@node ax_lua
@unnumberedsec ax_lua

@majorheading Synopsis

@smallexample
AX_PROG_LUA[([MINIMUM-VERSION], [TOO-BIG-VERSION], [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
AX_LUA_HEADERS[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
AX_LUA_LIBS[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
AX_LUA_READLINE[([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])]
@end smallexample

@majorheading Description

Detect a Lua interpreter, optionally specifying a minimum and maximum
version number. Set up important Lua paths, such as the directories in
which to install scripts and modules (shared libraries).

Also detect Lua headers and libraries. The Lua version contained in the
header is checked to match the Lua interpreter version exactly. When
searching for Lua libraries, the version number is used as a suffix.
This is done with the goal of supporting multiple Lua installs (5.1,
5.2, and 5.3 side-by-side).

A note on compatibility with previous versions: This file has been
mostly rewritten for serial 18. Most developers should be able to use
these macros without needing to modify configure.ac. Care has been taken
to preserve each macro's behavior, but there are some differences:

1) AX_WITH_LUA is deprecated; it now expands to the exact same thing as
AX_PROG_LUA with no arguments.

2) AX_LUA_HEADERS now checks that the version number defined in lua.h
matches the interpreter version. AX_LUA_HEADERS_VERSION is therefore
unnecessary, so it is deprecated and does not expand to anything.

3) The configure flag --with-lua-suffix no longer exists; the user
should instead specify the LUA precious variable on the command line.
See the AX_PROG_LUA description for details.

Please read the macro descriptions below for more information.

This file was inspired by Andrew Dalke's and James Henstridge's
python.m4 and Tom Payne's, Matthieu Moy's, and Reuben Thomas's ax_lua.m4
(serial 17). Basically, this file is a mash-up of those two files. I
like to think it combines the best of the two!

AX_PROG_LUA: Search for the Lua interpreter, and set up important Lua
paths. Adds precious variable LUA, which may contain the path of the Lua
interpreter. If LUA is blank, the user's path is searched for an
suitable interpreter.

If MINIMUM-VERSION is supplied, then only Lua interpreters with a
version number greater or equal to MINIMUM-VERSION will be accepted. If
TOO-BIG-VERSION is also supplied, then only Lua interpreters with a
version number greater or equal to MINIMUM-VERSION and less than
TOO-BIG-VERSION will be accepted.

The Lua version number, LUA_VERSION, is found from the interpreter, and
substituted. LUA_PLATFORM is also found, but not currently supported (no
standard representation).

Finally, the macro finds four paths:

@smallexample
  luadir             Directory to install Lua scripts.
  pkgluadir          $luadir/$PACKAGE
  luaexecdir         Directory to install Lua modules.
  pkgluaexecdir      $luaexecdir/$PACKAGE
@end smallexample

These paths are found based on $prefix, $exec_prefix, Lua's
package.path, and package.cpath. The first path of package.path
beginning with $prefix is selected as luadir. The first path of
package.cpath beginning with $exec_prefix is used as luaexecdir. This
should work on all reasonable Lua installations. If a path cannot be
determined, a default path is used. Of course, the user can override
these later when invoking make.

@smallexample
  luadir             Default: $prefix/share/lua/$LUA_VERSION
  luaexecdir         Default: $exec_prefix/lib/lua/$LUA_VERSION
@end smallexample

These directories can be used by Automake as install destinations. The
variable name minus 'dir' needs to be used as a prefix to the
appropriate Automake primary, e.g. lua_SCRIPS or luaexec_LIBRARIES.

If an acceptable Lua interpreter is found, then ACTION-IF-FOUND is
performed, otherwise ACTION-IF-NOT-FOUND is preformed. If ACTION-IF-NOT-
FOUND is blank, then it will default to printing an error. To prevent
the default behavior, give ':' as an action.

AX_LUA_HEADERS: Search for Lua headers. Requires that AX_PROG_LUA be
expanded before this macro. Adds precious variable LUA_INCLUDE, which
may contain Lua specific include flags, e.g. -I/usr/include/lua5.1. If
LUA_INCLUDE is blank, then this macro will attempt to find suitable
flags.

LUA_INCLUDE can be used by Automake to compile Lua modules or
executables with embedded interpreters. The *_CPPFLAGS variables should
be used for this purpose, e.g. myprog_CPPFLAGS = $(LUA_INCLUDE).

This macro searches for the header lua.h (and others). The search is
performed with a combination of CPPFLAGS, CPATH, etc, and LUA_INCLUDE.
If the search is unsuccessful, then some common directories are tried.
If the headers are then found, then LUA_INCLUDE is set accordingly.

The paths automatically searched are:

@smallexample
  * /usr/include/luaX.Y
  * /usr/include/lua/X.Y
  * /usr/include/luaXY
  * /usr/local/include/luaX.Y
  * /usr/local/include/lua-X.Y
  * /usr/local/include/lua/X.Y
  * /usr/local/include/luaXY
@end smallexample

(Where X.Y is the Lua version number, e.g. 5.1.)

The Lua version number found in the headers is always checked to match
the Lua interpreter's version number. Lua headers with mismatched
version numbers are not accepted.

If headers are found, then ACTION-IF-FOUND is performed, otherwise
ACTION-IF-NOT-FOUND is performed. If ACTION-IF-NOT-FOUND is blank, then
it will default to printing an error. To prevent the default behavior,
set the action to ':'.

AX_LUA_LIBS: Search for Lua libraries. Requires that AX_PROG_LUA be
expanded before this macro. Adds precious variable LUA_LIB, which may
contain Lua specific linker flags, e.g. -llua5.1. If LUA_LIB is blank,
then this macro will attempt to find suitable flags.

LUA_LIB can be used by Automake to link Lua modules or executables with
embedded interpreters. The *_LIBADD and *_LDADD variables should be used
for this purpose, e.g. mymod_LIBADD = $(LUA_LIB).

This macro searches for the Lua library. More technically, it searches
for a library containing the function lua_load. The search is performed
with a combination of LIBS, LIBRARY_PATH, and LUA_LIB.

If the search determines that some linker flags are missing, then those
flags will be added to LUA_LIB.

If libraries are found, then ACTION-IF-FOUND is performed, otherwise
ACTION-IF-NOT-FOUND is performed. If ACTION-IF-NOT-FOUND is blank, then
it will default to printing an error. To prevent the default behavior,
set the action to ':'.

AX_LUA_READLINE: Search for readline headers and libraries. Requires the
AX_LIB_READLINE macro, which is provided by ax_lib_readline.m4 from the
Autoconf Archive.

If a readline compatible library is found, then ACTION-IF-FOUND is
performed, otherwise ACTION-IF-NOT-FOUND is performed.

@majorheading Source Code

Download the
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_lua.m4,latest
version of @file{ax_lua.m4}} or browse
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=history;f=m4/ax_lua.m4,the
macro's revision history}.

@majorheading License

@w{Copyright @copyright{} 2015 Reuben Thomas @email{rrt@@sc3d.org}} @* @w{Copyright @copyright{} 2014 Tim Perkins @email{tprk77@@gmail.com}}

This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your
option) any later version.

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WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
Public License for more details.

You should have received a copy of the GNU General Public License along
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