Select a block of YAML with regex - php

Question

I have a big YAML file and I want to select an entire node using regex. For instance:
Node1:
Child:
GrandChild: foo
Node2:
AnotherChild:
AnotherGrandChild: bar
Node3:
LastChild:
LastGrandChild: foo
How can I use regex to select all of Node2 in the above example, and return:
Node2:
AnotherChild:
AnotherGrandChild: bar

Answer 1

As everything else in that node is indented (if I understand YAML right), this does work at least at your example string:
$mask = '~(^%s:\n(?:^[ ].*\n?)*$)~m';
$pattern = sprintf($mask, 'Node2');
$r = preg_match($pattern, $yaml, $matches);
$node = reset($matches);
At least on my computer. Wanted to make a codepad demo, but it gives error. Will check the regex.
Full blown:
$yaml = <<<EOD
Node1:
Child:
GrandChild: foo
Node2:
AnotherChild:
AnotherGrandChild: bar
Node3:
LastChild:
LastGrandChild: foo
EOD;
$mask = '~
( # start matching group
^ # a node start always at the beginning of a line
%s: # placeholder for sprintf for the nodname + :
$ # end of line for the nodename
\n
(?: # non-matching group to hold all subsequent, indented lines
^ # beginning of sublines
(?:[ ]{2})+ # indentation is required, always a muliple of two spaces, non matching group
.*\n? # match anything else on that subsequent line, optionally the newline character
)* # 0 or more subsequent, indented lines
)$ # this ends a line, to not take over the newline of the last subsequent line (see \n? above).
# the following are modifiers:
# m - pcre multiline modifier (in php same as in perl)
# x - to allow spaces and the comments all over here ;)
~mx
';
$pattern = sprintf($mask, 'Node2');
$r = preg_match($pattern, $yaml, $matches);
$node = reset($matches);
var_dump($node);

Answer 2

You probably want to use a library like php-yaml.