convert an array of files into a multi-dimensional array

manifest.php

<?php
/**
 * Build Manifest
 *
 * Requires: PHP 5.3+
 *
 * Takes an array of file names and builds a multi-dimensional array
 * representing a simple file-system.
 *
 * NOTE: Files are only currently supported as leaf elements in the array. 
 *       For example, if the files array contains '/var/www/html' it will
 *       create a file called 'html' in the /var/www/ directory.
 *
 * Example Use Case:
 *
 * I am building a web interface for Mercurial repositories and I want
 * to be able to show the files from any specified revision in a tree view.
 * From Mercurial we can call `hg manifest -r REV` and we will get back a list
 * of files that we can split on the newline character. We can then pass this array
 * on to build_manifest() to get a more tree-friendly data structure.
 *
 *		$files = explode("\n", `hg manifest /path/to/your/repository`);
 *		$files_arr = build_manifest($files);
 *
 *
 */
function build_manifest ($files = array())
{
	// break each file up into segments
	$files = array_map(function($file) {
		return explode('/', $file);
	}, $files);

	// doc root
	$manifest = array();

	foreach ($files as $file)
	{
		_build_file($file, $manifest);
	}

	return $manifest;
}

// helper function
// recursively save file parts in to an array
function _build_file($file, &$parent)
{
	$i   = count($file) - 1;   // current index
	$seg = array_shift($file); // next segment

	if ($i < 0)
	{
		throw new Exception('Invalid file name.');
	}

	// add the file to the directory
	if ($i === 0)
	{
		// prevent duplicates
		in_array($seg, $parent) OR $parent[] = $seg;
		return;
	}

	// create the subdirectory if it does not yet exist
	isset($parent[$seg]) OR $parent[$seg] = array();

	return _build_file($file, $parent[$seg]);
}

// ------------------------------------------------------------------------

// Test
$files = array('readme.txt',
			   'foo.txt',
			   'foo/bar.txt',
			   'foo/bar/baz.txt',
			   'foo/bar/baz/foo.txt',
			   'foo/bar/baz/bar.txt',
			   'foo/bar/baz/baz.txt',
			   'bar.txt',
			   'bar/baz.txt',
			   'bar/baz/foo.txt',
			   'bar/baz/foo/foo.txt',
			   'bar/baz/foo/bar.txt',
			   'bar/baz/foo/baz.txt',
			   'baz.txt',
			   'baz/foo.txt',
			   'baz/foo/bar.txt',
			   'baz/foo/bar/foo.txt',
			   'baz/foo/bar/bar.txt',
			   'baz/foo/bar/baz.txt');

print_r(build_manifest($files));

output

// Output

Array
(
    [0] => readme.txt
    [1] => foo.txt
    [foo] => Array
        (
            [0] => bar.txt
            [bar] => Array
                (
                    [0] => baz.txt
                    [baz] => Array
                        (
                            [0] => foo.txt
                            [1] => bar.txt
                            [2] => baz.txt
                        )

                )

        )

    [2] => bar.txt
    [bar] => Array
        (
            [0] => baz.txt
            [baz] => Array
                (
                    [0] => foo.txt
                    [foo] => Array
                        (
                            [0] => foo.txt
                            [1] => bar.txt
                            [2] => baz.txt
                        )

                )

        )

    [3] => baz.txt
    [baz] => Array
        (
            [0] => foo.txt
            [foo] => Array
                (
                    [0] => bar.txt
                    [bar] => Array
                        (
                            [0] => foo.txt
                            [1] => bar.txt
                            [2] => baz.txt
                        )

                )

        )

)