/* Copyright 2005-2006 Garrett Rooney.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @file etl_variables.h
 * @brief Functions and data structures for working with ETL variables
 */

#ifndef ETL_VARIABLES_H
#define ETL_VARIABLES_H

#include <apr.h>
#include <apr_hash.h>
#include <apr_tables.h>

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/** The types of variables that can appear in a template. */
typedef enum {
  ETL_VARIABLE_STRING,  /**< @c char * */
  ETL_VARIABLE_INTEGER, /**< @c apr_int64_t */
  ETL_VARIABLE_ARRAY,   /**< @c apr_array_header_t of @c etl_variable_t's */
  ETL_VARIABLE_HASH     /**< @c apr_hash_t of <tt>char *</tt> to variable */
} etl_variable_type_t;

/** A variable that can be accessed inside a template. */
typedef struct {
  etl_variable_type_t type;

  union {
    char *s;
    apr_int64_t i;
    apr_array_header_t *a;
    apr_hash_t *h;
  } contents;
} etl_variable_t;

/* note:  the following helper functions are TOTALLY OPTIONAL, in fact there
 *        are situations (usually with the int and string versions) where you
 *        DON'T want to use them because they result in excess copying, but
 *        i find myself writing them over and over again, so here they are. */

/**
 * Helper function to turn an @c apr_int64_t into a template variable,
 * the variable is allocated in @a pool.
 */
etl_variable_t *
etl_variable_make_int(apr_int64_t i, apr_pool_t *pool);

/**
 * Helper function to turn a string @a str into a template variable,
 * the variable is allocated in @a pool. */
etl_variable_t *
etl_variable_make_str(const char *str, apr_pool_t *pool);

/**
 * Helper function to create a template variable wrapped around an
 * empty array.  The array is initially sized to hold @a nitems and
 * is allocated in @a pool.
 */
etl_variable_t *
etl_variable_make_array(int nitems, apr_pool_t *pool);

/**
 * Helper function to create a template variable wrapped around an
 * empty hash.  The array is allocated in @a pool.
 */
etl_variable_t *
etl_variable_make_hash(apr_pool_t *pool);

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif /* ETL_VARIABLES_H */