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regex v0.2.0 Release Notes

  • 🚀 This is a new major release of the regex crate, and is an implementation of the regex 1.0 RFC. We are releasing a 0.2 first, and if there are no major problems, we will 👌 release a 1.0 shortly. For 0.2, the minimum supported Rust version is 1.12.

    💥 There are a number of breaking changes in 0.2. They are split into two types. The first type correspond to breaking changes in regular expression syntax. The second type correspond to breaking changes in the API.

    💥 Breaking changes for regex syntax:

    • POSIX character classes now require double bracketing. Previously, the regex [:upper:] would parse as the upper POSIX character class. Now it parses as the character class containing the characters :upper:. The fix to this change is to use [[:upper:]] instead. Note that variants like [[:upper:][:blank:]] continue to work.
    • The character [ must always be escaped inside a character class.
    • The characters &, - and ~ must be escaped if any one of them are repeated consecutively. For example, [&], [\&], [\&\&], [&-&] are all equivalent while [&&] is illegal. (The motivation for this and the prior change is to provide a backwards compatible path for adding character class set notation.)
    • 0️⃣ A bytes::Regex now has Unicode mode enabled by default (like the main Regex type). This means regexes compiled with bytes::Regex::new that don't have the Unicode flag set should add (?-u) to recover the original behavior.

    💥 Breaking changes for the regex API:

    • find and find_iter now return Match values instead of (usize, usize). Match values have start and end methods, which return the match offsets. Match values also have an as_str method, which returns the text of the match itself.
    • The Captures type now only provides a single iterator over all capturing matches, which should replace uses of iter and iter_pos. Uses of iter_named should use the capture_names method on Regex.
    • The at method on the Captures type has been renamed to get, and it now returns a Match. Similarly, the name method on Captures now returns a Match.
    • The replace methods now return Cow values. The Cow::Borrowed variant is returned when no replacements are made.
    • The Replacer trait has been completely overhauled. This should only impact clients that implement this trait explicitly. Standard uses of the replace methods should continue to work unchanged. If you implement the Replacer trait, please consult the new documentation.
    • 🆓 The quote free function has been renamed to escape.
    • The Regex::with_size_limit method has been removed. It is replaced by RegexBuilder::size_limit.
    • The RegexBuilder type has switched from owned self method receivers to &mut self method receivers. Most uses will continue to work unchanged, but some code may require naming an intermediate variable to hold the builder.
    • 🏗 The compile method on RegexBuilder has been renamed to build.
    • 🚚 The free is_match function has been removed. It is replaced by compiling a Regex and calling its is_match method.
    • The PartialEq and Eq impls on Regex have been dropped. If you relied on these impls, the fix is to define a wrapper type around Regex, impl Deref on it and provide the necessary impls.
    • 🚚 The is_empty method on Captures has been removed. This always returns false, so its use is superfluous.
    • The Syntax variant of the Error type now contains a string instead of a regex_syntax::Error. If you were examining syntax errors more closely, you'll need to explicitly use the regex_syntax crate to re-parse the regex.
    • 🚚 The InvalidSet variant of the Error type has been removed since it is no longer used.
    • Most of the iterator types have been renamed to match conventions. If you were using these iterator types explicitly, please consult the documentation for its new name. For example, RegexSplits has been renamed to Split.

    🛠 A number of bugs have been fixed:

    • BUG #151: The Replacer trait has been changed to permit the caller to control allocation.
    • BUG #165: Remove the free is_match function.
    • BUG #166: Expose more knobs (available in 0.1) and remove with_size_limit.
    • BUG #168: Iterators produced by Captures now have the correct lifetime parameters.
    • BUG #175: Fix a corner case in the parsing of POSIX character classes.
    • BUG #178: Drop the PartialEq and Eq impls on Regex.
    • BUG #179: Remove is_empty from Captures since it always returns false.
    • BUG #276: Position of named capture can now be retrieved from a Captures.
    • BUG #296: Remove winapi/kernel32-sys dependency on UNIX.
    • BUG #307: Fix error on emscripten.