v1.10.4

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v1.10.3

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===================
This is a new patch release that fixes the feature configuration of optional
dependencies, and fixes an unsound use of bounds check elision.

Bug fixes:

• BUG #​1147:
  Set default-features=false for the memchr and aho-corasick dependencies.
• BUG #​1154:
  Fix unsound bounds check elision.

v1.10.2

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===================
This is a new patch release that fixes a search regression where incorrect
matches could be reported.

Bug fixes:

• BUG #​1110:
  Revert broadening of reverse suffix literal optimization introduced in 1.10.1.

v1.10.1

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===================
This is a new patch release with a minor increase in the number of valid
patterns and a broadening of some literal optimizations.

New features:

• FEATURE 04f5d7be:
  Loosen ASCII-compatible rules such that regexes like (?-u:☃) are now allowed.

Performance improvements:

• PERF 8a8d599f:
  Broader the reverse suffix optimization to apply in more cases.

v1.10.0

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===================
This is a new minor release of regex that adds support for start and end
word boundary assertions. That is, \< and \>. The minimum supported Rust
version has also been raised to 1.65, which was released about one year ago.

The new word boundary assertions are:

• \< or \b{start}: a Unicode start-of-word boundary (\W|\A on the left,
  \w on the right).
• \> or \b{end}: a Unicode end-of-word boundary (\w on the left, \W|\z
  on the right)).
• \b{start-half}: half of a Unicode start-of-word boundary (\W|\A on the
  left).
• \b{end-half}: half of a Unicode end-of-word boundary (\W|\z on the
  right).

The \< and \> are GNU extensions to POSIX regexes. They have been added
to the regex crate because they enjoy somewhat broad support in other regex
engines as well (for example, vim). The \b{start} and \b{end} assertions
are aliases for \< and \>, respectively.

The \b{start-half} and \b{end-half} assertions are not found in any
other regex engine (although regex engines with general look-around support
can certainly express them). They were added principally to support the
implementation of word matching in grep programs, where one generally wants to
be a bit more flexible in what is considered a word boundary.

New features:

• FEATURE #​469:
  Add support for \< and \> word boundary assertions.
• FEATURE(regex-automata) #​1031:
  DFAs now have a start_state method that doesn't use an Input.

Performance improvements:

• PERF #​1051:
  Unicode character class operations have been optimized in regex-syntax.
• PERF #​1090:
  Make patterns containing lots of literal characters use less memory.

Bug fixes:

• BUG #​1046:
  Fix a bug that could result in incorrect match spans when using a Unicode word
  boundary and searching non-ASCII strings.
• BUG(regex-syntax) #​1047:
  Fix panics that can occur in Ast->Hir translation (not reachable from regex
  crate).
• BUG(regex-syntax) #​1088:
  Remove guarantees in the API that connect the u flag with a specific HIR
  representation.

regex-automata breaking change release:

This release includes a regex-automata 0.4.0 breaking change release, which
was necessary in order to support the new word boundary assertions. For
example, the Look enum has new variants and the LookSet type now uses u32
instead of u16 to represent a bitset of look-around assertions. These are
overall very minor changes, and most users of regex-automata should be able
to move to 0.4 from 0.3 without any changes at all.

regex-syntax breaking change release:

This release also includes a regex-syntax 0.8.0 breaking change release,
which, like regex-automata, was necessary in order to support the new word
boundary assertions. This release also includes some changes to the Ast
type to reduce heap usage in some cases. If you are using the Ast type
directly, your code may require some minor modifications. Otherwise, users of
regex-syntax 0.7 should be able to migrate to 0.8 without any code changes.

regex-lite release:

The regex-lite 0.1.1 release contains support for the new word boundary
assertions. There are no breaking changes.

v1.9.6

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==================
This is a patch release that fixes a panic that can occur when the default
regex size limit is increased to a large number.

• BUG aa4e4c71:
  Fix a bug where computing the maximum haystack length for the bounded
  backtracker could result underflow and thus provoke a panic later in a search
  due to a broken invariant.

v1.9.5

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==================
This is a patch release that hopefully mostly fixes a performance bug that
occurs when sharing a regex across multiple threads.

