1 files changed, 358 insertions, 0 deletions

diff --git a/src/lj_meta.c b/src/lj_meta.c
new file mode 100644
index 00000000..dff01f85
--- /dev/null
+++ b/src/lj_meta.c
@@ -0,0 +1,358 @@
+/*
+** Metamethod handling.
+** Copyright (C) 2005-2009 Mike Pall. See Copyright Notice in luajit.h
+**
+** Portions taken verbatim or adapted from the Lua interpreter.
+** Copyright (C) 1994-2008 Lua.org, PUC-Rio. See Copyright Notice in lua.h
+*/
+
+#define lj_meta_c
+#define LUA_CORE
+
+#include "lj_obj.h"
+#include "lj_gc.h"
+#include "lj_err.h"
+#include "lj_str.h"
+#include "lj_tab.h"
+#include "lj_meta.h"
+#include "lj_bc.h"
+#include "lj_vm.h"
+
+/* -- Metamethod handling ------------------------------------------------- */
+
+/* String interning of metamethod names for fast indexing. */
+void lj_meta_init(lua_State *L)
+{
+#define MMNAME(name)    "__" #name
+  const char *metanames = MMDEF(MMNAME);
+#undef MMNAME
+  global_State *g = G(L);
+  const char *p, *q;
+  uint32_t i;
+  for (i = 0, p = metanames; *p; i++, p = q) {
+    GCstr *s;
+    for (q = p+2; *q && *q != '_'; q++) ;
+    s = lj_str_new(L, p, (size_t)(q-p));
+    fixstring(s);  /* Never collect these names. */
+    /* NOBARRIER: g->mmname[] is a GC root. */
+    setgcref(g->mmname[i], obj2gco(s));
+  }
+}
+
+/* Negative caching of a few fast metamethods. See the lj_meta_fast() macro. */
+cTValue *lj_meta_cache(GCtab *mt, MMS mm, GCstr *name)
+{
+  cTValue *mo = lj_tab_getstr(mt, name);
+  lua_assert(mm <= MM_FAST);
+  if (!mo || tvisnil(mo)) {  /* No metamethod? */
+    mt->nomm |= cast_byte(1u<<mm);  /* Set negative cache flag. */
+    return NULL;
+  }
+  return mo;
+}
+
+/* Lookup metamethod for object. */
+cTValue *lj_meta_lookup(lua_State *L, cTValue *o, MMS mm)
+{
+  GCtab *mt;
+  if (tvistab(o))
+    mt = tabref(tabV(o)->metatable);
+  else if (tvisudata(o))
+    mt = tabref(udataV(o)->metatable);
+  else
+    mt = tabref(G(L)->basemt[itypemap(o)]);
+  if (mt) {
+    cTValue *mo = lj_tab_getstr(mt, strref(G(L)->mmname[mm]));
+    if (mo)
+      return mo;
+  }
+  return niltv(L);
+}
+
+/* Setup call to metamethod to be run by Assembler VM. */
+static TValue *mmcall(lua_State *L, ASMFunction cont, cTValue *mo,
+                    cTValue *a, cTValue *b)
+{
+  /*
+  **           |-- framesize -> top       top+1       top+2 top+3
+  ** before:   [func slots ...]
+  ** mm setup: [func slots ...] [cont|?]  [mo|tmtype] [a]   [b]
+  ** in asm:   [func slots ...] [cont|PC] [mo|delta]  [a]   [b]
+  **           ^-- func base                          ^-- mm base
+  ** after mm: [func slots ...]           [result]
+  **                ^-- copy to base[PC_RA] --/     for lj_cont_ra
+  **                          istruecond + branch   for lj_cont_cond*
+  **                                       ignore   for lj_cont_nop
+  ** next PC:  [func slots ...]
