Writing Apache Modules with Perl and C By:   Lincoln Stein and Doug MacEachern Published:   O'Reilly & Associates, Inc.  - March 1999 Copyright © 1999 by O'Reilly & Associates, Inc.

Chapter 10 - C API Reference Guide, Part I / The Table API
Other Table Functions

Here are a few miscellaneous table functions that don't fit into the previous categories:

table *ap_overlay_tables (pool *p, const table *overlay, const table *base)

This function takes the contents of the table at overlay and adds it to the table at base. Entries in overlay that don't exist in base are added to base. Entries that already exist in base are overwritten. You can use ap_overlay_tables() to perform a bulk update of a table. This example overlays the fields listed in my_headers onto the table of outgoing headers:

table *new_table = _ap_overlay_tables(r->pool, my_headers, r->headers_out);

array_header *ap_table_elts (table *t)

If you wish to access the contents of the table directly, you can call the ap_table_elts() function (it's a preprocessor macro, actually). It will return an array_header *, which you can then iterate through, casting each element to a table_entry.

array_header *arr = ap_table_elts(my_table);

int ap_is_empty_table (table *t)

This function (it's a preprocessor macro, actually) returns true if there are no entries in the given table, or false otherwise.

if(!ap_is_empty_table(my_table)) {
       /* this table has one or more elements */
}

void ap_clear_table (table *t)

The ap_clear_table() function clears all entries from the table. Example:

ap_clear_table(my_table);

Footnotes

² Despite the differences between Perl hashes and Apache tables, the Perl API allows programmers to access tables via tied Perl hashes. See "The Apache::Table Class" in Chapter 9.