export.inc

<?php


/**
 * @file
 * Contains code to make it easier to have exportable objects.
 *
 * Documentation for exportable objects is contained in help/export.html.
 */

/**
 * A bit flag used to let us know if an object is in the database.
 */
define('EXPORT_IN_DATABASE', 0x1);

/**
 * A bit flag used to let us know if an object is a 'default' in code.
 */
define('EXPORT_IN_CODE', 0x2);

/**
 * @defgroup export_crud CRUD functions for export.
 * @{
 * export.inc supports a small number of CRUD functions that should always
 * work for every exportable object, no matter how complicated. These
 * functions allow complex objects to provide their own callbacks, but
 * in most cases, the default callbacks will be used.
 *
 * Note that defaults are NOT set in the $schema because it is presumed
 * that a module's personalized CRUD functions will already know which
 * $table to use and not want to clutter up the arguments with it.
 */

/**
 * Create a new object for the given $table.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $set_defaults
 *   If TRUE, which is the default, then default values will be retrieved
 *   from schema fields and set on the object.
 *
 * @return
 *   The loaded object.
 */
function ctools_export_crud_new($table, $set_defaults = TRUE) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    if (!empty($export['create callback']) && function_exists($export['create callback'])) {
        return $export['create callback']($set_defaults);
    }
    else {
        return ctools_export_new_object($table, $set_defaults);
    }
}

/**
 * Load a single exportable object.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $name
 *   The unique ID to load. The field for this ID will be specified by
 *   the export key, which normally defaults to 'name'.
 *
 * @return
 *   The loaded object.
 */
function ctools_export_crud_load($table, $name) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    if (!empty($export['load callback']) && function_exists($export['load callback'])) {
        return $export['load callback']($name);
    }
    else {
        $result = ctools_export_load_object($table, 'names', array(
            $name,
        ));
        if (isset($result[$name])) {
            return $result[$name];
        }
    }
}

/**
 * Load multiple exportable objects.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $names
 *   An array of unique IDs to load. The field for these IDs will be specified
 *   by the export key, which normally defaults to 'name'.
 *
 * @return
 *   An array of the loaded objects.
 */
function ctools_export_crud_load_multiple($table, array $names) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    $results = array();
    if (!empty($export['load multiple callback']) && function_exists($export['load multiple callback'])) {
        $results = $export['load multiple callback']($names);
    }
    else {
        $results = ctools_export_load_object($table, 'names', $names);
    }
    // Ensure no empty results are returned.
    return array_filter($results);
}

/**
 * Load all exportable objects of a given type.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $reset
 *   If TRUE, the static cache of all objects will be flushed prior to
 *   loading all. This can be important on listing pages where items
 *   might have changed on the page load.
 *
 * @return
 *   An array of all loaded objects, keyed by the unique IDs of the export key.
 */
function ctools_export_crud_load_all($table, $reset = FALSE) {
    $schema = ctools_export_get_schema($table);
    if (empty($schema['export'])) {
        return array();
    }
    $export = $schema['export'];
    if ($reset) {
        ctools_export_load_object_reset($table);
    }
    if (!empty($export['load all callback']) && function_exists($export['load all callback'])) {
        return $export['load all callback']($reset);
    }
    else {
        return ctools_export_load_object($table, 'all');
    }
}

/**
 * Save a single exportable object.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to save.
 *
 * @return
 *   Failure to write a record will return FALSE. Otherwise SAVED_NEW or
 *   SAVED_UPDATED is returned depending on the operation performed. The
 *   $object parameter contains values for any serial fields defined by the $table
 */
function ctools_export_crud_save($table, &$object) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    if (!empty($export['save callback']) && function_exists($export['save callback'])) {
        return $export['save callback']($object);
    }
    else {
        // Objects should have a serial primary key. If not, simply fail to write.
        if (empty($export['primary key'])) {
            return FALSE;
        }
        $key = $export['primary key'];
        if ($object->export_type & EXPORT_IN_DATABASE) {
            // Existing record.
            $update = array(
                $key,
            );
        }
        else {
            // New record.
            $update = array();
            $object->export_type = EXPORT_IN_DATABASE;
        }
        return drupal_write_record($table, $object, $update);
    }
}

