refactor: Rename method Processor#writeToDisk to saveToFile

* Add a brief explanation to the classes in the Processors namespace

src/Actions/GenerateClassDiagram.php

@@ -59,7 +59,7 @@ public function generate(CodeFinder $finder, string $imagePath): void
         $this->command()->runningProcessor($this->imageProcessor());
         $image = $this->imageProcessor()->process($dotLanguage);
         $this->command()->savingResult();
-        $this->imageProcessor->writeToDisk($image, $imagePath);
+        $this->imageProcessor->saveToFile($image, $imagePath);
     }
 
     /** @throws LogicException If no image processor is provided */

src/Actions/GenerateDotFile.php

@@ -52,6 +52,6 @@ public function generate(CodeFinder $finder, string $dotFilePath): void
         $this->command()->runningProcessor($this->dotProcessor);
         $dotLanguage = $this->dotProcessor->process($structure);
         $this->command()->savingResult();
-        $this->dotProcessor->writeToDisk($dotLanguage, $dotFilePath);
+        $this->dotProcessor->saveToFile($dotLanguage, $dotFilePath);
     }
 }

src/Actions/GenerateStatistics.php

@@ -47,6 +47,6 @@ public function generate(CodeFinder $finder, string $filePath): void
         $this->command()->runningProcessor($this->processor);
         $statistics = $this->processor->process($structure);
         $this->command()->savingResult();
-        $this->processor->writeToDisk($statistics, $filePath);
+        $this->processor->saveToFile($statistics, $filePath);
     }
 }

src/Processors/DotProcessor.php

@@ -4,8 +4,12 @@
  *
  * This source file is subject to the license that is bundled with this package in the file LICENSE.
  */
+
 namespace PhUml\Processors;
 
+/**
+ * It creates a `png` class diagram using the `dot` command
+ */
 class DotProcessor extends ImageProcessor
 {
     public function command(): string

src/Processors/GraphvizProcessor.php

@@ -18,6 +18,9 @@
 use Twig_Environment as TemplateEngine;
 use Twig_Loader_Filesystem as Filesystem;
 
+/**
+ * It creates a digraph from a `Structure` and returns it as a string in DOT format
+ */
 class GraphvizProcessor extends Processor
 {
     /** @var ClassGraphBuilder */

src/Processors/ImageGenerationFailure.php

@@ -4,14 +4,18 @@
  *
  * This source file is subject to the license that is bundled with this package in the file LICENSE.
  */
+
 namespace PhUml\Processors;
 
 use RuntimeException;
 
+/**
+ * It is thrown when either the `dot` or `neato` commands fail
+ */
 class ImageGenerationFailure extends RuntimeException
 {
-    public function __construct($output)
+    public static function withOutput(string $errorMessage): ImageGenerationFailure
     {
-        parent::__construct("Execution of external program failed:\n{$output}");
+        return new ImageGenerationFailure("Execution of external program failed:\n{$errorMessage}");
     }
 }

src/Processors/ImageProcessor.php

@@ -4,11 +4,19 @@
  *
  * This source file is subject to the license that is bundled with this package in the file LICENSE.
  */
+
 namespace PhUml\Processors;
 
 use Symfony\Component\Filesystem\Filesystem;
 use Symfony\Component\Process\Process;
 
+/**
+ * It generates a `png` class diagram from a digraph in DOT format
+ *
+ * It takes a digraph in DOT format, saves it to a temporary location and creates a `png` class
+ * diagram out of it.
+ * It uses either the `dot` or `neato` command to create the image
+ */
 abstract class ImageProcessor extends Processor
 {
     /** @var Process */
@@ -23,6 +31,9 @@ public function __construct(Process $process = null, Filesystem $fileSystem = nu
         $this->fileSystem = $fileSystem ?? new Filesystem();
     }
 
+    /**
+     * It returns the contents of a `png` class diagram
+     */
     public function process(string $digraphInDotFormat): string
     {
         $dotFile = $this->fileSystem->tempnam('/tmp', 'phuml');
@@ -41,12 +52,15 @@ public function process(string $digraphInDotFormat): string
         return $image;
     }
 
+    /**
+     * @throws ImageGenerationFailure If the Grpahviz command failed
+     */
     public function execute(string $inputFile, string $outputFile): void
     {
         $this->process->setCommandLine([$this->command(), '-Tpng', '-o', $outputFile, $inputFile]);
         $this->process->run();
         if (!$this->process->isSuccessful()) {
-            throw new ImageGenerationFailure($this->process->getErrorOutput());
+            throw ImageGenerationFailure::withOutput($this->process->getErrorOutput());
         }
     }
 

src/Processors/NeatoProcessor.php

@@ -4,8 +4,12 @@
  *
  * This source file is subject to the license that is bundled with this package in the file LICENSE.
  */
+
 namespace PhUml\Processors;
 
+/**
+ * It creates a `png` class diagram using the `neato` command
+ */
 class NeatoProcessor extends ImageProcessor
 {
     public function command(): string

src/Processors/Processor.php

@@ -6,9 +6,12 @@
  */
 namespace PhUml\Processors;
 
+/**
+ * Every processor has a name and can write their output to a file
+ */
 abstract class Processor
 {
-    public function writeToDisk(string $contents, string $filePath): void
+    public function saveToFile(string $contents, string $filePath): void
     {
         file_put_contents($filePath, $contents);
     }

src/Processors/StatisticsProcessor.php

@@ -9,6 +9,9 @@
 use PhUml\Code\Structure;
 use PhUml\Code\Summary;
 
+/**
+ * It takes a code `Structure` and extracts a `Summary` of its contents as text
+ */
 class StatisticsProcessor extends Processor
 {
     public function name(): string