Update to Drupal 8.2.0. For more information, see https://www.drupal.org/project/drupal/releases/8.2.0

core/lib/Drupal/Component/Serialization/Yaml.php

@@ -2,42 +2,37 @@
 
 namespace Drupal\Component\Serialization;
 
-use Drupal\Component\Serialization\Exception\InvalidDataTypeException;
-use Symfony\Component\Yaml\Parser;
-use Symfony\Component\Yaml\Dumper;
-
 /**
- * Default serialization for YAML using the Symfony component.
+ * Provides a YAML serialization implementation.
+ *
+ * Proxy implementation that will choose the best library based on availability.
  */
 class Yaml implements SerializationInterface {
 
+  /**
+   * The YAML implementation to use.
+   *
+   * @var \Drupal\Component\Serialization\SerializationInterface
+   */
+  protected static $serializer;
+
   /**
    * {@inheritdoc}
    */
   public static function encode($data) {
-    try {
-      $yaml = new Dumper();
-      $yaml->setIndentation(2);
-      return $yaml->dump($data, PHP_INT_MAX, 0, TRUE, FALSE);
-    }
-    catch (\Exception $e) {
-      throw new InvalidDataTypeException($e->getMessage(), $e->getCode(), $e);
-    }
+    // Instead of using \Drupal\Component\Serialization\Yaml::getSerializer(),
+    // always using Symfony for writing the data, to reduce the risk of having
+    // differences if different environments (like production and development)
+    // do not match in terms of what YAML implementation is available.
+    return YamlSymfony::encode($data);
   }
 
   /**
    * {@inheritdoc}
    */
   public static function decode($raw) {
-    try {
-      $yaml = new Parser();
-      // Make sure we have a single trailing newline. A very simple config like
-      // 'foo: bar' with no newline will fail to parse otherwise.
-      return $yaml->parse($raw, TRUE, FALSE);
-    }
-    catch (\Exception $e) {
-      throw new InvalidDataTypeException($e->getMessage(), $e->getCode(), $e);
-    }
+    $serializer = static::getSerializer();
+    return $serializer::decode($raw);
   }
 
   /**
@@ -47,4 +42,23 @@ class Yaml implements SerializationInterface {
     return 'yml';
   }
 
+  /**
+   * Determines which implementation to use for parsing YAML.
+   */
+  protected static function getSerializer() {
+
+    if (!isset(static::$serializer)) {
+      // Use the PECL YAML extension if it is available. It has better
+      // performance for file reads and is YAML compliant.
+      if (extension_loaded('yaml')) {
+        static::$serializer = YamlPecl::class;
+      }
+      else {
+        // Otherwise, fallback to the Symfony implementation.
+        static::$serializer = YamlSymfony::class;
+      }
+    }
+    return static::$serializer;
+  }
+
 }

core/lib/Drupal/Component/Serialization/YamlPecl.php

@@ -0,0 +1,101 @@
+<?php
+
+namespace Drupal\Component\Serialization;
+
+use Drupal\Component\Serialization\Exception\InvalidDataTypeException;
+
+/**
+ * Provides default serialization for YAML using the PECL extension.
+ */
+class YamlPecl implements SerializationInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function encode($data) {
+    static $init;
+    if (!isset($init)) {
+      ini_set('yaml.output_indent', 2);
+      // Do not break lines at 80 characters.
+      ini_set('yaml.output_width', -1);
+      $init = TRUE;
+    }
+    return yaml_emit($data, YAML_UTF8_ENCODING, YAML_LN_BREAK);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function decode($raw) {
+    // yaml_parse() will error with an empty value.
+    if (!trim($raw)) {
+      return NULL;
+    }
+    // @todo Use ErrorExceptions when https://drupal.org/node/1247666 is in.
+    // yaml_parse() will throw errors instead of raising an exception. Until
+    // such time as Drupal supports native PHP ErrorExceptions as the error
+    // handler, we need to temporarily set the error handler as ::errorHandler()
+    // and then restore it after decoding has occurred. This allows us to turn
+    // parsing errors into a throwable exception.
+    // @see Drupal\Component\Serialization\Exception\InvalidDataTypeException
+    // @see http://php.net/manual/en/class.errorexception.php
+    set_error_handler([__CLASS__, 'errorHandler']);
+    $ndocs = 0;
+    $data = yaml_parse($raw, 0, $ndocs, [
+      YAML_BOOL_TAG => '\Drupal\Component\Serialization\YamlPecl::applyBooleanCallbacks',
+    ]);
+    restore_error_handler();
+    return $data;
+  }
+
+  /**
+   * Handles errors for \Drupal\Component\Serialization\YamlPecl::decode().
+   *
+   * @param int $severity
+   *   The severity level of the error.
+   * @param string $message
+   *   The error message to display.
+   *
+   * @see \Drupal\Component\Serialization\YamlPecl::decode()
+   */
+  public static function errorHandler($severity, $message) {
+    restore_error_handler();
+    throw new InvalidDataTypeException($message, $severity);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getFileExtension() {
+    return 'yml';
+  }
+
+  /**
+   * Applies callbacks after parsing to ignore 1.1 style booleans.
+   *
+   * @param mixed $value
+   *   Value from YAML file.
+   * @param string $tag
+   *   Tag that triggered the callback.
+   * @param int $flags
+   *   Scalar entity style flags.
+   *
+   * @return string|bool
+   *   FALSE, false, TRUE and true are returned as booleans, everything else is
+   *   returned as a string.
+   */
+  public static function applyBooleanCallbacks($value, $tag, $flags) {
+    // YAML 1.1 spec dictates that 'Y', 'N', 'y' and 'n' are booleans. But, we
+    // want the 1.2 behavior, so we only consider 'false', 'FALSE', 'true' and
+    // 'TRUE' as booleans.
+    if (!in_array(strtolower($value), ['false', 'true'], TRUE)) {
+      return $value;
+    }
+    $map = [
+      'false' => FALSE,
+      'true' => TRUE,
+    ];
+    return $map[strtolower($value)];
+  }
+
+}

core/lib/Drupal/Component/Serialization/YamlSymfony.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\Component\Serialization;
+
+use Drupal\Component\Serialization\Exception\InvalidDataTypeException;
+use Symfony\Component\Yaml\Parser;
+use Symfony\Component\Yaml\Dumper;
+
+/**
+ * Default serialization for YAML using the Symfony component.
+ */
+class YamlSymfony implements SerializationInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function encode($data) {
+    try {
+      $yaml = new Dumper();
+      $yaml->setIndentation(2);
+      return $yaml->dump($data, PHP_INT_MAX, 0, TRUE, FALSE);
+    }
+    catch (\Exception $e) {
+      throw new InvalidDataTypeException($e->getMessage(), $e->getCode(), $e);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function decode($raw) {
+    try {
+      $yaml = new Parser();
+      // Make sure we have a single trailing newline. A very simple config like
+      // 'foo: bar' with no newline will fail to parse otherwise.
+      return $yaml->parse($raw, TRUE, FALSE);
+    }
+    catch (\Exception $e) {
+      throw new InvalidDataTypeException($e->getMessage(), $e->getCode(), $e);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getFileExtension() {
+    return 'yml';
+  }
+
+}