PHP function to recursively implode multi-dimensional arrays.

PHP-Recursive-Implosion.php

<?php

/**
 * Recursively implodes an array with optional key inclusion
 * 
 * Example of $include_keys output: key, value, key, value, key, value
 * 
 * @access  public
 * @param   array   $array         multi-dimensional array to recursively implode
 * @param   string  $glue          value that glues elements together	
 * @param   bool    $include_keys  include keys before their values
 * @param   bool    $trim_all      trim ALL whitespace from string
 * @return  string  imploded array
 */ 
function recursive_implode(array $array, $glue = ',', $include_keys = false, $trim_all = true)
{
	$glued_string = '';

	// Recursively iterates array and adds key/value to glued string
	array_walk_recursive($array, function($value, $key) use ($glue, $include_keys, &$glued_string)
	{
		$include_keys and $glued_string .= $key.$glue;
		$glued_string .= $value.$glue;
	});

	// Removes last $glue from string
	strlen($glue) > 0 and $glued_string = substr($glued_string, 0, -strlen($glue));

	// Trim ALL whitespace
	$trim_all and $glued_string = preg_replace("/(\s)/ixsm", '', $glued_string);

	return (string) $glued_string;
}

$arr = [
    "INTO xxx",
    "(",
    [ 'a', 'b', 'c' ],
    ")",
    "VALUES",
    "(",
    [ ':a', ':b', ':c' ],
    ")"
];

var_dump(recursive_implode($arr, ", ", false, false));

Return:

"INTO xxx, (, a, b, c, ), VALUES, (, :a, :b, :c, )"

does not work as expected 😢

Here's my version :-)
It doesn't use regexp, and deals with associative arrays but also objects, and makes key display as optional.
The output format is the most intuitive and can easily be used for debugging, it looks a bit like the var_dump one.
For example :
0 => [ 0 => [ 'id' => "1d8e9eb4", 'key' => "value", 'settings' => { 'width' => "full" }, 'empty_object' => { }, 'empty_array' => [ ] ], 1 => "string_value" ]

function recursive_implode( string $separator, mixed $mixed, bool $display_keys = false ) {
    $output = "";
    $value_index = 0;
    if( is_array( $mixed ) || is_object( $mixed ) ) {
        foreach( $mixed as $key => $value ) {
            $output .= ( $value_index ? $separator : '' ) . ( $display_keys ? ( is_int( $key ) ? $key : "'" . $key . "'" ) . ' => ' : '' );
            if( is_array( $value ) ) {
                $array_ouput = recursive_implode( $separator, $value, $display_keys );
                if( $array_ouput ) {
                    $output .= '[ ' . $array_ouput . ' ]';
                } else {
                    $output .= '[]';
                }
            } else
            if( is_object( $value ) ) {
                $object_output = recursive_implode( $separator, $value, $display_keys );
                if( $object_output ) {
                    $output .= '{ ' . $object_output . ' }';
                } else {
                    $output .= '{}';
                }
            } else {
                $output .= '"' . $value . '"';
            }
            $value_index++;
        }
    } else {
        $output = $mixed;
    }
    return $output;
}