How to transform a simple array of file paths into a nested array representing a file hierarchy in PHP?

Question

I need to write a function in PHP that takes the following input array:

$inputArray = [
[
    "path" => "/C",
    "basename" => "C",
    "size" => 4096,
    "modified" => 1540579748,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/Recycle.Bin",
    "basename" => "Recycle.Bin",
    "size" => 0,
    "modified" => 1539012172,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/Pictures",
    "basename" => "Pictures",
    "size" => 3164422144,
    "modified" => 1540581569,
    "type" => "file",
    "contents" => []
],
[
    "path" => "/C/Videos",
    "basename" => "Videos",
    "size" => 970752,
    "modified" => 1540579792,
    "type" => "file",
    "contents" => []
],
[
    "path" => "/C/Documents and Settings",
    "basename" => "Documents and Settings",
    "size" => 4096,
    "modified" => 1539022708,
    "type" => "link",
    "contents" => []
],
[
    "path" => "/C/Documents and Settings/Public",
    "basename" => "Public",
    "size" => 4096,
    "modified" => 1539012079,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/Documents and Settings/desktop.ini",
    "basename" => "desktop.ini",
    "size" => 174,
    "modified" => 1506692592,
    "type" => "file",
    "contents" => []
],
[
    "path" => "/C/PerfLogs",
    "basename" => "PerfLogs",
    "size" => 0,
    "modified" => 1506692704,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/Program Files",
    "basename" => "Program Files",
    "size" => 4096,
    "modified" => 1540579745,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/Program Files (x86)",
    "basename" => "Program Files (x86)",
    "size" => 4096,
    "modified" => 1506692707,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/ProgramData",
    "basename" => "ProgramData",
    "size" => 4096,
    "modified" => 1539012665,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/Recovery",
    "basename" => "Recovery",
    "size" => 0,
    "modified" => 1539022717,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/System Volume Information",
    "basename" => "System Volume Information",
    "size" => 4096,
    "modified" => 1539012967,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/Users",
    "basename" => "Users",
    "size" => 4096,
    "modified" => 1539012384,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/Windows",
    "basename" => "Windows",
    "size" => 24576,
    "modified" => 1539011957,
    "type" => "dir",
    "contents" => []
],
[
    "path" => "/C/pagefile.sys",
    "basename" => "pagefile.sys",
    "size" => 1207959552,
    "modified" => 1540581479,
    "type" => "file",
    "contents" => []
],
[
    "path" => "/C/swapfile.sys",
    "basename" => "swapfile.sys",
    "size" => 268435456,
    "modified" => 1540581479,
    "type" => "file",
    "contents" => []
]
];

and produces the following output array:

$outputArray = [
[
    "path" => "/C",
    "basename" => "C",
    "size" => 4096,
    "modified" => 1540579748,
    "type" => "dir",
    "contents" => [
        [
            "path" => "/C/Recycle.Bin",
            "basename" => "Recycle.Bin",
            "size" => 0,
            "modified" => 1539012172,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/Pictures",
            "basename" => "Pictures",
            "size" => 3164422144,
            "modified" => 1540581569,
            "type" => "file",
            "contents" => []
        ],
        [
            "path" => "/C/Videos",
            "basename" => "Videos",
            "size" => 970752,
            "modified" => 1540579792,
            "type" => "file",
            "contents" => []
        ],
        [
            "path" => "/C/Documents and Settings",
            "basename" => "Documents and Settings",
            "size" => 4096,
            "modified" => 1539022708,
            "type" => "link",
            "contents" => [
                [
                    "path" => "/C/Documents and Settings/Public",
                    "basename" => "Public",
                    "size" => 4096,
                    "modified" => 1539012079,
                    "type" => "dir",
                    "contents" => []
                ],
                [
                    "path" => "/C/Documents and Settings/desktop.ini",
                    "basename" => "desktop.ini",
                    "size" => 174,
                    "modified" => 1506692592,
                    "type" => "file",
                    "contents" => []
                ]
            ]
        ],
        [
            "path" => "/C/PerfLogs",
            "basename" => "PerfLogs",
            "size" => 0,
            "modified" => 1506692704,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/Program Files",
            "basename" => "Program Files",
            "size" => 4096,
            "modified" => 1540579745,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/Program Files (x86)",
            "basename" => "Program Files (x86)",
            "size" => 4096,
            "modified" => 1506692707,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/ProgramData",
            "basename" => "ProgramData",
            "size" => 4096,
            "modified" => 1539012665,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/Recovery",
            "basename" => "Recovery",
            "size" => 0,
            "modified" => 1539022717,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/System Volume Information",
            "basename" => "System Volume Information",
            "size" => 4096,
            "modified" => 1539012967,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/Users",
            "basename" => "Users",
            "size" => 4096,
            "modified" => 1539012384,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/Windows",
            "basename" => "Windows",
            "size" => 24576,
            "modified" => 1539011957,
            "type" => "dir",
            "contents" => []
        ],
        [
            "path" => "/C/pagefile.sys",
            "basename" => "pagefile.sys",
            "size" => 1207959552,
            "modified" => 1540581479,
            "type" => "file",
            "contents" => []
        ],
        [
            "path" => "/C/swapfile.sys",
            "basename" => "swapfile.sys",
            "size" => 268435456,
            "modified" => 1540581479,
            "type" => "file",
            "contents" => []
        ]
    ]
]
];

I understand that this can be done with recursion, but I'm having a hard time with it. If somebody could point me in the right direction or provide a working solution, that would be really cool.

Answer 1

Sort the array by path if it's not already ordered:

usort($inputArray, function ($a, $b) {
    return $a['path'] <=> $b['path'];
});

Then nest the items recursively by path:

function nest(&$directory)
{
    for ($i = 0; $i < count($directory); $i++)
    {
        while ($i + 1 < count($directory) && strpos($directory[$i + 1]['path'], $directory[$i]['path'] . '/') === 0)
        {
            $directory[$i]['contents'][] = $directory[$i + 1];
            array_splice($directory, $i + 1, 1);
        }

        nest($directory[$i]['contents']);
    }
}

On case-insensitive filesystems (such as Windows) you may want to replace strpos() with stripos(), but I didn't test for this so I leave it to you to decide.