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102 lines
4.3 KiB
Markdown
102 lines
4.3 KiB
Markdown
# How Does Rector Work?
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(Inspired by [*How it works* in BetterReflection](https://github.com/Roave/BetterReflection/blob/master/docs/how-it-works.md))
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## 1. Finds all files and Load Configured Rectors
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- The application finds files in the source code you provide and registered Rectors - from `--config` or local `rector.php`
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- Then it iterates all found files and applies relevant Rectors to them.
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- A *Rector* in this context is 1 single class that modifies 1 thing, e.g. changes the class name
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## 2. Parse and Reconstruct 1 File
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The iteration of files, nodes and Rectors respects this lifecycle:
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```php
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<?php
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declare(strict_types=1);
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use Rector\Contract\Rector\PhpRectorInterface;
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use PhpParser\Parser;
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/** @var SplFileInfo[] $fileInfos */
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foreach ($fileInfos as $fileInfo) {
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// 1 file => nodes
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/** @var Parser $phpParser */
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$nodes = $phpParser->parse(file_get_contents($fileInfo->getRealPath()));
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// nodes => 1 node
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foreach ($nodes as $node) { // rather traverse all of them
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/** @var PhpRectorInterface[] $rectors */
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foreach ($rectors as $rector) {
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foreach ($rector->getNodeTypes() as $nodeType) {
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if (is_a($node, $nodeType, true)) {
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$rector->refactor($node);
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}
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}
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}
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}
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}
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```
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### 2.1 Prepare Phase
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- Files are parsed by [`nikic/php-parser`](https://github.com/nikic/PHP-Parser), 4.0 that supports writing modified tree back to a file
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- Then nodes (array of objects by parser) are traversed by `StandaloneTraverseNodeTraverser` to prepare their metadata, e.g. the class name, the method node the node is in, the namespace name etc. added by `$node->setAttribute('key', 'value')`.
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### 2.2 Rectify Phase
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- When all nodes are ready, the application iterates on all active Rectors
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- Each node is compared with `$rector->getNodeTypes()` method to see if this Rector should do some work on it, e.g. is this class name called `OldClassName`?
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- If it doesn't match, it goes to next node.
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- If it matches, the `$rector->reconstruct($node)` method is called
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- Active Rector change everything they have to and return changed nodes
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### 2.2.1 Order of Rectors
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- Nodes to run rectors are iterated in the node traversal order.
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E.g. rectors for `Class_` node always run before rectors for `ClassMethod` in one class.
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- Rectors are run by the natural order in the configuration, meaning the first
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in the configuration will be run first.
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E.g. in this case, first the `@expectedException` annotation will be changed to a method,
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then the `setExpectedException` method will be changed to `expectedException`.
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```php
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use Rector\PHPUnit\Rector\ClassMethod\ExceptionAnnotationRector;
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use Rector\Renaming\Rector\MethodCall\RenameMethodRector;
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use Rector\Config\RectorConfig
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use Rector\Renaming\ValueObject\MethodCallRename;
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return static function (RectorConfig $rectorConfig): void {
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$rectorConfig->rule(ExceptionAnnotationRector::class);
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$rectorConfig->ruleWithConfiguration(Rector\Renaming\Rector\MethodCall\RenameMethodRector::class, [
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new MethodCallRename('PHPUnit\Framework\TestClass', 'setExpectedException', 'expectedException'),
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new MethodCallRename('PHPUnit\Framework\TestClass', 'setExpectedExceptionRegExp', 'expectedException'),
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]);
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};
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```
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### 2.3 Save File/Diff Phase
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- When work on all nodes of 1 file is done, the file will be saved if it has some changes
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- Or if the `--dry-run` option is on, it will store the *git-like* diff thanks to [GeckoPackages/GeckoDiffOutputBuilder](https://github.com/GeckoPackages/GeckoDiffOutputBuilder)
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- Then Rector will go to the next file
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## 3 Reporting
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- After this, Rector displays the list of changed files
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- Or with `--dry-run` option the diff of these files
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### Similar Projects
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- [ClangMR](https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/41342.pdf) for C++ by Google (closed source) - almost identical workflow, developed independently though
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- [hhast](https://github.com/hhvm/hhast) - HHVM AST + format preserving + migrations
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- [facebook/jscodeshift](https://github.com/facebook/jscodeshift) for Javascript
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- [silverstripe/silverstripe-upgrader](https://github.com/silverstripe/silverstripe-upgrader) for PHP CMS, Silverstripe
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- [dereuromark/upgrade](https://github.com/dereuromark/upgrade) for PHP Framework, CakePHP
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