Issue #​934
explains this in more detail. It is also noted in the crate
documentation.
The bug can appear when sharing a regex across multiple threads simultaneously,
as might be the case when using a regex from a OnceLock, lazy_static or
similar primitive. Usually high contention only results when using many threads
to execute searches on small haystacks.

One can avoid the contention problem entirely through one of two methods.
The first is to use lower level APIs from regex-automata that require passing
state explicitly, such as meta::Regex::search_with.
The second is to clone a regex and send it to other threads explicitly. This
will not use any additional memory usage compared to sharing the regex. The
only downside of this approach is that it may be less convenient, for example,
it won't work with things like OnceLock or lazy_static or once_cell.

With that said, as of this release, the contention performance problems have
been greatly reduced. This was achieved by changing the free-list so that it
was sharded across threads, and that ensuring each sharded mutex occupies a
single cache line to mitigate false sharing. So while contention may still
impact performance in some cases, it should be a lot better now.

Because of the changes to how the free-list works, please report any issues you
find with this release. That not only includes search time regressions but also
significant regressions in memory usage. Reporting improvements is also welcome
as well! If possible, provide a reproduction.

Bug fixes:

• BUG #​934:
  Fix a performance bug where high contention on a single regex led to massive
  slow downs.

v1.9.4

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==================
This is a patch release that fixes a bug where RegexSet::is_match(..) could
incorrectly return false (even when RegexSet::matches(..).matched_any()
returns true).

Bug fixes:

• BUG #​1070:
  Fix a bug where a prefilter was incorrectly configured for a RegexSet.

v1.9.3

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==================
This is a patch release that fixes a bug where some searches could result in
incorrect match offsets being reported. It is difficult to characterize the
types of regexes susceptible to this bug. They generally involve patterns
that contain no prefix or suffix literals, but have an inner literal along with
a regex prefix that can conditionally match.

Bug fixes:

• BUG #​1060:
  Fix a bug with the reverse inner literal optimization reporting incorrect match
  offsets.

v1.9.2

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==================
This is a patch release that fixes another memory usage regression. This
particular regression occurred only when using a RegexSet. In some cases,
much more heap memory (by one or two orders of magnitude) was allocated than in
versions prior to 1.9.0.

Bug fixes:

• BUG #​1059:
  Fix a memory usage regression when using a RegexSet.

v1.9.1

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==================
This is a patch release which fixes a memory usage regression. In the regex
1.9 release, one of the internal engines used a more aggressive allocation
strategy than what was done previously. This patch release reverts to the
prior on-demand strategy.

Bug fixes:

• BUG #​1027:
  Change the allocation strategy for the backtracker to be less aggressive.

v1.9.0

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==================
This release marks the end of a years long rewrite of the regex crate
internals. Since this is
such a big release, please report any issues or regressions you find. We would
also love to hear about improvements as well.

In addition to many internal improvements that should hopefully result in
"my regex searches are faster," there have also been a few API additions:

• A new Captures::extract method for quickly accessing the substrings
  that match each capture group in a regex.
• A new inline flag, R, which enables CRLF mode. This makes . match any
  Unicode scalar value except for \r and \n, and also makes (?m:^) and
  (?m:$) match after and before both \r and \n, respectively, but never
  between a \r and \n.
• RegexBuilder::line_terminator was added to further customize the line
  terminator used by (?m:^) and (?m:$) to be any arbitrary byte.
• The std Cargo feature is now actually optional. That is, the regex crate
  can be used without the standard library.
• Because regex 1.9 may make binary size and compile times even worse, a
  new experimental crate called regex-lite has been published. It prioritizes
  binary size and compile times over functionality (like Unicode) and
  performance. It shares no code with the regex crate.

New features:

• FEATURE #​244:
  One can opt into CRLF mode via the R flag.
  e.g., (?mR:$) matches just before \r\n.
• FEATURE #​259:
  Multi-pattern searches with offsets can be done with regex-automata 0.3.
• FEATURE #​476:
  std is now an optional feature. regex may be used with only alloc.
• FEATURE #​644:
  RegexBuilder::line_terminator configures how (?m:^) and (?m:$) behave.
• FEATURE #​675:
  Anchored search APIs are now available in regex-automata 0.3.
• FEATURE #​824:
  Add new Captures::extract method for easier capture group access.
• FEATURE #​961:
  Add regex-lite crate with smaller binary sizes and faster compile times.
• FEATURE #​1022:
  Add TryFrom implementations for the Regex type.

