text: /*
  ** $Id: lparser.c,v 1.116 2000/10/27 11:39:52 roberto Exp $
  ** LL(1) Parser and code generator for Lua
  ** See Copyright Notice in lua.h
  */
  
  
  #include <stdio.h>
  #include <string.h>
  
  #include "lua.h"
  
  #include "lcode.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"
  
  
  /*
  ** Constructors descriptor:
  ** `n' indicates number of elements, and `k' signals whether
  ** it is a list constructor (k = 0) or a record constructor (k = 1)
  ** or empty (k = ';' or '}')
  */
  typedef struct Constdesc {
    int n;
    int k;
  } Constdesc;
  
  
  typedef struct Breaklabel {
    struct Breaklabel *previous;  /* chain */
    int breaklist;
    int stacklevel;
  } Breaklabel;
  
  
  
  
  /*
  ** prototypes for recursive non-terminal functions
  */
  static void body (LexState *ls, int needself, int line);
  static void chunk (LexState *ls);
  static void constructor (LexState *ls);
  static void expr (LexState *ls, expdesc *v);
  static void exp1 (LexState *ls);
  
  
  
  static void next (LexState *ls) {
    ls->lastline = ls->linenumber;
    if (ls->lookahead.token != TK_EOS) {  /* is there a look-ahead token? */
      ls->t = ls->lookahead;  /* use this one */
      ls->lookahead.token = TK_EOS;  /* and discharge it */
    }
    else
      ls->t.token = luaX_lex(ls, &ls->t.seminfo);  /* read next token */
  }
  
  
  static void lookahead (LexState *ls) {
    LUA_ASSERT(ls->lookahead.token == TK_EOS, "two look-aheads");
    ls->lookahead.token = luaX_lex(ls, &ls->lookahead.seminfo);
  }
  
  
  static void error_expected (LexState *ls, int token) {
    char buff[100], t[TOKEN_LEN];
    luaX_token2str(token, t);
    sprintf(buff, "`%.20s' expected", t);
    luaK_error(ls, buff);
  }
  
  
  static void check (LexState *ls, int c) {
    if (ls->t.token != c)
      error_expected(ls, c);
    next(ls);
  }
  
  
  static void check_condition (LexState *ls, int c, const char *msg) {
    if (!c) luaK_error(ls, msg);
  }
  
  
  static int optional (LexState *ls, int c) {
    if (ls->t.token == c) {
      next(ls);
      return 1;
    }
    else return 0;
  }
  
  
  static void check_match (LexState *ls, int what, int who, int where) {
    if (ls->t.token != what) {
      if (where == ls->linenumber)
        error_expected(ls, what);
      else {
        char buff[100];
        char t_what[TOKEN_LEN], t_who[TOKEN_LEN];
        luaX_token2str(what, t_what);
        luaX_token2str(who, t_who);
        sprintf(buff, "`%.20s' expected (to close `%.20s' at line %d)",
                t_what, t_who, where);
        luaK_error(ls, buff);
      }
    }
    next(ls);
  }
  
  
  static int string_constant (FuncState *fs, TString *s) {
    Proto *f = fs->f;
    int c = s->u.s.constindex;
    if (c >= f->nkstr || f->kstr[c] != s) {
      luaM_growvector(fs->L, f->kstr, f->nkstr, 1, TString *,
                      "constant table overflow", MAXARG_U);
      c = f->nkstr++;
      f->kstr[c] = s;
      s->u.s.constindex = c;  /* hint for next time */
    }
    return c;
  }
  
  
  static void code_string (LexState *ls, TString *s) {
    luaK_kstr(ls, string_constant(ls->fs, s));
  }
  
  
  static TString *str_checkname (LexState *ls) {
    TString *ts;
    check_condition(ls, (ls->t.token == TK_NAME), "<name> expected");
    ts = ls->t.seminfo.ts;
    next(ls);
    return ts;
  }
  
  
  static int checkname (LexState *ls) {
    return string_constant(ls->fs, str_checkname(ls));
  }
  
  
  static int luaI_registerlocalvar (LexState *ls, TString *varname) {
    Proto *f = ls->fs->f;
    luaM_growvector(ls->L, f->locvars, f->nlocvars, 1, LocVar, "", MAX_INT);
    f->locvars[f->nlocvars].varname = varname;
    return f->nlocvars++;
  }
  
  
  static void new_localvar (LexState *ls, TString *name, int n) {
    FuncState *fs = ls->fs;
    luaX_checklimit(ls, fs->nactloc+n+1, MAXLOCALS, "local variables");
    fs->actloc[fs->nactloc+n] = luaI_registerlocalvar(ls, name);
  }
  
