Merge pull request #11 from msva/proper-backward-compat

lmpack.c: rework of compat-defines (fixes #9)

Author: tarruda

lmpack.c

@@ -15,12 +15,13 @@
  * compilation.
  */
 #define LUA_LIB
+#include <limits.h>
 #include <stdlib.h>
 #include <string.h>
-#include <limits.h>
 
-#include <lua.h>
 #include <lauxlib.h>
+#include <lua.h>
+#include <luaconf.h>
 
 #ifdef MPACK_USE_AMALGAMATION
 # define MPACK_API static
@@ -34,15 +35,19 @@
 #define SESSION_META_NAME "mpack.Session"
 #define NIL_NAME "mpack.NIL"
 
-#if LUA_VERSION_NUM > 501
 /* 
  * TODO(tarruda): When targeting lua 5.3 and being compiled with `long long`
  * support(not -ansi), we should make use of lua 64 bit integers for
  * representing msgpack integers, since `double` can't represent the full range.
  */
-typedef luaL_Reg luaL_reg;
-#define luaL_register(L, name, lreg) (luaL_setfuncs((L), (lreg), 0))
-#define lua_objlen(L, idx) (lua_rawlen(L, (idx)))
+
+#ifndef luaL_reg
+/* Taken from Lua5.1's lauxlib.h */
+#define luaL_reg    luaL_Reg
+#endif
+
+#if LUA_VERSION_NUM > 501
+#define luaL_register(L,n,f) luaL_setfuncs(L,f,0)
 #endif
 
 typedef struct {
@@ -198,7 +203,13 @@ static mpack_uint32_t lmpack_objlen(lua_State *L, int *is_array)
   assert(top = lua_gettop(L));
 
   if ((type = lua_type(L, -1)) != LUA_TTABLE) {
+#if LUA_VERSION_NUM >= 502
+    len = lua_rawlen(L, -1);
+#elif LUA_VERSION_NUM == 501
     len = lua_objlen(L, -1);
+#else
+    #error You have either broken or too old Lua installation. This library requires Lua>=5.1
+#endif
     goto end;
   }