31     let y = call_it_mut(&mut square, 22);
  32     let z = call_it_once(square, 22);
  33     assert_eq!(x, square(22));
  34     assert_eq!(y, square(22));
  35     assert_eq!(z, square(22));
  36 }