add support for local variable declared with attribute 'close' and 'const' for Lua 5.4.

1 files changed, 1996 insertions, 0 deletions

diff --git a/src/lua/lparser.c b/src/lua/lparser.c
new file mode 100644
index 0000000..bc7d9a4
--- /dev/null
+++ b/src/lua/lparser.c
@@ -0,0 +1,1996 @@
+/*
+** $Id: lparser.c $
+** Lua Parser
+** See Copyright Notice in lua.h
+*/
+
+#define lparser_c
+#define LUA_CORE
+
+#include "lprefix.h"
+
+
+#include <limits.h>
+#include <string.h>
+
+#include "lua.h"
+
+#include "lcode.h"
+#include "ldebug.h"
+#include "ldo.h"
+#include "lfunc.h"
+#include "llex.h"
+#include "lmem.h"
+#include "lobject.h"
+#include "lopcodes.h"
+#include "lparser.h"
+#include "lstate.h"
+#include "lstring.h"
+#include "ltable.h"
+
+
+
+/* maximum number of local variables per function (must be smaller
+   than 250, due to the bytecode format) */
+#define MAXVARS         200
+
+
+#define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
+
+
+/* because all strings are unified by the scanner, the parser
+   can use pointer equality for string equality */
+#define eqstr(a,b)      ((a) == (b))
+
+
+/*
+** nodes for block list (list of active blocks)
+*/
+typedef struct BlockCnt {
+  struct BlockCnt *previous;  /* chain */
+  int firstlabel;  /* index of first label in this block */
+  int firstgoto;  /* index of first pending goto in this block */
+  lu_byte nactvar;  /* # active locals outside the block */
+  lu_byte upval;  /* true if some variable in the block is an upvalue */
+  lu_byte isloop;  /* true if 'block' is a loop */
+  lu_byte insidetbc;  /* true if inside the scope of a to-be-closed var. */
+} BlockCnt;
+
+
+
+/*
+** prototypes for recursive non-terminal functions
+*/
+static void statement (LexState *ls);
+static void expr (LexState *ls, expdesc *v);
+
+
+static l_noret error_expected (LexState *ls, int token) {
+  luaX_syntaxerror(ls,
+      luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
+}
+
+
+static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
+  lua_State *L = fs->ls->L;
+  const char *msg;
+  int line = fs->f->linedefined;
+  const char *where = (line == 0)
+                      ? "main function"
+                      : luaO_pushfstring(L, "function at line %d", line);
+  msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
+                             what, limit, where);
+  luaX_syntaxerror(fs->ls, msg);
+}
+
+
+static void checklimit (FuncState *fs, int v, int l, const char *what) {
+  if (v > l) errorlimit(fs, l, what);
+}
+
+
+/*
+** Test whether next token is 'c'; if so, skip it.
+*/
+static int testnext (LexState *ls, int c) {
+  if (ls->t.token == c) {
+    luaX_next(ls);
+    return 1;
+  }
+  else return 0;
+}
+
+
+/*
+** Check that next token is 'c'.
+*/
+static void check (LexState *ls, int c) {
+  if (ls->t.token != c)
+    error_expected(ls, c);
+}
+
+
+/*
+** Check that next token is 'c' and skip it.
+*/
+static void checknext (LexState *ls, int c) {
+  check(ls, c);
+  luaX_next(ls);
+}
+
+
+#define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
+
+
+/*
+** Check that next token is 'what' and skip it. In case of error,
+** raise an error that the expected 'what' should match a 'who'
+** in line 'where' (if that is not the current line).
+*/
+static void check_match (LexState *ls, int what, int who, int where) {
+  if (unlikely(!testnext(ls, what))) {
+    if (where == ls->linenumber)  /* all in the same line? */
+      error_expected(ls, what);  /* do not need a complex message */
+    else {
+      luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
+             "%s expected (to close %s at line %d)",
+              luaX_token2str(ls, what), luaX_token2str(ls, who), where));
+    }
+  }
+}
+
+
+static TString *str_checkname (LexState *ls) {
+  TString *ts;
+  check(ls, TK_NAME);
+  ts = ls->t.seminfo.ts;
+  luaX_next(ls);
+  return ts;
+}
+
+
+static void init_exp (expdesc *e, expkind k, int i) {
+  e->f = e->t = NO_JUMP;
+  e->k = k;
+  e->u.info = i;
+}
+
+
+static void codestring (expdesc *e, TString *s) {
+  e->f = e->t = NO_JUMP;
+  e->k = VKSTR;
+  e->u.strval = s;
+}
+
+
+static void codename (LexState *ls, expdesc *e) {
+  codestring(e, str_checkname(ls));
+}
+
+
+/*
+** Register a new local variable in the active 'Proto' (for debug
+** information).
+*/
+static int registerlocalvar (LexState *ls, FuncState *fs, TString *varname) {
+  Proto *f = fs->f;
+  int oldsize = f->sizelocvars;
+  luaM_growvector(ls->L, f->locvars, fs->ndebugvars, f->sizelocvars,
+                  LocVar, SHRT_MAX, "local variables");
+  while (oldsize < f->sizelocvars)
+    f->locvars[oldsize++].varname = NULL;
+  f->locvars[fs->ndebugvars].varname = varname;
+  f->locvars[fs->ndebugvars].startpc = fs->pc;
+  luaC_objbarrier(ls->L, f, varname);
+  return fs->ndebugvars++;
+}
+
+
+/*
+** Create a new local variable with the given 'name'. Return its index
+** in the function.
+*/
+static int new_localvar (LexState *ls, TString *name) {
+  lua_State *L = ls->L;
+  FuncState *fs = ls->fs;
+  Dyndata *dyd = ls->dyd;
+  Vardesc *var;
+  checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
+                 MAXVARS, "local variables");
+  luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1,
+                  dyd->actvar.size, Vardesc, USHRT_MAX, "local variables");
+  var = &dyd->actvar.arr[dyd->actvar.n++];
+  var->vd.kind = VDKREG;  /* default */
+  var->vd.name = name;
+  return dyd->actvar.n - 1 - fs->firstlocal;
+}
+
+#define new_localvarliteral(ls,v) \
+    new_localvar(ls,  \
+      luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char)) - 1));
+
+
+
+/*
+** Return the "variable description" (Vardesc) of a given variable.
+** (Unless noted otherwise, all variables are referred to by their
+** compiler indices.)
+*/
+static Vardesc *getlocalvardesc (FuncState *fs, int vidx) {
+  return &fs->ls->dyd->actvar.arr[fs->firstlocal + vidx];
+}
+
+
+/*
+** Convert 'nvar', a compiler index level, to it corresponding
+** stack index level. For that, search for the highest variable
+** below that level that is in the stack and uses its stack
+** index ('sidx').
+*/
+static int stacklevel (FuncState *fs, int nvar) {
+  while (nvar-- > 0) {
+    Vardesc *vd = getlocalvardesc(fs, nvar);  /* get variable */
+    if (vd->vd.kind != RDKCTC)  /* is in the stack? */
+      return vd->vd.sidx + 1;
+  }
+  return 0;  /* no variables in the stack */
+}
+
+
+/*
+** Return the number of variables in the stack for function 'fs'
+*/
+int luaY_nvarstack (FuncState *fs) {
+  return stacklevel(fs, fs->nactvar);
+}
+
+
+/*
+** Get the debug-information entry for current variable 'vidx'.
+*/
+static LocVar *localdebuginfo (FuncState *fs, int vidx) {
+  Vardesc *vd = getlocalvardesc(fs,  vidx);
+  if (vd->vd.kind == RDKCTC)
+    return NULL;  /* no debug info. for constants */
+  else {
+    int idx = vd->vd.pidx;
+    lua_assert(idx < fs->ndebugvars);
+    return &fs->f->locvars[idx];
+  }
+}
+
+
+/*
+** Create an expression representing variable 'vidx'
+*/
+static void init_var (FuncState *fs, expdesc *e, int vidx) {
+  e->f = e->t = NO_JUMP;
+  e->k = VLOCAL;
+  e->u.var.vidx = vidx;
+  e->u.var.sidx = getlocalvardesc(fs, vidx)->vd.sidx;
+}
+
+
+/*
+** Raises an error if variable described by 'e' is read only
+*/
+static void check_readonly (LexState *ls, expdesc *e) {
+  FuncState *fs = ls->fs;
+  TString *varname = NULL;  /* to be set if variable is const */
+  switch (e->k) {
+    case VCONST: {
+      varname = ls->dyd->actvar.arr[e->u.info].vd.name;
+      break;
+    }
+    case VLOCAL: {
+      Vardesc *vardesc = getlocalvardesc(fs, e->u.var.vidx);
+      if (vardesc->vd.kind != VDKREG)  /* not a regular variable? */
+        varname = vardesc->vd.name;
+      break;
+    }
+    case VUPVAL: {
+      Upvaldesc *up = &fs->f->upvalues[e->u.info];
+      if (up->kind != VDKREG)
+        varname = up->name;
+      break;
+    }
+    default:
+      return;  /* other cases cannot be read-only */
+  }
+  if (varname) {
+    const char *msg = luaO_pushfstring(ls->L,
+       "attempt to assign to const variable '%s'", getstr(varname));
+    luaK_semerror(ls, msg);  /* error */
+  }
+}
+
+
+/*
+** Start the scope for the last 'nvars' created variables.