Performance improvements:

• PERF #​68:
  Added a one-pass DFA engine for faster capture group matching.
• PERF #​510:
  Inner literals are now used to accelerate searches, e.g., \w+@​\w+ will scan
  for @.
• PERF #​787,
  PERF #​891:
  Makes literal optimizations apply to regexes of the form \b(foo|bar|quux)\b.

(There are many more performance improvements as well, but not all of them have
specific issues devoted to them.)

Bug fixes:

• BUG #​429:
  Fix matching bugs related to \B and inconsistencies across internal engines.
• BUG #​517:
  Fix matching bug with capture groups.
• BUG #​579:
  Fix matching bug with word boundaries.
• BUG #​779:
  Fix bug where some regexes like (re)+ were not equivalent to (re)(re)*.
• BUG #​850:
  Fix matching bug inconsistency between NFA and DFA engines.
• BUG #​921:
  Fix matching bug where literal extraction got confused by $.
• BUG #​976:
  Add documentation to replacement routines about dealing with fallibility.
• BUG #​1002:
  Use corpus rejection in fuzz testing.

v1.8.4

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==================
This is a patch release that fixes a bug where (?-u:\B) was allowed in
Unicode regexes, despite the fact that the current matching engines can report
match offsets between the code units of a single UTF-8 encoded codepoint. That
in turn means that match offsets that split a codepoint could be reported,
which in turn results in panicking when one uses them to slice a &str.

This bug occurred in the transition to regex 1.8 because the underlying
syntactical error that prevented this regex from compiling was intentionally
removed. That's because (?-u:\B) will be permitted in Unicode regexes in
regex 1.9, but the matching engines will guarantee to never report match
offsets that split a codepoint. When the underlying syntactical error was
removed, no code was added to ensure that (?-u:\B) didn't compile in the
regex 1.8 transition release. This release, regex 1.8.4, adds that code
such that Regex::new(r"(?-u:\B)") returns to the regex <1.8 behavior of
not compiling. (A bytes::Regex can still of course compile it.)

Bug fixes:

• BUG #​1006:
  Fix a bug where (?-u:\B) was allowed in Unicode regexes, and in turn could
  lead to match offsets that split a codepoint in &str.

v1.8.3

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==================
This is a patch release that fixes a bug where the regex would report a
match at every position even when it shouldn't. This could occur in a very
small subset of regexes, usually an alternation of simple literals that
have particular properties. (See the issue linked below for a more precise
description.)

Bug fixes:

• BUG #​999:
  Fix a bug where a match at every position is erroneously reported.

v1.8.2

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==================
This is a patch release that fixes a bug where regex compilation could panic
in debug mode for regexes with large counted repetitions. For example,
a{2147483516}{2147483416}{5} resulted in an integer overflow that wrapped
in release mode but panicking in debug mode. Despite the unintended wrapping
arithmetic in release mode, it didn't cause any other logical bugs since the
errant code was for new analysis that wasn't used yet.

Bug fixes:

• BUG #​995:
  Fix a bug where regex compilation with large counted repetitions could panic.

v1.8.1

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==================
This is a patch release that fixes a bug where a regex match could be reported
where none was found. Specifically, the bug occurs when a pattern contains some
literal prefixes that could be extracted and an optional word boundary in the
prefix.

Bug fixes:

• BUG #​981:
  Fix a bug where a word boundary could interact with prefix literal
  optimizations and lead to a false positive match.

v1.8.0

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==================
This is a sizeable release that will be soon followed by another sizeable
release. Both of them will combined close over 40 existing issues and PRs.

This first release, despite its size, essentially represents preparatory work
for the second release, which will be even bigger. Namely, this release:

• Increases the MSRV to Rust 1.60.0, which was released about 1 year ago.
• Upgrades its dependency on aho-corasick to the recently released 1.0
  version.
• Upgrades its dependency on regex-syntax to the simultaneously released
  0.7 version. The changes to regex-syntax principally revolve around a
  rewrite of its literal extraction code and a number of simplifications and
  optimizations to its high-level intermediate representation (HIR).