/**
 * Delete a single exportable object.
 *
 * This only deletes from the database, which means that if an item is in
 * code, then this is actually a revert.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to delete, or the export key.
 */
function ctools_export_crud_delete($table, $object) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    if (!empty($export['delete callback']) && function_exists($export['delete callback'])) {
        return $export['delete callback']($object);
    }
    else {
        // If we were sent an object, get the export key from it. Otherwise
        // assume we were sent the export key.
        $value = is_object($object) ? $object->{$export['key']} : $object;
        db_delete($table)->condition($export['key'], $value)
            ->execute();
    }
}

/**
 * Get the exported code of a single exportable object.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to delete, or the export key.
 * @param $indent
 *   Any indentation to apply to the code, in case this object is embedded
 *   into another, for example.
 *
 * @return
 *   A string containing the executable export of the object.
 */
function ctools_export_crud_export($table, $object, $indent = '') {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    if (!empty($export['export callback']) && function_exists($export['export callback'])) {
        return $export['export callback']($object, $indent);
    }
    else {
        return ctools_export_object($table, $object, $indent);
    }
}

/**
 * Turn exported code into an object.
 *
 * Note: If the code is poorly formed, this could crash and there is no
 * way to prevent this.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $code
 *   The code to eval to create the object.
 *
 * @return
 *   An object created from the export. This object will NOT have been saved
 *   to the database. In the case of failure, a string containing all errors
 *   that the system was able to determine.
 */
function ctools_export_crud_import($table, $code) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    if (!empty($export['import callback']) && function_exists($export['import callback'])) {
        return $export['import callback']($code);
    }
    else {
        ob_start();
        eval($code);
        ob_end_clean();
        if (empty(${$export['identifier']})) {
            $errors = ob_get_contents();
            if (empty($errors)) {
                $errors = t('No item found.');
            }
            return $errors;
        }
        $item = ${$export['identifier']};
        // Set these defaults just the same way that ctools_export_new_object sets
        // them.
        $item->export_type = NULL;
        $item->{$export['export type string']} = t('Local');
        return $item;
    }
}

/**
 * Change the status of a certain object.
 *
 * @param $table
 *   The name of the table to use to enable a certain object. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to enable, or the machine readable name.
 * @param $status
 *   The status, in this case, is whether or not it is 'disabled'.
 */
function ctools_export_crud_set_status($table, $object, $status) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    if (!empty($export['status callback']) && function_exists($export['status callback'])) {
        $export['status callback']($object, $status);
    }
    else {
        if (is_object($object)) {
            ctools_export_set_object_status($object, $status);
        }
        else {
            ctools_export_set_status($table, $object, $status);
        }
    }
}

/**
 * Enable a certain object.
 *
 * @param $table
 *   The name of the table to use to enable a certain object. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to enable, or the machine readable name.
 */
function ctools_export_crud_enable($table, $object) {
    return ctools_export_crud_set_status($table, $object, FALSE);
}

/**
 * Disable a certain object.
 *
 * @param $table
 *   The name of the table to use to disable a certain object. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to disable, or the machine readable name.
 */
function ctools_export_crud_disable($table, $object) {
    return ctools_export_crud_set_status($table, $object, TRUE);
}

