Add support for __pairs and __ipairs metamethods (from Lua 5.2).

1 files changed, 30 insertions, 4 deletions

diff --git a/src/lib_base.c b/src/lib_base.c
index 908099d4..aa55faba 100644
--- a/src/lib_base.c
+++ b/src/lib_base.c
@@ -246,17 +246,43 @@ LJ_STATIC_ASSERT((int)FF_next == FF_next_N);
 LJLIB_ASM(next)
 {
   lj_lib_checktab(L, 1);
-  lj_lib_checknum(L, 2);  /* For ipairs_aux. */
   return FFH_UNREACHABLE;
 }
 
+static int ffh_pairs(lua_State *L, MMS mm)
+{
+  TValue *o = lj_lib_checkany(L, 1);
+  cTValue *mo = lj_meta_lookup(L, o, mm);
+  if (!tvisnil(mo)) {
+    L->top = o+1;  /* Only keep one argument. */
+    copyTV(L, L->base-1, mo);  /* Replace callable. */
+    return FFH_TAILCALL;
+  } else {
+    if (!tvistab(o)) lj_err_argt(L, 1, LUA_TTABLE);
+    setfuncV(L, o-1, funcV(lj_lib_upvalue(L, 1)));
+    if (mm == MM_pairs) setnilV(o+1); else setintV(o+1, 0);
+    return FFH_RES(3);
+  }
+}
+
 LJLIB_PUSH(lastcl)
-LJLIB_ASM_(pairs)
+LJLIB_ASM(pairs)
+{
+  return ffh_pairs(L, MM_pairs);
+}
 
-LJLIB_NOREGUV LJLIB_ASM_(ipairs_aux)    LJLIB_REC(.)
+LJLIB_NOREGUV LJLIB_ASM(ipairs_aux)     LJLIB_REC(.)
+{
+  lj_lib_checktab(L, 1);
+  lj_lib_checknum(L, 2);
+  return FFH_UNREACHABLE;
+}
 
 LJLIB_PUSH(lastcl)
-LJLIB_ASM_(ipairs)              LJLIB_REC(.)
+LJLIB_ASM(ipairs)               LJLIB_REC(.)
+{
+  return ffh_pairs(L, MM_ipairs);
+}
 
 /* -- Base library: throw and catch errors -------------------------------- */