  
  static void adjustlocalvars (LexState *ls, int nvars) {
    FuncState *fs = ls->fs;
    while (nvars--)
      fs->f->locvars[fs->actloc[fs->nactloc++]].startpc = fs->pc;
  }
  
  
  static void removelocalvars (LexState *ls, int nvars) {
    FuncState *fs = ls->fs;
    while (nvars--)
      fs->f->locvars[fs->actloc[--fs->nactloc]].endpc = fs->pc;
  }
  
  
  static void new_localvarstr (LexState *ls, const char *name, int n) {
    new_localvar(ls, luaS_newfixed(ls->L, name), n);
  }
  
  
  static int search_local (LexState *ls, TString *n, expdesc *var) {
    FuncState *fs;
    int level = 0;
    for (fs=ls->fs; fs; fs=fs->prev) {
      int i;
      for (i=fs->nactloc-1; i >= 0; i--) {
        if (n == fs->f->locvars[fs->actloc[i]].varname) {
          var->k = VLOCAL;
          var->u.index = i;
          return level;
        }
      }
      level++;  /* `var' not found; check outer level */
    }
    var->k = VGLOBAL;  /* not found in any level; must be global */
    return -1;
  }
  
  
  static void singlevar (LexState *ls, TString *n, expdesc *var) {
    int level = search_local(ls, n, var);
    if (level >= 1)  /* neither local (0) nor global (-1)? */
      luaX_syntaxerror(ls, "cannot access a variable in outer scope", n->str);
    else if (level == -1)  /* global? */
      var->u.index = string_constant(ls->fs, n);
  }
  
  
  static int indexupvalue (LexState *ls, expdesc *v) {
    FuncState *fs = ls->fs;
    int i;
    for (i=0; i<fs->nupvalues; i++) {
      if (fs->upvalues[i].k == v->k && fs->upvalues[i].u.index == v->u.index)
        return i;
    }
    /* new one */
    luaX_checklimit(ls, fs->nupvalues+1, MAXUPVALUES, "upvalues");
    fs->upvalues[fs->nupvalues] = *v;
    return fs->nupvalues++;
  }
  
  
  static void pushupvalue (LexState *ls, TString *n) {
    FuncState *fs = ls->fs;
    expdesc v;
    int level = search_local(ls, n, &v);
    if (level == -1) {  /* global? */
      if (fs->prev == NULL)
        luaX_syntaxerror(ls, "cannot access upvalue in main", n->str);
      v.u.index = string_constant(fs->prev, n);
    }
    else if (level != 1)
      luaX_syntaxerror(ls,
           "upvalue must be global or local to immediately outer scope", n->str);
    luaK_code1(fs, OP_PUSHUPVALUE, indexupvalue(ls, &v));
  }
  
  
  static void adjust_mult_assign (LexState *ls, int nvars, int nexps) {
    FuncState *fs = ls->fs;
    int diff = nexps - nvars;
    if (nexps > 0 && luaK_lastisopen(fs)) { /* list ends in a function call */
      diff--;  /* do not count function call itself */
      if (diff <= 0) {  /* more variables than values? */
        luaK_setcallreturns(fs, -diff);  /* function call provide extra values */
        diff = 0;  /* no more difference */
      }
      else  /* more values than variables */
        luaK_setcallreturns(fs, 0);  /* call should provide no value */
    }
    /* push or pop eventual difference between list lengths */
    luaK_adjuststack(fs, diff);
  }
  
  
  static void code_params (LexState *ls, int nparams, int dots) {
    FuncState *fs = ls->fs;
    adjustlocalvars(ls, nparams);
    luaX_checklimit(ls, fs->nactloc, MAXPARAMS, "parameters");
    fs->f->numparams = fs->nactloc;  /* `self' could be there already */
    fs->f->is_vararg = dots;
    if (dots) {
      new_localvarstr(ls, "arg", 0);
      adjustlocalvars(ls, 1);
    }
    luaK_deltastack(fs, fs->nactloc);  /* count parameters in the stack */
  }
  
  
  static void enterbreak (FuncState *fs, Breaklabel *bl) {
    bl->stacklevel = fs->stacklevel;
    bl->breaklist = NO_JUMP;
    bl->previous = fs->bl;
    fs->bl = bl;
  }
  
  
  static void leavebreak (FuncState *fs, Breaklabel *bl) {
    fs->bl = bl->previous;
    LUA_ASSERT(bl->stacklevel == fs->stacklevel, "wrong levels");
    luaK_patchlist(fs, bl->breaklist, luaK_getlabel(fs));
  }
  
