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Behavior of \b word anchor when applied to non-word characters #1275

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learnbyexample opened this issue May 8, 2019 · 1 comment
Closed

Behavior of \b word anchor when applied to non-word characters #1275

learnbyexample opened this issue May 8, 2019 · 1 comment
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bug A bug. rollup A PR that has been merged with many others in a rollup.

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@learnbyexample
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What version of ripgrep are you using?

$ rg --version
ripgrep 11.0.1 (rev 1f1cd9b467)
-SIMD -AVX (compiled)
+SIMD -AVX (runtime)

How did you install ripgrep?

Using https://github.com/BurntSushi/ripgrep/releases/download/11.0.1/ripgrep_11.0.1_amd64.deb

What operating system are you using ripgrep on?

Ubuntu 16.04.1

Describe your question, feature request, or bug.

Behavior of \b word anchor applied on non-word characters is different than what is observed on other regex engines. I found this accidentally, wasn't a usecase I needed. But filing the issue anyway, incase this may be a bug.

If this is a bug, what are the steps to reproduce the behavior?

See example below.

If this is a bug, what is the actual behavior?

$ echo 'I have 12, he has 2!' | rg -o '\b..\b'
I 
12

If this is a bug, what is the expected behavior?

I feel ripgrep should also behave as seen in other regex engines.

$ # GNU grep 3.3
$ # grep -oP '\b..\b' and rg -oP '\b..\b' also produce same result
$ echo 'I have 12, he has 2!' | grep -o '\b..\b'
I 
12
, 
he
 2

$ echo 'I have 12, he has 2!' | perl -lne 'print join "|", /\b..\b/g'
I |12|, |he| 2
$ echo 'I have 12, he has 2!' | ruby -ne 'puts $_.scan(/\b..\b/).join("|")'
I |12|, |he| 2

$ # python3.7
>>> import re
>>> re.findall(r'\b..\b', 'I have 12, he has 2!')
['I ', '12', ', ', 'he', ' 2']

The below image might help in understanding what is happening in all these regex engines. Vertical bar represents word boundary. Note that even though ! is at end of line, it doesn't have boundary after as it is not a word character.

ripgrep_word_boundary

Note

  • grep -o '\<..\>' (also in vim) will be different compared to \b as \b cannot differentiate between start and end word boundary
  • grep -ow '..' is same as rg -ow '..' (perhaps because both do (?<!\w)pattern(?!\w) for -w option)
@BurntSushi
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Thanks for the report! This smells like a bug in the regex engine. I've filed an issue for it here: rust-lang/regex#579

@BurntSushi BurntSushi added the bug A bug. label May 8, 2019
@BurntSushi BurntSushi mentioned this issue May 8, 2019
Closed
@BurntSushi BurntSushi added the rollup A PR that has been merged with many others in a rollup. label Oct 9, 2023
BurntSushi added a commit that referenced this issue Oct 10, 2023
@BurntSushi
changelog: add bug fix for \b
36ba5fb 
This was probably fixed in a past commit where I bumped the regex engine
to 1.9 (or perhaps more precisely, regex-automata 0.3). But I didn't
track it as fixed at the time.

Fixes #1275
@sankalp-khare sankalp-khare mentioned this issue Nov 26, 2023
Merged
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this issue Nov 28, 2023
@0323pin
textproc/ripgrep: update to 14.0.2
3d89a00 
14.0.2 (2023-11-27)
===================
This is a patch release with a few small bug fixes.

Bug fixes:

* [BUG #2654](BurntSushi/ripgrep#2654):
  Fix `deb` release sha256 sum file.
* [BUG #2658](BurntSushi/ripgrep#2658):
  Fix partial regression in the behavior of `--null-data --line-regexp`.
* [BUG #2659](BurntSushi/ripgrep#2659):
  Fix Fish shell completions.
* [BUG #2662](BurntSushi/ripgrep#2662):
  Fix typo in documentation for `-i/--ignore-case`.


14.0.1 (2023-11-26)
===================
This a patch release meant to fix `cargo install ripgrep` on Windows.

Bug fixes:

* [BUG #2653](BurntSushi/ripgrep#2653):
  Include `pkg/windows/Manifest.xml` in crate package.


