first import

sites/all/modules/ctools/plugins/access/context_exists.inc

@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * @file
+ * Plugin to provide access control/visibility based on existence of a specified context
+ */
+
+$plugin = array(
+  'title' => t("Context exists"),
+  'description' => t('Control access by whether or not a context exists and contains data.'),
+  'callback' => 'ctools_context_exists_ctools_access_check',
+  'settings form' => 'ctools_context_exists_ctools_access_settings',
+  'summary' => 'ctools_context_exists_ctools_access_summary',
+  'required context' => new ctools_context_required(t('Context'), 'any', TRUE),
+  'defaults' => array('exists' => TRUE),
+);
+
+/**
+ * Settings form
+ */
+function ctools_context_exists_ctools_access_settings($form, &$form_state, $conf) {
+  $form['settings']['exists'] = array(
+    '#type' => 'radios',
+    '#description' => t("Check to see if the context exists (contains data) or does not exist (contains no data). For example, if a context is optional and the path does not contain an argument for that context, it will not exist."),
+    '#options' => array(TRUE => t('Exists'), FALSE => t("Doesn't exist")),
+    '#default_value' => $conf['exists'],
+  );
+  return $form;
+}
+
+/**
+ * Check for access
+ */
+function ctools_context_exists_ctools_access_check($conf, $context) {
+  // xor returns false if the two bools are the same, and true if they are not.
+  // i.e, if we asked for context_exists and it does, return true.
+  // If we asked for context does not exist and it does, return false.
+  return (empty($context->data) xor !empty($conf['exists']));
+}
+
+/**
+ * Provide a summary description based upon the specified context
+ */
+function ctools_context_exists_ctools_access_summary($conf, $context) {
+  if (!empty($conf['exists'])) {
+    return t('@identifier exists', array('@identifier' => $context->identifier));
+  }
+  else {
+    return t('@identifier does not exist', array('@identifier' => $context->identifier));
+  }
+}