/*
** $Id: ltm.h,v 2.5 2005/05/20 15:53:42 roberto Exp roberto $
** Tag methods
** See Copyright Notice in lua.h
*/

#ifndef ltm_h
#define ltm_h


#include "lobject.h"


/*
* WARNING: if you change the order of this enumeration,
* grep "ORDER TM"
*/
typedef enum {
  TM_INDEX,
  TM_NEWINDEX,
  TM_GC,
  TM_MODE,
  TM_EQ,  /* last tag method with `fast' access */
  TM_ADD,
  TM_SUB,
  TM_MUL,
  TM_DIV,
  TM_MOD,
  TM_POW,
  TM_UNM,
  TM_LEN,
  TM_LT,
  TM_LE,
  TM_CONCAT,
  TM_CALL,
  TM_N		/* number of elements in the enum */
} TMS;


// 先判断et是否存在，不存在则直接返回NULL
// 再判断 flags & (unsigned 1 << e), 若flags的指定二进制位=1, 那么意味着元表中没设置e对应的元方法; 若指定二进制为0，则表示可能设置了，尝试查找
// global_State->tmname中存储了各个元方法key值对应的短字符串
#define gfasttm(g,et,e) ((et) == NULL ? NULL : \
  ((et)->flags & (1u<<(e))) ? NULL : luaT_gettm(et, e, (g)->tmname[e]))

// l = lua_State *, et = metatable, e = 元方法的枚举值
#define fasttm(l,et,e)	gfasttm(G(l), et, e)

LUAI_DATA const char *const luaT_typenames[];


LUAI_FUNC const TValue *luaT_gettm (Table *events, TMS event, TString *ename);
LUAI_FUNC const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o,
                                                       TMS event);
LUAI_FUNC void luaT_init (lua_State *L);

#endif