+  */
+  TValue *top = L->top;
+  if (curr_funcisL(L)) top = curr_topL(L);
+  setcont(top, cont);  /* Assembler VM stores PC in upper word. */
+  copyTV(L, top+1, mo);  /* Store metamethod and two arguments. */
+  copyTV(L, top+2, a);
+  copyTV(L, top+3, b);
+  return top+2;  /* Return new base. */
+}
+
+/* -- C helpers for some instructions, called from assembler VM ----------- */
+
+/* Helper for TGET*. __index chain and metamethod. */
+cTValue *lj_meta_tget(lua_State *L, cTValue *o, cTValue *k)
+{
+  int loop;
+  for (loop = 0; loop < LJ_MAX_IDXCHAIN; loop++) {
+    cTValue *mo;
+    if (tvistab(o)) {
+      GCtab *t = tabV(o);
+      cTValue *tv = lj_tab_get(L, t, k);
+      if (!tvisnil(tv) ||
+          !(mo = lj_meta_fast(L, tabref(t->metatable), MM_index)))
+        return tv;
+    } else if (tvisnil(mo = lj_meta_lookup(L, o, MM_index))) {
+      lj_err_optype(L, o, LJ_ERR_OPINDEX);
+      return NULL;  /* unreachable */
+    }
+    if (tvisfunc(mo)) {
+      L->top = mmcall(L, lj_cont_ra, mo, o, k);
+      return NULL;  /* Trigger metamethod call. */
+    }
+    o = mo;
+  }
+  lj_err_msg(L, LJ_ERR_GETLOOP);
+  return NULL;  /* unreachable */
+}
+
+/* Helper for TSET*. __newindex chain and metamethod. */
+TValue *lj_meta_tset(lua_State *L, cTValue *o, cTValue *k)
+{
+  TValue tmp;
+  int loop;
+  for (loop = 0; loop < LJ_MAX_IDXCHAIN; loop++) {
+    cTValue *mo;
+    if (tvistab(o)) {
+      GCtab *t = tabV(o);
+      TValue *tv = lj_tab_set(L, t, k);
+      if (!tvisnil(tv) ||
+          !(mo = lj_meta_fast(L, tabref(t->metatable), MM_newindex))) {
+        if (isblack(obj2gco(t))) lj_gc_barrierback(G(L), t);
+        return tv;
+      }
+    } else if (tvisnil(mo = lj_meta_lookup(L, o, MM_newindex))) {
+      lj_err_optype(L, o, LJ_ERR_OPINDEX);
+      return NULL;  /* unreachable */
+    }
+    if (tvisfunc(mo)) {
+      L->top = mmcall(L, lj_cont_nop, mo, o, k);
+      /* L->top+2 = v filled in by caller. */
+      return NULL;  /* Trigger metamethod call. */
+    }
+    copyTV(L, &tmp, mo);
+    o = &tmp;
+  }
+  lj_err_msg(L, LJ_ERR_SETLOOP);
+  return NULL;  /* unreachable */
+}
+
+static cTValue *str2num(cTValue *o, TValue *n)
+{
+  if (tvisnum(o))
+    return o;
+  else if (tvisstr(o) && lj_str_numconv(strVdata(o), n))
+    return n;
+  else
+    return NULL;
+}
+
+/* Helper for arithmetic instructions. Coercion, metamethod. */
+TValue *lj_meta_arith(lua_State *L, TValue *ra, cTValue *rb, cTValue *rc,
+                      BCReg op)
+{
+  MMS mm = bcmode_mm(op);
+  TValue tempb, tempc;
+  cTValue *b, *c;
+  if ((b = str2num(rb, &tempb)) != NULL &&
+      (c = str2num(rc, &tempc)) != NULL) {  /* Try coercion first. */
+    setnumV(ra, lj_vm_foldarith(numV(b), numV(c), (int)mm-MM_add));
+    return NULL;
+  } else {
+    cTValue *mo = lj_meta_lookup(L, rb, mm);
+    if (tvisnil(mo)) {
+      mo = lj_meta_lookup(L, rc, mm);
+      if (tvisnil(mo)) {
+        if (str2num(rb, &tempb) == NULL) rc = rb;
