[英]How can I find _all_ locations of a regex match in Perl?
I can see from this answer that if I do 我可以从这个答案看到,如果我这样做
sub match_all_positions {
my ($regex, $string) = @_;
my @ret;
while ($string =~ /$regex/g) { push @ret, $-[0] }
return @ret
}
print join ',', match_all_positions('0{3}', '001100010000');
I get 我明白了
4,8
What do I need to do to get the indexes of all matches, even when the overlap, such as positions 8 and 9 in the example above? 我需要做什么来获得所有匹配的索引,即使重叠,例如上面示例中的位置8和9?
I can do 我可以
sub match_all_positions_b {
my ($substr, $string) = @_;
return unless index($string, $substr) > 0;
my @res;
my $i = 0;
while ($i <= (length($string) - $length)) {
$i = index($string, $substr, $i);
last if $i < 0;
push @res, $i++;
}
return @res;
}
print join ',', match_all_positions_b('000', '001100010000');
which just lets me match a substring, or 它只是让我匹配一个子字符串,或
sub match_all_positions_c {
my ($substr, $string) = @_;
my $re = '^' . $substr;
my @res;
for (0..(length($string) - $length)) {
push @res, $_ if substr($string, $_) =~ /$re/;
}
return @res;
}
print join ',', match_all_positions_c('0{3}', '001100010000');
Which is twice as slow. 这是慢两倍。
is there a way to get all matches, even when they overlap? 是否有办法获得所有比赛,即使它们重叠? Or should I just take the speed loss because it's inherent to using regex matches?
或者我应该采取速度损失,因为它是使用正则表达式匹配固有的?
You need to update your regex for zero-width look-ahead matching. 您需要更新正则表达式以进行零宽度前瞻匹配。
Try calling your function like this: 尝试像这样调用你的函数:
print join ',', match_all_positions('(?=0{3})', '001100010000');
If you want to find the positions at which it matches: 如果要查找匹配的位置:
my @matches;
push @matches, "$-[1]:$+[1]" while "aabbcc" =~ /(?=(a.*c))/sg;
Output: 输出:
0:6
1:6
If you want all possible matches, 如果你想要所有可能的比赛,
local our @matches;
"aabbcc" =~ /(a.*?c)(?{ push @matches, "$-[1]:$+[1]" })(?!)/s;
Output: 输出:
0:5
0:6
1:5
1:6
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