  
  static void pushclosure (LexState *ls, FuncState *func) {
    FuncState *fs = ls->fs;
    Proto *f = fs->f;
    int i;
    for (i=0; i<func->nupvalues; i++)
      luaK_tostack(ls, &func->upvalues[i], 1);
    luaM_growvector(ls->L, f->kproto, f->nkproto, 1, Proto *,
                    "constant table overflow", MAXARG_A);
    f->kproto[f->nkproto++] = func->f;
    luaK_code2(fs, OP_CLOSURE, f->nkproto-1, func->nupvalues);
  }
  
  
  static void open_func (LexState *ls, FuncState *fs) {
    Proto *f = luaF_newproto(ls->L);
    fs->prev = ls->fs;  /* linked list of funcstates */
    fs->ls = ls;
    fs->L = ls->L;
    ls->fs = fs;
    fs->stacklevel = 0;
    fs->nactloc = 0;
    fs->nupvalues = 0;
    fs->bl = NULL;
    fs->f = f;
    f->source = ls->source;
    fs->pc = 0;
    fs->lasttarget = 0;
    fs->lastline = 0;
    fs->jlt = NO_JUMP;
    f->code = NULL;
    f->maxstacksize = 0;
    f->numparams = 0;  /* default for main chunk */
    f->is_vararg = 0;  /* default for main chunk */
  }
  
  
  static void close_func (LexState *ls) {
    lua_State *L = ls->L;
    FuncState *fs = ls->fs;
    Proto *f = fs->f;
    luaK_code0(fs, OP_END);
    luaK_getlabel(fs);  /* close eventual list of pending jumps */
    luaM_reallocvector(L, f->code, fs->pc, Instruction);
    luaM_reallocvector(L, f->kstr, f->nkstr, TString *);
    luaM_reallocvector(L, f->knum, f->nknum, Number);
    luaM_reallocvector(L, f->kproto, f->nkproto, Proto *);
    removelocalvars(ls, fs->nactloc);
    luaM_reallocvector(L, f->locvars, f->nlocvars, LocVar);
    luaM_reallocvector(L, f->lineinfo, f->nlineinfo+1, int);
    f->lineinfo[f->nlineinfo++] = MAX_INT;  /* end flag */
    luaF_protook(L, f, fs->pc);  /* proto is ok now */
    ls->fs = fs->prev;
    LUA_ASSERT(fs->bl == NULL, "wrong list end");
  }
  
  
  Proto *luaY_parser (lua_State *L, ZIO *z) {
    struct LexState lexstate;
    struct FuncState funcstate;
    luaX_setinput(L, &lexstate, z, luaS_new(L, zname(z)));
    open_func(&lexstate, &funcstate);
    next(&lexstate);  /* read first token */
    chunk(&lexstate);
    check_condition(&lexstate, (lexstate.t.token == TK_EOS), "<eof> expected");
    close_func(&lexstate);
    LUA_ASSERT(funcstate.prev == NULL, "wrong list end");
    LUA_ASSERT(funcstate.nupvalues == 0, "no upvalues in main");
    return funcstate.f;
  }
  
  
  
  /*============================================================*/
  /* GRAMMAR RULES */
  /*============================================================*/
  
  
  static int explist1 (LexState *ls) {
    /* explist1 -> expr { ',' expr } */
    int n = 1;  /* at least one expression */
    expdesc v;
    expr(ls, &v);
    while (ls->t.token == ',') {
      luaK_tostack(ls, &v, 1);  /* gets only 1 value from previous expression */
      next(ls);  /* skip comma */
      expr(ls, &v);
      n++;
    }
    luaK_tostack(ls, &v, 0);  /* keep open number of values of last expression */
    return n;
  }
  
  
  static void funcargs (LexState *ls, int slf) {
    FuncState *fs = ls->fs;
    int slevel = fs->stacklevel - slf - 1;  /* where is func in the stack */
    switch (ls->t.token) {
      case '(': {  /* funcargs -> '(' [ explist1 ] ')' */
        int line = ls->linenumber;
        int nargs = 0;
        next(ls);
        if (ls->t.token != ')')  /* arg list not empty? */
          nargs = explist1(ls);
        check_match(ls, ')', '(', line);
  #ifdef LUA_COMPAT_ARGRET
        if (nargs > 0)  /* arg list is not empty? */
          luaK_setcallreturns(fs, 1);  /* last call returns only 1 value */
  #else
        UNUSED(nargs);  /* to avoid warnings */
  #endif
        break;
      }
      case '{': {  /* funcargs -> constructor */
        constructor(ls);
        break;
      }
      case TK_STRING: {  /* funcargs -> STRING */
        code_string(ls, ls->t.seminfo.ts);  /* must use `seminfo' before `next' */
        next(ls);
        break;
      }
      default: {
        luaK_error(ls, "function arguments expected");
        break;
      }
    }
    fs->stacklevel = slevel;  /* call will remove function and arguments */
    luaK_code2(fs, OP_CALL, slevel, MULT_RET);
  }
  
