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HowItWorks.md

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How Does Rector Work?

(Inspired by How it works in BetterReflection)

1. Finds all files and Load Configured Rectors

  • The application finds files in source you provide and registeres Rectors - from --level, --config or local rector.yaml
  • Then it iterates all found files and applies relevant Rectors to them.
  • Rector in this context is 1 single class that modifies 1 thing, e.g. changes class name

2. Parse and Reconstruct 1 File

The iteration of files, nodes and Rectors respects this life cycle:

<?php declare(strict_types=1);

use Rector\Contract\Rector\PhpRectorInterface;
use PhpParser\Parser;

/** @var SplFileInfo[] $fileInfos */
foreach ($fileInfos as $fileInfo) {
    // 1 file => nodes
    /** @var Parser $phpParser */
    $nodes = $phpParser->parse(file_get_contents($fileInfo->getRealPath()));

    // nodes => 1 node
    foreach ($nodes as $node) { // rather traverse all of them
        /** @var PhpRectorInterface[] $rectors */
        foreach ($rectors as $rector) {
            foreach ($rector->getNodeTypes() as $nodeType) {
                if (is_a($node, $nodeType, true)) {
                    $rector->refactor($node);
                }
            }
        }
    }
}

2.1 Prepare Phase

  • File is parsed by nikic/php-parser, 4.0 that supports writing modified tree back to a file
  • Then nodes (array of objects by parser) are traversed by StandaloneTraverseNodeTraverser to prepare it's metadata, e.g. class name, method node the node is in, namespace name etc. added by $node->setAttribute(Attribute::CLASS_NODE, 'value').

2.2 Rectify Phase

  • When all nodes are ready, applicies iterates all active Rector
  • Each nodes is compared to $rector->getNodeTypes() method to see, if this Rector should do some work on it, e.g. is this class name called OldClassName?
  • If it doesn't match, it goes to next node.
  • If it matches, the $rector->reconstruct($node) method is called
  • Active Rector changes all what he should and returns changed node

2.2.1 Order of Rectors

  • Rectors are run by they natural order in config, first will be run first.

E.g. in this case, first will be changed @expectedException annotation to method, then a method setExpectedException to expectedException.

# rector.yaml
services:
    Rector\PHPUnit\Rector\ExceptionAnnotationRector: ~

    Rector\Rector\MethodCall\RenameMethodRector:
        $perClassOldToNewMethods:
                'PHPUnit\Framework\TestClass':
                    'setExpectedException': 'expectedException'
                    'setExpectedExceptionRegExp': 'expectedException'

2.3 Save File/Diff Phase

  • When work on all nodes of 1 file is done, the file will be saved if it has some changes
  • Or if the --dry-run option is on, it will store the git-like diff thanks to GeckoPackages/GeckoDiffOutputBuilder
  • Then go to next file

3 Reporting

  • After this Rector displays list of changed files
  • Or with --dry-run option the diff of these files

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