Turn string into multi-dimensional array equivalent - php

Question

I'm trying to parse a string from a URL and convert it into a PHP array, but so far I haven't been able to get it to work correctly.
The string contains comma separated values which are then grouped by periods, for example:
course.id,course.title,course.author,course.duration,course.trailer.video_key,course.trailer.duration,course.lessons.id,course.lessons.title,track.id,track.title,track.caption.srt,track.caption.vtt,track.caption.text
The Array equivalent to this string would be:
PHP:
$array = [
'course' => [
'id',
'title',
'author',
'duration',
'trailer' => [
'video_key',
'duration'
],
'lessons' => [
'id',
'title'
]
],
'track' => [
'id',
'title',
'caption' => [
'srt',
'vtt',
'text'
]
]
];
My current solution is this:
PHP:
$string = 'course.id,course.title,course.author,course.duration,course.trailer.video_key,course.trailer.duration,course.lessons.id,course.lessons.title,track.id,track.title,track.caption.srt,track.caption.vtt,track.caption.text';
$parameters = explode( ',', $string );
$array = array();
$inset = array();
foreach ( $parameters as $parameter ) {
$segments = explode( '.', $parameter );
if ( ! array_key_exists( $segments[0], $inset ) ) {
$array[ $segments[0] ] = array();
$inset[ $segments[0] ] = true;
}
$array[ $segments[0] ] = array_merge( $array[ $segments[0] ], addSegment( $segments, 1 ) );
}
function addSegment( $segments, $counter ) {
$results = array();
if ( end( $segments ) == $segments[ $counter ] ) {
return array( $segments[ $counter ] => null );
}
$results[ $segments[ $counter ] ] = addSegment( $segments, $counter + 1 );
return $results;
}
This somewhat works, however; it fails with simpler string like this one
course,track,lessons
I think this calls for recursion but I'm not good at writing this so I'm hoping someone has already done this and can help me.
Thank you.

Answer 1

You can achieve this without recursion - just double loop and use of &:
$arr = explode(",", "course.id,course.title,course.author,course.duration,course.trailer.video_key,course.trailer.duration,course.lessons.id,course.lessons.title,track.id,track.title,track.caption.srt,track.caption.vtt,track.caption.text");
foreach($arr as $e) {
$e = explode(".", $e);
$obj = &$res; //set the current place root
while(count($e) > 1) { // last element will be add as value
$key = array_shift($e);
if (!isset($obj[$key]))
$obj[$key] = [];
$obj = &$obj[$key]; //reset the current place
}
$obj[] = array_shift($e); // add the last as value to current place
}
$res will contain your desire output