  
  static void var_or_func_tail (LexState *ls, expdesc *v) {
    for (;;) {
      switch (ls->t.token) {
        case '.': {  /* var_or_func_tail -> '.' NAME */
          next(ls);
          luaK_tostack(ls, v, 1);  /* `v' must be on stack */
          luaK_kstr(ls, checkname(ls));
          v->k = VINDEXED;
          break;
        }
        case '[': {  /* var_or_func_tail -> '[' exp1 ']' */
          next(ls);
          luaK_tostack(ls, v, 1);  /* `v' must be on stack */
          v->k = VINDEXED;
          exp1(ls);
          check(ls, ']');
          break;
        }
        case ':': {  /* var_or_func_tail -> ':' NAME funcargs */
          int name;
          next(ls);
          name = checkname(ls);
          luaK_tostack(ls, v, 1);  /* `v' must be on stack */
          luaK_code1(ls->fs, OP_PUSHSELF, name);
          funcargs(ls, 1);
          v->k = VEXP;
          v->u.l.t = v->u.l.f = NO_JUMP;
          break;
        }
        case '(': case TK_STRING: case '{': {  /* var_or_func_tail -> funcargs */
          luaK_tostack(ls, v, 1);  /* `v' must be on stack */
          funcargs(ls, 0);
          v->k = VEXP;
          v->u.l.t = v->u.l.f = NO_JUMP;
          break;
        }
        default: return;  /* should be follow... */
      }
    }
  }
  
  
  static void var_or_func (LexState *ls, expdesc *v) {
    /* var_or_func -> ['%'] NAME var_or_func_tail */
    if (optional(ls, '%')) {  /* upvalue? */
      pushupvalue(ls, str_checkname(ls));
      v->k = VEXP;
      v->u.l.t = v->u.l.f = NO_JUMP;
    }
    else  /* variable name */
      singlevar(ls, str_checkname(ls), v);
    var_or_func_tail(ls, v);
  }
  
  
  
  /*
  ** {======================================================================
  ** Rules for Constructors
  ** =======================================================================
  */
  
  
  static void recfield (LexState *ls) {
    /* recfield -> (NAME | '['exp1']') = exp1 */
    switch (ls->t.token) {
      case TK_NAME: {
        luaK_kstr(ls, checkname(ls));
        break;
      }
      case '[': {
        next(ls);
        exp1(ls);
        check(ls, ']');
        break;
      }
      default: luaK_error(ls, "<name> or `[' expected");
    }
    check(ls, '=');
    exp1(ls);
  }
  
  
  static int recfields (LexState *ls) {
    /* recfields -> recfield { ',' recfield } [','] */
    FuncState *fs = ls->fs;
    int n = 1;  /* at least one element */
    recfield(ls);
    while (ls->t.token == ',') {
      next(ls);
      if (ls->t.token == ';' || ls->t.token == '}')
        break;
      recfield(ls);
      n++;
      if (n%RFIELDS_PER_FLUSH == 0)
        luaK_code1(fs, OP_SETMAP, RFIELDS_PER_FLUSH);
    }
    luaK_code1(fs, OP_SETMAP, n%RFIELDS_PER_FLUSH);
    return n;
  }
  
  
  static int listfields (LexState *ls) {
    /* listfields -> exp1 { ',' exp1 } [','] */
    FuncState *fs = ls->fs;
    int n = 1;  /* at least one element */
    exp1(ls);
    while (ls->t.token == ',') {
      next(ls);
      if (ls->t.token == ';' || ls->t.token == '}')
        break;
      exp1(ls);
      n++;
      luaX_checklimit(ls, n/LFIELDS_PER_FLUSH, MAXARG_A,
                 "`item groups' in a list initializer");
      if (n%LFIELDS_PER_FLUSH == 0)
        luaK_code2(fs, OP_SETLIST, n/LFIELDS_PER_FLUSH - 1, LFIELDS_PER_FLUSH);
    }
    luaK_code2(fs, OP_SETLIST, n/LFIELDS_PER_FLUSH, n%LFIELDS_PER_FLUSH);
    return n;
  }
  
