This is very half-baked at the moment and very inefficient, e.g.
inappropriate use of by-value `self` (and thus being forced into an
overuse of `clone`). People get the wrong impression about Rust when
using it, e.g. that Rust cannot express what other languages can because
the implementation is inefficient: https://news.ycombinator.com/item?id=8187831 .
The first commit improves code generation through a few changes:
- The `#[inline]` attributes allow llvm to constant fold the encoding step away in certain situations. For example, code like this changes from a call to `encode_utf8` in a inner loop to the pushing of a byte constant:
```rust
let mut s = String::new();
for _ in range(0u, 21) {
s.push_char('a');
}
```
- Both methods changed their semantic from causing run time failure if the target buffer is not large enough to returning `None` instead. This makes llvm no longer emit code for causing failure for these methods.
- A few debug `assert!()` calls got removed because they affected code generation due to unwinding, and where basically unnecessary with today's sound handling of `char` as a Unicode scalar value.
~~The second commit is optional. It changes the methods from regular indexing with the `dst[i]` syntax to unsafe indexing with `dst.unsafe_mut_ref(i)`. This does not change code generation directly - in both cases llvm is smart enough to see that there can never be an out-of-bounds access. But it makes it emit a `nounwind` attribute for the function.
However, I'm not sure whether that is a real improvement, so if there is any objection to this I'll remove the commit.~~
This changes how the methods behave on a too small buffer, so this is a
[breaking-change]
declared with the same name in the same scope.
This breaks several common patterns. First are unused imports:
use foo::bar;
use baz::bar;
Change this code to the following:
use baz::bar;
Second, this patch breaks globs that import names that are shadowed by
subsequent imports. For example:
use foo::*; // including `bar`
use baz::bar;
Change this code to remove the glob:
use foo::{boo, quux};
use baz::bar;
Or qualify all uses of `bar`:
use foo::{boo, quux};
use baz;
... baz::bar ...
Finally, this patch breaks code that, at top level, explicitly imports
`std` and doesn't disable the prelude.
extern crate std;
Because the prelude imports `std` implicitly, there is no need to
explicitly import it; just remove such directives.
The old behavior can be opted into via the `import_shadowing` feature
gate. Use of this feature gate is discouraged.
This implements RFC #116.
Closes#16464.
[breaking-change]
This is very half-baked at the moment and very inefficient, e.g.
inappropriate use of by-value `self` (and thus being forced into an
overuse of `clone`). People get the wrong impression about Rust when
using it, e.g. that Rust cannot express what other languages can because
the implementation is inefficient.
- Both can now be inlined and constant folded away
- Both can no longer cause failure
- Both now return an `Option` instead
Removed debug `assert!()`s over the valid ranges of a `char`
- It affected optimizations due to unwinding
- Char handling is now sound enought that they became uneccessary
These are like the existing bsearch methods but if the search fails,
it returns the next insertion point.
The new `binary_search` returns a `BinarySearchResult` that is either
`Found` or `NotFound`. For convenience, the `found` and `not_found`
methods convert to `Option`, ala `Result`.
Deprecate bsearch and bsearch_elem.
This required some contortions because importing both raw::Slice
and slice::Slice makes rustc crash.
Since `Slice` is in the prelude, this renaming is unlikely to
casue breakage.
[breaking-change]
ImmutableVector -> ImmutableSlice
ImmutableEqVector -> ImmutableEqSlice
ImmutableOrdVector -> ImmutableOrdSlice
MutableVector -> MutableSlice
MutableVectorAllocating -> MutableSliceAllocating
MutableCloneableVector -> MutableCloneableSlice
MutableOrdVector -> MutableOrdSlice
These are all in the prelude so most code will not break.
[breaking-change]
Implement `Index` for `RingBuf`, `HashMap`, `TreeMap`, `SmallIntMap`, and `TrieMap`.
If there’s anything that I missed or should be removed, let me know.
- Moved examples for permutations and next into trait definition as
comments on pull request #16244.
- Fixed (hopefully) issue with erronious commit of changes to src/llvm.