/**
 * @}
 */

/**
 * Load some number of exportable objects.
 *
 * This function will cache the objects, load subsidiary objects if necessary,
 * check default objects in code and properly set them up. It will cache
 * the results so that multiple calls to load the same objects
 * will not cause problems.
 *
 * It attempts to reduce, as much as possible, the number of queries
 * involved.
 *
 * @param $table
 *   The name of the table to be loaded from. Data is expected to be in the
 *   schema to make all this work.
 * @param $type
 *   A string to notify the loader what the argument is
 *   - all: load all items. This is the default. $args is unused.
 *   - names: $args will be an array of specific named objects to load.
 *   - conditions: $args will be a keyed array of conditions. The conditions
 *       must be in the schema for this table or errors will result.
 * @param $args
 *   An array of arguments whose actual use is defined by the $type argument.
 */
function ctools_export_load_object($table, $type = 'all', $args = array()) {
    $cache =& drupal_static(__FUNCTION__);
    $cache_table_exists =& drupal_static(__FUNCTION__ . '_table_exists', array());
    $cached_database =& drupal_static('ctools_export_load_object_all');
    if (!array_key_exists($table, $cache_table_exists)) {
        $cache_table_exists[$table] = db_table_exists($table);
    }
    $schema = ctools_export_get_schema($table);
    if (empty($schema) || !$cache_table_exists[$table]) {
        return array();
    }
    $export = $schema['export'];
    if (!isset($cache[$table])) {
        $cache[$table] = array();
    }
    // If fetching all and cached all, we've done so and we are finished.
    if ($type == 'all' && !empty($cached_database[$table])) {
        return $cache[$table];
    }
    $return = array();
    // Don't load anything we've already cached.
    if ($type == 'names' && !empty($args)) {
        foreach ($args as $id => $name) {
            if (isset($cache[$table][$name])) {
                $return[$name] = $cache[$table][$name];
                unset($args[$id]);
            }
        }
        // If nothing left to load, return the result.
        if (empty($args)) {
            return $return;
        }
    }
    // Build the query.
    $query = db_select($table, 't__0')->fields('t__0');
    $alias_count = 1;
    if (!empty($schema['join'])) {
        foreach ($schema['join'] as $join_key => $join) {
            if ($join_schema = drupal_get_schema($join['table'])) {
                $query->join($join['table'], 't__' . $alias_count, 't__0.' . $join['left_key'] . ' = ' . 't__' . $alias_count . '.' . $join['right_key']);
                $query->fields('t__' . $alias_count);
                $alias_count++;
                // Allow joining tables to alter the query through a callback.
                if (isset($join['callback']) && function_exists($join['callback'])) {
                    $join['callback']($query, $schema, $join_schema);
                }
            }
        }
    }
    $conditions = array();
    $query_args = array();
    // If they passed in names, add them to the query.
    if ($type == 'names') {
        $query->condition($export['key'], $args, 'IN');
    }
    elseif ($type == 'conditions') {
        foreach ($args as $key => $value) {
            if (isset($schema['fields'][$key])) {
                $query->condition($key, $value);
            }
        }
    }
    $result = $query->execute();
    $status = variable_get($export['status'], array());
    // Unpack the results of the query onto objects and cache them.
    foreach ($result as $data) {
        if (isset($schema['export']['object factory']) && function_exists($schema['export']['object factory'])) {
            $object = $schema['export']['object factory']($schema, $data);
        }
        else {
            $object = _ctools_export_unpack_object($schema, $data, $export['object']);
        }
        $object->table = $table;
        $object->{$export['export type string']} = t('Normal');
        $object->export_type = EXPORT_IN_DATABASE;
        // Determine if default object is enabled or disabled.
        if (isset($status[$object->{$export['key']}])) {
            $object->disabled = $status[$object->{$export['key']}];
        }
        $cache[$table][$object->{$export['key']}] = $object;
        if ($type == 'conditions') {
            $return[$object->{$export['key']}] = $object;
        }
    }
    // Load subrecords.
    if (isset($export['subrecords callback']) && function_exists($export['subrecords callback'])) {
        $export['subrecords callback']($cache[$table]);
    }
    if ($type == 'names' && !empty($args) && !empty($export['cache defaults'])) {
        $defaults = _ctools_export_get_some_defaults($table, $export, $args);
    }
    else {
        $defaults = _ctools_export_get_defaults($table, $export);
    }
    if ($defaults) {
        foreach ($defaults as $object) {
            if ($type == 'conditions') {
                // If this does not match all of our conditions, skip it.
                foreach ($args as $key => $value) {
                    if (!isset($object->{$key})) {
                        continue 2;
                    }
                    if (is_array($value)) {
                        if (!in_array($object->{$key}, $value)) {
                            continue 2;
                        }
                    }
                    elseif ($object->{$key} != $value) {
                        continue 2;
                    }
                }
            }
            elseif ($type == 'names') {
                if (!in_array($object->{$export['key']}, $args)) {
                    continue;
                }
            }
            // Determine if default object is enabled or disabled.
            if (isset($status[$object->{$export['key']}])) {
                $object->disabled = $status[$object->{$export['key']}];
            }
            if (!empty($cache[$table][$object->{$export['key']}])) {
                $cache[$table][$object->{$export['key']}]->{$export['export type string']} = t('Overridden');
                $cache[$table][$object->{$export['key']}]->export_type |= EXPORT_IN_CODE;
                $cache[$table][$object->{$export['key']}]->export_module = isset($object->export_module) ? $object->export_module : NULL;
                if ($type == 'conditions') {
                    $return[$object->{$export['key']}] = $cache[$table][$object->{$export['key']}];
                }
            }
            else {
                $object->{$export['export type string']} = t('Default');
                $object->export_type = EXPORT_IN_CODE;
                $object->in_code_only = TRUE;
                $object->table = $table;
                $cache[$table][$object->{$export['key']}] = $object;
                if ($type == 'conditions') {
                    $return[$object->{$export['key']}] = $object;
                }
            }
        }
    }
    // If fetching all, we've done so and we are finished.
    if ($type == 'all') {
        $cached_database[$table] = TRUE;
        return $cache[$table];
    }
    if ($type == 'names') {
        foreach ($args as $name) {
            if (isset($cache[$table][$name])) {
                $return[$name] = $cache[$table][$name];
            }
        }
    }
    return $return;
}