  
  
  static void constructor_part (LexState *ls, Constdesc *cd) {
    switch (ls->t.token) {
      case ';': case '}': {  /* constructor_part -> empty */
        cd->n = 0;
        cd->k = ls->t.token;
        break;
      }
      case TK_NAME: {  /* may be listfields or recfields */
        lookahead(ls);
        if (ls->lookahead.token != '=')  /* expression? */
          goto case_default;
        /* else go through to recfields */
      }
      case '[': {  /* constructor_part -> recfields */
        cd->n = recfields(ls);
        cd->k = 1;  /* record */
        break;
      }
      default: {  /* constructor_part -> listfields */
      case_default:
        cd->n = listfields(ls);
        cd->k = 0;  /* list */
        break;
      }
    }
  }
  
  
  static void constructor (LexState *ls) {
    /* constructor -> '{' constructor_part [';' constructor_part] '}' */
    FuncState *fs = ls->fs;
    int line = ls->linenumber;
    int pc = luaK_code1(fs, OP_CREATETABLE, 0);
    int nelems;
    Constdesc cd;
    check(ls, '{');
    constructor_part(ls, &cd);
    nelems = cd.n;
    if (optional(ls, ';')) {
      Constdesc other_cd;
      constructor_part(ls, &other_cd);
      check_condition(ls, (cd.k != other_cd.k), "invalid constructor syntax");
      nelems += other_cd.n;
    }
    check_match(ls, '}', '{', line);
    luaX_checklimit(ls, nelems, MAXARG_U, "elements in a table constructor");
    SETARG_U(fs->f->code[pc], nelems);  /* set initial table size */
  }
  
  /* }====================================================================== */
  
  
  
  
  /*
  ** {======================================================================
  ** Expression parsing
  ** =======================================================================
  */
  
  
  static void simpleexp (LexState *ls, expdesc *v) {
    FuncState *fs = ls->fs;
    switch (ls->t.token) {
      case TK_NUMBER: {  /* simpleexp -> NUMBER */
        Number r = ls->t.seminfo.r;
        next(ls);
        luaK_number(fs, r);
        break;
      }
      case TK_STRING: {  /* simpleexp -> STRING */
        code_string(ls, ls->t.seminfo.ts);  /* must use `seminfo' before `next' */
        next(ls);
        break;
      }
      case TK_NIL: {  /* simpleexp -> NIL */
        luaK_adjuststack(fs, -1);
        next(ls);
        break;
      }
      case '{': {  /* simpleexp -> constructor */
        constructor(ls);
        break;
      }
      case TK_FUNCTION: {  /* simpleexp -> FUNCTION body */
        next(ls);
        body(ls, 0, ls->linenumber);
        break;
      }
      case '(': {  /* simpleexp -> '(' expr ')' */
        next(ls);
        expr(ls, v);
        check(ls, ')');
        return;
      }
      case TK_NAME: case '%': {
        var_or_func(ls, v);
        return;
      }
      default: {
        luaK_error(ls, "<expression> expected");
        return;
      }
    }
    v->k = VEXP;
    v->u.l.t = v->u.l.f = NO_JUMP;
  }
  
  
  static void exp1 (LexState *ls) {
    expdesc v;
    expr(ls, &v);
    luaK_tostack(ls, &v, 1);
  }
  
  
  static UnOpr getunopr (int op) {
    switch (op) {
      case TK_NOT: return OPR_NOT;
      case '-': return OPR_MINUS;
      default: return OPR_NOUNOPR;
    }
  }
  
  
  static BinOpr getbinopr (int op) {
    switch (op) {
      case '+': return OPR_ADD;
      case '-': return OPR_SUB;
      case '*': return OPR_MULT;
      case '/': return OPR_DIV;
      case '^': return OPR_POW;
      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;
    }
  }
  
  
  static const struct {
    char left;  /* left priority for each binary operator */
    char right; /* right priority */
  } priority[] = {  /* ORDER OPR */
     {5, 5}, {5, 5}, {6, 6}, {6, 6},  /* arithmetic */
     {9, 8}, {4, 3},                  /* power and concat (right associative) */
     {2, 2}, {2, 2},                  /* equality */
     {2, 2}, {2, 2}, {2, 2}, {2, 2},  /* order */
     {1, 1}, {1, 1}                   /* logical */
  };
  
