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make\_pcre is a plugin for GNU make providing ability to use Perl compatible
regular expressions. It requires make 4.0 or higher (tested with 4.1)
and libpcre3 (tested with 8.30).
[](https://travis-ci.org/mikhirev/make\_pcre)
Installation
============
Prerequisites
-------------
- GNU make 4.0+
- libpcre3 8.30+
Build
-----
To get plugin built, simply type
$ make
in source directory. Optionally, type
$ make -k check
to run self-tests. Please report me if it fails on your system.
Install
-------
Copy `pcre.so` into the directory where your makefile is stored.
Usage
=====
Load the plugin by adding
load pcre.so
to your makefile.
Currently only one function `pcre_find` (with shorthand `m`) is implemented.
It is similar to builtin `findstring` function, but it takes PCRE pattern
instead substring as first argument:
$(pcre_find PATTERN,IN)
$(m PATTERN,IN)
It searches IN for matching PATTERN. If it occurs, the matched substring is
returned; otherwise returned string is empty. Note that normally PATTERN is
not expanded, but IN is expanded before search.
Capturing strings
-----------------
### Capture by number ###
When matching found, `pcre_find` sets variable `$(0)` to whole matched string
and variables `$(1)`, `$(2)`, ... to substrings captured by round brackets
(like Perl does). Maximum number of strings that can be captured is 256 (`$(0)`
to `$(255)`). These variables can be used until the next `pcre_find` call
because it will reset them.
### Capture by name ###
`pcre_find` also provides ability to set named variables to matched substrings.
It can be useful if you want to preserve captured value after another matching
function called or if your pattern is quite complicated, and it is difficult
to handle substring numbers.
In PCRE, a subpattern can be named in one of three ways: `(?<name>...)`
or `(?'name'...)` as in Perl, or `(?P<name>...)` as in Python. If pattern
matches, variable `$(name)` will be set to matched substring.
Options
-------
`pcre_find` can take optional third argument consisting of one ore more
characters, each of which enables some option:
$(pcre_find PATTERN,IN,EimsuUxX8)
$(m PATTERN,IN,EimsuUxX8)
The following options are implemented:
- `E` enables expansion of pattern before compilation. Note that you will need
to use `$$` instead `$` for matching end of line in this case;
- `g` enables global search, like in Perl. Space separated list of all matched
substrings will be returned;
- `i` makes search case insensitive. The same as in Perl;
- `m` makes regexp treating string as multi-line, i. e. `^` and `$` will match
immediately after or immediately before internal newlines. The same
as in Perl;
- `s` forces `.` metacharacter to match any character including newline.
The same as in Perl;
- `u` changes the way of processing \B, \b, \D, \d, \S, \s, \W, \w and some
of the POSIX character classes forsing them to use Unicode properties;
- `U` ungreedies quantifiers by default (they still can be made greedy
if followed by `?`);
- `x` forces regexp to ignore unescaped whitespaces and comments after `#`.
The same as in Perl;
- `X` enables extra PCRE functionality making the pattern incompatible to Perl.
See PCRE documentation for additional information;
- `8` makes both pattern and subject string treated as UTF8.
See also
--------
See `pcrepattern(3)` and `pcresyntax(3)` man pages for more information
on PCRE pattern syntax.
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