58 lines
1.6 KiB
Rust
58 lines
1.6 KiB
Rust
// Copyright 2012 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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// Tests that type assignability is used to search for instances when
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// making method calls, but only if there aren't any matches without
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// it.
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trait iterable<A> {
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fn iterate(blk: fn(x: &A) -> bool);
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}
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impl<A> &[A]: iterable<A> {
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fn iterate(f: fn(x: &A) -> bool) {
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for vec::each(self) |e| {
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if !f(e) { break; }
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}
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}
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}
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impl<A> ~[A]: iterable<A> {
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fn iterate(f: fn(x: &A) -> bool) {
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for vec::each(self) |e| {
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if !f(e) { break; }
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}
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}
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}
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fn length<A, T: iterable<A>>(x: T) -> uint {
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let mut len = 0;
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for x.iterate() |_y| { len += 1 }
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return len;
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}
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fn main() {
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let x = ~[0,1,2,3];
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// Call a method
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for x.iterate() |y| { assert x[*y] == *y; }
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// Call a parameterized function
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assert length(x) == vec::len(x);
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// Call a parameterized function, with type arguments that require
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// a borrow
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assert length::<int, &[int]>(x) == vec::len(x);
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// Now try it with a type that *needs* to be borrowed
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let z = [0,1,2,3];
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// Call a method
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for z.iterate() |y| { assert z[*y] == *y; }
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// Call a parameterized function
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assert length::<int, &[int]>(z) == vec::len(z);
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}
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