# How to Add Tag File Support to Software Tools

Exuberant Ctags now includes a library to easily add tag file support to software tools, such as editors. The distributed makefile contains a target for library object file, `readtags.o`, and a demonstration program for the library, `readtags`.

The functions provided by this library are intended to provide tag file support to a software tool. The tag lookups provided are sufficiently fast enough to permit opening a sorted tag file, searching for a matching tag, then closing the tag file each time a tag is looked up (search times are on the order of hundreths of a second, even for huge tag files). This is the recommended use of this library for most tool applications. Adhering to this approach permits a user to regenerate a tag file at will without the tool needing to detect and resynchronize with changes to the tag file. Even for an unsorted 24MB tag file, tag searches take about one second on my 650 MHz Athlon Linux machine.

The interface to the library is documented in the include file `readtags.h`. For an example implementation, see the function `findTag()` in the conditionally compiled portion of the source file `readtags.c`.

To facilitate widespread support of tag files, the readtags library is released in the public domain, allowing its use in even commercial applications.