From 777ad8b20452d94111f9c834d0f277575a564ca3 Mon Sep 17 00:00:00 2001 From: Daniel Micay Date: Fri, 29 Mar 2013 14:16:52 -0400 Subject: [PATCH 1/6] tutorial: use "owned box" consistently --- doc/tutorial.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/doc/tutorial.md b/doc/tutorial.md index 9f36786648a..ad422aa8ea2 100644 --- a/doc/tutorial.md +++ b/doc/tutorial.md @@ -1035,10 +1035,10 @@ let z = x; // no new memory allocated, x can no longer be used # Borrowed pointers Rust's borrowed pointers are a general purpose reference type. In contrast with -owned pointers, where the holder of an owned pointer is the owner of the -pointed-to memory, borrowed pointers never imply ownership. A pointer can be -borrowed to any object, and the compiler verifies that it cannot outlive the -lifetime of the object. +owned boxes, where the holder of an owned box is the owner of the pointed-to +memory, borrowed pointers never imply ownership. A pointer can be borrowed to +any object, and the compiler verifies that it cannot outlive the lifetime of +the object. As an example, consider a simple struct type, `Point`: From dd088afd4323cbaad3c6e3692e7d52658d1f2de6 Mon Sep 17 00:00:00 2001 From: Brian Anderson Date: Thu, 28 Mar 2013 18:19:14 -0700 Subject: [PATCH 2/6] Stop building clang Removing it from the tree is an ordeal and there is no official way to disable clang via LLVM's Makefiles so this edits the Makefile in llvm/tools after running configure. --- configure | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/configure b/configure index 287705a0e58..71beb8214b9 100755 --- a/configure +++ b/configure @@ -881,6 +881,10 @@ do ;; esac need_ok "LLVM configure failed" + + # Hack the tools Makefile to turn off the clang build + sed -i 's/clang//g' tools/Makefile + cd $CFG_BUILD_DIR fi From 518c295a03c5422aec26ac067307c32d11a92e66 Mon Sep 17 00:00:00 2001 From: Brian Anderson Date: Fri, 29 Mar 2013 11:18:35 -0700 Subject: [PATCH 3/6] Register snapshots --- src/librustc/middle/astencode.rs | 39 -------------------------------- src/libstd/ebml.rs | 30 ------------------------ src/libstd/json.rs | 13 ----------- src/libstd/serialize.rs | 6 ----- src/snapshots.txt | 8 +++++++ 5 files changed, 8 insertions(+), 88 deletions(-) diff --git a/src/librustc/middle/astencode.rs b/src/librustc/middle/astencode.rs index c5018bbe13f..7b7cf01d2b5 100644 --- a/src/librustc/middle/astencode.rs +++ b/src/librustc/middle/astencode.rs @@ -681,45 +681,6 @@ impl vtable_decoder_helpers for reader::Decoder { @self.read_to_vec(|| self.read_vtable_origin(xcx) ) } - #[cfg(stage0)] - fn read_vtable_origin(&self, xcx: @ExtendedDecodeContext) - -> typeck::vtable_origin { - do self.read_enum(~"vtable_origin") { - do self.read_enum_variant |i| { - match i { - 0 => { - typeck::vtable_static( - do self.read_enum_variant_arg(0u) { - self.read_def_id(xcx) - }, - do self.read_enum_variant_arg(1u) { - self.read_tys(xcx) - }, - do self.read_enum_variant_arg(2u) { - self.read_vtable_res(xcx) - } - ) - } - 1 => { - typeck::vtable_param( - do self.read_enum_variant_arg(0u) { - self.read_uint() - }, - do self.read_enum_variant_arg(1u) { - self.read_uint() - } - ) - } - // hard to avoid - user input - _ => fail!(~"bad enum variant") - } - } - } - } - - #[cfg(stage1)] - #[cfg(stage2)] - #[cfg(stage3)] fn read_vtable_origin(&self, xcx: @ExtendedDecodeContext) -> typeck::vtable_origin { do self.read_enum("vtable_origin") { diff --git a/src/libstd/ebml.rs b/src/libstd/ebml.rs index 98c4b3c6b16..484220776c3 100644 --- a/src/libstd/ebml.rs +++ b/src/libstd/ebml.rs @@ -334,19 +334,6 @@ pub mod reader { self.push_doc(self.next_doc(EsEnum), f) } - #[cfg(stage0)] - fn read_enum_variant(&self, f: &fn(uint) -> T) -> T { - debug!