src/test/run-pass/method-projection.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 // Test that we can use method notation to call methods based on a
  12 // projection bound from a trait. Issue #20469.
  13
  14 ///////////////////////////////////////////////////////////////////////////
  15
  16
  17 trait MakeString {
  18     fn make_string(&self) -> String;
  19 }
  20
  21 impl MakeString for isize {
  22     fn make_string(&self) -> String {
  23         format!("{}", *self)
  24     }
  25 }
  26
  27 impl MakeString for usize {
  28     fn make_string(&self) -> String {
  29         format!("{}", *self)
  30     }
  31 }
  32
  33 ///////////////////////////////////////////////////////////////////////////
  34
  35 trait Foo {
  36     type F: MakeString;
  37
  38     fn get(&self) -> &Self::F;
  39 }
  40
  41 fn foo<F:Foo>(f: &F) -> String {
  42     f.get().make_string()
  43 }
  44
  45 ///////////////////////////////////////////////////////////////////////////
  46
  47 struct SomeStruct {
  48     field: isize,
  49 }
  50
  51 impl Foo for SomeStruct {
  52     type F = isize;
  53
  54     fn get(&self) -> &isize {
  55         &self.field
  56     }
  57 }
  58
  59 ///////////////////////////////////////////////////////////////////////////
  60
  61 struct SomeOtherStruct {
  62     field: usize,
  63 }
  64
  65 impl Foo for SomeOtherStruct {
  66     type F = usize;
  67
  68     fn get(&self) -> &usize {
  69         &self.field
  70     }
  71 }
  72
  73 fn main() {
  74     let x = SomeStruct { field: 22 };
  75     assert_eq!(foo(&x), format!("22"));
  76
  77     let x = SomeOtherStruct { field: 44 };
  78     assert_eq!(foo(&x), format!("44"));
  79 }