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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).
Installation
============
Prerequisites
-------------
- GNU make 4.0+
- libpcre3 8.30+
Build
-----
To get plugin built, simply type
$ make
in source directory. Optionally, type
$ make check
to run self-tests.
Install
-------
Copy pcre.so into the directory where your makefile is stored.
Usage
=====
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)
$(m PATTERN,IN)
It searches IN for matching PATTERN. If it occurs, the matched substring is
returned; otherwise returned string is empty. Note that normally PATTERN is
not expanded, but IN is expanded before search.
Capturing strings
-----------------
When matching found, `pcre_find` sets variable `$(0)` to whole matched string
and variables `$(1)`, `$(2)`, ... to substrings captured by round brackets
(like perl does). These variables can be used until the next `pcre_find` call
because it will reset them.
Options
-------
`pcre_find` can take optional third argument consisting of one ore more
characters, each of which enables some option:
$(pcre_find PATTERN,IN,emsuUxX8)
$(m PATTERN,IN,emsuUxX8)
The following options are implemented:
- `e` enables expansion of pattern before compilation. Note that you will need
to use `$$` instead `$` for matching end of line in this case;
- `m` makes regexp treating string as multi-line, i. e. `^` and `$` 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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