The second release, which will follow ~shortly after the release above, will
contain a soup-to-nuts rewrite of every regex engine. This will be done by
bringing regex-automata into
this repository, and then changing the regex crate to be nothing but an API
shim layer on top of regex-automata's API.

These tandem releases are the culmination of about 3
years of on-and-off work that began in earnest in March
2020.

Because of the scale of changes involved in these releases, I would love to
hear about your experience. Especially if you notice undocumented changes in
behavior or performance changes (positive or negative).

Most changes in the first release are listed below. For more details, please
see the commit log, which reflects a linear and decently documented history
of all changes.

New features:

• FEATURE #​501:
  Permit many more characters to be escaped, even if they have no significance.
  More specifically, any ASCII character except for [0-9A-Za-z<>] can now be
  escaped. Also, a new routine, is_escapeable_character, has been added to
  regex-syntax to query whether a character is escapeable or not.
• FEATURE #​547:
  Add Regex::captures_at. This fills a hole in the API, but doesn't otherwise
  introduce any new expressive power.
• FEATURE #​595:
  Capture group names are now Unicode-aware. They can now begin with either a _
  or any "alphabetic" codepoint. After the first codepoint, subsequent codepoints
  can be any sequence of alpha-numeric codepoints, along with _, ., [ and
  ]. Note that replacement syntax has not changed.
• FEATURE #​810:
  Add Match::is_empty and Match::len APIs.
• FEATURE #​905:
  Add an impl Default for RegexSet, with the default being the empty set.
• FEATURE #​908:
  A new method, Regex::static_captures_len, has been added which returns the
  number of capture groups in the pattern if and only if every possible match
  always contains the same number of matching groups.
• FEATURE #​955:
  Named captures can now be written as (?<name>re) in addition to
  (?P<name>re).
• FEATURE: regex-syntax now supports empty character classes.
• FEATURE: regex-syntax now has an optional std feature. (This will come
  to regex in the second release.)
• FEATURE: The Hir type in regex-syntax has had a number of simplifications
  made to it.
• FEATURE: regex-syntax has support for a new R flag for enabling CRLF
  mode. This will be supported in regex proper in the second release.
• FEATURE: regex-syntax now has proper support for "regex that never
  matches" via Hir::fail().
• FEATURE: The hir::literal module of regex-syntax has been completely
  re-worked. It now has more documentation, examples and advice.
• FEATURE: The allow_invalid_utf8 option in regex-syntax has been renamed
  to utf8, and the meaning of the boolean has been flipped.

Performance improvements:

• PERF: The upgrade to aho-corasick 1.0 may improve performance in some
  cases. It's difficult to characterize exactly which patterns this might impact,
  but if there are a small number of longish (>= 4 bytes) prefix literals, then
  it might be faster than before.

Bug fixes:

• BUG #​514:
  Improve Debug impl for Match so that it doesn't show the entire haystack.
• BUGS #​516,
  #​731:
  Fix a number of issues with printing Hir values as regex patterns.
• BUG #​610:
  Add explicit example of foo|bar in the regex syntax docs.
• BUG #​625:
  Clarify that SetMatches::len does not (regretably) refer to the number of
  matches in the set.
• BUG #​660:
  Clarify "verbose mode" in regex syntax documentation.
• BUG #​738,
  #​950:
  Fix CaptureLocations::get so that it never panics.
• BUG #​747:
  Clarify documentation for Regex::shortest_match.
• BUG #​835:
  Fix \p{Sc} so that it is equivalent to \p{Currency_Symbol}.
• BUG #​846:
  Add more clarifying documentation to the CompiledTooBig error variant.
• BUG #​854:
  Clarify that regex::Regex searches as if the haystack is a sequence of
  Unicode scalar values.
• BUG #​884:
  Replace __Nonexhaustive variants with #[non_exhaustive] attribute.
• BUG #​893:
  Optimize case folding since it can get quite slow in some pathological cases.
• BUG #​895:
  Reject (?-u:\W) in regex::Regex APIs.
• BUG #​942:
  Add a missing void keyword to indicate "no parameters" in C API.
• BUG #​965:
  Fix \p{Lc} so that it is equivalent to \p{Cased_Letter}.
• BUG #​975:
  Clarify documentation for \pX syntax.

v1.7.3

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==================
This is a small release that fixes a bug in Regex::shortest_match_at that
could cause it to panic, even when the offset given is valid.

