1 files changed, 80 insertions, 0 deletions
diff --git a/includes/common.inc b/includes/common.inc
index bd41d283c..df885d362 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -4917,3 +4917,83 @@ function _drupal_flush_css_js() {
   }
   variable_set('css_js_query_string', $new_character . substr($string_history, 0, 19));
 }
+
+/**
+ * Parse a dependency for comparison by drupal_check_incompatibility().
+ *
+ * @param $dependency
+ *   A dependency string, for example 'foo (>=7.x-4.5-beta5, 3.x)'.
+ * @return
+ *   An associative array with three keys:
+ *   - 'name' includes the name of the thing to depend on (e.g. 'foo').
+ *   - 'original_version' contains the original version string (which can be
+ *     used in the UI for reporting incompatibilities).
+ *   - 'versions' is a list of associative arrays, each containing the keys
+ *     'op' and 'version'. 'op' can be one of: '=', '==', '!=', '<>', '<',
+ *     '<=', '>', or '>='. 'version' is one piece like '4.5-beta3'.
+ *   Callers should pass this structure to drupal_check_incompatibility().
+ *
+ * @see drupal_check_incompatibility()
+ */
+function drupal_parse_dependency($dependency) {
+  // We use named subpatterns and support every op that version_compare
+  // supports. Also, op is optional and defaults to equals.
+  $p_op = '(?P<operation>!=|==|=|<|<=|>|>=|<>)?';
+  // Core version is always optional: 7.x-2.x and 2.x is treated the same.
+  $p_core = '(?:' . preg_quote(DRUPAL_CORE_COMPATIBILITY) . '-)?';
+  $p_major = '(?P<major>\d+)';
+  // By setting the minor version to x, branches can be matched.
+  $p_minor = '(?P<minor>(?:\d+|x)(?:-[A-Za-z]+\d+)?)';
+  $value = array();
+  $parts = explode('(', $dependency, 2);
+  $value['name'] = trim($parts[0]);
+  if (isset($parts[1])) {
+    $value['original_version'] = ' (' . $parts[1];
+    foreach (explode(',', $parts[1]) as $version) {
+      if (preg_match("/^\s*$p_op\s*$p_core$p_major\.$p_minor/", $version, $matches)) {
+        $op = !empty($matches['operation']) ? $matches['operation'] : '=';
+        if ($matches['minor'] == 'x') {
+          // Drupal considers "2.x" to mean any version that begins with
+          // "2" (e.g. 2.0, 2.9 are all "2.x"). PHP's version_compare(),
+          // on the other hand, treats "x" as a string; so to
+          // version_compare(), "2.x" is considered less than 2.0. This
+          // means that >=2.x and <2.x are handled by version_compare()
+          // as we need, but > and <= are not.
+          if ($op == '>' || $op == '<=') {
+            $matches['major']++;
+          }
+          // Equivalence can be checked by adding two restrictions.
+          if ($op == '=' || $op == '==') {
+            $value['versions'][] = array('op' => '<', 'version' => ($matches['major'] + 1) . '.x');
+            $op = '>=';
+          }
+        }
+        $value['versions'][] = array('op' => $op, 'version' => $matches['major'] . '.' . $matches['minor']);
+      }
+    }
+  }
+  return $value;
+}
+
+/**
+ * Check whether a version is compatible with a given dependency.
+ *
+ * @param $v
+ *   The parsed dependency structure from drupal_parse_dependency().
+ * @param $current_version
+ *   The version to check against (like 4.2).
+ * @return
+ *   NULL if compatible, otherwise the original dependency version string that
+ *   caused the incompatiblity.
+ *
+ * @see drupal_parse_dependency()
+ */
+function drupal_check_incompatibility($v, $current_version) {
+  if (!empty($v['versions'])) {
+    foreach ($v['versions'] as $required_version) {
+      if ((isset($required_version['op']) && !version_compare($current_version, $required_version['version'], $required_version['op']))) {
+        return $v['original_version'];
+      }
+    }
+  }
+}