apr_tables.h

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 * Get the value associated with a given key from the table.  After this call,
 * The data is still in the table
 * @param t The table to search for the key
 * @param key The key to search for
 * @return The value associated with the key
 */
APR_DECLARE(const char *) apr_table_get(const apr_table_t *t, const char *key);

/**
 * Add a key/value pair to a table, if another element already exists with the
 * same key, this will over-write the old data.
 * @param t The table to add the data to.
 * @param key The key fo use
 * @param val The value to add
 * @remark When adding data, this function makes a copy of both the key and the
 *         value.
 */
APR_DECLARE(void) apr_table_set(apr_table_t *t, const char *key,
                                const char *val);

/**
 * Add a key/value pair to a table, if another element already exists with the
 * same key, this will over-write the old data.
 * @param t The table to add the data to.
 * @param key The key to use
 * @param val The value to add
 * @warning When adding data, this function does not make a copy of the key or 
 *          the value, so care should be taken to ensure that the values will 
 *          not change after they have been added..
 */
APR_DECLARE(void) apr_table_setn(apr_table_t *t, const char *key,
                                 const char *val);

/**
 * Remove data from the table
 * @param t The table to remove data from
 * @param key The key of the data being removed
 */
APR_DECLARE(void) apr_table_unset(apr_table_t *t, const char *key);

/**
 * Add data to a table by merging the value with data that has already been 
 * stored
 * @param t The table to search for the data
 * @param key The key to merge data for
 * @param val The data to add
 * @remark If the key is not found, then this function acts like apr_table_add
 */
APR_DECLARE(void) apr_table_merge(apr_table_t *t, const char *key,
                                  const char *val);

/**
 * Add data to a table by merging the value with data that has already been 
 * stored
 * @param t The table to search for the data
 * @param key The key to merge data for
 * @param val The data to add
 * @remark If the key is not found, then this function acts like apr_table_addn
 */
APR_DECLARE(void) apr_table_mergen(apr_table_t *t, const char *key,
                                   const char *val);

/**
 * Add data to a table, regardless of whether there is another element with the
 * same key.
 * @param t The table to add to
 * @param key The key to use
 * @param val The value to add.
 * @remark When adding data, this function makes a copy of both the key and the
 *         value.
 */
APR_DECLARE(void) apr_table_add(apr_table_t *t, const char *key,
                                const char *val);

/**
 * Add data to a table, regardless of whether there is another element with the
 * same key.
 * @param t The table to add to
 * @param key The key to use
 * @param val The value to add.
 * @remark When adding data, this function does not make a copy of the key or the
 *         value, so care should be taken to ensure that the values will not 
 *         change after they have been added..
 */
APR_DECLARE(void) apr_table_addn(apr_table_t *t, const char *key,
                                 const char *val);

/**
 * Merge two tables into one new table
 * @param p The pool to use for the new table
 * @param overlay The first table to put in the new table
 * @param base The table to add at the end of the new table
 * @return A new table containing all of the data from the two passed in
 */
APR_DECLARE(apr_table_t *) apr_table_overlay(apr_pool_t *p,
                                             const apr_table_t *overlay,
                                             const apr_table_t *base);

/**
 * Declaration prototype for the iterator callback function of apr_table_do()
 * and apr_table_vdo().
 * @param rec The data passed as the first argument to apr_table_[v]do()
 * @param key The key from this iteration of the table
 * @param value The value from this iteration of the table
 * @remark Iteration continues while this callback function returns non-zero.
 * To export the callback function for apr_table_[v]do() it must be declared 
 * in the _NONSTD convention.
 */
typedef int (apr_table_do_callback_fn_t)(void *rec, const char *key, 
                                                    const char *value);

/** 
 * Iterate over a table running the provided function once for every
 * element in the table.  If there is data passed in as a vararg, then the 
 * function is only run on those elements whose key matches something in 
 * the vararg.  If the vararg is NULL, then every element is run through the
 * function.  Iteration continues while the function returns non-zero.
 * @param comp The function to run
 * @param rec The data to pass as the first argument to the function
 * @param t The table to iterate over
 * @param ... The vararg.  If this is NULL, then all elements in the table are
 *            run through the function, otherwise only those whose key matches
 *            are run.
 * @return FALSE if one of the comp() iterations returned zero; TRUE if all
 *            iterations returned non-zero
 * @see apr_table_do_callback_fn_t
 */
APR_DECLARE_NONSTD(int) apr_table_do(apr_table_do_callback_fn_t *comp,
                                     void *rec, const apr_table_t *t, ...);

/** 
 * Iterate over a table running the provided function once for every
 * element in the table.  If there is data passed in as a vararg, then the 
 * function is only run on those element's whose key matches something in 
 * the vararg.  If the vararg is NULL, then every element is run through the
 * function.  Iteration continues while the function returns non-zero.
 * @param comp The function to run
 * @param rec The data to pass as the first argument to the function
 * @param t The table to iterate over
 * @param vp The vararg table.  If this is NULL, then all elements in the 
 *                table are run through the function, otherwise only those 
 *                whose key matches are run.
 * @return FALSE if one of the comp() iterations returned zero; TRUE if all
 *            iterations returned non-zero
 * @see apr_table_do_callback_fn_t
 */
APR_DECLARE(int) apr_table_vdo(apr_table_do_callback_fn_t *comp,
                               void *rec, const apr_table_t *t, va_list vp);

/** flag for overlap to use apr_table_setn */
#define APR_OVERLAP_TABLES_SET   (0)
/** flag for overlap to use apr_table_mergen */
#define APR_OVERLAP_TABLES_MERGE (1)
/**
 * For each element in table b, either use setn or mergen to add the data
 * to table a.  Which method is used is determined by the flags passed in.
 * @param a The table to add the data to.
 * @param b The table to iterate over, adding its data to table a
 * @param flags How to add the table to table a.  One of:
 *          APR_OVERLAP_TABLES_SET        Use apr_table_setn
 *          APR_OVERLAP_TABLES_MERGE      Use apr_table_mergen
 * @remark  This function is highly optimized, and uses less memory and CPU cycles
 *          than a function that just loops through table b calling other functions.
 */
/**
 *<PRE>
 * Conceptually, apr_table_overlap does this:
 *
 *  apr_array_header_t *barr = apr_table_elts(b);
 *  apr_table_entry_t *belt = (apr_table_entry_t *)barr->elts;
 *  int i;
 *
 *  for (i = 0; i < barr->nelts; ++i) {
 *      if (flags & APR_OVERLAP_TABLES_MERGE) {
 *          apr_table_mergen(a, belt[i].key, belt[i].val);
 *      }
 *      else {
 *          apr_table_setn(a, belt[i].key, belt[i].val);
 *      }
 *  }
 *
 *  Except that it is more efficient (less space and cpu-time) especially
 *  when b has many elements.
 *
 *  Notice the assumptions on the keys and values in b -- they must be
 *  in an ancestor of a's pool.  In practice b and a are usually from
 *  the same pool.
 * </PRE>
 */

APR_DECLARE(void) apr_table_overlap(apr_table_t *a, const apr_table_t *b,
                                     unsigned flags);

/**
 * Eliminate redunandant entries in a table by either overwriting
 * or merging duplicates
 *
 * @param t Table.
 * @param flags APR_OVERLAP_TABLES_MERGE to merge, or
 *              APR_OVERLAP_TABLES_SET to overwrite
 */
APR_DECLARE(void) apr_table_compress(apr_table_t *t, unsigned flags);

/** @} */

#ifdef __cplusplus
}
#endif

#endif	/* ! APR_TABLES_H */