/vendor/magento/framework/ObjectManager/Profiler/Code/Generator/Logger.php

<?php
/**
 *
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Framework\ObjectManager\Profiler\Code\Generator;

class Logger extends \Magento\Framework\Code\Generator\EntityAbstract
{
    /**
     * Entity type
     */
    const ENTITY_TYPE = 'logger';

    /**
     * @param string $modelClassName
     * @return string
     */
    protected function _getDefaultResultClassName($modelClassName)
    {
        return $modelClassName . '\\' . ucfirst(static::ENTITY_TYPE);
    }

    /**
     * Returns list of properties for class generator
     *
     * @return array
     */
    protected function _getClassProperties()
    {
        return [
            [
                'name' => 'log',
                'visibility' => 'protected',
                'docblock' => [
                    'shortDescription' => 'Object Manager factory log',
                    'tags' => [
                        ['name' => 'var', 'description' => '\Magento\Framework\ObjectManager\Factory\Log'],
                    ],
                ],
            ],
            [
                'name' => 'subject',
                'visibility' => 'protected',
                'docblock' => [
                    'shortDescription' => 'Object Manager instance',
                    'tags' => [
                        ['name' => 'var', 'description' => '\Magento\Framework\ObjectManagerInterface'],
                    ],
                ],
            ],
        ];
    }

    /**
     * Get default constructor definition for generated class
     *
     * @return array
     */
    protected function _getDefaultConstructorDefinition()
    {
        return [
            'name'       => '__construct',
            'parameters' => [
                ['name' => 'subject'],
                ['name' => 'log'],
            ],
            'body' => "\$this->log = \$log;"
                . "\n\$this->subject = \$subject;"
        ];
    }

    /**
     * Returns list of methods for class generator
     *
     * @return mixed
     */
    protected function _getClassMethods()
    {
        $methods = [$this->_getDefaultConstructorDefinition()];
        $methods[] = [
            'name' => '_invoke',
            'visibility' => 'protected',
            'parameters' => [
                ['name' => 'methodName'],
                ['name' => 'methodArguments', 'type' => 'array', 'passedByReference' => true],
            ],
            'body' => $this->_getInvokeMethodBody(),
            'docblock' => [
                'shortDescription' => 'Invoke method',
                'tags' => [
                    ['name' => 'param', 'description' => 'string $methodName'],
                    ['name' => 'param', 'description' => 'array $methodArguments'],
                    ['name' => 'return', 'description' => 'mixed'],
                ],
            ],
        ];
        $methods[] = [
            'name' => '__clone',
            'body' => "\$this->subject = clone \$this->subject;"
                . "\n\$this->log->add(\$this->subject);",
            'docblock' => [
                'shortDescription' => 'Clone subject instance',
            ],
        ];

        $methods[] = [
            'name' => '__sleep',
            'body' => "return array('subject');",
        ];

        $methods[] = [
            'name' => '__wakeUp',
            'body' => "\$this->log = \\Magento\\Framework\\ObjectManager\\Profiler\\Log::getInstance();"
                . "\n\$this->log->add(\$this->subject);",
        ];

        $reflectionClass = new \ReflectionClass($this->getSourceClassName());
        $publicMethods   = $reflectionClass->getMethods(\ReflectionMethod::IS_PUBLIC);
        foreach ($publicMethods as $method) {
            if (!($method->isConstructor() || $method->isFinal() || $method->isStatic() || $method->isDestructor())
                && !in_array($method->getName(), ['__sleep', '__wakeup', '__clone'])
            ) {
                $methods[] = $this->_getMethodInfo($method);
            }
        }

        return $methods;
    }

    /**
     * Retrieve body of the _invoke method
     *
     * @return string
     */
    protected function _getInvokeMethodBody()
    {
        return "\n\$this->log->invoked(\$this->subject, \$methodName);"
        . "\n\$result = call_user_func_array(array(\$this->subject, \$methodName), \$methodArguments);"
        . "\nif (\$result === \$this->subject) {"
        . "\n    return \$this;"
        . "\n}"
        . "\nreturn \$result;";
    }

    /**
     * Retrieve method info
     *
     * @param \ReflectionMethod $method
     * @return array
     */
    protected function _getMethodInfo(\ReflectionMethod $method)
    {
        $parameters = [];
        foreach ($method->getParameters() as $parameter) {
            $parameters[] = $this->_getMethodParameterInfo($parameter);
        }

        $body = "\$args = func_get_args();";
        foreach ($parameters as $key => $parameter) {
            if ($parameter['passedByReference']) {
                $body .= "\$args[$key] = &\$" . $parameter['name'] . ';';
            }
        }

        $methodInfo = [
            'name' => $method->getName(),
            'parameters' => $parameters,
            'body' => $body . "\nreturn \$this->_invoke('{$method->getName()}', \$args);",
            'docblock' => [
                'shortDescription' => '{@inheritdoc}',
            ],
        ];

        return $methodInfo;
    }

    /**
     * Generate resulting class source code
     *
     * @return string
     */
    protected function _generateCode()
    {
        $typeName = $this->getSourceClassName();
        $reflection = new \ReflectionClass($typeName);

        if ($reflection->isInterface()) {
            $this->_classGenerator->setImplementedInterfaces([$typeName]);
        } else {
            $this->_classGenerator->setExtendedClass($typeName);
        }
        return parent::_generateCode();
    }

    /**
     * {@inheritdoc}
     */
    protected function _validateData()
    {
        $result = parent::_validateData();

        if ($result) {
            $sourceClassName = $this->getSourceClassName();
            $resultClassName = $this->_getResultClassName();

            if ($resultClassName !== $sourceClassName . '\\Logger') {
                $this->_addError(
                    'Invalid Logger class name [' . $resultClassName . ']. Use ' . $sourceClassName . '\\Logger'
                );
                $result = false;
            }
        }
        return $result;
    }
}