diff --git a/core/modules/search/lib/Drupal/search/SearchExpression.php b/core/modules/search/lib/Drupal/search/SearchExpression.php
new file mode 100644
index 0000000..cd5e5dc
--- /dev/null
+++ b/core/modules/search/lib/Drupal/search/SearchExpression.php
@@ -0,0 +1,93 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\search\SearchExpression.
+ */
+
+namespace Drupal\search;
+
+/**
+ * Defines a search expression.
+ */
+class SearchExpression {
+
+  /**
+   * The search expression string
+   *
+   * @var string
+   */
+  protected $expression;
+
+  /**
+   * Constructs a SearchExpression.
+   *
+   * @param string $expression
+   *   The search expression.
+   */
+  public function __construct($expression) {
+    $this->expression = $expression;
+  }
+
+  /**
+   * Gets the expression.
+   *
+   * @return string
+   */
+  public function getExpression() {
+    return $this->expression;
+  }
+
+  /**
+   * Extracts a module-specific search option from a search expression.
+   *
+   * Search options are added using SearchExpression::insert() and retrieved
+   * using SearchExpression::extract(). They take the form option:value, and
+   * are added to the ordinary keywords in the search expression.
+   *
+   * @param string $option
+   *   The name of the option to retrieve from the search expression.
+   *
+   * @return string
+   *   The value previously stored in the search expression for option $option,
+   *   if any. Trailing spaces in values will not be included.
+   */
+  public function extract($option) {
+    if (preg_match('/(^| )' . $option . ':([^ ]*)( |$)/i', $this->expression, $matches)) {
+      return $matches[2];
+    }
+  }
+
+  /**
+   * Adds a module-specific search option to a search expression.
+   *
+   * Search options are added using SearchExpression::insert() and retrieved
+   * using SearchExpression::extract(). They take the form option:value, and
+   * are added to the ordinary keywords in the search expression.
+   *
+   * @param string $option
+   *   The name of the option to add to the search expression.
+   * @param string $value
+   *   The value to add for the option. If present, it will replace any previous
+   *   value added for the option. Cannot contain any spaces or | characters, as
+   *   these are used as delimiters. If you want to add a blank value $option: to
+   *   the search expression, pass in an empty string or a string that is
+   *   composed of only spaces. To clear a previously-stored option without
+   *   adding a replacement, pass in NULL for $value or omit.
+   *
+   * @return static|\Drupal\search\SearchExpression
+   *   The search expression, with any previous value for this option removed, and
+   *   a new $option:$value pair added if $value was provided.
+   */
+  public function insert($option, $value = NULL) {
+    // Remove any previous values stored with $option.
+    $this->expression = trim(preg_replace('/(^| )' . $option . ':[^ ]*/i', '', $this->expression));
+
+    // Set new value, if provided.
+    if (isset($value)) {
+      $this->expression .= ' ' . $option . ':' . trim($value);
+    }
+    return $this;
+  }
+
+}
diff --git a/core/modules/search/lib/Drupal/search/Tests/SearchExpressionInsertExtractTest.php b/core/modules/search/lib/Drupal/search/Tests/SearchExpressionInsertExtractTest.php
deleted file mode 100644
index b7ea84a..0000000
--- a/core/modules/search/lib/Drupal/search/Tests/SearchExpressionInsertExtractTest.php
+++ /dev/null
@@ -1,71 +0,0 @@
-<?php
-
-/**
- * @file
- * Definition of Drupal\search\Tests\SearchExpressionInsertExtractTest.
- */
-
-namespace Drupal\search\Tests;
-
-use Drupal\simpletest\UnitTestBase;
-
-/**
- * Tests search_expression_insert() and search_expression_extract().
- *
- * @see http://drupal.org/node/419388 (issue)
- */
-class SearchExpressionInsertExtractTest extends UnitTestBase {
-  public static function getInfo() {
-    return array(
-      'name' => 'Search expression insert/extract',
-      'description' => 'Tests the functions search_expression_insert() and search_expression_extract()',
-      'group' => 'Search',
-    );
-  }
-
-  function setUp() {
-    drupal_load('module', 'search');
-    parent::setUp();
-  }
-
-  /**
-   * Tests search_expression_insert() and search_expression_extract().
-   */
-  function testInsertExtract() {
-    $base_expression = "mykeyword";
-    // Build an array of option, value, what should be in the expression, what
-    // should be retrieved from expression.
-    $cases = array(
-      array('foo', 'bar', 'foo:bar', 'bar'), // Normal case.
-      array('foo', NULL, '', NULL), // Empty value: shouldn't insert.
-      array('foo', ' ', 'foo:', ''), // Space as value: should insert but retrieve empty string.
-      array('foo', '', 'foo:', ''), // Empty string as value: should insert but retrieve empty string.
-      array('foo', '0', 'foo:0', '0'), // String zero as value: should insert.
-      array('foo', 0, 'foo:0', '0'), // Numeric zero as value: should insert.
-    );
-
-    foreach ($cases as $index => $case) {
-      $after_insert = search_expression_insert($base_expression, $case[0], $case[1]);
-      if (empty($case[2])) {
-        $this->assertEqual($after_insert, $base_expression, "Empty insert does not change expression in case $index");
-      }
-      else {
-        $this->assertEqual($after_insert, $base_expression . ' ' . $case[2], "Insert added correct expression for case $index");
-      }
-
-      $retrieved = search_expression_extract($after_insert, $case[0]);
-      if (!isset($case[3])) {
-        $this->assertFalse(isset($retrieved), "Empty retrieval results in unset value in case $index");
-      }
-      else {
-        $this->assertEqual($retrieved, $case[3], "Value is retrieved for case $index");
-      }
-
-      $after_clear = search_expression_insert($after_insert, $case[0]);
-      $this->assertEqual(trim($after_clear), $base_expression, "After clearing, base expression is restored for case $index");
-
-      $cleared = search_expression_extract($after_clear, $case[0]);
-      $this->assertFalse(isset($cleared), "After clearing, value could not be retrieved for case $index");
-    }
-  }
-}
diff --git a/core/modules/search/search.module b/core/modules/search/search.module
index 9de229b..48b75f4 100644
--- a/core/modules/search/search.module
+++ b/core/modules/search/search.module
@@ -7,6 +7,7 @@
 
