calculator.php

<?php
use Formapro\Pvm\DefaultBehaviorRegistry;
use Formapro\Pvm\Exception\WaitExecutionException;
use Formapro\Pvm\ProcessBuilder;
use Formapro\Pvm\ProcessEngine;
use Formapro\Pvm\Token;
use Formapro\Pvm\FileDAL;
use Formapro\Pvm\TokenTransition;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;

require_once __DIR__.'/vendor/autoload.php';

$httpRequest = Request::createFromGlobals();

$fileDal = new FileDAL(__DIR__.'/store');

$process = null;
if ($httpRequest->get('token')) {
    try {
        $token = $fileDal->getToken($httpRequest->get('token'));
        $process = $token->getProcess();
    } catch (\InvalidArgumentException $e) {
    }
}

if (false == $process) {
    $process = (new ProcessBuilder())
        ->createNode('provide_a', 'a')->end()
        ->createNode('provide_b', 'b')->end()
        ->createNode('provide_operator', 'operator')->end()
        ->createNode('result', 'result')->end()
        ->createTransition('provide_a', 'provide_b')->end()
        ->createTransition('provide_b', 'provide_operator')->end()
        ->createTransition('provide_operator', 'result')->end()
        ->createStartTransition('provide_a')->end()

        ->getProcess()
    ;

    $token = $fileDal->createProcessToken($process);
    $token->addTransition(TokenTransition::createFor($process->getStartTransition(), 1));
}

$token->httpRequest = $httpRequest;

$registry = new DefaultBehaviorRegistry([
    'a' => function(Token $token) {
        /** @var Request $httpRequest */
        $httpRequest = $token->httpRequest;

        if ($token->getCurrentTransition()->isWaiting() && Request::METHOD_POST === $httpRequest->getMethod()) {
            $token->setValue('a', $httpRequest->request->getInt('a'));

            return;
        }

        $token->httpResponse = new Response('
            <form method="post" action="'.$_SERVER['REQUEST_URI'].'?token='.$token->getId().'">
                <label for="a">Select A:</label>
                <input name="a" value="1" type="number" />
                <input type="submit" title="Submit" />
            </form>
        ');

        throw new WaitExecutionException();
    },
    'b' => function(Token $token) {
        /** @var Request $httpRequest */
        $httpRequest = $token->httpRequest;

        if ($token->getCurrentTransition()->isWaiting() && Request::METHOD_POST === $httpRequest->getMethod()) {
            $token->setValue('b', $httpRequest->request->getInt('b'));

            return;
        }

        $token->httpResponse = new Response('
            <form method="post" action="'.$_SERVER['REQUEST_URI'].'">
                <label for="b">Select B:</label>
                <input name="b" value="2" type="number" />
                <input type="submit" title="Submit" />
            </form>
        ');

        throw new WaitExecutionException();
    },
    'operator' => function(Token $token) {
        /** @var Request $httpRequest */
        $httpRequest = $token->httpRequest;

        if ($token->getCurrentTransition()->isWaiting() && Request::METHOD_POST === $httpRequest->getMethod()) {
            $token->setValue('operator', $httpRequest->request->get('operator'));

            return;
        }

        $token->httpResponse = new Response('
            <form method="post" action="'.$_SERVER['REQUEST_URI'].'">
                <fieldset>
                    <legend>Select an operator:</legend>
            
                    <div>
                        <input type="radio" name="operator" value="+" checked />
                        <label for="huey">Addition "+"</label>
                    </div>
            
                    <div>
                        <input type="radio" name="operator" value="-" />
                        <label for="dewey">Subtraction "-"</label>
                    </div>
            
                    <div>
                        <input type="radio" name="operator" value="*" />
                        <label for="louie">Multiplication "*"</label>
                    </div>
                </fieldset>
                <input type="submit" title="Submit" />
            </form>
        ');

        throw new WaitExecutionException();
    },
    'result' => function(Token $token) {
        $result = $token->getValue('result');
        $operator = $token->getValue('operator');
        $a = $token->getValue('a');
        $b = $token->getValue('b');

        if (false == $result) {
            switch ($operator) {
                case '+':
                    $result = $a + $b;
                    break;
                case '-':
                    $result = $a - $b;
                    break;
                case '*':
                    $result = $a * $b;
                    break;
                default:
                    throw new \LogicException('Invalid operator');
            }

