Add a helper for anonymous reference of object's key-values

[ppKrauss]

Solving the problem of "no anonymous reference for objects"... Example:

$abc = ['foo','bar','baz'];
echo $m->render(  "\n\t 1: <ul>{{#.}}<li>{{.}}</li>{{/.}}</ul>\n",  $abc  );

works fine with anonymous reference for array. But when using a "dictionary" like associative array,

$abc = ['a'=>'foo','b'=>'bar','c'=>'baz'];

it is impossible with Mustache. A workaround is to use a function that transforms the $abc dictionary into keys and vals,

$abc_ugly = [  ['_key'=>'a', '_val'=>'foo'], 
          ['_key'=>'b', '_val'=>'bar'],  ['_key'=>'c', '_val'=>'baz']  ];
echo $m->render(
  "\n\t 2: <ul>{{#.}}<li>{{_key}}={{_val}}</li>{{/.}}</ul>\n",
  $abc_ugly  // ideal will be objs2list($abc) instead $abc_ugly
);

Another problem is to transform not the full root-dictionary, but only the object pointed by a path, example:

echo $m->render(
  "\n\t 3: xx={{xx}}  <ul>{{#yy}}<li>{{_key}}={{_val}}</li>{{/yy}}</ul>\n",
  objs2list(  ['xx'=>123,'yy'=>$abc],  ['yy']  )
);

and, ideal, is to add it as a internal method, to call in standard way $m->objs2list(). So, this is the suggestion.

Suggested helper

/**
 * Transforns objects into array of "_key" and "_val" objects.
 * The object can be pointed by a $path (array of reference-labels). 
 */
function objs2list($obj,$path=NULL) {
  $l = [];
  $flag = ($path && count($path));
  foreach(($flag? arrayPath($obj, $path): $obj) as $k=>$v) 
     $l[] = ['_key'=>$k,'_val'=>$v];
  if ($flag) {
    arrayPath($obj, $path, $l); return $obj;
  } else return $l;
}


/**
 * set/return a nested array value
 *
 * @param array $array the array to modify
 * @param array $path  the path to the value
 * @param mixed $value (optional) value to set
 *
 * @return mixed previous value
 * @see https://stackoverflow.com/a/36042293/287948
 */
function arrayPath(&$array, $path = array(), &$value = null)
{
    $args = func_get_args();
    $ref = &$array;
    foreach ($path as $key) {
        if (!is_array($ref)) {
            $ref = array();
        }
        $ref = &$ref[$key];
    }
    $prev = $ref;
    if (array_key_exists(2, $args)) {
        // value param was passed -> we're setting
        $ref = $value;  // set the value
    }
    return $prev;
}