Architecture

This guide is dedicated to all PHP developers that want to learn more about each component.

As application is following the Domain-driven design (DDD) principle, the directory structure match this one.

src/
├── Application
├── Infrastructure
└── Presentation

Application layer

Analyser(s)

The CompatibilityAnalyser has the responsibility to collects different metrics to find out the minimum version and the extensions required for a piece of code to run.

To do so, we mainly use the PhpParser, DataCollector and Sniffs.

Collection(s)

Configuration

The ConfigResolver component is in charge to handle all arguments/options provided by an instance of Symfony\Component\Console\Input\InputInterface

You will find usage into the Bartlett\CompatInfo\Application\Kernel\ConsoleKernel::createFromInput function.

Data Collector(s)

This element is in charge to store data (rule id, php and extension versions found) for later produce results by Extension/Reporter.

Event(s)

CompatInfo use the Symfony Event-Dispatcher component to avoid tight coupling between a set of interacting objects.

Bartlett\CompatInfo\Application\Event\Dispatcher\EventDispatcher is in charge to dispatch all events to other elements (extensions: logger, progressbar and reporters) of this application.

Extension(s)

Kernel

This element is the main entry point of the bin/phpcompatinfo command line runner.

Logger

Parser

We use a PHP Parser to parse source code into an abstract syntax tree (AST). Each Sniffs (rules) identified by a fingerprint (AST nodes) will then be stored into the DataCollector.

Polyfill(s)

Profiler

Query(s)

Service(s)

Sniffs

Each one has responsibility to detect a specific PHP feature.

Infrastructure layer

Both layers Application and Presentation talk to each other with two buses (one for Queries, and another one for Commands).

We used the use the Symfony Messenger component to realize these actions.

Presentation layer

The Command Line Runner of CompatInfo is a Symfony Console Application with many Command.

• all db:* commands are inherited directly from CompatInfoDB
• analyser:run is the main command to parse a datasource and print results of analysis
• rule:list is a command to identify each rule found during analysis (id, description, sniff used)