Bug fixes:

• BUG #​969:
  Fix a bug in how the reverse DFA was called for Regex::shortest_match_at.

v1.7.2

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==================
This is a small release that fixes a failing test on FreeBSD.

Bug fixes:

• BUG #​967:
  Fix "no stack overflow" test which can fail due to the small stack size.

v1.7.1

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==================
This release was done principally to try and fix the doc.rs rendering for the
regex crate.

Performance improvements:

• PERF #​930:
  Optimize replacen. This also applies to replace, but not replace_all.

Bug fixes:

• BUG #​945:
  Maybe fix rustdoc rendering by just bumping a new release?

v1.7.0

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==================
This release principally includes an upgrade to Unicode 15.

New features:

• FEATURE #​832:
  Upgrade to Unicode 15.

v1.6.0

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==================
This release principally includes an upgrade to Unicode 14.

New features:

• FEATURE #​832:
  Clarify that Captures::len includes all groups, not just matching groups.
• FEATURE #​857:
  Add an ExactSizeIterator impl for SubCaptureMatches.
• FEATURE #​861:
  Improve RegexSet documentation examples.
• FEATURE #​877:
  Upgrade to Unicode 14.

Bug fixes:

• BUG #​792:
  Fix error message rendering bug.

v1.5.6

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==================
This release includes a few bug fixes, including a bug that produced incorrect
matches when a non-greedy ? operator was used.

• BUG #​680:
  Fixes a bug where [[:alnum:][:^ascii:]] dropped [:alnum:] from the class.
• BUG #​859:
  Fixes a bug where Hir::is_match_empty returned false for \b.
• BUG #​862:
  Fixes a bug where 'ab??' matches 'ab' instead of 'a' in 'ab'.

v1.5.5

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==================
This releases fixes a security bug in the regex compiler. This bug permits a
vector for a denial-of-service attack in cases where the regex being compiled
is untrusted. There are no known problems where the regex is itself trusted,
including in cases of untrusted haystacks.

• SECURITY #GHSA-m5pq-gvj9-9vr8:
  Fixes a bug in the regex compiler where empty sub-expressions subverted the
  existing mitigations in place to enforce a size limit on compiled regexes.
  The Rust Security Response WG published an advisory about this:
  https://groups.google.com/g/rustlang-security-announcements/c/NcNNL1Jq7Yw

v1.5.4

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==================
This release fixes another compilation failure when building regex. This time,
the fix is for when the pattern feature is enabled, which only works on
nightly Rust. CI has been updated to test this case.

• BUG #​772:
  Fix build when pattern feature is enabled.

v1.5.3

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==================
This releases fixes a bug when building regex with only the unicode-perl
feature. It turns out that while CI was building this configuration, it wasn't
actually failing the overall build on a failed compilation.

• BUG #​769:
  Fix build in regex-syntax when only the unicode-perl feature is enabled.

v1.5.2

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==================
This release fixes a performance bug when Unicode word boundaries are used.
Namely, for certain regexes on certain inputs, it's possible for the lazy DFA
to stop searching (causing a fallback to a slower engine) when it doesn't
actually need to.

PR #​768 fixes the bug, which was
originally reported in
ripgrep#1860.

v1.5.1

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==================
This is a patch release that fixes a compilation error when the perf-literal
feature is not enabled.

v1.5.0

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==================
This release primarily updates to Rust 2018 (finally) and bumps the MSRV to
Rust 1.41 (from Rust 1.28). Rust 1.41 was chosen because it's still reasonably
old, and is what's in Debian stable at the time of writing.

This release also drops this crate's own bespoke substring search algorithms
in favor of a new
memmem implementation provided by the memchr crate.
This will change the performance profile of some regexes, sometimes getting a
little worse, and hopefully more frequently, getting a lot better. Please
report any serious performance regressions if you find them.

v1.4.6

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==================
This is a small patch release that fixes the compiler's size check on how much
heap memory a regex uses. Previously, the compiler did not account for the
heap usage of Unicode character classes. Now it does. It's possible that this
may make some regexes fail to compile that previously did compile. If that
happens, please file an issue.

