What do you think about adding another option to preg_match() to allow the
$offset parameter to be treated as the start anchor?
The manual proposes to do this:
$subject = "abcdef";
$pattern = '/^def/';
$offset = 3;
preg_match($pattern, substr($subject, $offset), $matches);
In other words, use substr() to copy the entire remainder of the string.
I just wrote a simple SQL parser tonight, and had to use this approach,
which (I imagine) must be pretty inefficient?
I'd like to be able to do the following:
$subject = "abcdef";
$pattern = '/^def/';
$offset = 3;
preg_match($pattern, $subject, $matches, PREG_ANCHOR_OFFSET, $offset);
This new option would make the ^ anchor work from the given $offset, which
allows me to parse the entire $subject without copying anything.
Thoughts?
What do you think about adding another option to
preg_match()to allow the
$offset parameter to be treated as the start anchor?The manual proposes to do this:
$subject = "abcdef"; $pattern = '/^def/'; $offset = 3; preg_match($pattern, substr($subject, $offset), $matches);In other words, use
substr()to copy the entire remainder of the string.I just wrote a simple SQL parser tonight, and had to use this approach,
which (I imagine) must be pretty inefficient?I'd like to be able to do the following:
$subject = "abcdef"; $pattern = '/^def/'; $offset = 3; preg_match($pattern, $subject, $matches, PREG_ANCHOR_OFFSET, $offset);This new option would make the ^ anchor work from the given $offset, which
allows me to parse the entire $subject without copying anything.Thoughts?
How would you propose to implement this? Is it something PCRE already
supports? Or would you manipulate the subject string pointer at the
point it's passed down? The latter approach seems doable, but I'm not
sure if there are any subtle gotchas.
Regards,
--
Rowan Collins
[IMSoP]
What do you think about adding another option to
preg_match()to allow the
$offset parameter to be treated as the start anchor?The manual proposes to do this:
$subject = "abcdef"; $pattern = '/^def/'; $offset = 3; preg_match($pattern, substr($subject, $offset), $matches);In other words, use
substr()to copy the entire remainder of the string.I just wrote a simple SQL parser tonight, and had to use this approach,
which (I imagine) must be pretty inefficient?I'd like to be able to do the following:
$subject = "abcdef"; $pattern = '/^def/'; $offset = 3; preg_match($pattern, $subject, $matches, PREG_ANCHOR_OFFSET, $offset);This new option would make the ^ anchor work from the given $offset, which
allows me to parse the entire $subject without copying anything.Thoughts?
You are looking for the \G anchor or the A modifier.
Nikita
You are looking for the \G anchor or the A modifier.
Both of these options work great!
I've submitted a patch to the manual page with a note explaining these
options.
Thanks :-)
On Wed, Jun 7, 2017 at 10:03 PM, Rasmus Schultz rasmus@mindplay.dk
wrote:What do you think about adding another option to
preg_match()to allow the
$offset parameter to be treated as the start anchor?The manual proposes to do this:
$subject = "abcdef"; $pattern = '/^def/'; $offset = 3; preg_match($pattern, substr($subject, $offset), $matches);In other words, use
substr()to copy the entire remainder of the string.I just wrote a simple SQL parser tonight, and had to use this approach,
which (I imagine) must be pretty inefficient?I'd like to be able to do the following:
$subject = "abcdef"; $pattern = '/^def/'; $offset = 3; preg_match($pattern, $subject, $matches, PREG_ANCHOR_OFFSET, $offset);This new option would make the ^ anchor work from the given $offset, which
allows me to parse the entire $subject without copying anything.Thoughts?
You are looking for the \G anchor or the A modifier.
Nikita