+*/
+static void adjustlocalvars (LexState *ls, int nvars) {
+  FuncState *fs = ls->fs;
+  int stklevel = luaY_nvarstack(fs);
+  int i;
+  for (i = 0; i < nvars; i++) {
+    int vidx = fs->nactvar++;
+    Vardesc *var = getlocalvardesc(fs, vidx);
+    var->vd.sidx = stklevel++;
+    var->vd.pidx = registerlocalvar(ls, fs, var->vd.name);
+  }
+}
+
+
+/*
+** Close the scope for all variables up to level 'tolevel'.
+** (debug info.)
+*/
+static void removevars (FuncState *fs, int tolevel) {
+  fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
+  while (fs->nactvar > tolevel) {
+    LocVar *var = localdebuginfo(fs, --fs->nactvar);
+    if (var)  /* does it have debug information? */
+      var->endpc = fs->pc;
+  }
+}
+
+
+/*
+** Search the upvalues of the function 'fs' for one
+** with the given 'name'.
+*/
+static int searchupvalue (FuncState *fs, TString *name) {
+  int i;
+  Upvaldesc *up = fs->f->upvalues;
+  for (i = 0; i < fs->nups; i++) {
+    if (eqstr(up[i].name, name)) return i;
+  }
+  return -1;  /* not found */
+}
+
+
+static Upvaldesc *allocupvalue (FuncState *fs) {
+  Proto *f = fs->f;
+  int oldsize = f->sizeupvalues;
+  checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
+  luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
+                  Upvaldesc, MAXUPVAL, "upvalues");
+  while (oldsize < f->sizeupvalues)
+    f->upvalues[oldsize++].name = NULL;
+  return &f->upvalues[fs->nups++];
+}
+
+
+static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
+  Upvaldesc *up = allocupvalue(fs);
+  FuncState *prev = fs->prev;
+  if (v->k == VLOCAL) {
+    up->instack = 1;
+    up->idx = v->u.var.sidx;
+    up->kind = getlocalvardesc(prev, v->u.var.vidx)->vd.kind;
+    lua_assert(eqstr(name, getlocalvardesc(prev, v->u.var.vidx)->vd.name));
+  }
+  else {
+    up->instack = 0;
+    up->idx = cast_byte(v->u.info);
+    up->kind = prev->f->upvalues[v->u.info].kind;
+    lua_assert(eqstr(name, prev->f->upvalues[v->u.info].name));
+  }
+  up->name = name;
+  luaC_objbarrier(fs->ls->L, fs->f, name);
+  return fs->nups - 1;
+}
+
+
+/*
+** Look for an active local variable with the name 'n' in the
+** function 'fs'. If found, initialize 'var' with it and return
+** its expression kind; otherwise return -1.
+*/
+static int searchvar (FuncState *fs, TString *n, expdesc *var) {
+  int i;
+  for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
+    Vardesc *vd = getlocalvardesc(fs, i);
+    if (eqstr(n, vd->vd.name)) {  /* found? */
+      if (vd->vd.kind == RDKCTC)  /* compile-time constant? */
+        init_exp(var, VCONST, fs->firstlocal + i);
+      else  /* real variable */
+        init_var(fs, var, i);
+      return var->k;
+    }
+  }
+  return -1;  /* not found */
+}
+
+
+/*
+** Mark block where variable at given level was defined
+** (to emit close instructions later).
+*/
+static void markupval (FuncState *fs, int level) {
+  BlockCnt *bl = fs->bl;
+  while (bl->nactvar > level)
+    bl = bl->previous;
+  bl->upval = 1;
+  fs->needclose = 1;
+}
+
+
+/*
+** Find a variable with the given name 'n'. If it is an upvalue, add
+** this upvalue into all intermediate functions. If it is a global, set
+** 'var' as 'void' as a flag.
+*/
+static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
+  if (fs == NULL)  /* no more levels? */
+    init_exp(var, VVOID, 0);  /* default is global */
+  else {
+    int v = searchvar(fs, n, var);  /* look up locals at current level */
+    if (v >= 0) {  /* found? */
+      if (v == VLOCAL && !base)
+        markupval(fs, var->u.var.vidx);  /* local will be used as an upval */
+    }
+    else {  /* not found as local at current level; try upvalues */
+      int idx = searchupvalue(fs, n);  /* try existing upvalues */
+      if (idx < 0) {  /* not found? */
+        singlevaraux(fs->prev, n, var, 0);  /* try upper levels */
+        if (var->k == VLOCAL || var->k == VUPVAL)  /* local or upvalue? */
+          idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
+        else  /* it is a global or a constant */
+          return;  /* don't need to do anything at this level */
+      }
+      init_exp(var, VUPVAL, idx);  /* new or old upvalue */
+    }
+  }
+}
+
+
+/*
+** Find a variable with the given name 'n', handling global variables
+** too.
+*/
+static void singlevar (LexState *ls, expdesc *var) {
+  TString *varname = str_checkname(ls);
+  FuncState *fs = ls->fs;
+  singlevaraux(fs, varname, var, 1);
+  if (var->k == VVOID) {  /* global name? */
+    expdesc key;
+    singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
+    lua_assert(var->k != VVOID);  /* this one must exist */
+    codestring(&key, varname);  /* key is variable name */
+    luaK_indexed(fs, var, &key);  /* env[varname] */
+  }
+}
+
+
+/*
+** Adjust the number of results from an expression list 'e' with 'nexps'
+** expressions to 'nvars' values.
+*/
+static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
+  FuncState *fs = ls->fs;
+  int needed = nvars - nexps;  /* extra values needed */
+  if (hasmultret(e->k)) {  /* last expression has multiple returns? */
+    int extra = needed + 1;  /* discount last expression itself */
+    if (extra < 0)
+      extra = 0;
+    luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
+  }
+  else {
+    if (e->k != VVOID)  /* at least one expression? */
+      luaK_exp2nextreg(fs, e);  /* close last expression */
+    if (needed > 0)  /* missing values? */
+      luaK_nil(fs, fs->freereg, needed);  /* complete with nils */
+  }
+  if (needed > 0)
+    luaK_reserveregs(fs, needed);  /* registers for extra values */
+  else  /* adding 'needed' is actually a subtraction */
+    fs->freereg += needed;  /* remove extra values */
+}
+
+
+/*
+** Macros to limit the maximum recursion depth while parsing
+*/
+#define enterlevel(ls)  luaE_enterCcall((ls)->L)
+
+#define leavelevel(ls)  luaE_exitCcall((ls)->L)
+
+
+/*
+** Generates an error that a goto jumps into the scope of some
+** local variable.
+*/
+static l_noret jumpscopeerror (LexState *ls, Labeldesc *gt) {
+  const char *varname = getstr(getlocalvardesc(ls->fs, gt->nactvar)->vd.name);
+  const char *msg = "<goto %s> at line %d jumps into the scope of local '%s'";
+  msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line, varname);
+  luaK_semerror(ls, msg);  /* raise the error */
+}
+
+
+/*
+** Solves the goto at index 'g' to given 'label' and removes it
+** from the list of pending goto's.
+** If it jumps into the scope of some variable, raises an error.
+*/
+static void solvegoto (LexState *ls, int g, Labeldesc *label) {
+  int i;
+  Labellist *gl = &ls->dyd->gt;  /* list of goto's */
+  Labeldesc *gt = &gl->arr[g];  /* goto to be resolved */
+  lua_assert(eqstr(gt->name, label->name));
+  if (unlikely(gt->nactvar < label->nactvar))  /* enter some scope? */
+    jumpscopeerror(ls, gt);
+  luaK_patchlist(ls->fs, gt->pc, label->pc);
+  for (i = g; i < gl->n - 1; i++)  /* remove goto from pending list */
+    gl->arr[i] = gl->arr[i + 1];
+  gl->n--;
+}
+
+
+/*
+** Search for an active label with the given name.