• BUG OSS-fuzz#33579:
  Some regexes can use more heap memory than one would expect.

v1.4.5

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==================
This is a small patch release that fixes a regression in the size of a Regex
in the 1.4.4 release. Prior to 1.4.4, a Regex was 552 bytes. In the 1.4.4
release, it was 856 bytes due to internal changes. In this release, a Regex
is now 16 bytes. In general, the size of a Regex was never something that was
on my radar, but this increased size in the 1.4.4 release seems to have crossed
a threshold and resulted in stack overflows in some programs.

• BUG #​750:
  Fixes stack overflows seemingly caused by a large Regex size by decreasing
  its size.

v1.4.4

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==================
This is a small patch release that contains some bug fixes. Notably, it also
drops the thread_local (and lazy_static, via transitivity) dependencies.

Bug fixes:

• BUG #​362:
  Memory leaks caused by an internal caching strategy should now be fixed.
• BUG #​576:
  All regex types now implement UnwindSafe and RefUnwindSafe.
• BUG #​728:
  Add missing Replacer impls for Vec<u8>, String, Cow, etc.

v1.4.3

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==================
This is a small patch release that adds some missing standard trait
implementations for some types in the public API.

Bug fixes:

• BUG #​734:
  Add FusedIterator and ExactSizeIterator impls to iterator types.
• BUG #​735:
  Add missing Debug impls to public API types.

v1.4.2

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==================
This is a small bug fix release that bans \P{any}. We previously banned empty
classes like [^\w\W], but missed the \P{any} case. In the future, we hope
to permit empty classes.

• BUG #​722:
  Ban \P{any} to avoid a panic in the regex compiler. Found by OSS-Fuzz.

v1.4.1

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==================
This is a small bug fix release that makes \p{cf} work. Previously, it would
report "property not found" even though cf is a valid abbreviation for the
Format general category.

• BUG #​719:
  Fixes bug that prevented \p{cf} from working.

v1.4.0

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==================
This releases has a few minor documentation fixes as well as some very minor
API additions. The MSRV remains at Rust 1.28 for now, but this is intended to
increase to at least Rust 1.41.1 soon.

This release also adds support for OSS-Fuzz. Kudos to
@​DavidKorczynski
for doing the heavy lifting for that!

New features:

• FEATURE #​649:
  Support [, ] and . in capture group names.
• FEATURE #​687:
  Add is_empty predicate to RegexSet.
• FEATURE #​689:
  Implement Clone for SubCaptureMatches.
• FEATURE #​715:
  Add empty constructor to RegexSet for convenience.

Bug fixes:

• BUG #​694:
  Fix doc example for Replacer::replace_append.
• BUG #​698:
  Clarify docs for s flag when using a bytes::Regex.
• BUG #​711:
  Clarify is_match docs to indicate that it can match anywhere in string.

v1.3.9

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==================
This release fixes a MSRV (Minimum Support Rust Version) regression in the
1.3.8 release. Namely, while 1.3.8 compiles on Rust 1.28, it actually does not
compile on other Rust versions, such as Rust 1.39.

Bug fixes:

• BUG #​685:
  Remove use of doc_comment crate, which cannot be used before Rust 1.43.

v1.3.8

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==================
This release contains a couple of important bug fixes driven
by better support for empty-subexpressions in regexes. For
example, regexes like b| are now allowed. Major thanks to
@​sliquister for implementing support for this
in #​677.

Bug fixes:

• BUG #​523:
  Add note to documentation that spaces can be escaped in x mode.
• BUG #​524:
  Add support for empty sub-expressions, including empty alternations.
• BUG #​659:
  Fix match bug caused by an empty sub-expression miscompilation.

v1.3.7

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==================
This release contains a small bug fix that fixes how regex forwards crate
features to regex-syntax. In particular, this will reduce recompilations in
some cases.

Bug fixes:

• BUG #​665:
  Fix feature forwarding to regex-syntax.

v1.3.6

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==================
This release contains a sizable (~30%) performance improvement when compiling
some kinds of large regular expressions.

Performance improvements:

• PERF #​657:
  Improvement performance of compiling large regular expressions.

v1.3.5

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==================
This release updates this crate to Unicode 13.