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Component\Utility\Unicode;
+use Drupal\search\SearchExpression;
 
 /**
  * Matches all 'N' Unicode character classes (numbers)
@@ -867,9 +868,8 @@ function search_comment_unpublish($comment) {
  *   if any. Trailing spaces in values will not be included.
  */
 function search_expression_extract($expression, $option) {
-  if (preg_match('/(^| )' . $option . ':([^ ]*)( |$)/i', $expression, $matches)) {
-    return $matches[2];
-  }
+  $expression = new SearchExpression($expression);
+  return $expression->extract($option);
 }
 
 /**
@@ -896,14 +896,8 @@ function search_expression_extract($expression, $option) {
  *   a new $option:$value pair added if $value was provided.
  */
 function search_expression_insert($expression, $option, $value = NULL) {
-  // Remove any previous values stored with $option.
-  $expression = trim(preg_replace('/(^| )' . $option . ':[^ ]*/i', '', $expression));
-
-  // Set new value, if provided.
-  if (isset($value)) {
-    $expression .= ' ' . $option . ':' . trim($value);
-  }
-  return $expression;
+  $expression = new SearchExpression($expression);
+  return $expression->insert($option, $value)->getExpression();
 }
 
 /**
diff --git a/core/modules/search/tests/Drupal/search/Tests/SearchExpressionTest.php b/core/modules/search/tests/Drupal/search/Tests/SearchExpressionTest.php
new file mode 100644
index 0000000..27f59ed
--- /dev/null
+++ b/core/modules/search/tests/Drupal/search/Tests/SearchExpressionTest.php
@@ -0,0 +1,89 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\search\Tests\SearchExpressionTest.
+ */
+
+namespace Drupal\search\Tests;
+
+use Drupal\search\SearchExpression;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Tests the search expression class.
+ *
+ * @see \Drupal\search\SearchExpression
+ */
+class SearchExpressionTest extends UnitTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Search expression insert/extract',
+      'description' => 'Tests the search expression class.',
+      'group' => 'Search',
+    );
+  }
+
+
+  /**
+   * Provides data for the search expression tests.
+   *
+   * @return array
+   *   An array of values passed to the test methods.
+   */
+  public function dataProvider() {
+    $cases = array(
+      // Normal case.
+      array('foo', 'bar', 'foo:bar', 'bar'),
+      // Empty value: shouldn't insert.
+      array('foo', NULL, '', NULL),
+      // Space as value: should insert but retrieve empty string.
+      array('foo', ' ', 'foo:', ''),
+      // Empty string as value: should insert but retrieve empty string.
+      array('foo', '', 'foo:', ''),
+      // String zero as value: should insert.
+      array('foo', '0', 'foo:0', '0'),
+      // Numeric zero as value: should insert.
+      array('foo', 0, 'foo:0', '0'),
+    );
+    return $cases;
+  }
+
+  /**
+   * Tests the search expression methods.
+   *
+   * @dataProvider dataProvider
+   */
+  public function testInsertExtract($case_0, $case_1, $case_2, $case_3) {
+    $base_expression = 'mykeyword';
+    // Build an array of option, value, what should be in the expression, what
+    // should be retrieved from expression.
+
+    $after_insert = new SearchExpression($base_expression);
+    $after_insert->insert($case_0, $case_1);
+
+    if (empty($case_2)) {
+      $this->assertEquals($base_expression, $after_insert->getExpression(), 'Empty insert does change expression.');
+    }
+    else {
+      $this->assertEquals($base_expression . ' ' . $case_2, $after_insert->getExpression(), 'Insert added incorrect expression.');
+    }
+
+    $retrieved = $after_insert->extract($case_0);
+
+    if (!isset($case_3)) {
+      $this->assertFalse(isset($retrieved), 'Empty retrieval results in unset value.');
+    }
+    else {
+      $this->assertEquals($case_3, $retrieved, 'Value is retrieved.');
+    }
+
+    $after_clear = $after_insert->insert($case_0);
+    $this->assertEquals($base_expression, $after_clear->getExpression(), 'After clearing, base expression is not restored.');
+
+    $cleared = $after_clear->extract($case_0);
+    $this->assertFalse(isset($cleared), 'After clearing, value could be retrieved.');
+  }
+
+}