("read_enum_variant()"); - let idx = self._next_uint(EsEnumVid); - debug!(" idx=%u", idx); - do self.push_doc(self.next_doc(EsEnumBody)) { - f(idx) - } - } - - #[cfg(stage1)] - #[cfg(stage2)] - #[cfg(stage3)] fn read_enum_variant(&self, _names: &[&str], f: &fn(uint) -> T) -> T { debug!("read_enum_variant()"); let idx = self._next_uint(EsEnumVid); @@ -410,23 +397,6 @@ pub mod reader { f() } - #[cfg(stage0)] - fn read_option(&self, f: &fn(bool) -> T) -> T { - debug!("read_option()"); - do self.read_enum("Option") || { - do self.read_enum_variant |idx| { - match idx { - 0 => f(false), - 1 => f(true), - _ => fail!(), - } - } - } - } - - #[cfg(stage1)] - #[cfg(stage2)] - #[cfg(stage3)] fn read_option(&self, f: &fn(bool) -> T) -> T { debug!("read_option()"); do self.read_enum("Option") || { diff --git a/src/libstd/json.rs b/src/libstd/json.rs index 4b0e313330d..190d2d3fe0b 100644 --- a/src/libstd/json.rs +++ b/src/libstd/json.rs @@ -854,19 +854,6 @@ impl<'self> serialize::Decoder for Decoder<'self> { f() } - #[cfg(stage0)] - fn read_enum_variant(&self, f: &fn(uint) -> T) -> T { - debug!("read_enum_variant()"); - let idx = match *self.peek() { - Null => 0, - _ => 1, - }; - f(idx) - } - - #[cfg(stage1)] - #[cfg(stage2)] - #[cfg(stage3)] fn read_enum_variant(&self, names: &[&str], f: &fn(uint) -> T) -> T { debug!("read_enum_variant(names=%?)", names); let name = match *self.peek() { diff --git a/src/libstd/serialize.rs b/src/libstd/serialize.rs index 3c9ad0d77d1..8e7ab318e17 100644 --- a/src/libstd/serialize.rs +++ b/src/libstd/serialize.rs @@ -93,12 +93,6 @@ pub trait Decoder { // Compound types: fn read_enum(&self, name: &str, f: &fn() -> T) -> T; - #[cfg(stage0)] - fn read_enum_variant(&self, f: &fn(uint) -> T) -> T; - - #[cfg(stage1)] - #[cfg(stage2)] - #[cfg(stage3)] fn read_enum_variant(&self, names: &[&str], f: &fn(uint) -> T) -> T; fn read_enum_variant_arg(&self, idx: uint, f: &fn() -> T) -> T; diff --git a/src/snapshots.txt b/src/snapshots.txt index c3f8c8b1e63..fafd5467655 100644 --- a/src/snapshots.txt +++ b/src/snapshots.txt @@ -1,3 +1,11 @@ +S 2013-03-28 f7a2371 + macos-i386 2e05a33716fc4982db53946c3b0dccf0194826fe + macos-x86_64 fbd3feec8dd17a6b6c8df114e6e9b4cd17cc6172 + linux-i386 b89197edd3ba5be7c2ee6577f048d7663640e1d1 + linux-x86_64 61a4377c6d0ca5814c2b2b752d73b61b741a23c9 + winnt-i386 858a74afb210b30697227a87b67e44786b383a0c + freebsd-x86_64 01f1e4b94504045e763eecb71c7e0852f6e85036 + S 2013-03-27 8c15409 macos-x86_64 05eb3801b60056d95715c891d00c5d372e34d00c macos-i386 4119e3fa614fa86adf60ed0183d00db3ce6d0dbc From 85ed840e234184b7975d9ee7b022c0ca2cb5d8ff Mon Sep 17 00:00:00 2001 From: Daniel Micay Date: Fri, 29 Mar 2013 14:51:52 -0400 Subject: [PATCH 4/6] tutorial: improve the owned boxes section --- doc/tutorial.md | 45 ++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 40 insertions(+), 5 deletions(-) diff --git a/doc/tutorial.md b/doc/tutorial.md index ad422aa8ea2..009c1054737 100644 --- a/doc/tutorial.md +++ b/doc/tutorial.md @@ -1002,11 +1002,46 @@ refer to that through a pointer. ## Owned boxes -An owned box (`~`) is a uniquely owned allocation on the heap. An owned box -inherits the mutability and lifetime of the owner as it would if there was no -box. The purpose of an owned box is to add a layer of indirection in order to -create recursive data structures or cheaply pass around an object larger than a -pointer. +An owned box (`~`) is