Function jointable

other_src/lua/src/lpeg.cpp:966–994

** join the elements of the ktable from pattern 'p1' into the ktable of ** the pattern at the top of the stack ('p'). If 'p1' has no elements, ** 'p' keeps its original ktable. If 'p' has no elements, it shares ** 'p1' ktable. Otherwise, this function creates a new ktable for 'p'. ** Return the offset of original 'p' elements in the new ktable. */

** Return the offset of original 'p' elements in the new ktable.
*/ 
static int jointable (lua_State *L, int p1) {
  int n, n1, i;
  lua_getfenv(L, p1);
  n1 = ktablelen(L, -1);  /* number of elements in p1's env */
  lua_getfenv(L, -2);
  if (n1 == 0 || lua_equal(L, -2, -1)) {
    lua_pop(L, 2);
    return 0;  /* no need to change anything */
  }
  n = ktablelen(L, -1);  /* number of elements in p's env */
  if (n == 0) {
    lua_pop(L, 1);  /* removes p env */
    lua_setfenv(L, -2);  /* p now shares p1's env */
    return 0;  /* no need to correct anything */
  }
  lua_createtable(L, n + n1, 0);
  /* stack: p; p1 env; p env; new p env */
  for (i = 1; i <= n; i++) {
    lua_rawgeti(L, -2, i);
    lua_rawseti(L, -2, i);
  }
  for (i = 1; i <= n1; i++) {
    lua_rawgeti(L, -3, i);
    lua_rawseti(L, -2, n + i);
  }
  lua_setfenv(L, -4);  /* new table becomes p env */
  lua_pop(L, 2);  /* remove p1 env and old p env */
  return n;
}


#define copypatt(p1,p2,sz)	memcpy(p1, p2, (sz) * sizeof(Instruction));