Evaluating and Running

Expressions
Returning values from scripts

The engine offers three ways to run PHP Script code.

Method	Input	Returns
`execute($script)`	a script	the echo output as string
`run($script)`	a script	an `ExecutionResult` with output, returned value and operation count
`evaluate($expression)`	a single expression	the typed value of the expression

Expressions

evaluate() computes one expression and returns its PHP value: bool, int, float, string, null, a list (array) or a map (stdClass). Use it for conditions and mappings.

use PhpScript\Core\Engine;

$engine = new Engine;
$engine->set('data', ['amount' => 150, 'customer' => ['name' => 'Ada']])
    ->set('now', new DateTimeImmutable);

$engine->evaluate('data.amount > 100');        // true
$engine->evaluate('data.amount + 50');         // 200 (int)
$engine->evaluate('data.amount * 1.5');        // 225.0 (float)
$engine->evaluate('data.customer.name');       // 'Ada'
$engine->evaluate("now.modify('+14 days')");   // DateTimeImmutable

Expressions cannot assign, but they can call methods of context objects. evaluate() is only free of side effects when the methods you expose are.

Statements are not expressions. echo, assignments, ++/--, loops and return throw an EngineException, as do incomplete expressions like data.amount >.

Returning values from scripts

run() executes a script and returns the value of its return statement next to the echo output. A script without return returns null.

$result = $engine->run(<<<'SCRIPT'
    echo 'calculating'
    net = data.amount
    return {net: net, gross: net * 1.19}
    SCRIPT);

$result->output;     // 'calculating'
$result->value;      // stdClass {net: 150, gross: 178.5}
$result->operations; // 3

execute() keeps working as before and returns only the output.

Evaluating and Running

Table of contents

Expressions

Returning values from scripts