New features:

• FEATURE #​653:
  Update regex-syntax to Unicode 13.

v1.3.4

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==================
This is a small bug fix release that fixes a bug related to the scoping of
flags in a regex. Namely, before this fix, a regex like ((?i)a)b) would
match aB despite the fact that b should not be matched case insensitively.

Bug fixes:

• BUG #​640:
  Fix bug related to the scoping of flags in a regex.

v1.3.3

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This is a small maintenance release that upgrades the dependency on
thread_local from 0.3 to 1.0. The minimum supported Rust version remains
at Rust 1.28.

v1.3.2

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This is a small maintenance release with some house cleaning and bug fixes.

New features:

• FEATURE #​631:
  Add a Match::range method an a From<Match> for Range impl.

Bug fixes:

• BUG #​521:
  Corrects /-/.splitn("a", 2) to return ["a"] instead of ["a", ""].
• BUG #​594:
  Improve error reporting when writing \p\.
• BUG #​627:
  Corrects /-/.split("a-") to return ["a", ""] instead of ["a"].
• BUG #​633:
  Squash deprecation warnings for the std::error::Error::description method.

v1.3.1

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This is a maintenance release with no changes in order to try to work-around
a docs.rs/Cargo issue.

v1.3.0

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This release adds a plethora of new crate features that permit users of regex
to shrink its size considerably, in exchange for giving up either functionality
(such as Unicode support) or runtime performance. When all such features are
disabled, the dependency tree for regex shrinks to exactly 1 crate
(regex-syntax). More information about the new crate features can be
found in the docs.

Note that while this is a new minor version release, the minimum supported
Rust version for this crate remains at 1.28.0.

New features:

• FEATURE #​474:
  The use_std feature has been deprecated in favor of the std feature.
  The use_std feature will be removed in regex 2. Until then, use_std will
  remain as an alias for the std feature.
• FEATURE #​583:
  Add a substantial number of crate features shrinking regex.

v1.2.1

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This release does a bit of house cleaning. Namely:

• This repository is now using rustfmt.
• License headers have been removed from all files, in following suit with the
  Rust project.
• Teddy has been removed from the regex crate, and is now part of the
  aho-corasick crate.
  See aho-corasick's new packed sub-module for details.
• The utf8-ranges crate has been deprecated, with its functionality moving
  into the
  utf8 sub-module of regex-syntax.
• The ucd-util dependency has been dropped, in favor of implementing what
  little we need inside of regex-syntax itself.

In general, this is part of an ongoing (long term) effort to make optimizations
in the regex engine easier to reason about. The current code is too convoluted
and thus it is very easy to introduce new bugs. This simplification effort is
the primary motivation behind re-working the aho-corasick crate to not only
bundle algorithms like Teddy, but to also provide regex-like match semantics
automatically.

Moving forward, the plan is to join up with the bstr and regex-automata
crates, with the former providing more sophisticated substring search
algorithms (thereby deleting existing code in regex) and the latter providing
ahead-of-time compiled DFAs for cases where they are inexpensive to compute.

v1.2.0

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This release updates regex's minimum supported Rust version to 1.28, which was
release almost 1 year ago. This release also updates regex's Unicode data
tables to 12.1.0.

v1.1.9

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This release contains a bug fix that caused regex's tests to fail, due to a
dependency on an unreleased behavior in regex-syntax.

• BUG #​593:
  Move an integration-style test on error messages into regex-syntax.

v1.1.8

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This release contains a few small internal refactorings. One of which fixes
an instance of undefined behavior in a part of the SIMD code.

Bug fixes:

• BUG #​545:
  Improves error messages when a repetition operator is used without a number.
• BUG #​588:
  Removes use of a repr(Rust) union used for type punning in the Teddy matcher.
• BUG #​591:
  Update docs for running benchmarks and improve failure modes.

v1.1.7

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This release fixes up a few warnings as a result of recent deprecations.

v1.1.6

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This release fixes a regression introduced by a bug fix (for
BUG #​557) which could cause
the regex engine to enter an infinite loop. This bug was originally
reported against ripgrep.

v1.1.5

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This release fixes a bug in regex's dependency specification where it requires
a newer version of regex-syntax, but this wasn't communicated correctly in the
Cargo.toml. This would have been caught by a minimal version check, but this
check was disabled because the rand crate itself advertises incorrect
dependency specifications.