/**
 * Reset all static caches in ctools_export_load_object() or static caches for
 * a given table in ctools_export_load_object().
 *
 * @param $table
 *   String that is the name of a table. If not defined, all static caches in
 *   ctools_export_load_object() will be reset.
 */
function ctools_export_load_object_reset($table = NULL) {
    // Reset plugin cache to make sure new include files are picked up.
    ctools_include('plugins');
    ctools_get_plugins_reset();
    if (empty($table)) {
        drupal_static_reset('ctools_export_load_object');
        drupal_static_reset('ctools_export_load_object_all');
        drupal_static_reset('_ctools_export_get_defaults');
    }
    else {
        $cache =& drupal_static('ctools_export_load_object');
        $cached_database =& drupal_static('ctools_export_load_object_all');
        $cached_defaults =& drupal_static('_ctools_export_get_defaults');
        unset($cache[$table]);
        unset($cached_database[$table]);
        unset($cached_defaults[$table]);
    }
}

/**
 * Get the default version of an object, if it exists.
 *
 * This function doesn't care if an object is in the database or not and
 * does not check. This means that export_type could appear to be incorrect,
 * because a version could exist in the database. However, it's not
 * incorrect for this function as it is *only* used for the default
 * in code version.
 */
function ctools_get_default_object($table, $name) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    if (!$export['default hook']) {
        return;
    }
    // Try to load individually from cache if this cache is enabled.
    if (!empty($export['cache defaults'])) {
        $defaults = _ctools_export_get_some_defaults($table, $export, array(
            $name,
        ));
    }
    else {
        $defaults = _ctools_export_get_defaults($table, $export);
    }
    $status = variable_get($export['status'], array());
    if (!isset($defaults[$name])) {
        return;
    }
    $object = $defaults[$name];
    // Determine if default object is enabled or disabled.
    if (isset($status[$object->{$export['key']}])) {
        $object->disabled = $status[$object->{$export['key']}];
    }
    $object->{$export['export type string']} = t('Default');
    $object->export_type = EXPORT_IN_CODE;
    $object->in_code_only = TRUE;
    return $object;
}

/**
 * Get export object defaults.
 *
 * Call the hook to get all default objects of the given type from the
 * export. If configured properly, this could include loading up an API
 * to get default objects.
 *
 * @param string $table
 *   The name of the table to be loaded. Data is expected to be in the
 *   schema to make all this work.
 * @param array $export
 *   The export definition from the table's hook_schema() definition.
 */
function _ctools_export_get_defaults($table, array $export) {
    $cache =& drupal_static(__FUNCTION__, array());
    // If defaults may be cached, first see if we can load from cache.
    if (!isset($cache[$table]) && !empty($export['cache defaults'])) {
        $cache[$table] = _ctools_export_get_defaults_from_cache($table, $export);
    }
    if (!isset($cache[$table])) {
        // If we're caching, attempt to get a lock. We will wait a short time
        // on the lock, but not too long, because it's better to just rebuild
        // and throw away results than wait too long on a lock.
        if (!empty($export['cache defaults'])) {
            for ($counter = 0; !($lock = lock_acquire('ctools_export:' . $table)) && $counter > 5; $counter++) {
                lock_wait('ctools_export:' . $table, 1);
                ++$counter;
            }
        }
        $cache[$table] = array();
        if ($export['default hook']) {
            if (!empty($export['api'])) {
                ctools_include('plugins');
                $info = ctools_plugin_api_include($export['api']['owner'], $export['api']['api'], $export['api']['minimum_version'], $export['api']['current_version']);
                $modules = array_keys($info);
            }
            else {
                $modules = module_implements($export['default hook']);
            }
            foreach ($modules as $module) {
                $function = $module . '_' . $export['default hook'];
                if (function_exists($function)) {
                    foreach ((array) $function($export) as $name => $object) {
                        // Record the module that provides this exportable.
                        $object->export_module = $module;
                        if (empty($export['api'])) {
                            $cache[$table][$name] = $object;
                        }
                        else {
                            // If version checking is enabled, ensure that the object can be
                            // used.
                            if (isset($object->api_version) && version_compare($object->api_version, $export['api']['minimum_version']) >= 0 && version_compare($object->api_version, $export['api']['current_version']) <= 0) {
                                $cache[$table][$name] = $object;
                            }
                        }
                    }
                }
            }
            drupal_alter($export['default hook'], $cache[$table]);
            // If we acquired a lock earlier, cache the results and release the
            // lock.
            if (!empty($lock)) {
                // Cache the index.
                $index = array_keys($cache[$table]);
                cache_set('ctools_export_index:' . $table, $index, $export['default cache bin']);
                // Cache each object.
                foreach ($cache[$table] as $name => $object) {
                    cache_set('ctools_export:' . $table . ':' . $name, $object, $export['default cache bin']);
                }
                lock_release('ctools_export:' . $table);
            }
        }
    }
    return $cache[$table];
}