+*/
+static Labeldesc *findlabel (LexState *ls, TString *name) {
+  int i;
+  Dyndata *dyd = ls->dyd;
+  /* check labels in current function for a match */
+  for (i = ls->fs->firstlabel; i < dyd->label.n; i++) {
+    Labeldesc *lb = &dyd->label.arr[i];
+    if (eqstr(lb->name, name))  /* correct label? */
+      return lb;
+  }
+  return NULL;  /* label not found */
+}
+
+
+/*
+** Adds a new label/goto in the corresponding list.
+*/
+static int newlabelentry (LexState *ls, Labellist *l, TString *name,
+                          int line, int pc) {
+  int n = l->n;
+  luaM_growvector(ls->L, l->arr, n, l->size,
+                  Labeldesc, SHRT_MAX, "labels/gotos");
+  l->arr[n].name = name;
+  l->arr[n].line = line;
+  l->arr[n].nactvar = ls->fs->nactvar;
+  l->arr[n].close = 0;
+  l->arr[n].pc = pc;
+  l->n = n + 1;
+  return n;
+}
+
+
+static int newgotoentry (LexState *ls, TString *name, int line, int pc) {
+  return newlabelentry(ls, &ls->dyd->gt, name, line, pc);
+}
+
+
+/*
+** Solves forward jumps. Check whether new label 'lb' matches any
+** pending gotos in current block and solves them. Return true
+** if any of the goto's need to close upvalues.
+*/
+static int solvegotos (LexState *ls, Labeldesc *lb) {
+  Labellist *gl = &ls->dyd->gt;
+  int i = ls->fs->bl->firstgoto;
+  int needsclose = 0;
+  while (i < gl->n) {
+    if (eqstr(gl->arr[i].name, lb->name)) {
+      needsclose |= gl->arr[i].close;
+      solvegoto(ls, i, lb);  /* will remove 'i' from the list */
+    }
+    else
+      i++;
+  }
+  return needsclose;
+}
+
+
+/*
+** Create a new label with the given 'name' at the given 'line'.
+** 'last' tells whether label is the last non-op statement in its
+** block. Solves all pending goto's to this new label and adds
+** a close instruction if necessary.
+** Returns true iff it added a close instruction.
+*/
+static int createlabel (LexState *ls, TString *name, int line,
+                        int last) {
+  FuncState *fs = ls->fs;
+  Labellist *ll = &ls->dyd->label;
+  int l = newlabelentry(ls, ll, name, line, luaK_getlabel(fs));
+  if (last) {  /* label is last no-op statement in the block? */
+    /* assume that locals are already out of scope */
+    ll->arr[l].nactvar = fs->bl->nactvar;
+  }
+  if (solvegotos(ls, &ll->arr[l])) {  /* need close? */
+    luaK_codeABC(fs, OP_CLOSE, luaY_nvarstack(fs), 0, 0);
+    return 1;
+  }
+  return 0;
+}
+
+
+/*
+** Adjust pending gotos to outer level of a block.
+*/
+static void movegotosout (FuncState *fs, BlockCnt *bl) {
+  int i;
+  Labellist *gl = &fs->ls->dyd->gt;
+  /* correct pending gotos to current block */
+  for (i = bl->firstgoto; i < gl->n; i++) {  /* for each pending goto */
+    Labeldesc *gt = &gl->arr[i];
+    /* leaving a variable scope? */
+    if (stacklevel(fs, gt->nactvar) > stacklevel(fs, bl->nactvar))
+      gt->close |= bl->upval;  /* jump may need a close */
+    gt->nactvar = bl->nactvar;  /* update goto level */
+  }
+}
+
+
+static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
+  bl->isloop = isloop;
+  bl->nactvar = fs->nactvar;
+  bl->firstlabel = fs->ls->dyd->label.n;
+  bl->firstgoto = fs->ls->dyd->gt.n;
+  bl->upval = 0;
+  bl->insidetbc = (fs->bl != NULL && fs->bl->insidetbc);
+  bl->previous = fs->bl;
+  fs->bl = bl;
+  lua_assert(fs->freereg == luaY_nvarstack(fs));
+}
+
+
+/*
+** generates an error for an undefined 'goto'.
+*/
+static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
+  const char *msg;
+  if (eqstr(gt->name, luaS_newliteral(ls->L, "break"))) {
+    msg = "break outside loop at line %d";
+    msg = luaO_pushfstring(ls->L, msg, gt->line);
+  }
+  else {
+    msg = "no visible label '%s' for <goto> at line %d";
+    msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
+  }
+  luaK_semerror(ls, msg);
+}
+
+
+static void leaveblock (FuncState *fs) {
+  BlockCnt *bl = fs->bl;
+  LexState *ls = fs->ls;
+  int hasclose = 0;
+  int stklevel = stacklevel(fs, bl->nactvar);  /* level outside the block */
+  if (bl->isloop)  /* fix pending breaks? */
+    hasclose = createlabel(ls, luaS_newliteral(ls->L, "break"), 0, 0);
+  if (!hasclose && bl->previous && bl->upval)
+    luaK_codeABC(fs, OP_CLOSE, stklevel, 0, 0);
+  fs->bl = bl->previous;
+  removevars(fs, bl->nactvar);
+  lua_assert(bl->nactvar == fs->nactvar);
+  fs->freereg = stklevel;  /* free registers */
+  ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
+  if (bl->previous)  /* inner block? */
+    movegotosout(fs, bl);  /* update pending gotos to outer block */
+  else {
+    if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
+      undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
+  }
+}
+
+
+/*
+** adds a new prototype into list of prototypes
+*/
+static Proto *addprototype (LexState *ls) {
+  Proto *clp;
+  lua_State *L = ls->L;
+  FuncState *fs = ls->fs;
+  Proto *f = fs->f;  /* prototype of current function */
+  if (fs->np >= f->sizep) {
+    int oldsize = f->sizep;
+    luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
+    while (oldsize < f->sizep)
+      f->p[oldsize++] = NULL;
+  }
+  f->p[fs->np++] = clp = luaF_newproto(L);
+  luaC_objbarrier(L, f, clp);
+  return clp;
+}
+
+
+/*
+** codes instruction to create new closure in parent function.
+** The OP_CLOSURE instruction uses the last available register,
+** so that, if it invokes the GC, the GC knows which registers
+** are in use at that time.
+
+*/
+static void codeclosure (LexState *ls, expdesc *v) {
+  FuncState *fs = ls->fs->prev;
+  init_exp(v, VRELOC, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
+  luaK_exp2nextreg(fs, v);  /* fix it at the last register */
+}
+
+
+static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
+  Proto *f = fs->f;
+  fs->prev = ls->fs;  /* linked list of funcstates */
+  fs->ls = ls;
+  ls->fs = fs;
+  fs->pc = 0;
+  fs->previousline = f->linedefined;
+  fs->iwthabs = 0;
+  fs->lasttarget = 0;
+  fs->freereg = 0;
+  fs->nk = 0;
+  fs->nabslineinfo = 0;
+  fs->np = 0;
+  fs->nups = 0;
+  fs->ndebugvars = 0;
+  fs->nactvar = 0;
+  fs->needclose = 0;
+  fs->firstlocal = ls->dyd->actvar.n;
+  fs->firstlabel = ls->dyd->label.n;
+  fs->bl = NULL;
+  f->source = ls->source;
+  luaC_objbarrier(ls->L, f, f->source);
+  f->maxstacksize = 2;  /* registers 0/1 are always valid */
+  enterblock(fs, bl, 0);
+}
+
+
+static void close_func (LexState *ls) {
+  lua_State *L = ls->L;
+  FuncState *fs = ls->fs;
+  Proto *f = fs->f;
+  luaK_ret(fs, luaY_nvarstack(fs), 0);  /* final return */
+  leaveblock(fs);
+  lua_assert(fs->bl == NULL);
+  luaK_finish(fs);
+  luaM_shrinkvector(L, f->code, f->sizecode, fs->pc, Instruction);
+  luaM_shrinkvector(L, f->lineinfo, f->sizelineinfo, fs->pc, ls_byte);
+  luaM_shrinkvector(L, f->abslineinfo, f->sizeabslineinfo,
+                       fs->nabslineinfo, AbsLineInfo);
+  luaM_shrinkvector(L, f->k, f->sizek, fs->nk, TValue);
+  luaM_shrinkvector(L, f->p, f->sizep, fs->np, Proto *);
+  luaM_shrinkvector(L, f->locvars, f->sizelocvars, fs->ndebugvars, LocVar);
+  luaM_shrinkvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
+  ls->fs = fs->prev;
+  luaC_checkGC(L);
+}
+
+
+
+/*============================================================*/
+/* GRAMMAR RULES */
+/*============================================================*/
+
+
+/*
+** check whether current token is in the follow set of a block.