- API doc/example for next() in Permutations
- API doc/example for permutations() in ImmutableCloneableVector
- Moved examples for permutations and next into trait definition as
comments on pull request #16244.
- Fix erroneus inclusion of src/llvm in older commit.
This does a few things:
- remove references to ~[] and the OwnedVector trait, which are both
obsolete
- correct the docs to say that this is the slice module, not the vec
module
- add a sentence pointing out that vectors are distinct from Vec
- remove documentation on Vec.
closes#15459
This does a few things:
- remove references to ~[] and the OwnedVector trait, which are both
obsolete
- correct the docs to say that this is the slice module, not the vec
module
- add a sentence pointing out that vectors are distinct from Vec
- remove documentation on Vec.
closes#15459
This adds a new `Recompositions` iterator, which performs canonical composition on the result of the `Decompositions` iterator (which is canonical or compatibility decomposition). In effect this implements Unicode normalization forms C and KC.
This is an alternative to upgrading the way rvalues are handled in the
borrow check. Making rvalues handled more like lvalues in the borrow
check caused numerous problems related to double mutable borrows and
rvalue scopes. Rather than come up with more borrow check rules to try
to solve these problems, I decided to just forbid pattern bindings after
`@`. This affected fewer than 10 lines of code in the compiler and
libraries.
This breaks code like:
match x {
y @ z => { ... }
}
match a {
b @ Some(c) => { ... }
}
Change this code to use nested `match` or `let` expressions. For
example:
match x {
y => {
let z = y;
...
}
}
match a {
Some(c) => {
let b = Some(c);
...
}
}
Closes#14587.
[breaking-change]
Previously the implementation of Hash was limited to tuples of up to arity 8. This increases it to tuples of up to arity 12.
Also, the implementation macro for `Hash` used to expand to something like this:
impl Hash for (a7,)
impl Hash for (a6, a7)
impl Hash for (a5, a6, a7)
...
This style is inconsistent with the implementations in core::tuple, which look like this:
impl Trait for (A,)
impl Trait for (A, B)
impl Trait for (A, B, C)
...
This is perhaps a minor point, but it does mean the documentation pages are inconsistent. Compare the tuple implementations in the documentation for [Hash](http://static.rust-lang.org/doc/master/std/hash/trait.Hash.html) and [PartialOrd](http://static.rust-lang.org/doc/master/core/cmp/trait.PartialOrd.html)
This changes the Hash implementation to be consistent with `core::tuple`.
This trait was only implemented by `String`. It provided the methods
`into_bytes` and `append`, both of which **are already implemented as normal
methods** of `String` (not as trait methods). This change improves the
consistency of strings.
This shouldn't break any code, except if somebody has implemented
`OwnedStr` for a user-defined type.
Implement for Vec, DList, RingBuf. Add MutableSeq to the prelude.
Since the collections traits are in the prelude most consumers of
these methods will continue to work without change.
[breaking-change]
1. Removed obsolete comment regarding recursive/iteration implementations of tree_find_with/tree_find_mut_with
2. Replaced easy breakable find_with example with simpler one (which only removes redundant allocation during search)
1. Removed obsolete comment regarding recursive/iteration implementations of tree_find_with/tree_find_mut_with
2. Replaced easy breakable find_with example with simpler one (which only removes redundant allocation during search)
Closes#15690 (Guide: improve error handling)
Closes#15729 (Guide: guessing game)
Closes#15751 (repair macro docs)
Closes#15766 (rustc: Print a smaller hash on -v)
Closes#15815 (Add unit test for rlibc)
Closes#15820 (Minor refactoring and features in rustc driver for embedders)
Closes#15822 (rustdoc: Add an --extern flag analagous to rustc's)
Closes#15824 (Document Deque trait and bitv.)
Closes#15832 (syntax: Join consecutive string literals in format strings together)
Closes#15837 (Update LLVM to include NullCheckElimination pass)
Closes#15841 (Rename to_str to to_string)
Closes#15847 (Purge #[!resolve_unexported] from the compiler)
Closes#15848 (privacy: Add publically-reexported foreign item to exported item set)
Closes#15849 (fix string in from_utf8_lossy_100_multibyte benchmark)
Closes#15850 (Get rid of few warnings in tests)
Closes#15852 (Clarify the std::vec::Vec::with_capacity docs)
This implements RFC 39. Omitted lifetimes in return values will now be
inferred to more useful defaults, and an error is reported if a lifetime
in a return type is omitted and one of the two lifetime elision rules
does not specify what it should be.
