36 lines
928 B
Rust
36 lines
928 B
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// A basic test of using a higher-ranked trait bound.
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trait FnLike<A,R> {
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fn call(&self, arg: A) -> R;
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}
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type FnObject<'b> = for<'a> FnLike<(&'a i32,), &'a i32> + 'b;
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struct Identity;
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impl<'a, T> FnLike<(&'a T,), &'a T> for Identity {
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fn call(&self, (arg,): (&'a T,)) -> &'a T {
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arg
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}
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}
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fn call_repeatedly(f: &FnObject) {
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let x = 3;
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let y = f.call((&x,));
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assert_eq!(3, *y);
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}
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fn main() {
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call_repeatedly(&Identity);
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}
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