+** 'until' closes syntactical blocks, but do not close scope,
+** so it is handled in separate.
+*/
+static int block_follow (LexState *ls, int withuntil) {
+  switch (ls->t.token) {
+    case TK_ELSE: case TK_ELSEIF:
+    case TK_END: case TK_EOS:
+      return 1;
+    case TK_UNTIL: return withuntil;
+    default: return 0;
+  }
+}
+
+
+static void statlist (LexState *ls) {
+  /* statlist -> { stat [';'] } */
+  while (!block_follow(ls, 1)) {
+    if (ls->t.token == TK_RETURN) {
+      statement(ls);
+      return;  /* 'return' must be last statement */
+    }
+    statement(ls);
+  }
+}
+
+
+static void fieldsel (LexState *ls, expdesc *v) {
+  /* fieldsel -> ['.' | ':'] NAME */
+  FuncState *fs = ls->fs;
+  expdesc key;
+  luaK_exp2anyregup(fs, v);
+  luaX_next(ls);  /* skip the dot or colon */
+  codename(ls, &key);
+  luaK_indexed(fs, v, &key);
+}
+
+
+static void yindex (LexState *ls, expdesc *v) {
+  /* index -> '[' expr ']' */
+  luaX_next(ls);  /* skip the '[' */
+  expr(ls, v);
+  luaK_exp2val(ls->fs, v);
+  checknext(ls, ']');
+}
+
+
+/*
+** {======================================================================
+** Rules for Constructors
+** =======================================================================
+*/
+
+
+typedef struct ConsControl {
+  expdesc v;  /* last list item read */
+  expdesc *t;  /* table descriptor */
+  int nh;  /* total number of 'record' elements */
+  int na;  /* number of array elements already stored */
+  int tostore;  /* number of array elements pending to be stored */
+} ConsControl;
+
+
+static void recfield (LexState *ls, ConsControl *cc) {
+  /* recfield -> (NAME | '['exp']') = exp */
+  FuncState *fs = ls->fs;
+  int reg = ls->fs->freereg;
+  expdesc tab, key, val;
+  if (ls->t.token == TK_NAME) {
+    checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
+    codename(ls, &key);
+  }
+  else  /* ls->t.token == '[' */
+    yindex(ls, &key);
+  cc->nh++;
+  checknext(ls, '=');
+  tab = *cc->t;
+  luaK_indexed(fs, &tab, &key);
+  expr(ls, &val);
+  luaK_storevar(fs, &tab, &val);
+  fs->freereg = reg;  /* free registers */
+}
+
+
+static void closelistfield (FuncState *fs, ConsControl *cc) {
+  if (cc->v.k == VVOID) return;  /* there is no list item */
+  luaK_exp2nextreg(fs, &cc->v);
+  cc->v.k = VVOID;
+  if (cc->tostore == LFIELDS_PER_FLUSH) {
+    luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
+    cc->na += cc->tostore;
+    cc->tostore = 0;  /* no more items pending */
+  }
+}
+
+
+static void lastlistfield (FuncState *fs, ConsControl *cc) {
+  if (cc->tostore == 0) return;
+  if (hasmultret(cc->v.k)) {
+    luaK_setmultret(fs, &cc->v);
+    luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
+    cc->na--;  /* do not count last expression (unknown number of elements) */
+  }
+  else {
+    if (cc->v.k != VVOID)
+      luaK_exp2nextreg(fs, &cc->v);
+    luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
+  }
+  cc->na += cc->tostore;
+}
+
+
+static void listfield (LexState *ls, ConsControl *cc) {
+  /* listfield -> exp */
+  expr(ls, &cc->v);
+  cc->tostore++;
+}
+
+
+static void field (LexState *ls, ConsControl *cc) {
+  /* field -> listfield | recfield */
+  switch(ls->t.token) {
+    case TK_NAME: {  /* may be 'listfield' or 'recfield' */
+      if (luaX_lookahead(ls) != '=')  /* expression? */
+        listfield(ls, cc);
+      else
+        recfield(ls, cc);
+      break;
+    }
+    case '[': {
+      recfield(ls, cc);
+      break;
+    }
+    default: {
+      listfield(ls, cc);
+      break;
+    }
+  }
+}
+
+
+static void constructor (LexState *ls, expdesc *t) {
+  /* constructor -> '{' [ field { sep field } [sep] ] '}'
+     sep -> ',' | ';' */
+  FuncState *fs = ls->fs;
+  int line = ls->linenumber;
+  int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
+  ConsControl cc;
+  luaK_code(fs, 0);  /* space for extra arg. */
+  cc.na = cc.nh = cc.tostore = 0;
+  cc.t = t;
+  init_exp(t, VNONRELOC, fs->freereg);  /* table will be at stack top */
+  luaK_reserveregs(fs, 1);
+  init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
+  checknext(ls, '{');
+  do {
+    lua_assert(cc.v.k == VVOID || cc.tostore > 0);
+    if (ls->t.token == '}') break;
+    closelistfield(fs, &cc);
+    field(ls, &cc);
+  } while (testnext(ls, ',') || testnext(ls, ';'));
+  check_match(ls, '}', '{', line);
+  lastlistfield(fs, &cc);
+  luaK_settablesize(fs, pc, t->u.info, cc.na, cc.nh);
+}
+
+/* }====================================================================== */
+
+
+static void setvararg (FuncState *fs, int nparams) {
+  fs->f->is_vararg = 1;
+  luaK_codeABC(fs, OP_VARARGPREP, nparams, 0, 0);
+}
+
+
+static void parlist (LexState *ls) {
+  /* parlist -> [ param { ',' param } ] */
+  FuncState *fs = ls->fs;
+  Proto *f = fs->f;
+  int nparams = 0;
+  int isvararg = 0;
+  if (ls->t.token != ')') {  /* is 'parlist' not empty? */
+    do {
+      switch (ls->t.token) {
+        case TK_NAME: {  /* param -> NAME */
+          new_localvar(ls, str_checkname(ls));
+          nparams++;
+          break;
+        }
+        case TK_DOTS: {  /* param -> '...' */
+          luaX_next(ls);
+          isvararg = 1;
+          break;
+        }
+        default: luaX_syntaxerror(ls, "<name> or '...' expected");
+      }
+    } while (!isvararg && testnext(ls, ','));
+  }
+  adjustlocalvars(ls, nparams);
+  f->numparams = cast_byte(fs->nactvar);
+  if (isvararg)
+    setvararg(fs, f->numparams);  /* declared vararg */
+  luaK_reserveregs(fs, fs->nactvar);  /* reserve registers for parameters */
+}
+
+
+static void body (LexState *ls, expdesc *e, int ismethod, int line) {
+  /* body ->  '(' parlist ')' block END */
+  FuncState new_fs;
+  BlockCnt bl;
+  new_fs.f = addprototype(ls);
+  new_fs.f->linedefined = line;
+  open_func(ls, &new_fs, &bl);
+  checknext(ls, '(');
+  if (ismethod) {
+    new_localvarliteral(ls, "self");  /* create 'self' parameter */
+    adjustlocalvars(ls, 1);
+  }
+  parlist(ls);
+  checknext(ls, ')');
+  statlist(ls);
+  new_fs.f->lastlinedefined = ls->linenumber;
+  check_match(ls, TK_END, TK_FUNCTION, line);
+  codeclosure(ls, e);
+  close_func(ls);
+}
+
+
+static int explist (LexState *ls, expdesc *v) {
+  /* explist -> expr { ',' expr } */
+  int n = 1;  /* at least one expression */
+  expr(ls, v);
+  while (testnext(ls, ',')) {
+    luaK_exp2nextreg(ls->fs, v);
+    expr(ls, v);
+    n++;
+  }
+  return n;
+}
+
+
+static void funcargs (LexState *ls, expdesc *f, int line) {
+  FuncState *fs = ls->fs;
+  expdesc args;
+  int base, nparams;
+  switch (ls->t.token) {
+    case '(': {  /* funcargs -> '(' [ explist ] ')' */
+      luaX_next(ls);
+      if (ls->t.token == ')')  /* arg list is empty? */
+        args.k = VVOID;
+      else {
+        explist(ls, &args);
+        if (hasmultret(args.k))
+          luaK_setmultret(fs, &args);
+      }
+      check_match(ls, ')', '(', line);
+      break;
+    }
+    case '{': {  /* funcargs -> constructor */
+      constructor(ls, &args);
+      break;
+    }
+    case TK_STRING: {  /* funcargs -> STRING */
+      codestring(&args, ls->t.seminfo.ts);
+      luaX_next(ls);  /* must use 'seminfo' before 'next' */
+      break;
+    }
+    default: {
+      luaX_syntaxerror(ls, "function arguments expected");
+    }
