73 lines
2.0 KiB
Rust
73 lines
2.0 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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#![feature(managed_boxes)]
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// Test cyclic detector when using trait instances.
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use std::cell::RefCell;
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struct Tree(@RefCell<TreeR>);
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struct TreeR {
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left: Option<Tree>,
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right: Option<Tree>,
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val: Box<to_str:Send>
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}
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trait to_str {
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fn to_str_(&self) -> String;
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}
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impl<T:to_str> to_str for Option<T> {
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fn to_str_(&self) -> String {
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match *self {
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None => { "none".to_string() }
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Some(ref t) => format!("some({})", t.to_str_()),
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}
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}
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}
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impl to_str for int {
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fn to_str_(&self) -> String {
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self.to_str().to_string()
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}
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}
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impl to_str for Tree {
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fn to_str_(&self) -> String {
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let Tree(t) = *self;
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let this = t.borrow();
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let (l, r) = (this.left, this.right);
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let val = &this.val;
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format!("[{}, {}, {}]", val.to_str_(), 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) -> String { x.to_str_() }
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pub fn main() {
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let t1 = Tree(@RefCell::new(TreeR{left: None,
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right: None,
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val: box 1 as Box<to_str:Send>}));
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let t2 = Tree(@RefCell::new(TreeR{left: Some(t1),
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right: Some(t1),
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val: box 2 as Box<to_str:Send>}));
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let expected =
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"[2, some([1, none, none]), some([1, none, none])]".to_string();
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assert!(t2.to_str_() == expected);
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assert!(foo(t2) == expected);
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{
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let Tree(t1_) = t1;
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let mut t1 = t1_.borrow_mut();
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t1.left = Some(t2); // create cycle
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}
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}
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