/**
 * Attempt to load default objects from cache.
 *
 * We can be instructed to cache default objects by the schema. If so
 * we cache them as an index which is a list of all default objects, and
 * then each default object is cached individually.
 *
 * @return Either an array of cached objects, or NULL indicating a cache
 *   rebuild is necessary.
 */
function _ctools_export_get_defaults_from_cache($table, $export) {
    $data = cache_get('ctools_export_index:' . $table, $export['default cache bin']);
    if (!$data || !is_array($data->data)) {
        return;
    }
    // This is the perfectly valid case where there are no default objects,
    // and we have cached this state.
    if (empty($data->data)) {
        return array();
    }
    $keys = array();
    foreach ($data->data as $name) {
        $keys[] = 'ctools_export:' . $table . ':' . $name;
    }
    $data = cache_get_multiple($keys, $export['default cache bin']);
    // If any of our indexed keys missed, then we have a fail and we need to
    // rebuild.
    if (!empty($keys)) {
        return;
    }
    // Now, translate the returned cache objects to actual objects.
    $cache = array();
    foreach ($data as $cached_object) {
        $cache[$cached_object->data->{$export['key']}] = $cached_object->data;
    }
    return $cache;
}

/**
 * Get a limited number of default objects.
 *
 * This attempts to load the objects directly from cache. If it cannot,
 * the cache is rebuilt. This does not disturb the general get defaults
 * from cache object.
 *
 * This function should ONLY be called if default caching is enabled.
 * It does not check, it is assumed the caller has already done so.
 */
function _ctools_export_get_some_defaults($table, $export, $names) {
    foreach ($names as $name) {
        $keys[] = 'ctools_export:' . $table . ':' . $name;
    }
    $data = cache_get_multiple($keys, $export['default cache bin']);
    // Cache hits remove the $key from $keys by reference. Cache
    // misses do not. A cache miss indicates we may have to rebuild.
    if (!empty($keys)) {
        return _ctools_export_get_defaults($table, $export);
    }
    // Now, translate the returned cache objects to actual objects.
    $cache = array();
    foreach ($data as $cached_object) {
        $cache[$cached_object->data->{$export['key']}] = $cached_object->data;
    }
    return $cache;
}

/**
 * Unpack data loaded from the database onto an object.
 *
 * @param $schema
 *   The schema from drupal_get_schema().
 * @param $data
 *   The data as loaded from the database.
 * @param $object
 *   If an object, data will be unpacked onto it. If a string
 *   an object of that type will be created.
 */
function _ctools_export_unpack_object($schema, $data, $object = 'stdClass') {
    if (is_string($object)) {
        if (class_exists($object)) {
            $object = new $object();
        }
        else {
            $object = new stdClass();
        }
    }
    // Go through our schema and build correlations.
    foreach ($schema['fields'] as $field => $info) {
        if (isset($data->{$field})) {
            $object->{$field} = empty($info['serialize']) ? $data->{$field} : unserialize($data->{$field});
        }
        else {
            $object->{$field} = NULL;
        }
    }
    if (isset($schema['join'])) {
        foreach ($schema['join'] as $join_key => $join) {
            $join_schema = ctools_export_get_schema($join['table']);
            if (!empty($join['load'])) {
                foreach ($join['load'] as $field) {
                    $info = $join_schema['fields'][$field];
                    $object->{$field} = empty($info['serialize']) ? $data->{$field} : unserialize($data->{$field});
                }
            }
        }
    }
    return $object;
}