  #define UNARY_PRIORITY	7  /* priority for unary operators */
  
  
  /*
  ** subexpr -> (simplexep | 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 = getunopr(ls->t.token);
    if (uop != OPR_NOUNOPR) {
      next(ls);
      subexpr(ls, v, UNARY_PRIORITY);
      luaK_prefix(ls, uop, v);
    }
    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;
      next(ls);
      luaK_infix(ls, op, v);
      /* read sub-expression with higher priority */
      nextop = subexpr(ls, &v2, priority[op].right);
      luaK_posfix(ls, op, v, &v2);
      op = nextop;
    }
    return op;  /* return first untreated operator */
  }
  
  
  static void expr (LexState *ls, expdesc *v) {
    subexpr(ls, v, -1);
  }
  
  /* }==================================================================== */
  
  
  /*
  ** {======================================================================
  ** Rules for Statements
  ** =======================================================================
  */
  
  
  static int block_follow (int token) {
    switch (token) {
      case TK_ELSE: case TK_ELSEIF: case TK_END:
      case TK_UNTIL: case TK_EOS:
        return 1;
      default: return 0;
    }
  }
  
  
  static void block (LexState *ls) {
    /* block -> chunk */
    FuncState *fs = ls->fs;
    int nactloc = fs->nactloc;
    chunk(ls);
    luaK_adjuststack(fs, fs->nactloc - nactloc);  /* remove local variables */
    removelocalvars(ls, fs->nactloc - nactloc);
  }
  
  
  static int assignment (LexState *ls, expdesc *v, int nvars) {
    int left = 0;  /* number of values left in the stack after assignment */
    luaX_checklimit(ls, nvars, MAXVARSLH, "variables in a multiple assignment");
    if (ls->t.token == ',') {  /* assignment -> ',' NAME assignment */
      expdesc nv;
      next(ls);
      var_or_func(ls, &nv);
      check_condition(ls, (nv.k != VEXP), "syntax error");
      left = assignment(ls, &nv, nvars+1);
    }
    else {  /* assignment -> '=' explist1 */
      int nexps;
      check(ls, '=');
      nexps = explist1(ls);
      adjust_mult_assign(ls, nvars, nexps);
    }
    if (v->k != VINDEXED)
      luaK_storevar(ls, v);
    else {  /* there may be garbage between table-index and value */
      luaK_code2(ls->fs, OP_SETTABLE, left+nvars+2, 1);
      left += 2;
    }
    return left;
  }
  
  
  static void cond (LexState *ls, expdesc *v) {
    /* cond -> exp */
    expr(ls, v);  /* read condition */
    luaK_goiftrue(ls->fs, v, 0);
  }
  
  
  static void whilestat (LexState *ls, int line) {
    /* whilestat -> WHILE cond DO block END */
    FuncState *fs = ls->fs;
    int while_init = luaK_getlabel(fs);
    expdesc v;
    Breaklabel bl;
    enterbreak(fs, &bl);
    next(ls);
    cond(ls, &v);
    check(ls, TK_DO);
    block(ls);
    luaK_patchlist(fs, luaK_jump(fs), while_init);
    luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
    check_match(ls, TK_END, TK_WHILE, line);
    leavebreak(fs, &bl);
  }
  
  
  static void repeatstat (LexState *ls, int line) {
    /* repeatstat -> REPEAT block UNTIL cond */
    FuncState *fs = ls->fs;
    int repeat_init = luaK_getlabel(fs);
    expdesc v;
    Breaklabel bl;
    enterbreak(fs, &bl);
    next(ls);
    block(ls);
    check_match(ls, TK_UNTIL, TK_REPEAT, line);
    cond(ls, &v);
    luaK_patchlist(fs, v.u.l.f, repeat_init);
    leavebreak(fs, &bl);
  }
  
  
  static void forbody (LexState *ls, int nvar, OpCode prepfor, OpCode loopfor) {
    /* forbody -> DO block END */
    FuncState *fs = ls->fs;
    int prep = luaK_code1(fs, prepfor, NO_JUMP);
    int blockinit = luaK_getlabel(fs);
    check(ls, TK_DO);
    adjustlocalvars(ls, nvar);  /* scope for control variables */
    block(ls);
    luaK_patchlist(fs, luaK_code1(fs, loopfor, NO_JUMP), blockinit);
    luaK_patchlist(fs, prep, luaK_getlabel(fs));
    removelocalvars(ls, nvar);
  }
  
