How to parse column separated key-value text with possible multiline strings - php

Question

I need to parse the following text:
First: 1
Second: 2
Multiline: blablablabla
bla2bla2bla2
bla3b and key: value in the middle if strting
Fourth: value
Value is a string OR multiline string, at the same time value could contain "key: blablabla" substring. Such subsctring should be ignored (not parsed as a separate key-value pair).
Please help me with regex or other algorithm.
Ideal result would be:
$regex = "/SOME REGEX/";
$matches = [];
preg_match_all($regex, $html, $matches);
// $mathes has all key and value parsed pairs, including multilines values
Thank you.
I tried with simple regexes but result is incorrect, because I don't know how to handle multilines:
$regex = "/(.+?): (.+?)/";
$regex = "/(.+?):(.+?)\n/";
...

Answer 1

You can do it with this pattern:
$pattern = '~(?<key>[^:\s]+): (?<value>(?>[^\n]*\R)*?[^\n]*)(?=\R\S+:|$)~';
preg_match_all($pattern, $txt, $matches, PREG_SET_ORDER);
print_r($matches);

Answer 2

You can sort of do it, as long as you consider a single word followed by a colon at the start of a line to be a new key start:
$data = 'First: 1
Second: 2
Multiline: blablablabla
bla2bla2bla2
bla3b and key: value in the middle if strting
Fourth: value';
preg_match_all('/^([a-z]+): (.*?)(?=(^[a-z]+:|\z))/ims', $data, $matches);
var_dump($matches);
This gives the following result:
array(4) {
[0]=>
array(4) {
[0]=>
string(10) "First: 1
"
[1]=>
string(11) "Second: 2
"
[2]=>
string(86) "Multiline: blablablabla
bla2bla2bla2
bla3b and key: value in the middle if strting
"
[3]=>
string(13) "Fourth: value"
}
[1]=>
array(4) {
[0]=>
string(5) "First"
[1]=>
string(6) "Second"
[2]=>
string(9) "Multiline"
[3]=>
string(6) "Fourth"
}
[2]=>
array(4) {
[0]=>
string(3) "1
"
[1]=>
string(3) "2
"
[2]=>
string(75) "blablablabla
bla2bla2bla2
bla3b and key: value in the middle if strting
"
[3]=>
string(5) "value"
}
[3]=>
array(4) {
[0]=>
string(7) "Second:"
[1]=>
string(10) "Multiline:"
[2]=>
string(7) "Fourth:"
[3]=>
string(0) ""
}
}