Subversion Repositories Kolibri OS

Rev

Blame | Last modification | View Log | RSS feed

  1. /*
  2. ** $Id: lparser.c,v 2.124 2011/12/02 13:23:56 roberto Exp $
  3. ** Lua Parser
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7.  
  8. #include <string.h>
  9.  
  10. #define lparser_c
  11. #define LUA_CORE
  12.  
  13. #include "lua.h"
  14.  
  15. #include "lcode.h"
  16. #include "ldebug.h"
  17. #include "ldo.h"
  18. #include "lfunc.h"
  19. #include "llex.h"
  20. #include "lmem.h"
  21. #include "lobject.h"
  22. #include "lopcodes.h"
  23. #include "lparser.h"
  24. #include "lstate.h"
  25. #include "lstring.h"
  26. #include "ltable.h"
  27.  
  28.  
  29.  
  30. /* maximum number of local variables per function (must be smaller
  31.    than 250, due to the bytecode format) */
  32. #define MAXVARS         200
  33.  
  34.  
  35. #define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
  36.  
  37.  
  38.  
  39. /*
  40. ** nodes for block list (list of active blocks)
  41. */
  42. typedef struct BlockCnt {
  43.   struct BlockCnt *previous;  /* chain */
  44.   short firstlabel;  /* index of first label in this block */
  45.   short firstgoto;  /* index of first pending goto in this block */
  46.   lu_byte nactvar;  /* # active locals outside the block */
  47.   lu_byte upval;  /* true if some variable in the block is an upvalue */
  48.   lu_byte isloop;  /* true if `block' is a loop */
  49. } BlockCnt;
  50.  
  51.  
  52.  
  53. /*
  54. ** prototypes for recursive non-terminal functions
  55. */
  56. static void statement (LexState *ls);
  57. static void expr (LexState *ls, expdesc *v);
  58.  
  59.  
  60. static void anchor_token (LexState *ls) {
  61.   /* last token from outer function must be EOS */
  62.   lua_assert(ls->fs != NULL || ls->t.token == TK_EOS);
  63.   if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) {
  64.     TString *ts = ls->t.seminfo.ts;
  65.     luaX_newstring(ls, getstr(ts), ts->tsv.len);
  66.   }
  67. }
  68.  
  69.  
  70. /* semantic error */
  71. static l_noret semerror (LexState *ls, const char *msg) {
  72.   ls->t.token = 0;  /* remove 'near to' from final message */
  73.   luaX_syntaxerror(ls, msg);
  74. }
  75.  
  76.  
  77. static l_noret error_expected (LexState *ls, int token) {
  78.   luaX_syntaxerror(ls,
  79.       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
  80. }
  81.  
  82.  
  83. static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
  84.   lua_State *L = fs->ls->L;
  85.   const char *msg;
  86.   int line = fs->f->linedefined;
  87.   const char *where = (line == 0)
  88.                       ? "main function"
  89.                       : luaO_pushfstring(L, "function at line %d", line);
  90.   msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
  91.                              what, limit, where);
  92.   luaX_syntaxerror(fs->ls, msg);
  93. }
  94.  
  95.  
  96. static void checklimit (FuncState *fs, int v, int l, const char *what) {
  97.   if (v > l) errorlimit(fs, l, what);
  98. }
  99.  
  100.  
  101. static int testnext (LexState *ls, int c) {
  102.   if (ls->t.token == c) {
  103.     luaX_next(ls);
  104.     return 1;
  105.   }
  106.   else return 0;
  107. }
  108.  
  109.  
  110. static void check (LexState *ls, int c) {
  111.   if (ls->t.token != c)
  112.     error_expected(ls, c);
  113. }
  114.  
  115.  
  116. static void checknext (LexState *ls, int c) {
  117.   check(ls, c);
  118.   luaX_next(ls);
  119. }
  120.  
  121.  
  122. #define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
  123.  
  124.  
  125.  
  126. static void check_match (LexState *ls, int what, int who, int where) {
  127.   if (!testnext(ls, what)) {
  128.     if (where == ls->linenumber)
  129.       error_expected(ls, what);
  130.     else {
  131.       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
  132.              "%s expected (to close %s at line %d)",
  133.               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
  134.     }
  135.   }
  136. }
  137.  
  138.  
  139. static TString *str_checkname (LexState *ls) {
  140.   TString *ts;
  141.   check(ls, TK_NAME);
  142.   ts = ls->t.seminfo.ts;
  143.   luaX_next(ls);
  144.   return ts;
  145. }
  146.  
  147.  
  148. static void init_exp (expdesc *e, expkind k, int i) {
  149.   e->f = e->t = NO_JUMP;
  150.   e->k = k;
