⊕ Recursively compute conditions, supports $or (like Mongo) ⊕

valid_conditions.php

<?php

/**
 * Recursively compute conditions against existing data, supports $or (like Mongo)
 * For example: 
 *	{
 *   		"$or": [
 * 			{ "foo": true },
 * 			{ "bar": true, "baz": true }
 * 		],
 * 		"foobar": false
 * 	}
 *
 * @param   array  $conditions
 * @param   array  $extra_pairs
 * @param   array  $data
 * @return  bool
 */
function valid_conditions(
	array $conditions,
	array $extra_pairs = [],
	array $data = []
)
{
	$bonafide = TRUE;

	// Prepare an array of available macros from extra pairs and internal
	$macros = array_merge([ '$or' ], array_keys($extra_pairs));
	$macros = array_map('strtolower', $macros);

	// Conditions start as an object: {}
	foreach ($conditions as $condition => $and)
	{
		// Making sure it's an array (supporting a single value string)
		$and = (array) $and;

		// Process a macro if the condition is indeed matching one of them.
		if (in_array(strtolower($condition), $macros))
		{
			$ok = FALSE;
			if ($condition === '$or')
			{
				// OR conditions start as an array: []
				foreach ($and as $or)
				{
					// Inside, each object represents an AND group: {}
					// Recursively process them with OR operator
					$ok = $ok || 
						valid_conditions($or, $extra_pairs, $data);
				}
			}
			else
			{
				// Fail if macro's value isn't in the allowed extra operands array
				$ok = in_array($extra_pairs[$condition], $and);
			}
			$bonafide = $bonafide && $ok;
		}
		else
		{
			// Iterate through operands and fail accordingly
			foreach ($and as $operand)
			{
				$bonafide = ($operand XOR isset($data[$condition]));
			}
		}
	}

	return $bonafide;
}