+  }
+  lua_assert(f->k == VNONRELOC);
+  base = f->u.info;  /* base register for call */
+  if (hasmultret(args.k))
+    nparams = LUA_MULTRET;  /* open call */
+  else {
+    if (args.k != VVOID)
+      luaK_exp2nextreg(fs, &args);  /* close last argument */
+    nparams = fs->freereg - (base+1);
+  }
+  init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
+  luaK_fixline(fs, line);
+  fs->freereg = base+1;  /* call remove function and arguments and leaves
+                            (unless changed) one result */
+}
+
+
+
+
+/*
+** {======================================================================
+** Expression parsing
+** =======================================================================
+*/
+
+
+static void primaryexp (LexState *ls, expdesc *v) {
+  /* primaryexp -> NAME | '(' expr ')' */
+  switch (ls->t.token) {
+    case '(': {
+      int line = ls->linenumber;
+      luaX_next(ls);
+      expr(ls, v);
+      check_match(ls, ')', '(', line);
+      luaK_dischargevars(ls->fs, v);
+      return;
+    }
+    case TK_NAME: {
+      singlevar(ls, v);
+      return;
+    }
+    default: {
+      luaX_syntaxerror(ls, "unexpected symbol");
+    }
+  }
+}
+
+
+static void suffixedexp (LexState *ls, expdesc *v) {
+  /* suffixedexp ->
+       primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
+  FuncState *fs = ls->fs;
+  int line = ls->linenumber;
+  primaryexp(ls, v);
+  for (;;) {
+    switch (ls->t.token) {
+      case '.': {  /* fieldsel */
+        fieldsel(ls, v);
+        break;
+      }
+      case '[': {  /* '[' exp ']' */
+        expdesc key;
+        luaK_exp2anyregup(fs, v);
+        yindex(ls, &key);
+        luaK_indexed(fs, v, &key);
+        break;
+      }
+      case ':': {  /* ':' NAME funcargs */
+        expdesc key;
+        luaX_next(ls);
+        codename(ls, &key);
+        luaK_self(fs, v, &key);
+        funcargs(ls, v, line);
+        break;
+      }
+      case '(': case TK_STRING: case '{': {  /* funcargs */
+        luaK_exp2nextreg(fs, v);
+        funcargs(ls, v, line);
+        break;
+      }
+      default: return;
+    }
+  }
+}
+
+
+static void simpleexp (LexState *ls, expdesc *v) {
+  /* simpleexp -> FLT | INT | STRING | NIL | TRUE | FALSE | ... |
+                  constructor | FUNCTION body | suffixedexp */
+  switch (ls->t.token) {
+    case TK_FLT: {
+      init_exp(v, VKFLT, 0);
+      v->u.nval = ls->t.seminfo.r;
+      break;
+    }
+    case TK_INT: {
+      init_exp(v, VKINT, 0);
+      v->u.ival = ls->t.seminfo.i;
+      break;
+    }
+    case TK_STRING: {
+      codestring(v, ls->t.seminfo.ts);
+      break;
+    }
+    case TK_NIL: {
+      init_exp(v, VNIL, 0);
+      break;
+    }
+    case TK_TRUE: {
+      init_exp(v, VTRUE, 0);
+      break;
+    }
+    case TK_FALSE: {
+      init_exp(v, VFALSE, 0);
+      break;
+    }
+    case TK_DOTS: {  /* vararg */
+      FuncState *fs = ls->fs;
+      check_condition(ls, fs->f->is_vararg,
+                      "cannot use '...' outside a vararg function");
+      init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 0, 1));
+      break;
+    }
+    case '{': {  /* constructor */
+      constructor(ls, v);
+      return;
+    }
+    case TK_FUNCTION: {
+      luaX_next(ls);
+      body(ls, v, 0, ls->linenumber);
+      return;
+    }
+    default: {
+      suffixedexp(ls, v);
+      return;
+    }
+  }
+  luaX_next(ls);
+}
+
+
+static UnOpr getunopr (int op) {
+  switch (op) {
+    case TK_NOT: return OPR_NOT;
+    case '-': return OPR_MINUS;
+    case '~': return OPR_BNOT;
+    case '#': return OPR_LEN;
+    default: return OPR_NOUNOPR;
+  }
+}
+
+
+static BinOpr getbinopr (int op) {
+  switch (op) {
+    case '+': return OPR_ADD;
+    case '-': return OPR_SUB;
+    case '*': return OPR_MUL;
+    case '%': return OPR_MOD;
+    case '^': return OPR_POW;
+    case '/': return OPR_DIV;
+    case TK_IDIV: return OPR_IDIV;
+    case '&': return OPR_BAND;
+    case '|': return OPR_BOR;
+    case '~': return OPR_BXOR;
+    case TK_SHL: return OPR_SHL;
+    case TK_SHR: return OPR_SHR;
+    case TK_CONCAT: return OPR_CONCAT;
+    case TK_NE: return OPR_NE;
+    case TK_EQ: return OPR_EQ;
+    case '<': return OPR_LT;
+    case TK_LE: return OPR_LE;
+    case '>': return OPR_GT;
+    case TK_GE: return OPR_GE;
+    case TK_AND: return OPR_AND;
+    case TK_OR: return OPR_OR;
+    default: return OPR_NOBINOPR;
+  }
+}
+
+
+/*
+** Priority table for binary operators.
+*/
+static const struct {
+  lu_byte left;  /* left priority for each binary operator */
+  lu_byte right; /* right priority */
+} priority[] = {  /* ORDER OPR */
+   {10, 10}, {10, 10},           /* '+' '-' */
+   {11, 11}, {11, 11},           /* '*' '%' */
+   {14, 13},                  /* '^' (right associative) */
+   {11, 11}, {11, 11},           /* '/' '//' */
+   {6, 6}, {4, 4}, {5, 5},   /* '&' '|' '~' */
+   {7, 7}, {7, 7},           /* '<<' '>>' */
+   {9, 8},                   /* '..' (right associative) */
+   {3, 3}, {3, 3}, {3, 3},   /* ==, <, <= */
+   {3, 3}, {3, 3}, {3, 3},   /* ~=, >, >= */
+   {2, 2}, {1, 1}            /* and, or */
+};
+
+#define UNARY_PRIORITY  12  /* priority for unary operators */
+
+
+/*
+** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
+** where 'binop' is any binary operator with a priority higher than 'limit'
+*/
+static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
+  BinOpr op;
+  UnOpr uop;
+  enterlevel(ls);
+  uop = getunopr(ls->t.token);
+  if (uop != OPR_NOUNOPR) {  /* prefix (unary) operator? */
+    int line = ls->linenumber;
+    luaX_next(ls);  /* skip operator */
+    subexpr(ls, v, UNARY_PRIORITY);
+    luaK_prefix(ls->fs, uop, v, line);
+  }
+  else simpleexp(ls, v);
+  /* expand while operators have priorities higher than 'limit' */
+  op = getbinopr(ls->t.token);
+  while (op != OPR_NOBINOPR && priority[op].left > limit) {
+    expdesc v2;
+    BinOpr nextop;
+    int line = ls->linenumber;
+    luaX_next(ls);  /* skip operator */
+    luaK_infix(ls->fs, op, v);
+    /* read sub-expression with higher priority */
+    nextop = subexpr(ls, &v2, priority[op].right);
+    luaK_posfix(ls->fs, op, v, &v2, line);
+    op = nextop;
+  }
+  leavelevel(ls);
+  return op;  /* return first untreated operator */
+}
+
+
+static void expr (LexState *ls, expdesc *v) {
+  subexpr(ls, v, 0);
+}
+
+/* }==================================================================== */
+
+
+
+/*
+** {======================================================================
+** Rules for Statements
+** =======================================================================
+*/
+
+
+static void block (LexState *ls) {
+  /* block -> statlist */
+  FuncState *fs = ls->fs;
+  BlockCnt bl;
+  enterblock(fs, &bl, 0);
+  statlist(ls);
+  leaveblock(fs);
+}
+
+
+/*
+** structure to chain all variables in the left-hand side of an
+** assignment
+*/
+struct LHS_assign {
+  struct LHS_assign *prev;
+  expdesc v;  /* variable (global, local, upvalue, or indexed) */
+};
+
+
+/*
+** check whether, in an assignment to an upvalue/local variable, the
+** upvalue/local variable is begin used in a previous assignment to a
+** table. If so, save original upvalue/local value in a safe place and
+** use this safe copy in the previous assignment.
