README

Wikipedia defines:

A domain-specific language (DSL) is a computer language specialized to a particular application domain.

Grammar of this implementation is partially inspired by basic arithmetic and Clojure language.

Syntax is very simple: (<operation name> [... list of nodes])

It's very easy to implement complicated equation:

(max
    ((+ {a} {b} {c}) * {-1.22})
    ({100.0} - {d})
    {3.1415}
)

Basic usage

Expression are evaluated in global context which is represented array.

$runtime = new Pilulka\DSL\Runtime();
$runtime->execute('{a}', ['a' => 1]); // 1        
$runtime->execute('{3.1415}', []); // 3.1415        
$runtime->execute('{"This is custom text!"}', []); // This is custom text!        
$runtime->execute('{a} + {b}', ['a' => 1, 'b' => 3]); // 4        
$runtime->execute('{a} - {b}', ['a' => 1, 'b' => 3]); // -2        
$runtime->execute('(max {a} {b})', ['a' => 1, 'b' => 3]); // 3        
$runtime->execute('(max {a} {b}) + {2.1}', ['a' => 1, 'b' => 3]); // 5.1
// ...        

Extending

Most important thing about this DSL implementation is extendability. You can extend syntax to your logic requirements by specifying list of operations in your domain context.

class CastNumber implements OperationInterface {
    public function execute(array $inputs) {
        // implement serious logic with validation etc.
        return (float) $inputs[0];
    }
}

$runtime = new Pilulka\DSL\Runtime([
    'castNumber' => CastNumber::class,
]);

$runtime->execute('(castNumber {price})', ['price' => '123.5 USD']) // 123.5 

Overloading operation loading

If you need to load your custom operations with external dependencies use your own OperationLoader by implementing OperationLoaderInterface.

I will recommend you to use some dependency injection container implementation and register your loader with it.

Note: You will have to implement also internal operation loading. It's king of trivial task.