  
  static void fornum (LexState *ls, TString *varname) {
    /* fornum -> NAME = exp1,exp1[,exp1] forbody */
    FuncState *fs = ls->fs;
    check(ls, '=');
    exp1(ls);  /* initial value */
    check(ls, ',');
    exp1(ls);  /* limit */
    if (optional(ls, ','))
      exp1(ls);  /* optional step */
    else
      luaK_code1(fs, OP_PUSHINT, 1);  /* default step */
    new_localvar(ls, varname, 0);
    new_localvarstr(ls, "(limit)", 1);
    new_localvarstr(ls, "(step)", 2);
    forbody(ls, 3, OP_FORPREP, OP_FORLOOP);
  }
  
  
  static void forlist (LexState *ls, TString *indexname) {
    /* forlist -> NAME,NAME IN exp1 forbody */
    TString *valname;
    check(ls, ',');
    valname = str_checkname(ls);
    /* next test is dirty, but avoids `in' being a reserved word */
    check_condition(ls,
         (ls->t.token == TK_NAME && ls->t.seminfo.ts == luaS_new(ls->L, "in")),
         "`in' expected");
    next(ls);  /* skip `in' */
    exp1(ls);  /* table */
    new_localvarstr(ls, "(table)", 0);
    new_localvar(ls, indexname, 1);
    new_localvar(ls, valname, 2);
    forbody(ls, 3, OP_LFORPREP, OP_LFORLOOP);
  }
  
  
  static void forstat (LexState *ls, int line) {
    /* forstat -> fornum | forlist */
    FuncState *fs = ls->fs;
    TString *varname;
    Breaklabel bl;
    enterbreak(fs, &bl);
    next(ls);  /* skip `for' */
    varname = str_checkname(ls);  /* first variable name */
    switch (ls->t.token) {
      case '=': fornum(ls, varname); break;
      case ',': forlist(ls, varname); break;
      default: luaK_error(ls, "`=' or `,' expected");
    }
    check_match(ls, TK_END, TK_FOR, line);
    leavebreak(fs, &bl);
  }
  
  
  static void test_then_block (LexState *ls, expdesc *v) {
    /* test_then_block -> [IF | ELSEIF] cond THEN block */
    next(ls);  /* skip IF or ELSEIF */
    cond(ls, v);
    check(ls, TK_THEN);
    block(ls);  /* `then' part */
  }
  
  
  static void ifstat (LexState *ls, int line) {
    /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
    FuncState *fs = ls->fs;
    expdesc v;
    int escapelist = NO_JUMP;
    test_then_block(ls, &v);  /* IF cond THEN block */
    while (ls->t.token == TK_ELSEIF) {
      luaK_concat(fs, &escapelist, luaK_jump(fs));
      luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
      test_then_block(ls, &v);  /* ELSEIF cond THEN block */
    }
    if (ls->t.token == TK_ELSE) {
      luaK_concat(fs, &escapelist, luaK_jump(fs));
      luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
      next(ls);  /* skip ELSE */
      block(ls);  /* `else' part */
    }
    else
      luaK_concat(fs, &escapelist, v.u.l.f);
    luaK_patchlist(fs, escapelist, luaK_getlabel(fs));
    check_match(ls, TK_END, TK_IF, line);
  }
  
  
  static void localstat (LexState *ls) {
    /* stat -> LOCAL NAME {',' NAME} ['=' explist1] */
    int nvars = 0;
    int nexps;
    do {
      next(ls);  /* skip LOCAL or ',' */
      new_localvar(ls, str_checkname(ls), nvars++);
    } while (ls->t.token == ',');
    if (optional(ls, '='))
      nexps = explist1(ls);
    else
      nexps = 0;
    adjust_mult_assign(ls, nvars, nexps);
    adjustlocalvars(ls, nvars);
  }
  
  
  static int funcname (LexState *ls, expdesc *v) {
    /* funcname -> NAME [':' NAME | '.' NAME] */
    int needself = 0;
    singlevar(ls, str_checkname(ls), v);
    if (ls->t.token == ':' || ls->t.token == '.') {
      needself = (ls->t.token == ':');
      next(ls);
      luaK_tostack(ls, v, 1);
      luaK_kstr(ls, checkname(ls));
      v->k = VINDEXED;
    }
    return needself;
  }
  
  
  static void funcstat (LexState *ls, int line) {
    /* funcstat -> FUNCTION funcname body */
    int needself;
    expdesc v;
    next(ls);  /* skip FUNCTION */
    needself = funcname(ls, &v);
    body(ls, needself, line);
    luaK_storevar(ls, &v);
  }
  
