diff options
Diffstat (limited to 'src/libstd')
| -rw-r--r-- | src/libstd/future.rs | 122 |
1 files changed, 32 insertions, 90 deletions
diff --git a/src/libstd/future.rs b/src/libstd/future.rs index e0aed60e803..960098c1db6 100644 --- a/src/libstd/future.rs +++ b/src/libstd/future.rs @@ -8,11 +8,6 @@ // option. This file may not be copied, modified, or distributed // except according to those terms. -// NB: transitionary, de-mode-ing. -// tjc: allowing deprecated modes due to function issue. -// can re-forbid them after snapshot -#[forbid(deprecated_pattern)]; - /*! * A type representing values that may be computed concurrently and * operations for working with them. @@ -44,27 +39,42 @@ impl<A> Future<A> : Drop { priv enum FutureState<A> { Pending(fn~() -> A), Evaluating, - Forced(~A) + Forced(A) } /// Methods on the `future` type impl<A:Copy> Future<A> { fn get() -> A { //! Get the value of the future - - get(&self) + *(self.get_ref()) } } impl<A> Future<A> { - fn get_ref(&self) -> &self/A { - get_ref(self) - } - - fn with<B>(blk: fn(&A) -> B) -> B { - //! Work with the value without copying it - with(&self, blk) + pure fn get_ref(&self) -> &self/A { + /*! + * Executes the future's closure and then returns a borrowed + * pointer to the result. The borrowed pointer lasts as long as + * the future. + */ + unsafe { + match self.state { + Forced(ref mut v) => { return cast::transmute(v); } + Evaluating => fail ~"Recursive forcing of future!", + Pending(_) => {} + } + + let mut state = Evaluating; + self.state <-> state; + match move state { + Forced(_) | Evaluating => fail ~"Logic error.", + Pending(move f) => { + self.state = Forced(move f()); + self.get_ref() + } + } + } } } @@ -76,7 +86,7 @@ pub fn from_value<A>(val: A) -> Future<A> { * not block. */ - Future {state: Forced(~(move val))} + Future {state: Forced(move val)} } pub fn from_port<A:Send>(port: PortOne<A>) -> @@ -130,62 +140,12 @@ pub fn spawn<A:Send>(blk: fn~() -> A) -> Future<A> { return from_port(move port); } -pub fn get_ref<A>(future: &r/Future<A>) -> &r/A { - /*! - * Executes the future's closure and then returns a borrowed - * pointer to the result. The borrowed pointer lasts as long as - * the future. - */ - - // The unsafety here is to hide the aliases from borrowck, which - // would otherwise be concerned that someone might reassign - // `future.state` and cause the value of the future to be freed. - // But *we* know that once `future.state` is `Forced()` it will - // never become "unforced"---so we can safely return a pointer - // into the interior of the Forced() variant which will last as - // long as the future itself. - - match future.state { - Forced(ref v) => { // v here has type &A, but with a shorter lifetime. - return unsafe{ copy_lifetime(future, &**v) }; // ...extend it. - } - Evaluating => { - fail ~"Recursive forcing of future!"; - } - Pending(_) => {} - } - - let mut state = Evaluating; - state <-> future.state; - match move state { - Forced(_) | Evaluating => { - fail ~"Logic error."; - } - Pending(move f) => { - future.state = Forced(~f()); - return get_ref(future); - } - } -} - -pub fn get<A:Copy>(future: &Future<A>) -> A { - //! Get the value of the future - - *get_ref(future) -} - -pub fn with<A,B>(future: &Future<A>, blk: fn(&A) -> B) -> B { - //! Work with the value without copying it - - blk(get_ref(future)) -} - #[allow(non_implicitly_copyable_typarams)] pub mod test { #[test] pub fn test_from_value() { let f = from_value(~"snail"); - assert get(&f) == ~"snail"; + assert f.get() == ~"snail"; } #[test] @@ -193,13 +153,13 @@ pub mod test { let (ch, po) = oneshot::init(); send_one(move ch, ~"whale"); let f = from_port(move po); - assert get(&f) == ~"whale"; + assert f.get() == ~"whale"; } #[test] pub fn test_from_fn() { let f = from_fn(|| ~"brail"); - assert get(&f) == ~"brail"; + assert f.get() == ~"brail"; } #[test] @@ -209,33 +169,15 @@ pub mod test { } #[test] - pub fn test_with() { - let f = from_value(~"nail"); - assert with(&f, |v| copy *v) == ~"nail"; - } - - #[test] pub fn test_get_ref_method() { let f = from_value(22); assert *f.get_ref() == 22; } #[test] - pub fn test_get_ref_fn() { - let f = from_value(22); - assert *get_ref(&f) == 22; - } - - #[test] - pub fn test_interface_with() { - let f = from_value(~"kale"); - assert f.with(|v| copy *v) == ~"kale"; - } - - #[test] pub fn test_spawn() { let f = spawn(|| ~"bale"); - assert get(&f) == ~"bale"; + assert f.get() == ~"bale"; } #[test] @@ -243,7 +185,7 @@ pub mod test { #[ignore(cfg(target_os = "win32"))] pub fn test_futurefail() { let f = spawn(|| fail); - let _x: ~str = get(&f); + let _x: ~str = f.get(); } #[test] @@ -251,7 +193,7 @@ pub mod test { let expected = ~"schlorf"; let f = do spawn |copy expected| { copy expected }; do task::spawn |move f, move expected| { - let actual = get(&f); + let actual = f.get(); assert actual == expected; } } |