/**
 * Unpack data loaded from the database onto an object.
 *
 * @param $table
 *   The name of the table this object represents.
 * @param $data
 *   The data as loaded from the database.
 */
function ctools_export_unpack_object($table, $data) {
    $schema = ctools_export_get_schema($table);
    return _ctools_export_unpack_object($schema, $data, $schema['export']['object']);
}

/**
 * Export a field.
 *
 * This is a replacement for var_export(), allowing us to more nicely
 * format exports. It will recurse down into arrays and will try to
 * properly export bools when it can, though PHP has a hard time with
 * this since they often end up as strings or ints.
 */
function ctools_var_export($var, $prefix = '') {
    if (is_array($var)) {
        if (empty($var)) {
            $output = 'array()';
        }
        else {
            $output = "array(\n";
            ksort($var);
            foreach ($var as $key => $value) {
                $output .= $prefix . "  " . ctools_var_export($key) . " => " . ctools_var_export($value, $prefix . '  ') . ",\n";
            }
            $output .= $prefix . ')';
        }
    }
    elseif (is_object($var) && get_class($var) === 'stdClass') {
        // var_export() will export stdClass objects using an undefined
        // magic method __set_state() leaving the export broken. This
        // workaround avoids this by casting the object as an array for
        // export and casting it back to an object when evaluated.
        $output = '(object) ' . ctools_var_export((array) $var, $prefix);
    }
    elseif (is_bool($var)) {
        $output = $var ? 'TRUE' : 'FALSE';
    }
    else {
        $output = var_export($var, TRUE);
    }
    return $output;
}

/**
 * Export an object into code.
 */
function ctools_export_object($table, $object, $indent = '', $identifier = NULL, $additions = array(), $additions2 = array()) {
    $schema = ctools_export_get_schema($table);
    if (!isset($identifier)) {
        $identifier = $schema['export']['identifier'];
    }
    $output = $indent . '$' . $identifier . ' = new ' . get_class($object) . "();\n";
    if ($schema['export']['can disable']) {
        $disabled = !isset($object->disabled) || $object->disabled != TRUE ? 'FALSE' : 'TRUE';
        $output .= $indent . '$' . $identifier . '->disabled = ' . $disabled . '; /* Edit this to true to make a default ' . $identifier . ' disabled initially */' . "\n";
    }
    if (!empty($schema['export']['api']['current_version'])) {
        $output .= $indent . '$' . $identifier . '->api_version = ' . $schema['export']['api']['current_version'] . ";\n";
    }
    // Put top additions here:
    foreach ($additions as $field => $value) {
        $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . ctools_var_export($value, $indent) . ";\n";
    }
    $fields = $schema['fields'];
    if (!empty($schema['join'])) {
        foreach ($schema['join'] as $join) {
            if (!empty($join['load'])) {
                foreach ($join['load'] as $join_field) {
                    $fields[$join_field] = $join['fields'][$join_field];
                }
            }
        }
    }
    // Go through our schema and joined tables and build correlations.
    foreach ($fields as $field => $info) {
        if (!empty($info['no export'])) {
            continue;
        }
        if (!isset($object->{$field})) {
            if (isset($info['default'])) {
                $object->{$field} = $info['default'];
            }
            else {
                $object->{$field} = '';
            }
        }
        // Note: This is the *field* export callback, not the table one!
        if (!empty($info['export callback']) && function_exists($info['export callback'])) {
            $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . $info['export callback']($object, $field, $object->{$field}, $indent) . ";\n";
        }
        else {
            $value = $object->{$field};
            if ($info['type'] == 'int') {
                if (isset($info['size']) && $info['size'] == 'tiny') {
                    $info['boolean'] = !isset($info['boolean']) ? $schema['export']['boolean'] : $info['boolean'];
                    $value = $info['boolean'] ? (bool) $value : (int) $value;
                }
                else {
                    $value = (int) $value;
                }
            }
            $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . ctools_var_export($value, $indent) . ";\n";
        }
    }
    // And bottom additions here.
    foreach ($additions2 as $field => $value) {
        $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . ctools_var_export($value, $indent) . ";\n";
    }
    return $output;
}