  
  static void namestat (LexState *ls) {
    /* stat -> func | ['%'] NAME assignment */
    FuncState *fs = ls->fs;
    expdesc v;
    var_or_func(ls, &v);
    if (v.k == VEXP) {  /* stat -> func */
      check_condition(ls, luaK_lastisopen(fs), "syntax error");  /* an upvalue? */
      luaK_setcallreturns(fs, 0);  /* call statement uses no results */
    }
    else {  /* stat -> ['%'] NAME assignment */
      int left = assignment(ls, &v, 1);
      luaK_adjuststack(fs, left);  /* remove eventual garbage left on stack */
    }
  }
  
  
  static void retstat (LexState *ls) {
    /* stat -> RETURN explist */
    FuncState *fs = ls->fs;
    next(ls);  /* skip RETURN */
    if (!block_follow(ls->t.token))
      explist1(ls);  /* optional return values */
    luaK_code1(fs, OP_RETURN, ls->fs->nactloc);
    fs->stacklevel = fs->nactloc;  /* removes all temp values */
  }
  
  
  static void breakstat (LexState *ls) {
    /* stat -> BREAK [NAME] */
    FuncState *fs = ls->fs;
    int currentlevel = fs->stacklevel;
    Breaklabel *bl = fs->bl;
    if (!bl)
      luaK_error(ls, "no loop to break");
    next(ls);  /* skip BREAK */
    luaK_adjuststack(fs, currentlevel - bl->stacklevel);
    luaK_concat(fs, &bl->breaklist, luaK_jump(fs));
    /* correct stack for compiler and symbolic execution */
    luaK_adjuststack(fs, bl->stacklevel - currentlevel);
  }
  
  
  static int stat (LexState *ls) {
    int line = ls->linenumber;  /* may be needed for error messages */
    switch (ls->t.token) {
      case TK_IF: {  /* stat -> ifstat */
        ifstat(ls, line);
        return 0;
      }
      case TK_WHILE: {  /* stat -> whilestat */
        whilestat(ls, line);
        return 0;
      }
      case TK_DO: {  /* stat -> DO block END */
        next(ls);  /* skip DO */
        block(ls);
        check_match(ls, TK_END, TK_DO, line);
        return 0;
      }
      case TK_FOR: {  /* stat -> forstat */
        forstat(ls, line);
        return 0;
      }
      case TK_REPEAT: {  /* stat -> repeatstat */
        repeatstat(ls, line);
        return 0;
      }
      case TK_FUNCTION: {  /* stat -> funcstat */
        funcstat(ls, line);
        return 0;
      }
      case TK_LOCAL: {  /* stat -> localstat */
        localstat(ls);
        return 0;
      }
      case TK_NAME: case '%': {  /* stat -> namestat */
        namestat(ls);
        return 0;
      }
      case TK_RETURN: {  /* stat -> retstat */
        retstat(ls);
        return 1;  /* must be last statement */
      }
      case TK_BREAK: {  /* stat -> breakstat */
        breakstat(ls);
        return 1;  /* must be last statement */
      }
      default: {
        luaK_error(ls, "<statement> expected");
        return 0;  /* to avoid warnings */
      }
    }
  }
  
  
  static void parlist (LexState *ls) {
    /* parlist -> [ param { ',' param } ] */
    int nparams = 0;
    int dots = 0;
    if (ls->t.token != ')') {  /* is `parlist' not empty? */
      do {
        switch (ls->t.token) {
          case TK_DOTS: next(ls); dots = 1; break;
          case TK_NAME: new_localvar(ls, str_checkname(ls), nparams++); break;
          default: luaK_error(ls, "<name> or `...' expected");
        }
      } while (!dots && optional(ls, ','));
    }
    code_params(ls, nparams, dots);
  }
  
  
  static void body (LexState *ls, int needself, int line) {
    /* body ->  '(' parlist ')' chunk END */
    FuncState new_fs;
    open_func(ls, &new_fs);
    new_fs.f->lineDefined = line;
    check(ls, '(');
    if (needself) {
      new_localvarstr(ls, "self", 0);
      adjustlocalvars(ls, 1);
    }
    parlist(ls);
    check(ls, ')');
    chunk(ls);
    check_match(ls, TK_END, TK_FUNCTION, line);
    close_func(ls);
    pushclosure(ls, &new_fs);
  }
  
  
  /* }====================================================================== */
  
  
  static void chunk (LexState *ls) {
    /* chunk -> { stat [';'] } */
    int islast = 0;
    while (!islast && !block_follow(ls->t.token)) {
      islast = stat(ls);
      optional(ls, ';');
      LUA_ASSERT(ls->fs->stacklevel == ls->fs->nactloc,
                 "stack size != # local vars");
    }
  }
  
  