This is Expat, a C library for parsing XML, started by James Clark in 1997. Expat is a stream-oriented XML parser. This means that you register handlers with the parser before starting the parse. These handlers are called when the parser discovers the associated structures in the document being parsed. A start tag is an example of the kind of structures for which you may register handlers.

Windows users should use the expat_win32 package, which includes both precompiled libraries and executables, and source code for developers.

Expat is free software. You may copy, distribute, and modify it under the terms of the License contained in the file COPYING distributed with this package. This license is the same as the MIT/X Consortium license.

If you are building Expat from a check-out from the Git repository, you need to run a script that generates the configure script using the GNU autoconf and libtool tools. To do this, you need to have autoconf 2.58 or newer. Run the script like this:

./buildconf.sh

Once this has been done, follow the same instructions as for building from a source distribution.

To build Expat from a source distribution, you first run the configuration shell script in the top level distribution directory:

./configure

There are many options which you may provide to configure (which you can discover by running configure with the --help option). But the one of most interest is the one that sets the installation directory. By default, the configure script will set things up to install libexpat into /usr/local/lib, expat.h into /usr/local/include, and xmlwf into /usr/local/bin. If, for example, you'd prefer to install into /home/me/mystuff/lib, /home/me/mystuff/include, and /home/me/mystuff/bin, you can tell configure about that with:

./configure --prefix=/home/me/mystuff

Another interesting option is to enable 64-bit integer support for line and column numbers and the over-all byte index:

./configure CPPFLAGS=-DXML_LARGE_SIZE

However, such a modification would be a breaking change to the ABI and is therefore not recommended for general use — e.g. as part of a Linux distribution — but rather for builds with special requirements.

After running the configure script, the make command will build things and make install will install things into their proper location. Have a look at the Makefile to learn about additional make options. Note that you need to have write permission into the directories into which things will be installed.

If you are interested in building Expat to provide document information in UTF-16 encoding rather than the default UTF-8, follow these instructions (after having run make distclean):

1. For UTF-16 output as unsigned short (and version/error strings as char), run:
   ./configure CPPFLAGS=-DXML_UNICODE
   For UTF-16 output as wchar_t (incl. version/error strings), run:
   ./configure CFLAGS="-g -O2 -fshort-wchar" CPPFLAGS=-DXML_UNICODE_WCHAR_T
   Note: The latter requires libc compiled with -fshort-wchar, as well.

2. Edit Makefile, changing:
   LIBRARY = libexpat.la
   to:
   LIBRARY = libexpatw.la
   (Note the additional "w" in the library name.)

3. Run make buildlib (which builds the library only). Or, to save step 2, run make buildlib LIBRARY=libexpatw.la.

4. Run make installlib (which installs the library only). Or, if step 2 was omitted, run make installlib LIBRARY=libexpatw.la.

Using DESTDIR or INSTALL_ROOT is enabled, with INSTALL_ROOT being the default value for DESTDIR, and the rest of the make file using only DESTDIR. It works as follows:

make install DESTDIR=/path/to/image

overrides the in-makefile set DESTDIR, while both

INSTALL_ROOT=/path/to/image make install
make install INSTALL_ROOT=/path/to/image

use DESTDIR=$(INSTALL_ROOT), even if DESTDIR eventually is defined in the environment, because variable-setting priority is

1. commandline
2. in-makefile
3. environment

Note: This only applies to the Expat library itself, building UTF-16 versions of xmlwf and the tests is currently not supported.

When using Expat with a project using autoconf for configuration, you can use the probing macro in conftools/expat.m4 to determine how to include Expat. See the comments at the top of that file for more information.

A reference manual is available in the file doc/reference.html in this distribution.