14.0.0 (2023-11-26)
===================
ripgrep 14 is a new major version release of ripgrep that has some new
features, performance improvements and a lot of bug fixes.

The headlining feature in this release is hyperlink support. In this release,
they are an opt-in feature but may change to an opt-out feature in the future.
To enable them, try passing `--hyperlink-format default`. If you use [VS Code],
then try passing `--hyperlink-format vscode`. Please [report your experience
with hyperlinks][report-hyperlinks], positive or negative.

[VS Code]: https://code.visualstudio.com/
[report-hyperlinks]: BurntSushi/ripgrep#2611

Another headlining development in this release is that it contains a rewrite
of its regex engine. You generally shouldn't notice any changes, except for
some searches may get faster. You can read more about the [regex engine rewrite
on my blog][regex-internals]. Please [report your performance improvements or
regressions that you notice][report-perf].

[report-perf]: BurntSushi/ripgrep#2652

Finally, ripgrep switched the library it uses for argument parsing. Users
should not notice a difference in most cases (error messages have changed
somewhat), but flag overrides should generally be more consistent. For example,
things like `--no-ignore --ignore-vcs` work as one would expect (disables all
filtering related to ignore rules except for rules found in version control
systems such as `git`).

[regex-internals]: https://blog.burntsushi.net/regex-internals/

**BREAKING CHANGES**:

* `rg -C1 -A2` used to be equivalent to `rg -A2`, but now it is equivalent to
  `rg -B1 -A2`. That is, `-A` and `-B` no longer completely override `-C`.
  Instead, they only partially override `-C`.

Build process changes:

* ripgrep's shell completions and man page are now created by running ripgrep
with a new `--generate` flag. For example, `rg --generate man` will write a
man page in `roff` format on stdout. The release archives have not changed.
* The optional build dependency on `asciidoc` or `asciidoctor` has been
dropped. Previously, it was used to produce ripgrep's man page. ripgrep now
owns this process itself by writing `roff` directly.

Performance improvements:

* [PERF #1746](BurntSushi/ripgrep#1746):
  Make some cases with inner literals faster.
* [PERF #1760](BurntSushi/ripgrep#1760):
  Make most searches with `\b` look-arounds (among others) much faster.
* [PERF #2591](BurntSushi/ripgrep#2591):
  Parallel directory traversal now uses work stealing for faster searches.
* [PERF #2642](BurntSushi/ripgrep#2642):
  Parallel directory traversal has some contention reduced.

Feature enhancements:

* Added or improved file type filtering for Ada, DITA, Elixir, Fuchsia, Gentoo,
  Gradle, GraphQL, Markdown, Prolog, Raku, TypeScript, USD, V
* [FEATURE #665](BurntSushi/ripgrep#665):
  Add a new `--hyperlink-format` flag that turns file paths into hyperlinks.
* [FEATURE #1709](BurntSushi/ripgrep#1709):
  Improve documentation of ripgrep's behavior when stdout is a tty.
* [FEATURE #1737](BurntSushi/ripgrep#1737):
  Provide binaries for Apple silicon.
* [FEATURE #1790](BurntSushi/ripgrep#1790):
  Add new `--stop-on-nonmatch` flag.
* [FEATURE #1814](BurntSushi/ripgrep#1814):
  Flags are now categorized in `-h/--help` output and ripgrep's man page.
* [FEATURE #1838](BurntSushi/ripgrep#1838):
  An error is shown when searching for NUL bytes with binary detection enabled.
* [FEATURE #2195](BurntSushi/ripgrep#2195):
  When `extra-verbose` mode is enabled in zsh, show extra file type info.
* [FEATURE #2298](BurntSushi/ripgrep#2298):
  Add instructions for installing ripgrep using `cargo binstall`.
* [FEATURE #2409](BurntSushi/ripgrep#2409):
  Added installation instructions for `winget`.
* [FEATURE #2425](BurntSushi/ripgrep#2425):
  Shell completions (and man page) can be created via `rg --generate`.
* [FEATURE #2524](BurntSushi/ripgrep#2524):
  The `--debug` flag now indicates whether stdin or `./` is being searched.
* [FEATURE #2643](BurntSushi/ripgrep#2643):
  Make `-d` a short flag for `--max-depth`.
* [FEATURE #2645](BurntSushi/ripgrep#2645):
  The `--version` output will now also contain PCRE2 availability information.