+*/
+static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
+  FuncState *fs = ls->fs;
+  int extra = fs->freereg;  /* eventual position to save local variable */
+  int conflict = 0;
+  for (; lh; lh = lh->prev) {  /* check all previous assignments */
+    if (vkisindexed(lh->v.k)) {  /* assignment to table field? */
+      if (lh->v.k == VINDEXUP) {  /* is table an upvalue? */
+        if (v->k == VUPVAL && lh->v.u.ind.t == v->u.info) {
+          conflict = 1;  /* table is the upvalue being assigned now */
+          lh->v.k = VINDEXSTR;
+          lh->v.u.ind.t = extra;  /* assignment will use safe copy */
+        }
+      }
+      else {  /* table is a register */
+        if (v->k == VLOCAL && lh->v.u.ind.t == v->u.var.sidx) {
+          conflict = 1;  /* table is the local being assigned now */
+          lh->v.u.ind.t = extra;  /* assignment will use safe copy */
+        }
+        /* is index the local being assigned? */
+        if (lh->v.k == VINDEXED && v->k == VLOCAL &&
+            lh->v.u.ind.idx == v->u.var.sidx) {
+          conflict = 1;
+          lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
+        }
+      }
+    }
+  }
+  if (conflict) {
+    /* copy upvalue/local value to a temporary (in position 'extra') */
+    if (v->k == VLOCAL)
+      luaK_codeABC(fs, OP_MOVE, extra, v->u.var.sidx, 0);
+    else
+      luaK_codeABC(fs, OP_GETUPVAL, extra, v->u.info, 0);
+    luaK_reserveregs(fs, 1);
+  }
+}
+
+/*
+** Parse and compile a multiple assignment. The first "variable"
+** (a 'suffixedexp') was already read by the caller.
+**
+** assignment -> suffixedexp restassign
+** restassign -> ',' suffixedexp restassign | '=' explist
+*/
+static void restassign (LexState *ls, struct LHS_assign *lh, int nvars) {
+  expdesc e;
+  check_condition(ls, vkisvar(lh->v.k), "syntax error");
+  check_readonly(ls, &lh->v);
+  if (testnext(ls, ',')) {  /* restassign -> ',' suffixedexp restassign */
+    struct LHS_assign nv;
+    nv.prev = lh;
+    suffixedexp(ls, &nv.v);
+    if (!vkisindexed(nv.v.k))
+      check_conflict(ls, lh, &nv.v);
+    enterlevel(ls);  /* control recursion depth */
+    restassign(ls, &nv, nvars+1);
+    leavelevel(ls);
+  }
+  else {  /* restassign -> '=' explist */
+    int nexps;
+    checknext(ls, '=');
+    nexps = explist(ls, &e);
+    if (nexps != nvars)
+      adjust_assign(ls, nvars, nexps, &e);
+    else {
+      luaK_setoneret(ls->fs, &e);  /* close last expression */
+      luaK_storevar(ls->fs, &lh->v, &e);
+      return;  /* avoid default */
+    }
+  }
+  init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
+  luaK_storevar(ls->fs, &lh->v, &e);
+}
+
+
+static int cond (LexState *ls) {
+  /* cond -> exp */
+  expdesc v;
+  expr(ls, &v);  /* read condition */
+  if (v.k == VNIL) v.k = VFALSE;  /* 'falses' are all equal here */
+  luaK_goiftrue(ls->fs, &v);
+  return v.f;
+}
+
+
+static void gotostat (LexState *ls) {
+  FuncState *fs = ls->fs;
+  int line = ls->linenumber;
+  TString *name = str_checkname(ls);  /* label's name */
+  Labeldesc *lb = findlabel(ls, name);
+  if (lb == NULL)  /* no label? */
+    /* forward jump; will be resolved when the label is declared */
+    newgotoentry(ls, name, line, luaK_jump(fs));
+  else {  /* found a label */
+    /* backward jump; will be resolved here */
+    int lblevel = stacklevel(fs, lb->nactvar);  /* label level */
+    if (luaY_nvarstack(fs) > lblevel)  /* leaving the scope of a variable? */
+      luaK_codeABC(fs, OP_CLOSE, lblevel, 0, 0);
+    /* create jump and link it to the label */
+    luaK_patchlist(fs, luaK_jump(fs), lb->pc);
+  }
+}
+
+
+/*
+** Break statement. Semantically equivalent to "goto break".
+*/
+static void breakstat (LexState *ls) {
+  int line = ls->linenumber;
+  luaX_next(ls);  /* skip break */
+  newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, luaK_jump(ls->fs));
+}
+
+
+/*
+** Check whether there is already a label with the given 'name'.
+*/
+static void checkrepeated (LexState *ls, TString *name) {
+  Labeldesc *lb = findlabel(ls, name);
+  if (unlikely(lb != NULL)) {  /* already defined? */
+    const char *msg = "label '%s' already defined on line %d";
+    msg = luaO_pushfstring(ls->L, msg, getstr(name), lb->line);
+    luaK_semerror(ls, msg);  /* error */
+  }
+}
+
+
+static void labelstat (LexState *ls, TString *name, int line) {
+  /* label -> '::' NAME '::' */
+  checknext(ls, TK_DBCOLON);  /* skip double colon */
+  while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
+    statement(ls);  /* skip other no-op statements */
+  checkrepeated(ls, name);  /* check for repeated labels */
+  createlabel(ls, name, line, block_follow(ls, 0));
+}
+
+
+static void whilestat (LexState *ls, int line) {
+  /* whilestat -> WHILE cond DO block END */
+  FuncState *fs = ls->fs;
+  int whileinit;
+  int condexit;
+  BlockCnt bl;
+  luaX_next(ls);  /* skip WHILE */
+  whileinit = luaK_getlabel(fs);
+  condexit = cond(ls);
+  enterblock(fs, &bl, 1);
+  checknext(ls, TK_DO);
+  block(ls);
+  luaK_jumpto(fs, whileinit);
+  check_match(ls, TK_END, TK_WHILE, line);
+  leaveblock(fs);
+  luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
+}
+
+
+static void repeatstat (LexState *ls, int line) {
+  /* repeatstat -> REPEAT block UNTIL cond */
+  int condexit;
+  FuncState *fs = ls->fs;
+  int repeat_init = luaK_getlabel(fs);
+  BlockCnt bl1, bl2;
+  enterblock(fs, &bl1, 1);  /* loop block */
+  enterblock(fs, &bl2, 0);  /* scope block */
+  luaX_next(ls);  /* skip REPEAT */
+  statlist(ls);
+  check_match(ls, TK_UNTIL, TK_REPEAT, line);
+  condexit = cond(ls);  /* read condition (inside scope block) */
+  leaveblock(fs);  /* finish scope */
+  if (bl2.upval) {  /* upvalues? */
+    int exit = luaK_jump(fs);  /* normal exit must jump over fix */
+    luaK_patchtohere(fs, condexit);  /* repetition must close upvalues */
+    luaK_codeABC(fs, OP_CLOSE, stacklevel(fs, bl2.nactvar), 0, 0);
+    condexit = luaK_jump(fs);  /* repeat after closing upvalues */
+    luaK_patchtohere(fs, exit);  /* normal exit comes to here */
+  }
+  luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
+  leaveblock(fs);  /* finish loop */
+}
+
+
+/*
+** Read an expression and generate code to put its results in next
+** stack slot.
+**
+*/
+static void exp1 (LexState *ls) {
+  expdesc e;
+  expr(ls, &e);
+  luaK_exp2nextreg(ls->fs, &e);
+  lua_assert(e.k == VNONRELOC);
+}
+
+
+/*
+** Fix for instruction at position 'pc' to jump to 'dest'.
+** (Jump addresses are relative in Lua). 'back' true means
+** a back jump.
+*/
+static void fixforjump (FuncState *fs, int pc, int dest, int back) {
+  Instruction *jmp = &fs->f->code[pc];
+  int offset = dest - (pc + 1);
+  if (back)
+    offset = -offset;
+  if (unlikely(offset > MAXARG_Bx))
+    luaX_syntaxerror(fs->ls, "control structure too long");
+  SETARG_Bx(*jmp, offset);
+}
+
+
+/*
+** Generate code for a 'for' loop.