a uniquely owned allocation on the heap. It inherits the +mutability and lifetime of the owner as it would if there was no box. + +~~~~ +let x = 5; // immutable +let mut y = 5; // mutable +y += 2; + +let x = ~5; // immutable +let mut y = ~5; // mutable +*y += 2; // the * operator is needed to access the contained value +~~~~ + +The purpose of an owned box is to add a layer of indirection in order to create +recursive data structures or cheaply pass around an object larger than a +pointer. Since an owned box has a unique owner, it can be used to represent any +tree data structure. + +The following struct won't compile, because the lack of indirection would mean +it has an infinite size: + +~~~~ {.xfail-test} +struct Foo { + child: Option +} +~~~~ + +> ***Note:*** The `Option` type is an enum that represents an *optional* value. +> It's comparable to a nullable pointer in many other languages, but stores the +> contained value unboxed. + +Adding indirection with an owned pointer allocates the child outside of the +struct on the heap, which makes it a finite size and won't result in a +compile-time error: + +~~~~ +struct Foo { + child: Option<~Foo> +} +~~~~ ## Managed boxes From f78af18127e2bc0075479e8495bfa63807e938fc Mon Sep 17 00:00:00 2001 From: Daniel Micay Date: Fri, 29 Mar 2013 15:07:36 -0400 Subject: [PATCH 5/6] tutorial: improve the managed boxes section --- doc/tutorial.md | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/doc/tutorial.md b/doc/tutorial.md index 009c1054737..fbeda4257f5 100644 --- a/doc/tutorial.md +++ b/doc/tutorial.md @@ -1053,6 +1053,20 @@ mutability. They do own the contained object, and mutability is defined by the type of the shared box (`@` or `@mut`). An object containing a managed box is not `Owned`, and can't be sent between tasks. +~~~~ +let a = @5; // immutable + +let mut b = @5; // mutable variable, immutable box +b = @10; + +let c = @mut 5; // immutable variable, mutable box +*c = 10; + +let mut d = @mut 5; // mutable variable, mutable box +*d += 5; +d = @mut 15; +~~~~ + # Move semantics Rust uses a shallow copy for parameter passing, assignment and returning values From 0189ef360092dbebfef5bdfd7a2ebe0c0ccc0f3c Mon Sep 17 00:00:00 2001 From: Daniel Micay Date: Fri, 29 Mar 2013 15:34:14 -0400 Subject: [PATCH 6/6] tutorial: add an example of freezing a managed box --- doc/tutorial.md | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/doc/tutorial.md b/doc/tutorial.md index fbeda4257f5..7518e3ef676 100644 --- a/doc/tutorial.md +++ b/doc/tutorial.md @@ -1173,10 +1173,7 @@ For a more in-depth explanation of borrowed pointers, read the ## Freezing Borrowing an immutable pointer to an object freezes it and prevents mutation. -`Owned` objects have freezing enforced statically at compile-time. Mutable -managed boxes handle freezing dynamically when any of their contents are -borrowed, and the task will fail if an attempt to modify them is made while -they are frozen. +`Owned` objects have freezing enforced statically at compile-time. ~~~~ let mut x = 5; @@ -1186,6 +1183,20 @@ let mut x = 5; // x is now unfrozen again ~~~~ +Mutable managed boxes handle freezing dynamically when any of their contents +are borrowed, and the task will fail if an attempt to modify them is made while +they are frozen: + +~~~~ +let x = @mut 5; +let y = x; +{ + let y = &*y; // the managed box is now frozen + // modifying it through x or y will cause a task failure +} +// the box is now unfrozen again +~~~~ + # Dereferencing pointers Rust uses the unary star operator (`*`) to access the contents of a