Bug fixes:

* [BUG #884](BurntSushi/ripgrep#884):
  Don't error when `-v/--invert-match` is used multiple times.
* [BUG #1275](BurntSushi/ripgrep#1275):
  Fix bug with `\b` assertion in the regex engine.
* [BUG #1376](BurntSushi/ripgrep#1376):
  Using `--no-ignore --ignore-vcs` now works as one would expect.
* [BUG #1622](BurntSushi/ripgrep#1622):
  Add note about error messages to `-z/--search-zip` documentation.
* [BUG #1648](BurntSushi/ripgrep#1648):
  Fix bug where sometimes short flags with values, e.g., `-M 900`, would fail.
* [BUG #1701](BurntSushi/ripgrep#1701):
  Fix bug where some flags could not be repeated.
* [BUG #1757](BurntSushi/ripgrep#1757):
  Fix bug when searching a sub-directory didn't have ignores applied correctly.
* [BUG #1891](BurntSushi/ripgrep#1891):
  Fix bug when using `-w` with a regex that can match the empty string.
* [BUG #1911](BurntSushi/ripgrep#1911):
  Disable mmap searching in all non-64-bit environments.
* [BUG #1966](BurntSushi/ripgrep#1966):
  Fix bug where ripgrep can panic when printing to stderr.
* [BUG #2046](BurntSushi/ripgrep#2046):
  Clarify that `--pre` can accept any kind of path in the documentation.
* [BUG #2108](BurntSushi/ripgrep#2108):
  Improve docs for `-r/--replace` syntax.
* [BUG #2198](BurntSushi/ripgrep#2198):
  Fix bug where `--no-ignore-dot` would not ignore `.rgignore`.
* [BUG #2201](BurntSushi/ripgrep#2201):
  Improve docs for `-r/--replace` flag.
* [BUG #2288](BurntSushi/ripgrep#2288):
  `-A` and `-B` now only each partially override `-C`.
* [BUG #2236](BurntSushi/ripgrep#2236):
  Fix gitignore parsing bug where a trailing `\/` resulted in an error.
* [BUG #2243](BurntSushi/ripgrep#2243):
  Fix `--sort` flag for values other than `path`.
* [BUG #2246](BurntSushi/ripgrep#2246):
  Add note in `--debug` logs when binary files are ignored.
* [BUG #2337](BurntSushi/ripgrep#2337):
  Improve docs to mention that `--stats` is always implied by `--json`.
* [BUG #2381](BurntSushi/ripgrep#2381):
  Make `-p/--pretty` override flags like `--no-line-number`.
* [BUG #2392](BurntSushi/ripgrep#2392):
  Improve global git config parsing of the `excludesFile` field.
* [BUG #2418](BurntSushi/ripgrep#2418):
  Clarify sorting semantics of `--sort=path`.
* [BUG #2458](BurntSushi/ripgrep#2458):
  Make `--trim` run before `-M/--max-columns` takes effect.
* [BUG #2479](BurntSushi/ripgrep#2479):
  Add documentation about `.ignore`/`.rgignore` files in parent directories.
* [BUG #2480](BurntSushi/ripgrep#2480):
  Fix bug when using inline regex flags with `-e/--regexp`.
* [BUG #2505](BurntSushi/ripgrep#2505):
  Improve docs for `--vimgrep` by mentioning footguns and some work-arounds.
* [BUG #2519](BurntSushi/ripgrep#2519):
  Fix incorrect default value in documentation for `--field-match-separator`.
* [BUG #2523](BurntSushi/ripgrep#2523):
  Make executable searching take `.com` into account on Windows.
* [BUG #2574](BurntSushi/ripgrep#2574):
  Fix bug in `-w/--word-regexp` that would result in incorrect match offsets.
* [BUG #2623](BurntSushi/ripgrep#2623):
  Fix a number of bugs with the `-w/--word-regexp` flag.
* [BUG #2636](BurntSushi/ripgrep#2636):
  Strip release binaries for macOS.
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