/**
 * Get the schema for a given table.
 *
 * This looks for data the export subsystem needs and applies defaults so
 * that it's easily available.
 */
function ctools_export_get_schema($table) {
    static $drupal_static_fast;
    if (!isset($drupal_static_fast)) {
        $drupal_static_fast['cache'] =& drupal_static(__FUNCTION__);
    }
    $cache =& $drupal_static_fast['cache'];
    if (empty($cache[$table])) {
        $schema = drupal_get_schema($table);
        // If our schema isn't loaded, it's possible we're in a state where it
        // simply hasn't been cached. If we've been asked, let's force the
        // issue.
        if (!$schema || empty($schema['export'])) {
            // Force a schema reset:
            $schema = drupal_get_schema($table, TRUE);
        }
        if (!isset($schema['export'])) {
            return array();
        }
        if (empty($schema['module'])) {
            return array();
        }
        // Add some defaults.
        $schema['export'] += array(
            'key' => 'name',
            'key name' => 'Name',
            'object' => 'stdClass',
            'status' => 'default_' . $table,
            'default hook' => 'default_' . $table,
            'can disable' => TRUE,
            'identifier' => $table,
            'primary key' => !empty($schema['primary key']) ? $schema['primary key'][0] : '',
            'bulk export' => TRUE,
            'list callback' => "{$schema['module']}_{$table}_list",
            'to hook code callback' => "{$schema['module']}_{$table}_to_hook_code",
            'cache defaults' => FALSE,
            'default cache bin' => 'cache',
            'export type string' => 'type',
            'boolean' => TRUE,
        );
        // If the export definition doesn't have the "primary key" then the CRUD
        // save callback won't work.
        if (empty($schema['export']['primary key']) && user_access('administer site configuration')) {
            drupal_set_message(t('The export definition of @table is missing the "primary key" property.', array(
                '@table' => $table,
            )), 'error');
        }
        // Notes:
        // The following callbacks may be defined to override default behavior
        // when using CRUD functions:
        //
        // create callback
        // load callback
        // load multiple callback
        // load all callback
        // save callback
        // delete callback
        // export callback
        // import callback
        //
        // See the appropriate ctools_export_crud function for details on what
        // arguments these callbacks should accept. Please do not call these
        // directly, always use the ctools_export_crud_* wrappers to ensure
        // that default implementations are honored.
        $cache[$table] = $schema;
    }
    return $cache[$table];
}

/**
 * Gets the schemas for all tables with ctools object metadata.
 */
function ctools_export_get_schemas($for_export = FALSE) {
    $export_tables =& drupal_static(__FUNCTION__);
    if (is_null($export_tables)) {
        $export_tables = array();
        $schemas = drupal_get_schema();
        foreach ($schemas as $table => $schema) {
            if (!isset($schema['export'])) {
                unset($schemas[$table]);
                continue;
            }
            $export_tables[$table] = ctools_export_get_schema($table);
        }
    }
    return $for_export ? array_filter($export_tables, '_ctools_export_filter_export_tables') : $export_tables;
}
function _ctools_export_filter_export_tables($schema) {
    return !empty($schema['export']['bulk export']);
}
function ctools_export_get_schemas_by_module($modules = array(), $for_export = FALSE) {
    $export_tables = array();
    $list = ctools_export_get_schemas($for_export);
    foreach ($list as $table => $schema) {
        $export_tables[$schema['module']][$table] = $schema;
    }
    return empty($modules) ? $export_tables : array_keys($export_tables, $modules);
}

/**
 * Set the status of a default $object as a variable.
 *
 * The status, in this case, is whether or not it is 'disabled'.
 * This function does not check to make sure $object actually
 * exists.
 */
function ctools_export_set_status($table, $name, $new_status = TRUE) {
    $schema = ctools_export_get_schema($table);
    $status = variable_get($schema['export']['status'], array());
    $status[$name] = $new_status;
    variable_set($schema['export']['status'], $status);
}

/**
 * Set the status of a default $object as a variable.
 *
 * This is more efficient than ctools_export_set_status because it
 * will actually unset the variable entirely if it's not necessary,
 * this saving a bit of space.
 */
function ctools_export_set_object_status($object, $new_status = TRUE) {
    $table = $object->table;
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    $status = variable_get($export['status'], array());
    // Compare.
    if (!$new_status && $object->export_type & EXPORT_IN_DATABASE) {
        unset($status[$object->{$export['key']}]);
    }
    else {
        $status[$object->{$export['key']}] = $new_status;
    }
    variable_set($export['status'], $status);
}

