From 256096da9ee680366b839f912e8d3ecccc0da033 Mon Sep 17 00:00:00 2001 From: Mark Mansi Date: Wed, 25 Apr 2018 16:33:02 -0500 Subject: Make Vec::new const --- src/liballoc/raw_vec.rs | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'src/liballoc/raw_vec.rs') diff --git a/src/liballoc/raw_vec.rs b/src/liballoc/raw_vec.rs index 7ef0a27fc72..dc8ad9ee061 100644 --- a/src/liballoc/raw_vec.rs +++ b/src/liballoc/raw_vec.rs @@ -68,6 +68,16 @@ impl RawVec { } } + /// Like `empty` but parametrized over the choice of allocator for the returned `RawVec`. + pub const fn empty_in(a: A) -> Self { + // Unique::empty() doubles as "unallocated" and "zero-sized allocation" + RawVec { + ptr: Unique::empty(), + cap: 0, + a, + } + } + /// Like `with_capacity` but parameterized over the choice of /// allocator for the returned RawVec. #[inline] @@ -124,6 +134,12 @@ impl RawVec { Self::new_in(Global) } + /// Create a `RawVec` with capcity 0 (on the system heap), regardless of `T`, without + /// allocating. + pub fn empty() -> Self { + Self::empty_in(Global) + } + /// Creates a RawVec (on the system heap) with exactly the /// capacity and alignment requirements for a `[T; cap]`. This is /// equivalent to calling RawVec::new when `cap` is 0 or T is -- cgit 1.4.1-3-g733a5 From a2105b8e21a71f513e6840ec0571cad5c1a36012 Mon Sep 17 00:00:00 2001 From: Mark Mansi Date: Wed, 25 Apr 2018 16:42:57 -0500 Subject: make RawVec::empty const --- src/liballoc/raw_vec.rs | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'src/liballoc/raw_vec.rs') diff --git a/src/liballoc/raw_vec.rs b/src/liballoc/raw_vec.rs index dc8ad9ee061..fe18979fb51 100644 --- a/src/liballoc/raw_vec.rs +++ b/src/liballoc/raw_vec.rs @@ -54,6 +54,7 @@ pub struct RawVec { } impl RawVec { + // FIXME: this should be made `const` when `if` statements are allowed /// Like `new` but parameterized over the choice of allocator for /// the returned RawVec. pub fn new_in(a: A) -> Self { @@ -68,6 +69,7 @@ impl RawVec { } } + // FIXME: this should removed when `new_in` can be made `const` /// Like `empty` but parametrized over the choice of allocator for the returned `RawVec`. pub const fn empty_in(a: A) -> Self { // Unique::empty() doubles as "unallocated" and "zero-sized allocation" @@ -134,9 +136,10 @@ impl RawVec { Self::new_in(Global) } + // FIXME: this should removed when `new` can be made `const` /// Create a `RawVec` with capcity 0 (on the system heap), regardless of `T`, without /// allocating. - pub fn empty() -> Self { + pub const fn empty() -> Self { Self::empty_in(Global) } -- cgit 1.4.1-3-g733a5 From e5280e452f194ea7b4066c50b7954e07cb054161 Mon Sep 17 00:00:00 2001 From: Mark Mansi Date: Sun, 29 Apr 2018 17:13:49 -0500 Subject: use const trick --- src/liballoc/raw_vec.rs | 29 ++++++----------------------- src/liballoc/vec.rs | 2 +- 2 files changed, 7 insertions(+), 24 deletions(-) (limited to 'src/liballoc/raw_vec.rs') diff --git a/src/liballoc/raw_vec.rs b/src/liballoc/raw_vec.rs index fe18979fb51..6ca668fda59 100644 --- a/src/liballoc/raw_vec.rs +++ b/src/liballoc/raw_vec.rs @@ -54,28 +54,18 @@ pub struct RawVec { } impl RawVec { - // FIXME: this should be made `const` when `if` statements are allowed /// Like `new` but parameterized over the choice of allocator for /// the returned RawVec. - pub fn new_in(a: A) -> Self { + pub const fn new_in(a: A) -> Self { // !0 is usize::MAX. This branch should be stripped at compile time. - let cap = if mem::size_of::() == 0 { !0 } else { 0 }; + // FIXME(mark-i-m): use this line when `if`s are allowed in `const` + //let cap = if mem::size_of::() == 0 { !0 } else { 0 }; // Unique::empty() doubles as "unallocated" and "zero-sized allocation" RawVec { ptr: Unique::empty(), - cap, - a, - } - } - - // FIXME: this should removed when `new_in` can be made `const` - /// Like `empty` but parametrized over the choice of allocator for the returned `RawVec`. - pub const fn empty_in(a: A) -> Self { - // Unique::empty() doubles as "unallocated" and "zero-sized allocation" - RawVec { - ptr: Unique::empty(), - cap: 0, + // FIXME(mark-i-m): use `cap` when ifs are allowed in const + cap: [0, !0][(mem::size_of::() != 0) as usize], a, } } @@ -132,17 +122,10 @@ impl RawVec { /// RawVec with capacity 0. If T has 0 size, then it makes a /// RawVec with capacity `usize::MAX`. Useful for implementing /// delayed allocation. - pub fn new() -> Self { + pub const fn new() -> Self { Self::new_in(Global) } - // FIXME: this should removed when `new` can be made `const` - /// Create a `RawVec` with capcity 0 (on the system heap), regardless of `T`, without - /// allocating. - pub const fn empty() -> Self { - Self::empty_in(Global) - } - /// Creates a RawVec (on the system heap) with exactly the /// capacity and alignment requirements for a `[T; cap]`. This is /// equivalent to calling RawVec::new when `cap` is 0 or T is diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs index 415d75664ff..35d0a69a05a 100644 --- a/src/liballoc/vec.rs +++ b/src/liballoc/vec.rs @@ -325,7 +325,7 @@ impl Vec { #[rustc_const_unstable(feature = "const_vec_new")] pub const fn new() -> Vec { Vec { - buf: RawVec::empty(), + buf: RawVec::new(), len: 0, } } -- cgit 1.4.1-3-g733a5 From f9f992379de4a82637ec4bf717ff42f27872bc48 Mon Sep 17 00:00:00 2001 From: Mark Mansi Date: Sun, 29 Apr 2018 17:27:17 -0500 Subject: heh, logic is hard --- src/liballoc/raw_vec.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/liballoc/raw_vec.rs') diff --git a/src/liballoc/raw_vec.rs b/src/liballoc/raw_vec.rs index 6ca668fda59..eb25ae17511 100644 --- a/src/liballoc/raw_vec.rs +++ b/src/liballoc/raw_vec.rs @@ -65,7 +65,7 @@ impl RawVec { RawVec { ptr: Unique::empty(), // FIXME(mark-i-m): use `cap` when ifs are allowed in const - cap: [0, !0][(mem::size_of::() != 0) as usize], + cap: [0, !0][(mem::size_of::() == 0) as usize], a, } } -- cgit 1.4.1-3-g733a5