            $token->setValue('result', $result);
        }

        $token->httpResponse = new Response("
            <p>The result of $a $operator $b equals <b>$result</b></p> 
        ");

        throw new WaitExecutionException();
    },
]);

$engine = new ProcessEngine($registry, $fileDal);

$waitTokens = $engine->proceed($token);

/** @var Response $httpResponse */
$httpResponse = $waitTokens[0]->httpResponse;

echo $httpResponse->getContent();

{
    "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Process.json",
    "id": "5d02e1f7-d04e-4522-8d12-efa57747a7b2",
    "nodes": {
        "provide_a": {
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Node.json",
            "id": "provide_a",
            "behavior": "a"
        },
        "provide_b": {
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Node.json",
            "id": "provide_b",
            "behavior": "b"
        },
        "provide_operator": {
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Node.json",
            "id": "provide_operator",
            "behavior": "operator"
        },
        "result": {
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Node.json",
            "id": "result",
            "behavior": "result"
        }
    },
    "transitions": {
        "3bbfcc81-6724-442c-b1ff-0394b412a71c": {
            "id": "3bbfcc81-6724-442c-b1ff-0394b412a71c",
            "weight": 1,
            "async": false,
            "active": true,
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
            "from": "provide_a",
            "to": "provide_b"
        },
        "a4516db6-6ed6-431c-8197-aa1c85770911": {
            "id": "a4516db6-6ed6-431c-8197-aa1c85770911",
            "weight": 1,
            "async": false,
            "active": true,
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
            "from": "provide_b",
            "to": "provide_operator"
        },
        "179fb78c-b533-4674-903a-f6c995cdbfee": {
            "id": "179fb78c-b533-4674-903a-f6c995cdbfee",
            "weight": 1,
            "async": false,
            "active": true,
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
            "from": "provide_operator",
            "to": "result"
        },
        "dfb61ff2-a77a-49cf-9adb-6799c86bce2a": {
            "id": "dfb61ff2-a77a-49cf-9adb-6799c86bce2a",
            "weight": 1,
            "async": false,
            "active": true,
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
            "to": "provide_a"
        }
    },
    "outTransitions": {
        "provide_a": [
            "3bbfcc81-6724-442c-b1ff-0394b412a71c"
        ],
        "provide_b": [
            "a4516db6-6ed6-431c-8197-aa1c85770911"
        ],
        "provide_operator": [
            "179fb78c-b533-4674-903a-f6c995cdbfee"
        ]
    },
    "inTransitions": {
        "provide_b": [
            "3bbfcc81-6724-442c-b1ff-0394b412a71c"
        ],
        "provide_operator": [
            "a4516db6-6ed6-431c-8197-aa1c85770911"
        ],
        "result": [
            "179fb78c-b533-4674-903a-f6c995cdbfee"
        ],
        "provide_a": [
            "dfb61ff2-a77a-49cf-9adb-6799c86bce2a"
        ]
    },
    "tokens": {
        "cfcef6cb-c417-4ed1-9173-166cc9297213": {
            "schema": "http:\/\/pvm.forma-pro.com\/schemas\/Token.json",
            "id": "cfcef6cb-c417-4ed1-9173-166cc9297213",
            "transitions": [
                {
                    "schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
                    "id": "7df47183-eeca-4ab4-9c72-cabc37548730",
                    "transitionId": "dfb61ff2-a77a-49cf-9adb-6799c86bce2a",
                    "weight": 1,
                    "state": "opened",
                    "time": 15606687562477
                },
                {
                    "schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
                    "id": "fdef3690-d008-446a-b61a-8cc5b53ad004",
                    "transitionId": "dfb61ff2-a77a-49cf-9adb-6799c86bce2a",
                    "weight": 1,
                    "state": "waiting",
                    "time": 15606687562484,
                    "reason": ""
                }
            ]
        }
    }
}