Reject codepoints \uD800 to \uDFFF which are the surrogates
(reserved/unused codepoints that are invalid to encode into UTF-8)
The surrogates is the only hole of invalid codepoints in the range from
\u0 to \u10FFFF.
The message of the first commit explains (edited for changed trait name):
The trait `ExactSize` is introduced to solve a few small niggles:
* We can't reverse (`.invert()`) an enumeration iterator
* for a vector, we have `v.iter().position(f)` but `v.rposition(f)`.
* We can't reverse `Zip` even if both iterators are from vectors
`ExactSize` is an empty trait that is intended to indicate that an
iterator, for example `VecIterator`, knows its exact finite size and
reports it correctly using `.size_hint()`. Only adaptors that preserve
this at all times, can expose this trait further. (Where here we say
finite for fitting in uint).
---
It may seem complicated just to solve these small "niggles",
(It's really the reversible enumerate case that's the most interesting)
but only a few core iterators need to implement this trait.
While we gain more capabilities generically for some iterators,
it becomes a tad more complicated to figure out if a type has
the right trait impls for it.
Address discussion with acrichto; inherit DoubleEndedIterator so that
`.rposition()` can be a default method, and that the nische of the trait
is clear. Use assertions when using `.size_hint()` in reverse enumerate
and `.rposition()`
Fix a bug in `s.slice_chars(a, b)` that did not accept `a == s.len()`.
Fix a bug in `!=` defined for DList.
Also simplify NormalizationIterator to use the CharIterator directly instead of mimicing the iteration itself.
These are very easy to replace with methods on string slices, basically
`.char_len()` and `.len()`.
These are the replacement implementations I did to clean these
functions up, but seeing this I propose removal:
/// ...
pub fn count_chars(s: &str, begin: uint, end: uint) -> uint {
// .slice() checks the char boundaries
s.slice(begin, end).char_len()
}
/// Counts the number of bytes taken by the first `n` chars in `s`
/// starting from byte index `begin`.
///
/// Fails if there are less than `n` chars past `begin`
pub fn count_bytes<'b>(s: &'b str, begin: uint, n: uint) -> uint {
s.slice_from(begin).slice_chars(0, n).len()
}
`s.slice_chars(a, b)` did not allow the case where `a == s.len()`, this
is a bug I introduced last time I touched the method; add a test for
this case.
These are very easy to replace with methods on string slices, basically
`.char_len()` and `.len()`.
These are the replacement implementations I did to clean these
functions up, but seeing this I propose removal:
/// ...
pub fn count_chars(s: &str, begin: uint, end: uint) -> uint {
// .slice() checks the char boundaries
s.slice(begin, end).char_len()
}
/// Counts the number of bytes taken by the first `n` chars in `s`
/// starting from byte index `begin`.
///
/// Fails if there are less than `n` chars past `begin`
pub fn count_bytes<'b>(s: &'b str, begin: uint, n: uint) -> uint {
s.slice_from(begin).slice_chars(0, n).len()
}
Make CharSplitIterator double-ended which is simple given that the operation is symmetric, once the split-N feature is factored out into its own adaptor.
`.rsplitn_iter()` allows splitting `N` times from the back of a string, so it is a completely new feature. With the double-ended impl, `.split_iter()`, `.line_iter()`, `.word_iter()` all allow picking off elements from either end.
`split_options_iter` is removed with the factoring of the split- and split-N- iterators, instead there is `split_terminator_iter`.
---
Add benchmarks using `#[bench]` and tune CharSplitIterator a bit after Huon Wilson's suggestions
Benchmarks 1-5 do the same split using different implementations of `CharEq`, all splitting an ascii string on ascii space. Benchmarks 6-7 split a unicode string on an ascii char.
Before this PR
test str::bench::split_iter_ascii ... bench: 166 ns/iter (+/- 2)
test str::bench::split_iter_closure ... bench: 113 ns/iter (+/- 1)
test str::bench::split_iter_extern_fn ... bench: 286 ns/iter (+/- 7)
test str::bench::split_iter_not_ascii ... bench: 114 ns/iter (+/- 4)
test str::bench::split_iter_slice ... bench: 220 ns/iter (+/- 12)
test str::bench::split_iter_unicode_ascii ... bench: 217 ns/iter (+/- 3)
test str::bench::split_iter_unicode_not_ascii ... bench: 248 ns/iter (+/- 3)
PR, first commit
test str::bench::split_iter_ascii ... bench: 331 ns/iter (+/- 9)
test str::bench::split_iter_closure ... bench: 114 ns/iter (+/- 2)
test str::bench::split_iter_extern_fn ... bench: 314 ns/iter (+/- 6)
test str::bench::split_iter_not_ascii ... bench: 132 ns/iter (+/- 1)
test str::bench::split_iter_slice ... bench: 157 ns/iter (+/- 3)
test str::bench::split_iter_unicode_ascii ... bench: 502 ns/iter (+/- 64)
test str::bench::split_iter_unicode_not_ascii ... bench: 250 ns/iter (+/- 3)
PR, final version
test str::bench::split_iter_ascii ... bench: 106 ns/iter (+/- 4)
test str::bench::split_iter_closure ... bench: 107 ns/iter (+/- 1)
test str::bench::split_iter_extern_fn ... bench: 267 ns/iter (+/- 6)
test str::bench::split_iter_not_ascii ... bench: 108 ns/iter (+/- 1)
test str::bench::split_iter_slice ... bench: 170 ns/iter (+/- 8)
test str::bench::split_iter_unicode_ascii ... bench: 128 ns/iter (+/- 5)
test str::bench::split_iter_unicode_not_ascii ... bench: 252 ns/iter (+/- 3)
---
There are several ways to deal with `CharEq::only_ascii`. It is a performance optimization, so with that in mind, we allow passing bogus char (outside ascii) as long as they don't match. We use a byte value check to make sure we don't split on these (would split substrings in the middle of encoded char). (A more principled way would be to only pass the ascii codepoints to the CharEq when it indicates only_ascii, but that undoes some of the performance optimization.)