+*/
+static void forbody (LexState *ls, int base, int line, int nvars, int isgen) {
+  /* forbody -> DO block */
+  static const OpCode forprep[2] = {OP_FORPREP, OP_TFORPREP};
+  static const OpCode forloop[2] = {OP_FORLOOP, OP_TFORLOOP};
+  BlockCnt bl;
+  FuncState *fs = ls->fs;
+  int prep, endfor;
+  checknext(ls, TK_DO);
+  prep = luaK_codeABx(fs, forprep[isgen], base, 0);
+  enterblock(fs, &bl, 0);  /* scope for declared variables */
+  adjustlocalvars(ls, nvars);
+  luaK_reserveregs(fs, nvars);
+  block(ls);
+  leaveblock(fs);  /* end of scope for declared variables */
+  fixforjump(fs, prep, luaK_getlabel(fs), 0);
+  if (isgen) {  /* generic for? */
+    luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
+    luaK_fixline(fs, line);
+  }
+  endfor = luaK_codeABx(fs, forloop[isgen], base, 0);
+  fixforjump(fs, endfor, prep + 1, 1);
+  luaK_fixline(fs, line);
+}
+
+
+static void fornum (LexState *ls, TString *varname, int line) {
+  /* fornum -> NAME = exp,exp[,exp] forbody */
+  FuncState *fs = ls->fs;
+  int base = fs->freereg;
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
+  new_localvar(ls, varname);
+  checknext(ls, '=');
+  exp1(ls);  /* initial value */
+  checknext(ls, ',');
+  exp1(ls);  /* limit */
+  if (testnext(ls, ','))
+    exp1(ls);  /* optional step */
+  else {  /* default step = 1 */
+    luaK_int(fs, fs->freereg, 1);
+    luaK_reserveregs(fs, 1);
+  }
+  adjustlocalvars(ls, 3);  /* control variables */
+  forbody(ls, base, line, 1, 0);
+}
+
+
+static void forlist (LexState *ls, TString *indexname) {
+  /* forlist -> NAME {,NAME} IN explist forbody */
+  FuncState *fs = ls->fs;
+  expdesc e;
+  int nvars = 5;  /* gen, state, control, toclose, 'indexname' */
+  int line;
+  int base = fs->freereg;
+  /* create control variables */
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
+  new_localvarliteral(ls, "(for state)");
+  /* create declared variables */
+  new_localvar(ls, indexname);
+  while (testnext(ls, ',')) {
+    new_localvar(ls, str_checkname(ls));
+    nvars++;
+  }
+  checknext(ls, TK_IN);
+  line = ls->linenumber;
+  adjust_assign(ls, 4, explist(ls, &e), &e);
+  adjustlocalvars(ls, 4);  /* control variables */
+  markupval(fs, fs->nactvar);  /* last control var. must be closed */
+  luaK_checkstack(fs, 3);  /* extra space to call generator */
+  forbody(ls, base, line, nvars - 4, 1);
+}
+
+
+static void forstat (LexState *ls, int line) {
+  /* forstat -> FOR (fornum | forlist) END */
+  FuncState *fs = ls->fs;
+  TString *varname;
+  BlockCnt bl;
+  enterblock(fs, &bl, 1);  /* scope for loop and control variables */
+  luaX_next(ls);  /* skip 'for' */
+  varname = str_checkname(ls);  /* first variable name */
+  switch (ls->t.token) {
+    case '=': fornum(ls, varname, line); break;
+    case ',': case TK_IN: forlist(ls, varname); break;
+    default: luaX_syntaxerror(ls, "'=' or 'in' expected");
+  }
+  check_match(ls, TK_END, TK_FOR, line);
+  leaveblock(fs);  /* loop scope ('break' jumps to this point) */
+}
+
+
+/*
+** Check whether next instruction is a single jump (a 'break', a 'goto'
+** to a forward label, or a 'goto' to a backward label with no variable
+** to close). If so, set the name of the 'label' it is jumping to
+** ("break" for a 'break') or to where it is jumping to ('target') and
+** return true. If not a single jump, leave input unchanged, to be
+** handled as a regular statement.
+*/
+static int issinglejump (LexState *ls, TString **label, int *target) {
+  if (testnext(ls, TK_BREAK)) {  /* a break? */
+    *label = luaS_newliteral(ls->L, "break");
+    return 1;
+  }
+  else if (ls->t.token != TK_GOTO || luaX_lookahead(ls) != TK_NAME)
+    return 0;  /* not a valid goto */
+  else {
+    TString *lname = ls->lookahead.seminfo.ts;  /* label's id */
+    Labeldesc *lb = findlabel(ls, lname);
+    if (lb) {  /* a backward jump? */
+      /* does it need to close variables? */
+      if (luaY_nvarstack(ls->fs) > stacklevel(ls->fs, lb->nactvar))
+        return 0;  /* not a single jump; cannot optimize */
+      *target = lb->pc;
+    }
+    else  /* jump forward */
+      *label = lname;
+    luaX_next(ls);  /* skip goto */
+    luaX_next(ls);  /* skip name */
+    return 1;
+  }
+}
+
+
+static void test_then_block (LexState *ls, int *escapelist) {
+  /* test_then_block -> [IF | ELSEIF] cond THEN block */
+  BlockCnt bl;
+  int line;
+  FuncState *fs = ls->fs;
+  TString *jlb = NULL;
+  int target = NO_JUMP;
+  expdesc v;
+  int jf;  /* instruction to skip 'then' code (if condition is false) */
+  luaX_next(ls);  /* skip IF or ELSEIF */
+  expr(ls, &v);  /* read condition */
+  checknext(ls, TK_THEN);
+  line = ls->linenumber;
+  if (issinglejump(ls, &jlb, &target)) {  /* 'if x then goto' ? */
+    luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
+    enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
+    if (jlb != NULL)  /* forward jump? */
+      newgotoentry(ls, jlb, line, v.t);  /* will be resolved later */
+    else  /* backward jump */
+      luaK_patchlist(fs, v.t, target);  /* jump directly to 'target' */
+    while (testnext(ls, ';')) {}  /* skip semicolons */
+    if (block_follow(ls, 0)) {  /* jump is the entire block? */
+      leaveblock(fs);
+      return;  /* and that is it */
+    }
+    else  /* must skip over 'then' part if condition is false */
+      jf = luaK_jump(fs);
+  }
+  else {  /* regular case (not a jump) */
+    luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
+    enterblock(fs, &bl, 0);
+    jf = v.f;
+  }
+  statlist(ls);  /* 'then' part */
+  leaveblock(fs);
+  if (ls->t.token == TK_ELSE ||
+      ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
+    luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
+  luaK_patchtohere(fs, jf);
+}
+
+
+static void ifstat (LexState *ls, int line) {
+  /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
+  FuncState *fs = ls->fs;
+  int escapelist = NO_JUMP;  /* exit list for finished parts */
+  test_then_block(ls, &escapelist);  /* IF cond THEN block */
+  while (ls->t.token == TK_ELSEIF)
+    test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
+  if (testnext(ls, TK_ELSE))
+    block(ls);  /* 'else' part */
+  check_match(ls, TK_END, TK_IF, line);
+  luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
+}
+
+
+static void localfunc (LexState *ls) {
+  expdesc b;
+  FuncState *fs = ls->fs;
+  int fvar = fs->nactvar;  /* function's variable index */
+  new_localvar(ls, str_checkname(ls));  /* new local variable */
+  adjustlocalvars(ls, 1);  /* enter its scope */
+  body(ls, &b, 0, ls->linenumber);  /* function created in next register */
+  /* debug information will only see the variable after this point! */
+  localdebuginfo(fs, fvar)->startpc = fs->pc;
+}
+
+
+static int getlocalattribute (LexState *ls) {
+  /* ATTRIB -> ['<' Name '>'] */
+  if (testnext(ls, '<')) {
+    const char *attr = getstr(str_checkname(ls));
+    checknext(ls, '>');
+    if (strcmp(attr, "const") == 0)
+      return RDKCONST;  /* read-only variable */
+    else if (strcmp(attr, "close") == 0)
+      return RDKTOCLOSE;  /* to-be-closed variable */
+    else
+      luaK_semerror(ls,
+        luaO_pushfstring(ls->L, "unknown attribute '%s'", attr));
+  }
+  return VDKREG;  /* regular variable */
+}
+
+
+static void checktoclose (LexState *ls, int level) {
+  if (level != -1) {  /* is there a to-be-closed variable? */
+    FuncState *fs = ls->fs;
+    markupval(fs, level + 1);
+    fs->bl->insidetbc = 1;  /* in the scope of a to-be-closed variable */
+    luaK_codeABC(fs, OP_TBC, stacklevel(fs, level), 0, 0);
+  }
+}
+
+
+static void localstat (LexState *ls) {
+  /* stat -> LOCAL ATTRIB NAME {',' ATTRIB NAME} ['=' explist] */
+  FuncState *fs = ls->fs;
+  int toclose = -1;  /* index of to-be-closed variable (if any) */
+  Vardesc *var;  /* last variable */
+  int vidx, kind;  /* index and kind of last variable */
+  int nvars = 0;
+  int nexps;
+  expdesc e;
+  do {
+    vidx = new_localvar(ls, str_checkname(ls));
+    kind = getlocalattribute(ls);
+    getlocalvardesc(fs, vidx)->vd.kind = kind;
+    if (kind == RDKTOCLOSE) {  /* to-be-closed? */
+      if (toclose != -1)  /* one already present? */
+        luaK_semerror(ls, "multiple to-be-closed variables in local list");
+      toclose = fs->nactvar + nvars;
+    }
+    nvars++;
+  } while (testnext(ls, ','));
+  if (testnext(ls, '='))
+    nexps = explist(ls, &e);
+  else {
+    e.k = VVOID;
+    nexps = 0;
+  }
+  var = getlocalvardesc(fs, vidx);  /* get last variable */
+  if (nvars == nexps &&  /* no adjustments? */
+      var->vd.kind == RDKCONST &&  /* last variable is const? */
+      luaK_exp2const(fs, &e, &var->k)) {  /* compile-time constant? */
+    var->vd.kind = RDKCTC;  /* variable is a compile-time constant */
+    adjustlocalvars(ls, nvars - 1);  /* exclude last variable */
+    fs->nactvar++;  /* but count it */
+  }
+  else {
+    adjust_assign(ls, nvars, nexps, &e);
+    adjustlocalvars(ls, nvars);
+  }
+  checktoclose(ls, toclose);
+}
+
+
+static int funcname (LexState *ls, expdesc *v) {
+  /* funcname -> NAME {fieldsel} [':' NAME] */
+  int ismethod = 0;
+  singlevar(ls, v);
+  while (ls->t.token == '.')
