feature #10194 [Console] Added standalone PSR-3 compliant logger (dunglas)

This PR was merged into the 2.5-dev branch.

Discussion
----------

[Console] Added standalone PSR-3 compliant logger

This PR adds a standalone, PSR-3 compliant, logger to the Console component. It logs all messages on the console output. Messages of `DEBUG`, `INFO` and `NOTICE` levels are displayed using the `info` format (default to green). Higher levels are displayed using the `error` formatter (default to red).

This logger is similar to the [Monolog's Console Handler](http://symfony.com/doc/current/cookbook/logging/monolog_console.html) but does not have any external dependency (except `php-fig/log`). This is useful for console applications and commands needing a lightweight PSR-3 compliant logger (e.g. required by a dependency or to display basic informations to the user).

An usage example is available here: https://github.com/dunglas/php-schema.org-model/blob/master/src/SchemaOrgModel/Command/GenerateEntitiesCommand.php#L71

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | symfony/symfony-docs#3696

Commits
-------

e40b34d [Console] Added standalone PSR-3 compliant logger

src/Symfony/Component/Console/Logger/ConsoleLogger.php

@@ -0,0 +1,116 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Console\Logger;
+
+use Psr\Log\AbstractLogger;
+use Psr\Log\InvalidArgumentException;
+use Psr\Log\LogLevel;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Output\ConsoleOutputInterface;
+
+/**
+ * PSR-3 compliant console logger
+ *
+ * @author Kévin Dunglas <dunglas@gmail.com>
+ * @link http://www.php-fig.org/psr/psr-3/
+ */
+class ConsoleLogger extends AbstractLogger
+{
+    const INFO = 'info';
+    const ERROR = 'error';
+
+    /**
+     * @var OutputInterface
+     */
+    private $output;
+    /**
+     * @var array
+     */
+    private $verbosityLevelMap = array(
+        LogLevel::EMERGENCY => OutputInterface::VERBOSITY_NORMAL,
+        LogLevel::ALERT => OutputInterface::VERBOSITY_NORMAL,
+        LogLevel::CRITICAL => OutputInterface::VERBOSITY_NORMAL,
+        LogLevel::ERROR => OutputInterface::VERBOSITY_NORMAL,
+        LogLevel::WARNING => OutputInterface::VERBOSITY_NORMAL,
+        LogLevel::NOTICE => OutputInterface::VERBOSITY_VERBOSE,
+        LogLevel::INFO => OutputInterface::VERBOSITY_VERY_VERBOSE,
+        LogLevel::DEBUG => OutputInterface::VERBOSITY_DEBUG
+    );
+    /**
+     * @var array
+     */
+    private $formatLevelMap = array(
+        LogLevel::EMERGENCY => self::ERROR,
+        LogLevel::ALERT => self::ERROR,
+        LogLevel::CRITICAL => self::ERROR,
+        LogLevel::ERROR => self::ERROR,
+        LogLevel::WARNING => self::INFO,
+        LogLevel::NOTICE => self::INFO,
+        LogLevel::INFO => self::INFO,
+        LogLevel::DEBUG => self::INFO
+    );
+
+    /**
+     * @param OutputInterface $output
+     * @param array           $verbosityLevelMap
+     * @param array           $formatLevelMap
+     */
+    public function __construct(OutputInterface $output, array $verbosityLevelMap = array(), array $formatLevelMap = array())
+    {
+        $this->output = $output;
+        $this->verbosityLevelMap = $verbosityLevelMap + $this->verbosityLevelMap;
+        $this->formatLevelMap = $formatLevelMap + $this->formatLevelMap;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function log($level, $message, array $context = array())
+    {
+        if (!isset($this->verbosityLevelMap[$level])) {
+            throw new InvalidArgumentException(sprintf('The log level "%s" does not exist.', $level));
+        }
+
+        // Write to the error output if necessary and available
+        if ($this->formatLevelMap[$level] === self::ERROR && $this->output instanceof ConsoleOutputInterface) {
+            $output = $this->output->getErrorOutput();
+        } else {
+            $output = $this->output;
+        }
+
+        if ($output->getVerbosity() >= $this->verbosityLevelMap[$level]) {
+            $output->writeln(sprintf('<%1$s>[%2$s] %3$s</%1$s>', $this->formatLevelMap[$level], $level, $this->interpolate($message, $context)));
+        }
+    }
+
+    /**
+     * Interpolates context values into the message placeholders
+     *
+     * @author PHP Framework Interoperability Group
+     * @param  string $message
+     * @param  array  $context
+     * @return string
+     */
+    private function interpolate($message, array $context)
+    {
+        // build a replacement array with braces around the context keys
+        $replace = array();
+        foreach ($context as $key => $val) {
+            if (!is_array($val) && (!is_object($val) || method_exists($val, '__toString'))) {
+                $replace[sprintf('{%s}', $key)] = $val;
+            }
+        }
+
+        // interpolate replacement values into the message and return
+        return strtr($message, $replace);
+    }
+}

