On Tue, Apr 14, 2015 at 08:58:29PM -0500, Patrick R. Michaud wrote: > Just an idea: instead of building strings to be interpolated into > a regex, could you just build regexes directly? > > my $pattern = rx/$<greeting>=[hello]/; > my $match = "hello" ~~ / <pattern=$pattern> /; > > The resulting string is captured into $match<pattern><greeting>; > The second statement can also be written as: > > # captures into $match<pattern><greeting> > my $match = "hello" ~~ / $<pattern>=$pattern /; > > # captures into $match[0]<greeting> > my $match = "hello" ~~ / $<0>=$pattern /; > > Hope this is useful, or at least illustrative.
I had given up on using regexes embedded within regexes, because
I could not get capturing to work.
I put together some test cases, to try to show what I would
expect to work. A bunch of the ones that I was planning to use
do not work. I do not know if that is because they have not been
implemented, or whether they are designed to not work this way.
In either case, I am looking for a solution that allows me to
define several regexes, then compose them into a single regex
that captures by name. The solution must be flexible enough to
allow me to combine the regexes in whatever order I need at the
time, and always capture by name.
-kolibrie
use v6;
use Test;
my $year = '2015';
my $month = '04';
my $day = '11';
my $date_string = "$year-$month-$day";
my $year_regex = rx/$<year>=[\d**4]/;
my $month_regex = rx/$<month>=[\d\d?]/;
my $day_regex = rx/$<day>=[\d\d?]/;
my $separator = rx/'-'/;
# Single named capture.
{
ok($date_string ~~ $year_regex, 'date string matches year regex');
is(~$/, $year, 'matched is year string');
is(~$/<year>, $year, 'year is captured');
}
# Single named capture in slashes.
{
ok($date_string ~~ /$year_regex/, 'date string matches year regex when in
slashes');
is(~$/, $year, 'matched is year string when in slashes');
is(~$/<year>, $year, 'year is captured when in slashes'); # Fails
}
# Single named capture embedded in named capture.
{
ok($date_string ~~ /$<pattern>=$year_regex/, 'date string matches year
regex when embedded');
is(~$/, $year, 'matched is year string when embedded');
is(~$/<pattern>, $year, 'pattern is captured when embedded');
is(~$/<pattern><year>, $year, 'year is captured when embedded');
}
# Single named capture embedded in named capture with brackets.
{
ok($date_string ~~ /$<pattern>=[$year_regex]/, 'date string matches year
regex when embedded with brackets');
is(~$/, $year, 'matched is year string when embedded with brackets');
is(~$/<pattern>, $year, 'pattern is captured when embedded with brackets');
is(~$/<pattern><year>, $year, 'year is captured when embedded with
brackets'); # Fails
}
# Multiple named captures.
{
ok($date_string ~~ /$year_regex $separator $month_regex $separator
$day_regex/, 'date string matches multiple regexes in slashes');
is(~$/, $date_string, 'matched is date string in multi regex with slashes');
is(~$/<year>, $year, 'year is captured in multi regex with slashes'); #
Fails
is(~$/<month>, $month, 'month is captured in multi regex with slashes'); #
Fails
is(~$/<day>, $day, 'day is captured in multi regex with slashes'); # Fails
}
# Multiple named captures embedded in named capture.
{
ok($date_string ~~ /$<pattern>=$year_regex $separator $month_regex
$separator $day_regex/, 'date string matches multiple regexes when embedded');
is(~$/, $date_string, 'matched is date string in multi regex when
embedded');
is(~$/<pattern>, $year, 'pattern is captured in multi regex when embedded');
is(~$/<pattern><year>, $year, 'year is captured in multi regex when
embedded');
is(~$/<month>, $month, 'month is captured in multi regex when embedded');
# Fails
is(~$/<day>, $day, 'day is captured in multi regex when embedded'); # Fails
}
# Multiple named captures embedded in named capture with brackets.
{
ok($date_string ~~ /$<pattern>=[$year_regex $separator $month_regex
$separator $day_regex]/, 'date string matches multiple regexes when embedded
with brackets');
is(~$/, $date_string, 'matched is date string in multi regex when embedded
with brackets');
is(~$/<pattern>, $date_string, 'pattern is captured in multi regex when
embedded with brackets');
is(~$/<pattern><year>, $year, 'year is captured in multi regex when
embedded with brackets'); # Fails
is(~$/<pattern><month>, $month, 'month is captured in multi regex when
embedded with brackets'); # Fails
is(~$/<pattern><day>, $day, 'day is captured in multi regex when embedded
with brackets'); # Fails
}
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