mwayi/expression

A multi-purpose php condition parser.

Expression

, _(*1)

A multi-purpose expression parser., _(*2)

The expression parser allows developers to pass in a plain text statement that can be resolved to one of the following:-, _(*3)

• An iterable conditions object
• A boolean (true or false) statement
• A MySql PDO object

Here is a sample use case:, _(*4)

$expression = new \Smrtr\Expression('a = b');
$conditions = $expression->execute()->toArray();
print_r($conditions);

Would resolve to:, _(*5)

Array
(
    [0] => Smrtr\Expression\Condition Object
        (
            [attributes:protected] => Array
                (
                    [key] => a
                    [value] => b
                    [original_value] => b
                    [operator] => =
                )

        )

)

You can now iterate the object recurrsively using a callback, _(*6)

$result = $expression->solve(function($condition) {

    return $this->myCustomAssertionEngine(
        $condition->key,
        $condition->operator, 
        $condition->value
    );

});

Where $this->myCustomAssertionEngine would be built to recognise keys and operators. The handlers would contain logic that would be able to return falsey and truthy results based upon the value supplied., _(*7)

protected function myCustomAssertionEngine($key, $operator, $value) 
{
    $handler = 'handle' . ucfirst($key) . 'Key'; 

    if(method_exists($handler, $this)) {
        return $this->{$handler}($operator, $value);
    }

    return false;
}

The result would be a boolean value., _(*8)

var_dump($result); // bool(true) or bool(false)

Definitions

Condition Elements

A condition consists of a key and value that are connected by an operator such as = that return true or false., _(*9)

[key] [operator] [value]
  a        =        b

Compound conditions

A compound condition combines two or more conditions that are connected by logical operators (for example, AND) that return true or false., _(*10)

a = b AND c = d

Nested conditions

A nested condition uses parentheses to group conditions that are contained in another condition and are connected using AND and OR., _(*11)

a = b AND (c = d OR e = f)

Logical operators

Logical operators combines two conditions together to return a set of results, _(*12)

AND 
OR

Todo

• Allow condition elements value and key to be extended.
• Pass responsiblity of creating an expression object to an expression interface.

Tests

php vendor/bin/phpunit