docs: regexp: Document the platform dependency

Patch by Nuri Jung; extension to cover PCRE by me.  See #747.

Fixes #747.
This commit is contained in:
Nuri Jung 2022-02-22 10:32:37 +00:00 committed by Daniel Shahaf
parent 56b4433461
commit caeca0bf6b

View file

@ -10,13 +10,46 @@ patterns.
To use this highlighter, associate regular expressions with styles in the
`ZSH_HIGHLIGHT_REGEXP` associative array, for example in `~/.zshrc`:
```zsh
typeset -A ZSH_HIGHLIGHT_REGEXP
ZSH_HIGHLIGHT_REGEXP+=('^rm .*' fg=red,bold)
```
This will highlight lines that start with a call to the `rm` command.
The regular expressions flavour used is [PCRE][pcresyntax] when the
`RE_MATCH_PCRE` option is set and POSIX Extended Regular Expressions (ERE),
as implemented by the platform's C library, otherwise. For details on the
latter, see [the `zsh/regex` module's documentation][MAN_ZSH_REGEX] and the
`regcomp(3)` and `re_format(7)` manual pages on your system.
For instance, to highlight `sudo` only as a complete word, i.e., `sudo cmd`,
but not `sudoedit`, one might use:
* When the `RE_MATCH_PCRE` is set:
```zsh
typeset -A ZSH_HIGHLIGHT_REGEXP
ZSH_HIGHLIGHT_REGEXP+=('\bsudo\b' fg=123,bold)
```
This will highlight "sudo" only as a complete word, i.e., "sudo cmd", but not
"sudoedit"
* When the `RE_MATCH_PCRE` is unset, on platforms with GNU `libc` (e.g., many GNU/Linux distributions):
```zsh
typeset -A ZSH_HIGHLIGHT_REGEXP
ZSH_HIGHLIGHT_REGEXP+=('\<sudo\>' fg=123,bold)
```
* When the `RE_MATCH_PCRE` is unset, on BSD-based platforms (e.g., macOS):
```zsh
typeset -A ZSH_HIGHLIGHT_REGEXP
ZSH_HIGHLIGHT_REGEXP+=('[[:<:]]sudo[[:>:]]' fg=123,bold)
```
Note, however, that PCRE and POSIX ERE have a large common subset:
for instance, the regular expressions `[abc]`, `a*`, and `(a|b)` have the same
meaning in both flavours.
The syntax for values is the same as the syntax of "types of highlighting" of
the zsh builtin `$zle_highlight` array, which is documented in [the `zshzle(1)`
@ -28,3 +61,5 @@ in [the `zshmisc(1)` manual page][zshmisc-Conditional-Expressions]
[zshzle-Character-Highlighting]: http://zsh.sourceforge.net/Doc/Release/Zsh-Line-Editor.html#Character-Highlighting
[perlretut]: http://perldoc.perl.org/perlretut.html
[zshmisc-Conditional-Expressions]: http://zsh.sourceforge.net/Doc/Release/Conditional-Expressions.html#Conditional-Expressions
[MAN_ZSH_REGEX]: https://zsh.sourceforge.io/Doc/Release/Zsh-Modules.html#The-zsh_002fregex-Module
[pcresyntax]: https://www.pcre.org/original/doc/html/pcresyntax.html