Chris@13: <?php declare(strict_types=1);
Chris@13: 
Chris@13: namespace PhpParser;
Chris@13: 
Chris@13: class JsonDecoder
Chris@13: {
Chris@13:     /** @var \ReflectionClass[] Node type to reflection class map */
Chris@13:     private $reflectionClassCache;
Chris@13: 
Chris@13:     public function decode(string $json) {
Chris@13:         $value = json_decode($json, true);
Chris@13:         if (json_last_error()) {
Chris@13:             throw new \RuntimeException('JSON decoding error: ' . json_last_error_msg());
Chris@13:         }
Chris@13: 
Chris@13:         return $this->decodeRecursive($value);
Chris@13:     }
Chris@13: 
Chris@13:     private function decodeRecursive($value) {
Chris@13:         if (\is_array($value)) {
Chris@13:             if (isset($value['nodeType'])) {
Chris@13:                 if ($value['nodeType'] === 'Comment' || $value['nodeType'] === 'Comment_Doc') {
Chris@13:                     return $this->decodeComment($value);
Chris@13:                 }
Chris@13:                 return $this->decodeNode($value);
Chris@13:             }
Chris@13:             return $this->decodeArray($value);
Chris@13:         }
Chris@13:         return $value;
Chris@13:     }
Chris@13: 
Chris@13:     private function decodeArray(array $array) : array {
Chris@13:         $decodedArray = [];
Chris@13:         foreach ($array as $key => $value) {
Chris@13:             $decodedArray[$key] = $this->decodeRecursive($value);
Chris@13:         }
Chris@13:         return $decodedArray;
Chris@13:     }
Chris@13: 
Chris@13:     private function decodeNode(array $value) : Node {
Chris@13:         $nodeType = $value['nodeType'];
Chris@13:         if (!\is_string($nodeType)) {
Chris@13:             throw new \RuntimeException('Node type must be a string');
Chris@13:         }
Chris@13: 
Chris@13:         $reflectionClass = $this->reflectionClassFromNodeType($nodeType);
Chris@13:         /** @var Node $node */
Chris@13:         $node = $reflectionClass->newInstanceWithoutConstructor();
Chris@13: 
Chris@13:         if (isset($value['attributes'])) {
Chris@13:             if (!\is_array($value['attributes'])) {
Chris@13:                 throw new \RuntimeException('Attributes must be an array');
Chris@13:             }
Chris@13: 
Chris@13:             $node->setAttributes($this->decodeArray($value['attributes']));
Chris@13:         }
Chris@13: 
Chris@13:         foreach ($value as $name => $subNode) {
Chris@13:             if ($name === 'nodeType' || $name === 'attributes') {
Chris@13:                 continue;
Chris@13:             }
Chris@13: 
Chris@13:             $node->$name = $this->decodeRecursive($subNode);
Chris@13:         }
Chris@13: 
Chris@13:         return $node;
Chris@13:     }
Chris@13: 
Chris@13:     private function decodeComment(array $value) : Comment {
Chris@13:         $className = $value['nodeType'] === 'Comment' ? Comment::class : Comment\Doc::class;
Chris@13:         if (!isset($value['text'])) {
Chris@13:             throw new \RuntimeException('Comment must have text');
Chris@13:         }
Chris@13: 
Chris@13:         return new $className(
Chris@13:             $value['text'], $value['line'] ?? -1, $value['filePos'] ?? -1, $value['tokenPos'] ?? -1
Chris@13:         );
Chris@13:     }
Chris@13: 
Chris@13:     private function reflectionClassFromNodeType(string $nodeType) : \ReflectionClass {
Chris@13:         if (!isset($this->reflectionClassCache[$nodeType])) {
Chris@13:             $className = $this->classNameFromNodeType($nodeType);
Chris@13:             $this->reflectionClassCache[$nodeType] = new \ReflectionClass($className);
Chris@13:         }
Chris@13:         return $this->reflectionClassCache[$nodeType];
Chris@13:     }
Chris@13: 
Chris@13:     private function classNameFromNodeType(string $nodeType) : string {
Chris@13:         $className = 'PhpParser\\Node\\' . strtr($nodeType, '_', '\\');
Chris@13:         if (class_exists($className)) {
Chris@13:             return $className;
Chris@13:         }
Chris@13: 
Chris@13:         $className .= '_';
Chris@13:         if (class_exists($className)) {
Chris@13:             return $className;
Chris@13:         }
Chris@13: 
Chris@13:         throw new \RuntimeException("Unknown node type \"$nodeType\"");
Chris@13:     }
Chris@13: }