我希望能够将“ m”修饰符添加到传递给函数的正则表达式中。
以下测试脚本演示了我正在尝试做的事情
#!/usr/bin/env perl
use strict;
use warnings;
use v5.16.3;
use Test::More tests => 3;
my $no_m_modifier_re = qr{^line1\n^line2};
my $with_m_modifier_re = qr{^line1\n^line2}m;
my $text = <<'EoM';
line1
line2
line3
EoM
unlike( $text, $no_m_modifier_re, 'Text will not match ^ that is equivalent to \A' );
like( $text, $with_m_modifier_re, 'Text will match ^ with m modifier' );
# This fails to add the m modifier to the subexpression
my $add_m_modifier_re = qr{(?m)$no_m_modifier_re};
#my $add_m_modifier_re = qr{(?m:$no_m_modifier_re)}; # Experimented other syntax, with same result
#my $add_m_modifier_re = qr{$no_m_modifier_re}m;
#my $add_m_modifier_re = qr{(?^m:$no_m_modifier_re)}; # suggested by mob, didn't work.
like( $text, $add_m_modifier_re, 'Want this to match, but it fails to add m modifier to subexpression' );
结果是
$ prove -v m_modifier.pl
m_modifier.pl ..
1..3
ok 1 - Text will not match ^ that is equivalent to \A
ok 2 - Text will match ^ with m modifier
not ok 3 - Want this to match, but it fails to add m modifier to subexpression
# Failed test 'Want this to match, but it fails to add m modifier to subexpression'
# at m_modifier.pl line 25.
# 'line1
# line2
# line3
# '
# doesn't match '(?^:(?m)(?^:^line1\n^line2))'
# Looks like you failed 1 test of 3.
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/3 subtests
Test Summary Report
-------------------
m_modifier.t (Wstat: 256 Tests: 3 Failed: 1)
Failed test: 3
Non-zero exit status: 1
Files=1, Tests=3, 1 wallclock secs ( 0.04 usr 0.01 sys + 0.14 cusr 0.05 csys = 0.24 CPU)
Result: FAIL
如您所见,我尝试了添加m修饰符的不同语法,但是它们似乎都不适用于原始模式。
有任何想法吗?
这在Perl 5.16.3下。我没有尝试过更现代的版本。
我按照
qr{(?^m:$no_m_modifier_re)}
您的建议尝试,但仍然失败。测试报告doesn't match '(?^u:(?^m:(?^u:^line1\n^line2)))'
您正在尝试修改已编译的模式。为此,您需要以下内容:
use re qw( is_regexp regexp_pattern );
my $re = qr/^line1\n^line2/;
my ($pat, $mods) =
is_regexp($re)
? regexp_pattern($re)
: ( $re, "" );
$mods .= 'm' if $mods !~ /m/;
defined( $re = eval("qr/\$pat/$mods") )
or die($@); # Should never happen.
它也可以与未编译的模式一起使用,从而产生具有最小(?:)
嵌套的已编译模式。
The result for "abc" is qr/abc/m which stringifies as (?^um:abc)
The result for qr/abc/ is qr/abc/m which stringifies as (?^um:abc)
The result for qr/abc/m is qr/abc/m which stringifies as (?^um:abc)
The result for qr/abc/s is qr/abc/sm which stringifies as (?^ums:abc)
The result for qr/abc/sm is qr/abc/sm which stringifies as (?^ums:abc)
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