Implement Huon Wilson's suggestions (since the benchmarks agree!).
Use `self.sep.matches(byte as char) && byte < 128u8` to match in the
only_ascii case so that mistaken matches outside the ascii range can't
create invalid substrings.
Put the conditional on only_ascii outside the loop.
Add new methods `.rsplit_iter()` and `.rsplitn_iter()` for &str.
Separate out CharSplitIterator and CharSplitNIterator,
CharSplitIterator (`split_iter` and `rsplit_iter`) is made double-ended
while `splitn_iter` and `rsplitn_iter` (limited to N splits) are not,
since these don't have the same symmetry.
With CharSplitIterator being double ended, derived iterators like
`line_iter` and `word_iter` are too.
Implement CharIterator as a separate struct, so that it can be .clone()'d. Fix `.char_range_at_reverse` so that it performs better, closer to the forwards version. This makes the reverse iterators and users like `.rfind()` perform better.
Before
test str::bench::char_iterator ... bench: 146 ns/iter (+/- 0)
test str::bench::char_iterator_ascii ... bench: 397 ns/iter (+/- 49)
test str::bench::char_iterator_rev ... bench: 576 ns/iter (+/- 8)
test str::bench::char_offset_iterator ... bench: 128 ns/iter (+/- 2)
test str::bench::char_offset_iterator_rev ... bench: 425 ns/iter (+/- 59)
After
test str::bench::char_iterator ... bench: 130 ns/iter (+/- 1)
test str::bench::char_iterator_ascii ... bench: 307 ns/iter (+/- 5)
test str::bench::char_iterator_rev ... bench: 185 ns/iter (+/- 8)
test str::bench::char_offset_iterator ... bench: 131 ns/iter (+/- 13)
test str::bench::char_offset_iterator_rev ... bench: 183 ns/iter (+/- 2)
To be able to use a string slice to represent the CharIterator, a function `slice_unchecked` is added, that does the same as `slice_bytes` but without any boundary checks.
It would be possible to implement CharIterator with pointer arithmetic to make it *much more efficient*, but since vec iterator is still improving, it's too early to attempt to re-implement it in other places. Hopefully CharIterator can be implemented on top of vec iterator without any unsafe code later.
Additional changes fix the documentation about null termination.
Let CharIterator be a separate type from CharOffsetIterator (so that
CharIterator can be cloned, for example).
Implement CharOffsetIterator by using the same technique as the method
subslice_offset.
Add a function like raw::slice_bytes, but it doesn't check slice
boundaries. For iterator use where we always know the begin, end indices
are in range.
I need `Clone` for `Tm` for my latest work on [rust-http](https://github.com/chris-morgan/rust-http) (static typing for headers, and headers like `Date` are a time), so here it is.
@huonw recommended deriving DeepClone while I was at it.
I also had to implement `DeepClone` for `~str` to get a derived implementation of `DeepClone` for `Tm`; I did `@str` while I was at it, for consistency.
If they are on the trait then it is extremely annoying to use them as
generic parameters to a function, e.g. with the iterator param on the trait
itself, if one was to pass an Extendable<int> to a function that filled it
either from a Range or a Map<VecIterator>, one needs to write something
like:
fn foo<E: Extendable<int, Range<int>> +
Extendable<int, Map<&'self int, int, VecIterator<int>>>
(e: &mut E, ...) { ... }
since using a generic, i.e. `foo<E: Extendable<int, I>, I: Iterator<int>>`
means that `foo` takes 2 type parameters, and the caller has to specify them
(which doesn't work anyway, as they'll mismatch with the iterators used in
`foo` itself).
This patch changes it to:
fn foo<E: Extendable<int>>(e: &mut E, ...) { ... }
If they are on the trait then it is extremely annoying to use them as
generic parameters to a function, e.g. with the iterator param on the trait
itself, if one was to pass an Extendable<int> to a function that filled it
either from a Range or a Map<VecIterator>, one needs to write something
like:
fn foo<E: Extendable<int, Range<int>> +
Extendable<int, Map<&'self int, int, VecIterator<int>>>
(e: &mut E, ...) { ... }
since using a generic, i.e. `foo<E: Extendable<int, I>, I: Iterator<int>>`
means that `foo` takes 2 type parameters, and the caller has to specify them
(which doesn't work anyway, as they'll mismatch with the iterators used in
`foo` itself).
This patch changes it to:
fn foo<E: Extendable<int>>(e: &mut E, ...) { ... }
This includes a number of improvements to `ifmt!`
* Implements formatting arguments -- `{:0.5x}` works now
* Formatting now works on all integer widths, not just `int` and `uint`
* Added a large doc block to `std::fmt` which should help explain what `ifmt!` is all about
* Added floating point formatters, although they have the same pitfalls from before (they're just proof-of-concept now)
Closed a couple of issues along the way, yay! Once this gets into a snapshot, I'll start looking into removing all of `fmt`
