[Swig-devel] Need to fix SWIG to handle Lua integer/unsigned APIs. How do I conditionalize the .swg typemaps for different Lua versions?

[Eric W. <ewm...@gm...>]

Hi,
I'm looking at the SWIG generation for Lua and it is out-of-date for
more recent Lua versions.

Back in Lua 5.0, there was only lua_Number which was by default a double.

In Lua 5.1, they introduced integer C-APIs  (e.g. lua_pushinteger)
In Lua 5.2, they introduced unsigned C-APIs (e.g. lua_pushunsigned)
In Lua 5.3, they now have full blown native integer backend so
integers and floating point don't get converted needlessly.

In 5.3, if you've been using the APIs in 5.1+5.2, everything just
works and you may get a performance boost. Or at the very least, you
avoid a lot more overflow cases.

(Also, Lua optionally provides architecture/platform specific
conversion routines to make conversion more efficient if you use their
APIs instead of casting yourself.)

Unfortunately, SWIG is still generating 5.0 code for everything.

I would like to fix this, but I need to understand how to correctly
conditionalize for versions in the .swg files.

For example, in lua.swg, there is currently this block:
%typemap(throws) int,unsigned int,signed int,
				long,unsigned long,signed long,
				short,unsigned short,signed short,
				float,double,
				long long,unsigned long long,
				unsigned char, signed char,
                int&,unsigned int&,signed int&,
				long&,unsigned long&,signed long&,
				short&,unsigned short&,signed short&,
				float&,double&,
				long long&,unsigned long long&,
				unsigned char&, signed char&
%{lua_pushnumber(L,(lua_Number)$1);SWIG_fail; %}

I would like to do something like the following, but don't know if
this actually will work:


/* Lua 5.1 introduced integer APIs so we should use them when available. */
#if !defined(LUA_VERSION_NUM) || LUA_VERSION_NUM < 501
%typemap(throws) int,unsigned int,signed int,
				long,unsigned long,signed long,
				short,unsigned short,signed short,
				float,double,
				long long,unsigned long long,
				unsigned char, signed char,
                int&,unsigned int&,signed int&,
				long&,unsigned long&,signed long&,
				short&,unsigned short&,signed short&,
				float&,double&,
				long long&,unsigned long long&,
				unsigned char&, signed char&
%{lua_pushnumber(L,(lua_Number)$1);SWIG_fail; %}

#else /* for Lua 5.1 and up (which have integer APIs) */

// number as number+error
%typemap(throws) float,double,
				float&,double&
%{lua_pushnumber(L,(lua_Number)$1);SWIG_fail; %}

/* Lua 5.2 introduced unsigned APIs so we should use them when available. */
#if !defined(LUA_VERSION_NUM) || LUA_VERSION_NUM < 502

%typemap(throws) int,unsigned int,signed int,
				long,unsigned long,signed long,
				short,unsigned short,signed short,
				long long,unsigned long long,
				unsigned char, signed char,
                int&,unsigned int&,signed int&,
				long&,unsigned long&,signed long&,
				short&,unsigned short&,signed short&,
				long long&,unsigned long long&,
				unsigned char&, signed char&
%{lua_pushinteger(L,(lua_Number)$1);SWIG_fail; %}

#else /* for Lua 5.2 and up (which have unsigned APIs) */

%typemap(throws) unsigned int,
				unsigned long,
				unsigned short,
				unsigned long long,
				unsigned char,
                unsigned int&,
				unsigned long&,
				unsigned short&,
				unsigned long long&,
				unsigned char&
%{lua_pushunsigned(L,(lua_Unsigned)$1);SWIG_fail; %}

%typemap(throws) int,signed int,
				long,signed long,
				short,signed short,
				long long,
				signed char,
                int&,signed int&,
				long&,signed long&,
				short&,signed short&,
				long long&,
				signed char&
%{lua_pushinteger(L,(lua_Integer)$1);SWIG_fail; %}

#endif /* for Lua 5.2 and up (which have unsigned APIs) */
#endif /* for Lua 5.1 and up (which have integer APIs) */


Thanks,
Eric
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Beginning iPhone Games Development
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