+        lj_err_optype(L, rc, LJ_ERR_OPARITH);
+        return NULL;  /* unreachable */
+      }
+    }
+    return mmcall(L, lj_cont_ra, mo, rb, rc);
+  }
+}
+
+/* In-place coercion of a number to a string. */
+static LJ_AINLINE int tostring(lua_State *L, TValue *o)
+{
+  if (tvisstr(o)) {
+    return 1;
+  } else if (tvisnum(o)) {
+    setstrV(L, o, lj_str_fromnum(L, &o->n));
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+/* Helper for CAT. Coercion, iterative concat, __concat metamethod. */
+TValue *lj_meta_cat(lua_State *L, TValue *top, int left)
+{
+  do {
+    int n = 1;
+    if (!(tvisstr(top-1) || tvisnum(top-1)) || !tostring(L, top)) {
+      cTValue *mo = lj_meta_lookup(L, top-1, MM_concat);
+      if (tvisnil(mo)) {
+        mo = lj_meta_lookup(L, top, MM_concat);
+        if (tvisnil(mo)) {
+          if (tvisstr(top-1) || tvisnum(top-1)) top++;
+          lj_err_optype(L, top-1, LJ_ERR_OPCAT);
+          return NULL;  /* unreachable */
+        }
+      }
+      /* One of the top two elements is not a string, call __cat metamethod:
+      **
+      ** before:    [...][CAT stack .........................]
+      **                                 top-1     top         top+1 top+2
+      ** pick two:  [...][CAT stack ...] [o1]      [o2]
+      ** setup mm:  [...][CAT stack ...] [cont|?]  [mo|tmtype] [o1]  [o2]
+      ** in asm:    [...][CAT stack ...] [cont|PC] [mo|delta]  [o1]  [o2]
+      **            ^-- func base                              ^-- mm base
+      ** after mm:  [...][CAT stack ...] <--push-- [result]
+      ** next step: [...][CAT stack .............]
+      */
+      copyTV(L, top+2, top)  /* Careful with the order of stack copies! */
+      copyTV(L, top+1, top-1)
+      copyTV(L, top, mo)
+      setcont(top-1, lj_cont_cat);
+      return top+1;  /* Trigger metamethod call. */
+    } else if (strV(top)->len == 0) {  /* Shortcut. */
+      (void)tostring(L, top-1);
+    } else {
+      /* Pick as many strings as possible from the top and concatenate them:
+      **
+      ** before:    [...][CAT stack ...........................]
+      ** pick str:  [...][CAT stack ...] [...... strings ......]
+      ** concat:    [...][CAT stack ...] [result]
+      ** next step: [...][CAT stack ............]
+      */
+      MSize tlen = strV(top)->len;
+      char *buffer;
+      int i;
+      for (n = 1; n <= left && tostring(L, top-n); n++) {
+        MSize len = strV(top-n)->len;
+        if (len >= LJ_MAX_STR - tlen)
+          lj_err_msg(L, LJ_ERR_STROV);
+        tlen += len;
+      }
+      buffer = lj_str_needbuf(L, &G(L)->tmpbuf, tlen);
+      n--;
+      tlen = 0;
+      for (i = n; i >= 0; i--) {
+        MSize len = strV(top-i)->len;
+        memcpy(buffer + tlen, strVdata(top-i), len);
+        tlen += len;
+      }
+      setstrV(L, top-n, lj_str_new(L, buffer, tlen));
+    }
+    left -= n;
+    top -= n;
+  } while (left >= 1);
+  lj_gc_check_fixtop(L);