Bug fixes:

• BUG #​570:
  Fix regex-syntax minimal version.

v1.1.4

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This release fixes a backwards compatibility regression where Regex was no
longer UnwindSafe. This was caused by the upgrade to aho-corasick 0.7, whose
AhoCorasick type was itself not UnwindSafe. This has been fixed in aho-corasick
0.7.4, which we now require.

Bug fixes:

• BUG #​568:
  Fix an API regression where Regex was no longer UnwindSafe.

v1.1.3

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This releases fixes a few bugs and adds a performance improvement when a regex
is a simple alternation of literals.

Performance improvements:

• OPT #​566:
  Upgrades aho-corasick to 0.7 and uses it for foo|bar|...|quux regexes.

Bug fixes:

• BUG #​527:
  Fix a bug where the parser would panic on patterns like ((?x)).
• BUG #​555:
  Fix a bug where the parser would panic on patterns like (?m){1,1}.
• BUG #​557:
  Fix a bug where captures could lead to an incorrect match.

v1.1.2

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This release fixes a bug found in the fix introduced in 1.1.1.

Bug fixes:

• BUG edf45e6f:
  Fix bug introduced in reverse suffix literal matcher in the 1.1.1 release.

v1.1.1

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This is a small release with one fix for a bug caused by literal optimizations.

Bug fixes:

• BUG 661bf53d:
  Fixes a bug in the reverse suffix literal optimization. This was originally
  reported
  against ripgrep.

v1.1.0

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This is a small release with a couple small enhancements. This release also
increases the minimal supported Rust version (MSRV) to 1.24.1 (from 1.20.0). In
accordance with this crate's MSRV policy, this release bumps the minor version
number.

Performance improvements:

• OPT #​511,
  OPT #​540:
  Improve lazy DFA construction for large regex sets.

New features:

• FEATURE #​538:
  Add Emoji and "break" Unicode properties. See UNICODE.md.

Bug fixes:

• BUG #​530:
  Add Unicode license (for data tables).
• Various typo/doc fixups.

v1.0.6

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This is a small release.

Performance improvements:

• OPT #​513:
  Improve performance of compiling large Unicode classes by 8-10%.

Bug fixes:

• BUG #​533:
  Fix definition of [[:blank:]] class that regressed in regex-syntax 0.5.

v1.0.5

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This is a small release with an API enhancement.

New features:

• FEATURE #​509:
  Generalize impls of the Replacer trait.

v1.0.4

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This is a small release that bumps the quickcheck dependency.

v1.0.3

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This is a small bug fix release.

Bug fixes:

• BUG #​504:
  Fix for Cargo's "minimal version" support.
• BUG 1e39165f:
  Fix doc examples for byte regexes.

v1.0.2

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This release exposes some new lower level APIs on Regex that permit
amortizing allocation and controlling the location at which a search is
performed in a more granular way. Most users of the regex crate will not
need or want to use these APIs.

New features:

• FEATURE #​493:
  Add a few lower level APIs for amortizing allocation and more fine grained
  searching.

Bug fixes:

• BUG 3981d2ad:
  Correct outdated documentation on RegexBuilder::dot_matches_new_line.
• BUG 7ebe4ae0:
  Correct outdated documentation on Parser::allow_invalid_utf8 in the
  regex-syntax crate.
• BUG 24c7770b:
  Fix a bug in the HIR printer where it wouldn't correctly escape meta
  characters in character classes.

v1.0.1

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This release upgrades regex's Unicode tables to Unicode 11, and enables SIMD
optimizations automatically on Rust stable (1.27 or newer).

New features:

• FEATURE #​486:
  Implement size_hint on RegexSet match iterators.
• FEATURE #​488:
  Update Unicode tables for Unicode 11.
• FEATURE #​490:
  SIMD optimizations are now enabled automatically in Rust stable, for versions
  1.27 and up. No compilation flags or features need to be set. CPU support
  SIMD is detected automatically at runtime.

Bug fixes:

• BUG #​482:
  Present a better compilation error when the use_std feature isn't used.