diff options
| -rw-r--r-- | src/libstd/cmp.rs | 17 | ||||
| -rw-r--r-- | src/test/compile-fail/issue-3344.rs | 3 | ||||
| -rw-r--r-- | src/test/run-pass/cmp-default.rs | 43 |
3 files changed, 53 insertions, 10 deletions
diff --git a/src/libstd/cmp.rs b/src/libstd/cmp.rs index 2c4bb46b23b..77d4e945aae 100644 --- a/src/libstd/cmp.rs +++ b/src/libstd/cmp.rs @@ -157,19 +157,20 @@ pub fn lexical_ordering(o1: Ordering, o2: Ordering) -> Ordering { /** * Trait for values that can be compared for a sort-order. * -* Eventually this may be simplified to only require -* an `le` method, with the others generated from -* default implementations. However it should remain -* possible to implement the others separately, for -* compatibility with floating-point NaN semantics +* Ord only requires implementation of the `lt` method, +* with the others generated from default implementations. +* +* However it remains possible to implement the others separately, +* for compatibility with floating-point NaN semantics * (cf. IEEE 754-2008 section 5.11). */ +#[allow(default_methods)] // NOTE: Remove when allowed in stage0 #[lang="ord"] pub trait Ord { fn lt(&self, other: &Self) -> bool; - fn le(&self, other: &Self) -> bool; - fn ge(&self, other: &Self) -> bool; - fn gt(&self, other: &Self) -> bool; + fn le(&self, other: &Self) -> bool { !other.lt(self) } + fn gt(&self, other: &Self) -> bool { other.lt(self) } + fn ge(&self, other: &Self) -> bool { !self.lt(other) } } /// The equivalence relation. Two values may be equivalent even if they are diff --git a/src/test/compile-fail/issue-3344.rs b/src/test/compile-fail/issue-3344.rs index ac5b469c56e..9a3fff453f3 100644 --- a/src/test/compile-fail/issue-3344.rs +++ b/src/test/compile-fail/issue-3344.rs @@ -9,8 +9,7 @@ // except according to those terms. struct thing(uint); -impl Ord for thing { //~ ERROR missing method `gt` - fn lt(&self, other: &thing) -> bool { **self < **other } +impl Ord for thing { //~ ERROR missing method `lt` fn le(&self, other: &thing) -> bool { **self < **other } fn ge(&self, other: &thing) -> bool { **self < **other } } diff --git a/src/test/run-pass/cmp-default.rs b/src/test/run-pass/cmp-default.rs new file mode 100644 index 00000000000..0dc5e7eb6ce --- /dev/null +++ b/src/test/run-pass/cmp-default.rs @@ -0,0 +1,43 @@ +// Copyright 2012 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// Test default methods in Ord +// +struct Int(int); + +impl Ord for Int { + fn lt(&self, other: &Int) -> bool { + **self < **other + } +} + +struct RevInt(int); + +impl Ord for RevInt { + fn lt(&self, other: &RevInt) -> bool { + **self > **other + } +} + +pub fn main() { + assert!(Int(2) > Int(1)); + assert!(Int(2) >= Int(1)); + assert!(Int(1) >= Int(1)); + assert!(Int(1) < Int(2)); + assert!(Int(1) <= Int(2)); + assert!(Int(1) <= Int(1)); + + assert!(RevInt(2) < RevInt(1)); + assert!(RevInt(2) <= RevInt(1)); + assert!(RevInt(1) <= RevInt(1)); + assert!(RevInt(1) > RevInt(2)); + assert!(RevInt(1) >= RevInt(2)); + assert!(RevInt(1) >= RevInt(1)); +} |