+  return NULL;
+}
+
+/* Helper for LEN. __len metamethod. */
+TValue *lj_meta_len(lua_State *L, cTValue *o)
+{
+  cTValue *mo = lj_meta_lookup(L, o, MM_len);
+  if (tvisnil(mo)) {
+    lj_err_optype(L, o, LJ_ERR_OPLEN);
+    return NULL;  /* unreachable */
+  }
+  return mmcall(L, lj_cont_ra, mo, o, niltv(L));
+}
+
+/* Helper for equality comparisons. __eq metamethod. */
+TValue *lj_meta_equal(lua_State *L, GCobj *o1, GCobj *o2, int ne)
+{
+  /* Field metatable must be at same offset for GCtab and GCudata! */
+  cTValue *mo = lj_meta_fast(L, tabref(o1->gch.metatable), MM_eq);
+  if (mo) {
+    TValue *top;
+    int it;
+    if (tabref(o1->gch.metatable) != tabref(o2->gch.metatable)) {
+      cTValue *mo2 = lj_meta_fast(L, tabref(o2->gch.metatable), MM_eq);
+      if (mo2 == NULL || !lj_obj_equal(mo, mo2))
+        return cast(TValue *, (intptr_t)ne);
+    }
+    top = curr_top(L);
+    setcont(top, ne ? lj_cont_condf : lj_cont_condt);
+    copyTV(L, top+1, mo);
+    it = o1->gch.gct == ~LJ_TTAB ? LJ_TTAB : LJ_TUDATA;
+    setgcV(L, top+2, &o1->gch, it);
+    setgcV(L, top+3, &o2->gch, it);
+    return top+2;  /* Trigger metamethod call. */
+  }
+  return cast(TValue *, (intptr_t)ne);
+}
+
+/* Helper for ordered comparisons. String compare, __lt/__le metamethods. */
+TValue *lj_meta_comp(lua_State *L, cTValue *o1, cTValue *o2, int op)
+{
+  if (itype(o1) == itype(o2)) {  /* Never called with two numbers. */
+    if (tvisstr(o1) && tvisstr(o2)) {
+      int32_t res = lj_str_cmp(strV(o1), strV(o2));
+      return cast(TValue *, (intptr_t)(((op&2) ? res <= 0 : res < 0) ^ (op&1)));
+    } else {
+    trymt:
+      while (1) {
+        ASMFunction cont = (op & 1) ? lj_cont_condf : lj_cont_condt;
+        MMS mm = (op & 2) ? MM_le : MM_lt;
+        cTValue *mo = lj_meta_lookup(L, o1, mm);
+        cTValue *mo2 = lj_meta_lookup(L, o2, mm);
+        if (tvisnil(mo) || !lj_obj_equal(mo, mo2)) {
+          if (op & 2) {  /* MM_le not found: retry with MM_lt. */
+            cTValue *ot = o1; o1 = o2; o2 = ot;  /* Swap operands. */
+            op ^= 3;  /* Use LT and flip condition. */
+            continue;
+          }
+          goto err;
+        }
+        return mmcall(L, cont, mo, o1, o2);
+      }
+    }
+  } else if (tvisbool(o1) && tvisbool(o2)) {
+    goto trymt;
+  } else {
+  err:
+    lj_err_comp(L, o1, o2);
+    return NULL;
+  }
+}
+
+/* Helper for calls. __call metamethod. */
+void lj_meta_call(lua_State *L, TValue *func, TValue *top)
+{
+  cTValue *mo = lj_meta_lookup(L, func, MM_call);
+  TValue *p;
+  if (!tvisfunc(mo))
+    lj_err_optype_call(L, func);
+  for (p = top; p > func; p--) copyTV(L, p, p-1);
+  copyTV(L, func, mo);
+}
+
+/* Helper for FORI. Coercion. */
+void lj_meta_for(lua_State *L, TValue *base)
+{
+  if (!str2num(base, base)) lj_err_msg(L, LJ_ERR_FORINIT);
+  if (!str2num(base+1, base+1)) lj_err_msg(L, LJ_ERR_FORLIM);
+  if (!str2num(base+2, base+2)) lj_err_msg(L, LJ_ERR_FORSTEP);
+}
+