src/Symfony/Component/Console/Tests/Fixtures/DummyOutput.php

@@ -0,0 +1,36 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Console\Tests\Fixtures;
+
+use Symfony\Component\Console\Output\BufferedOutput;
+
+/**
+ * Dummy output
+ *
+ * @author Kévin Dunglas <dunglas@gmail.com>
+ */
+class DummyOutput extends BufferedOutput
+{
+    /**
+     * @return array
+     */
+    public function getLogs()
+    {
+        $logs = array();
+        foreach (explode("\n", trim($this->fetch())) as $message) {
+            preg_match('/^\[(.*)\] (.*)/', $message, $matches);
+            $logs[] = sprintf('%s %s', $matches[1], $matches[2]);
+        }
+
+        return $logs;
+    }
+}

src/Symfony/Component/Console/Tests/Logger/ConsoleLoggerTest.php

@@ -0,0 +1,58 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Console\Tests\Logger;
+
+use Psr\Log\Test\LoggerInterfaceTest;
+use Psr\Log\LogLevel;
+use Symfony\Component\Console\Logger\ConsoleLogger;
+use Symfony\Component\Console\Tests\Fixtures\DummyOutput;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * Console logger test
+ *
+ * @author Kévin Dunglas <dunglas@gmail.com>
+ */
+class ConsoleLoggerTest extends LoggerInterfaceTest
+{
+    /**
+     * @var DummyOutput
+     */
+    protected $output;
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getLogger()
+    {
+        $this->output = new DummyOutput(OutputInterface::VERBOSITY_VERBOSE);
+
+        return new ConsoleLogger($this->output, array(
+            LogLevel::EMERGENCY => OutputInterface::VERBOSITY_NORMAL,
+            LogLevel::ALERT => OutputInterface::VERBOSITY_NORMAL,
+            LogLevel::CRITICAL => OutputInterface::VERBOSITY_NORMAL,
+            LogLevel::ERROR => OutputInterface::VERBOSITY_NORMAL,
+            LogLevel::WARNING => OutputInterface::VERBOSITY_NORMAL,
+            LogLevel::NOTICE => OutputInterface::VERBOSITY_NORMAL,
+            LogLevel::INFO => OutputInterface::VERBOSITY_NORMAL,
+            LogLevel::DEBUG => OutputInterface::VERBOSITY_NORMAL
+        ));
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getLogs()
+    {
+        return $this->output->getLogs();
+    }
+}

src/Symfony/Component/Console/composer.json

@@ -19,10 +19,12 @@
         "php": ">=5.3.3"
     },
     "require-dev": {
-        "symfony/event-dispatcher": "~2.1"
+        "symfony/event-dispatcher": "~2.1",
+        "psr/log": "~1.0"
     },
     "suggest": {
-        "symfony/event-dispatcher": ""
+        "symfony/event-dispatcher": "",
+        "psr/log": "For using the console logger"
     },
     "autoload": {
         "psr-0": { "Symfony\\Component\\Console\\": "" }