This primarily breaks two uncommon code patterns. The first is this:
unsafe fn get_foo_out_of_thin_air() -> &Foo {
...
}
This should be changed to:
unsafe fn get_foo_out_of_thin_air() -> &'static Foo {
...
}
The second pattern that needs to be changed is this:
enum MaybeBorrowed<'a> {
Borrowed(&'a str),
Owned(String),
}
fn foo() -> MaybeBorrowed {
Owned(format!("hello world"))
}
Change code like this to:
enum MaybeBorrowed<'a> {
Borrowed(&'a str),
Owned(String),
}
fn foo() -> MaybeBorrowed<'static> {
Owned(format!("hello world"))
}
Closes#15552.
[breaking-change]
Reimplement the string slice's `Iterator<char>` by wrapping the already efficient
slice iterator.
The iterator uses our guarantee that the string contains valid UTF-8, but its only unsafe
code is transmuting the decoded `u32` into `char`.
Benchmarks suggest that the runtime of `Chars` benchmarks are reduced by up to 30%,
runtime of `Chars` reversed reduced by up to 60%.
```
BEFORE
test str::bench::char_indicesator ... bench: 124 ns/iter (+/- 1)
test str::bench::char_indicesator_rev ... bench: 188 ns/iter (+/- 9)
test str::bench::char_iterator ... bench: 122 ns/iter (+/- 2)
test str::bench::char_iterator_ascii ... bench: 302 ns/iter (+/- 41)
test str::bench::char_iterator_for ... bench: 123 ns/iter (+/- 4)
test str::bench::char_iterator_rev ... bench: 189 ns/iter (+/- 14)
test str::bench::char_iterator_rev_for ... bench: 177 ns/iter (+/- 4)
AFTER
test str::bench::char_indicesator ... bench: 85 ns/iter (+/- 3)
test str::bench::char_indicesator_rev ... bench: 82 ns/iter (+/- 2)
test str::bench::char_iterator ... bench: 100 ns/iter (+/- 3)
test str::bench::char_iterator_ascii ... bench: 317 ns/iter (+/- 3)
test str::bench::char_iterator_for ... bench: 86 ns/iter (+/- 2)
test str::bench::char_iterator_rev ... bench: 80 ns/iter (+/- 6)
test str::bench::char_iterator_rev_for ... bench: 68 ns/iter (+/- 0)
```
Note: Branch name is no longer indicative of the implementation.
except where trait objects are involved.
Part of issue #15349, though I'm leaving it open for trait objects.
Cross borrowing for trait objects remains because it is needed until we
have DST.
This will break code like:
fn foo(x: &int) { ... }
let a = box 3i;
foo(a);
Change this code to:
fn foo(x: &int) { ... }
let a = box 3i;
foo(&*a);
[breaking-change]
Someone asked for an example usage of this on IRC, so I tossed together the simplest one. Obviously, this isn't up to snuff, but it's better than nothing.
- `width()` computes the displayed width of a string, ignoring the width of control characters.
- arguably we might do *something* else for control characters, but the question is, what?
- users who want to do something else can iterate over chars()
- `graphemes()` returns a `Graphemes` struct, which implements an iterator over the grapheme clusters of a &str.
- fully compliant with [UAX#29](http://www.unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries)
- passes all [Unicode-supplied tests](http://www.unicode.org/reports/tr41/tr41-15.html#Tests29)
- added code to generate additionial categories in `unicode.py`
- `Cn` aka `Not_Assigned`
- categories necessary for grapheme cluster breaking
- tidied up the exports from libunicode
- all exports are exposed through a module rather than directly at crate root.
- std::prelude imports UnicodeChar and UnicodeStrSlice from std::char and std::str rather than directly from libunicode
closes#7043
