Regex ungreedy from the left side (i.e., narrowest match possible from both sides)

Question

Let's say I'm trying to match /dog.*lab/ against this text:

"I have a dog. My dog is a black lab. He was created in a laboratory."

Greedily, it would match "dog. My dog is a black lab. He was created in a lab".

I want to find the smallest possible match from both sides. If I use the ungreedy modifier like
/dog.*?lab/ or /dog.*lab/U it will match less but still too much:
"dog. My dog is a black lab"

Is there a way to make my search ungreedy from the left also, thus matching only "dog is a black lab"?

Much thanks. Sorry for the contrived example.

Answer 1

An idea might be to try to use a negated character set, like [^.!?], which would match all characters except ., ? and !, and therefore you can be sure that it is within the same sentence:

$string = "I have a dog. My dog is a black lab. He was created in a laboratory.";
preg_match('/dog[^.!?]*?lab/', $string, $match);
echo $match[0]; // Echoes "dog is a black lab"

Answer 2

This works for me:

$str = "I have a dog. My dog is a black lab. He was created in a laboratory.";
if(preg_match('/.*(dog.*?lab)/',$str,$m)) {
    var_dump($m);
}

Answer 3

You could use a look-ahead assertion that excludes the occurrence of dog between dog and lab:

/dog(?:(?!dog).)*?lab/