/**
 * Provide a form for displaying an export.
 *
 * This is a simple form that should be invoked like this:
 * @code
 *   $output = drupal_get_form('ctools_export_form', $code, $object_title);
 * @endcode
 */
function ctools_export_form($form, &$form_state, $code, $title = '') {
    $lines = substr_count($code, "\n");
    $form['code'] = array(
        '#type' => 'textarea',
        '#title' => $title,
        '#default_value' => $code,
        '#rows' => $lines,
    );
    return $form;
}

/**
 * Create a new object based upon schema values.
 *
 * Because 'default' has ambiguous meaning on some fields, we will actually
 * use 'object default' to fill in default values if default is not set
 * That's a little safer to use as it won't cause weird database default
 * situations.
 */
function ctools_export_new_object($table, $set_defaults = TRUE) {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    $object = new $export['object']();
    foreach ($schema['fields'] as $field => $info) {
        if (isset($info['object default'])) {
            $object->{$field} = $info['object default'];
        }
        elseif (isset($info['default'])) {
            $object->{$field} = $info['default'];
        }
        else {
            $object->{$field} = NULL;
        }
    }
    if ($set_defaults) {
        // Set some defaults so this data always exists.
        // We don't set the export_type property here, as this object is not saved
        // yet. We do give it NULL so we don't generate notices trying to read it.
        $object->export_type = NULL;
        $object->{$export['export type string']} = t('Local');
    }
    return $object;
}

/**
 * Convert a group of objects to code based upon input and return this as a larger
 * export.
 */
function ctools_export_to_hook_code(&$code, $table, $names = array(), $name = 'foo') {
    $schema = ctools_export_get_schema($table);
    $export = $schema['export'];
    // Use the schema-specified function for generating hook code, if one exists.
    if (function_exists($export['to hook code callback'])) {
        $output = $export['to hook code callback']($names, $name);
    }
    else {
        $output = ctools_export_default_to_hook_code($schema, $table, $names, $name);
    }
    if (!empty($output)) {
        if (isset($export['api'])) {
            if (isset($code[$export['api']['owner']][$export['api']['api']]['version'])) {
                $code[$export['api']['owner']][$export['api']['api']]['version'] = max($code[$export['api']['owner']][$export['api']['api']]['version'], $export['api']['minimum_version']);
            }
            else {
                $code[$export['api']['owner']][$export['api']['api']]['version'] = $export['api']['minimum_version'];
                $code[$export['api']['owner']][$export['api']['api']]['code'] = '';
            }
            $code[$export['api']['owner']][$export['api']['api']]['code'] .= $output;
        }
        else {
            if (empty($code['general'])) {
                $code['general'] = '';
            }
            $code['general'] .= $output;
        }
    }
}

/**
 * Default function to export objects to code.
 *
 * Note that if your module provides a 'to hook code callback' then it will
 * receive only $names and $name as arguments. Your module is presumed to
 * already know the rest.
 */
function ctools_export_default_to_hook_code($schema, $table, $names, $name) {
    $export = $schema['export'];
    $output = '';
    $objects = ctools_export_crud_load_multiple($table, $names);
    if ($objects) {
        $output = "/**\n";
        $output .= " * Implements hook_{$export['default hook']}().\n";
        $output .= " */\n";
        $output .= "function " . $name . "_{$export['default hook']}() {\n";
        $output .= "  \${$export['identifier']}s = array();\n\n";
        foreach ($objects as $object) {
            $output .= ctools_export_crud_export($table, $object, '  ');
            $output .= "  \${$export['identifier']}s['" . check_plain($object->{$export['key']}) . "'] = \${$export['identifier']};\n\n";
        }
        $output .= "  return \${$export['identifier']}s;\n";
        $output .= "}\n";
    }
    return $output;
}

/**
 * Default function for listing bulk exportable objects.
 */
function ctools_export_default_list($table, $schema) {
    $list = array();
    $items = ctools_export_crud_load_all($table);
    $export_key = $schema['export']['key'];
    foreach ($items as $item) {
        // Try a couple of possible obvious title keys:
        $keys = array(
            'admin_title',
            'title',
        );
        if (isset($schema['export']['admin_title'])) {
            array_unshift($keys, $schema['export']['admin_title']);
        }
        $string = '';
        foreach ($keys as $key) {
            if (!empty($item->{$key})) {
                $string = $item->{$key} . " (" . $item->{$export_key} . ")";
                break;
            }
        }
        if (empty($string)) {
            $string = $item->{$export_key};
        }
        $list[$item->{$export_key}] = check_plain($string);
    }
    return $list;
}