materio-base-d7/sites/all/modules/contrib/fields/date/date_context/date_context.module

<?php
/**
 * @file
 * Add an option to set/not set the context on forms vs views.
 *
 * @TODO
 *
 * Currently only implemented for nodes. Need to add $plugin->execute()
 * for any other entities that might be supported.
 *
 * Cache the date processing, perhaps cache the formatted, timezone-adjusted
 * date strings for each entity (would have to be cached differently for each
 * timezone, based on the tz_handling method for the date).
 */

/**
 * Implements hook_context_node_condition_alter().
 */
function date_context_context_node_condition_alter($node, $op) {
  if ($plugin = context_get_plugin('condition', 'date_context_date_condition')) {
    $plugin->execute($node, $op);
  }
}

/**
 * Implements hook_context_plugins().
 */
function date_context_context_plugins() {
  $plugins = array();
  $plugins['date_context_date_condition'] = array(
    'handler' => array(
      'class' => 'date_context_date_condition',
      'parent' => 'context_condition_node',
      'path' => drupal_get_path('module', 'date_context') . '/plugins',
      'file' => 'date_context_date_condition.inc',
    ),
  );
  return $plugins;
}

/**
 * Implements hook_context_registry().
 */
function date_context_context_registry() {
  return array(
    'conditions' => array(
      'date_context_date_condition' => array(
        'title' => t('Date'),
        'description' => t('Set a condition based on the value of a date field'),
        'plugin' => 'date_context_date_condition',
      ),
    ),
  );
}