+    fieldsel(ls, v);
+  if (ls->t.token == ':') {
+    ismethod = 1;
+    fieldsel(ls, v);
+  }
+  return ismethod;
+}
+
+
+static void funcstat (LexState *ls, int line) {
+  /* funcstat -> FUNCTION funcname body */
+  int ismethod;
+  expdesc v, b;
+  luaX_next(ls);  /* skip FUNCTION */
+  ismethod = funcname(ls, &v);
+  body(ls, &b, ismethod, line);
+  luaK_storevar(ls->fs, &v, &b);
+  luaK_fixline(ls->fs, line);  /* definition "happens" in the first line */
+}
+
+
+static void exprstat (LexState *ls) {
+  /* stat -> func | assignment */
+  FuncState *fs = ls->fs;
+  struct LHS_assign v;
+  suffixedexp(ls, &v.v);
+  if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
+    v.prev = NULL;
+    restassign(ls, &v, 1);
+  }
+  else {  /* stat -> func */
+    Instruction *inst;
+    check_condition(ls, v.v.k == VCALL, "syntax error");
+    inst = &getinstruction(fs, &v.v);
+    SETARG_C(*inst, 1);  /* call statement uses no results */
+  }
+}
+
+
+static void retstat (LexState *ls) {
+  /* stat -> RETURN [explist] [';'] */
+  FuncState *fs = ls->fs;
+  expdesc e;
+  int nret;  /* number of values being returned */
+  int first = luaY_nvarstack(fs);  /* first slot to be returned */
+  if (block_follow(ls, 1) || ls->t.token == ';')
+    nret = 0;  /* return no values */
+  else {
+    nret = explist(ls, &e);  /* optional return values */
+    if (hasmultret(e.k)) {
+      luaK_setmultret(fs, &e);
+      if (e.k == VCALL && nret == 1 && !fs->bl->insidetbc) {  /* tail call? */
+        SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL);
+        lua_assert(GETARG_A(getinstruction(fs,&e)) == luaY_nvarstack(fs));
+      }
+      nret = LUA_MULTRET;  /* return all values */
+    }
+    else {
+      if (nret == 1)  /* only one single value? */
+        first = luaK_exp2anyreg(fs, &e);  /* can use original slot */
+      else {  /* values must go to the top of the stack */
+        luaK_exp2nextreg(fs, &e);
+        lua_assert(nret == fs->freereg - first);
+      }
+    }
+  }
+  luaK_ret(fs, first, nret);
+  testnext(ls, ';');  /* skip optional semicolon */
+}
+
+
+static void statement (LexState *ls) {
+  int line = ls->linenumber;  /* may be needed for error messages */
+  enterlevel(ls);
+  switch (ls->t.token) {
+    case ';': {  /* stat -> ';' (empty statement) */
+      luaX_next(ls);  /* skip ';' */
+      break;
+    }
+    case TK_IF: {  /* stat -> ifstat */
+      ifstat(ls, line);
+      break;
+    }
+    case TK_WHILE: {  /* stat -> whilestat */
+      whilestat(ls, line);
+      break;
+    }
+    case TK_DO: {  /* stat -> DO block END */
+      luaX_next(ls);  /* skip DO */
+      block(ls);
+      check_match(ls, TK_END, TK_DO, line);
+      break;
+    }
+    case TK_FOR: {  /* stat -> forstat */
+      forstat(ls, line);
+      break;
+    }
+    case TK_REPEAT: {  /* stat -> repeatstat */
+      repeatstat(ls, line);
+      break;
+    }
+    case TK_FUNCTION: {  /* stat -> funcstat */
+      funcstat(ls, line);
+      break;
+    }
+    case TK_LOCAL: {  /* stat -> localstat */
+      luaX_next(ls);  /* skip LOCAL */
+      if (testnext(ls, TK_FUNCTION))  /* local function? */
+        localfunc(ls);
+      else
+        localstat(ls);
+      break;
+    }
+    case TK_DBCOLON: {  /* stat -> label */
+      luaX_next(ls);  /* skip double colon */
+      labelstat(ls, str_checkname(ls), line);
+      break;
+    }
+    case TK_RETURN: {  /* stat -> retstat */
+      luaX_next(ls);  /* skip RETURN */
+      retstat(ls);
+      break;
+    }
+    case TK_BREAK: {  /* stat -> breakstat */
+      breakstat(ls);
+      break;
+    }
+    case TK_GOTO: {  /* stat -> 'goto' NAME */
+      luaX_next(ls);  /* skip 'goto' */
+      gotostat(ls);
+      break;
+    }
+    default: {  /* stat -> func | assignment */
+      exprstat(ls);
+      break;
+    }
+  }
+  lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
+             ls->fs->freereg >= luaY_nvarstack(ls->fs));
+  ls->fs->freereg = luaY_nvarstack(ls->fs);  /* free registers */
+  leavelevel(ls);
+}
+
+/* }====================================================================== */
+
+
+/*
+** compiles the main function, which is a regular vararg function with an
+** upvalue named LUA_ENV
+*/
+static void mainfunc (LexState *ls, FuncState *fs) {
+  BlockCnt bl;
+  Upvaldesc *env;
+  open_func(ls, fs, &bl);
+  setvararg(fs, 0);  /* main function is always declared vararg */
+  env = allocupvalue(fs);  /* ...set environment upvalue */
+  env->instack = 1;
+  env->idx = 0;
+  env->kind = VDKREG;
+  env->name = ls->envn;
+  luaC_objbarrier(ls->L, fs->f, env->name);
+  luaX_next(ls);  /* read first token */
+  statlist(ls);  /* parse main body */
+  check(ls, TK_EOS);
+  close_func(ls);
+}
+
+
+LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
+                       Dyndata *dyd, const char *name, int firstchar) {
+  LexState lexstate;
+  FuncState funcstate;
+  LClosure *cl = luaF_newLclosure(L, 1);  /* create main closure */
+  setclLvalue2s(L, L->top, cl);  /* anchor it (to avoid being collected) */
+  luaD_inctop(L);
+  lexstate.h = luaH_new(L);  /* create table for scanner */
+  sethvalue2s(L, L->top, lexstate.h);  /* anchor it */
+  luaD_inctop(L);
+  funcstate.f = cl->p = luaF_newproto(L);
+  luaC_objbarrier(L, cl, cl->p);
+  funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
+  luaC_objbarrier(L, funcstate.f, funcstate.f->source);
+  lexstate.buff = buff;
+  lexstate.dyd = dyd;
+  dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
+  luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
+  mainfunc(&lexstate, &funcstate);
+  lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
+  /* all scopes should be correctly finished */
+  lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
+  L->top--;  /* remove scanner's table */
+  return cl;  /* closure is on the stack, too */
+}
+