59 lines
1.6 KiB
Rust
59 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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// Test cyclic detector when using trait instances.
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enum Tree = @TreeR;
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struct TreeR {
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mut left: Option<Tree>,
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mut right: Option<Tree>,
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val: to_str
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}
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trait to_str {
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fn to_str() -> ~str;
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}
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impl <T: to_str> Option<T>: to_str {
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fn to_str() -> ~str {
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match self {
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None => { ~"none" }
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Some(ref t) => { ~"some(" + t.to_str() + ~")" }
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}
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}
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}
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impl int: to_str {
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fn to_str() -> ~str { int::str(self) }
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}
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impl Tree: to_str {
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fn to_str() -> ~str {
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let l = self.left, r = self.right;
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fmt!("[%s, %s, %s]", self.val.to_str(),
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l.to_str(), r.to_str())
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}
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}
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fn foo<T: to_str>(x: T) -> ~str { x.to_str() }
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pub fn main() {
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let t1 = Tree(@TreeR{mut left: None,
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mut right: None,
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val: 1 as to_str });
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let t2 = Tree(@TreeR{mut left: Some(t1),
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mut right: Some(t1),
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val: 2 as to_str });
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let expected = ~"[2, some([1, none, none]), some([1, none, none])]";
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assert t2.to_str() == expected;
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assert foo(t2 as to_str) == expected;
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t1.left = Some(t2); // create cycle
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}
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