85 lines
3.0 KiB
Rust
85 lines
3.0 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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// does the second one subsume the first?
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// xfail-test
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// xfail-fast
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// notes on this test case:
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// On Thu, Apr 18, 2013 at 6:30 PM, John Clements <clements@brinckerhoff.org> wrote:
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// the "issue-2185.rs" test was xfailed with a ref to #2263. Issue #2263 is now fixed, so I tried it again, and after adding some &self parameters, I got this error:
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//
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// Running /usr/local/bin/rustc:
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// issue-2185.rs:24:0: 26:1 error: conflicting implementations for a trait
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// issue-2185.rs:24 impl iterable<uint> for @fn(&fn(uint)) {
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// issue-2185.rs:25 fn iter(&self, blk: &fn(v: uint)) { self( |i| blk(i) ) }
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// issue-2185.rs:26 }
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// issue-2185.rs:20:0: 22:1 note: note conflicting implementation here
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// issue-2185.rs:20 impl<A> iterable<A> for @fn(&fn(A)) {
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// issue-2185.rs:21 fn iter(&self, blk: &fn(A)) { self(blk); }
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// issue-2185.rs:22 }
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//
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// … so it looks like it's just not possible to implement both the generic iterable<uint> and iterable<A> for the type iterable<uint>. Is it okay if I just remove this test?
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//
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// but Niko responded:
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// think it's fine to remove this test, just because it's old and cruft and not hard to reproduce. *However* it should eventually be possible to implement the same interface for the same type multiple times with different type parameters, it's just that our current trait implementation has accidental limitations.
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// so I'm leaving it in.
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// actually, it looks like this is related to bug #3429. I'll rename this bug.
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// This test had to do with an outdated version of the iterable trait.
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// However, the condition it was testing seemed complex enough to
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// warrant still having a test, so I inlined the old definitions.
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trait iterable<A> {
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fn iter(&self, blk: &fn(A));
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}
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impl<A> iterable<A> for @fn(&fn(A)) {
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fn iter(&self, blk: &fn(A)) { self(blk); }
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}
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impl iterable<uint> for @fn(&fn(uint)) {
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fn iter(&self, blk: &fn(v: uint)) { self( |i| blk(i) ) }
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}
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fn filter<A,IA:iterable<A>>(self: IA, prd: @fn(A) -> bool, blk: &fn(A)) {
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do self.iter |a| {
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if prd(a) { blk(a) }
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}
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}
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fn foldl<A,B,IA:iterable<A>>(self: IA, b0: B, blk: &fn(B, A) -> B) -> B {
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let mut b = b0;
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do self.iter |a| {
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b = blk(b, a);
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}
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b
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}
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fn range(lo: uint, hi: uint, it: &fn(uint)) {
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let mut i = lo;
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while i < hi {
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it(i);
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i += 1u;
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}
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}
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pub fn main() {
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let range: @fn(&fn(uint)) = |a| range(0u, 1000u, a);
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let filt: @fn(&fn(v: uint)) = |a| filter(
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range,
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|&&n: uint| n % 3u != 0u && n % 5u != 0u,
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a);
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let sum = foldl(filt, 0u, |accum, &&n: uint| accum + n );
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io::println(fmt!("%u", sum));
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}
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