  151.   e->u.info = i;
  152. }
  153.  
  154.  
  155. static void codestring (LexState *ls, expdesc *e, TString *s) {
  156.   init_exp(e, VK, luaK_stringK(ls->fs, s));
  157. }
  158.  
  159.  
  160. static void checkname (LexState *ls, expdesc *e) {
  161.   codestring(ls, e, str_checkname(ls));
  162. }
  163.  
  164.  
  165. static int registerlocalvar (LexState *ls, TString *varname) {
  166.   FuncState *fs = ls->fs;
  167.   Proto *f = fs->f;
  168.   int oldsize = f->sizelocvars;
  169.   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
  170.                   LocVar, SHRT_MAX, "local variables");
  171.   while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;
  172.   f->locvars[fs->nlocvars].varname = varname;
  173.   luaC_objbarrier(ls->L, f, varname);
  174.   return fs->nlocvars++;
  175. }
  176.  
  177.  
  178. static void new_localvar (LexState *ls, TString *name) {
  179.   FuncState *fs = ls->fs;
  180.   Dyndata *dyd = ls->dyd;
  181.   int reg = registerlocalvar(ls, name);
  182.   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
  183.                   MAXVARS, "local variables");
  184.   luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
  185.                   dyd->actvar.size, Vardesc, MAX_INT, "local variables");
  186.   dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
  187. }
  188.  
  189.  
  190. static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
  191.   new_localvar(ls, luaX_newstring(ls, name, sz));
  192. }
  193.  
  194. #define new_localvarliteral(ls,v) \
  195.         new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
  196.  
  197.  
  198. static LocVar *getlocvar (FuncState *fs, int i) {
  199.   int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
  200.   lua_assert(idx < fs->nlocvars);
  201.   return &fs->f->locvars[idx];
  202. }
  203.  
  204.  
  205. static void adjustlocalvars (LexState *ls, int nvars) {
  206.   FuncState *fs = ls->fs;
  207.   fs->nactvar = cast_byte(fs->nactvar + nvars);
  208.   for (; nvars; nvars--) {
  209.     getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
  210.   }
  211. }
  212.  
  213.  
  214. static void removevars (FuncState *fs, int tolevel) {
  215.   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
  216.   while (fs->nactvar > tolevel)
  217.     getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
  218. }
  219.  
  220.  
  221. static int searchupvalue (FuncState *fs, TString *name) {
  222.   int i;
  223.   Upvaldesc *up = fs->f->upvalues;
  224.   for (i = 0; i < fs->nups; i++) {
  225.     if (eqstr(up[i].name, name)) return i;
  226.   }
  227.   return -1;  /* not found */
  228. }
  229.  
  230.  
  231. static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
  232.   Proto *f = fs->f;
  233.   int oldsize = f->sizeupvalues;
  234.   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
  235.   luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
  236.                   Upvaldesc, MAXUPVAL, "upvalues");
  237.   while (oldsize < f->sizeupvalues) f->upvalues[oldsize++].name = NULL;
  238.   f->upvalues[fs->nups].instack = (v->k == VLOCAL);
  239.   f->upvalues[fs->nups].idx = cast_byte(v->u.info);
  240.   f->upvalues[fs->nups].name = name;
  241.   luaC_objbarrier(fs->ls->L, f, name);
  242.   return fs->nups++;
  243. }
  244.  
  245.  
  246. static int searchvar (FuncState *fs, TString *n) {
  247.   int i;
  248.   for (i=fs->nactvar-1; i >= 0; i--) {
  249.     if (eqstr(n, getlocvar(fs, i)->varname))
  250.       return i;
  251.   }
  252.   return -1;  /* not found */
  253. }
  254.  
  255.  
  256. /*
  257.   Mark block where variable at given level was defined
  258.   (to emit close instructions later).
  259. */
  260. static void markupval (FuncState *fs, int level) {
  261.   BlockCnt *bl = fs->bl;
  262.   while (bl->nactvar > level) bl = bl->previous;
  263.   bl->upval = 1;
  264. }
  265.  
  266.  
  267. /*
  268.   Find variable with given name 'n'. If it is an upvalue, add this
  269.   upvalue into all intermediate functions.
  270. */
  271. static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
  272.   if (fs == NULL)  /* no more levels? */
  273.     return VVOID;  /* default is global */
  274.   else {
  275.     int v = searchvar(fs, n);  /* look up locals at current level */
  276.     if (v >= 0) {  /* found? */
  277.       init_exp(var, VLOCAL, v);  /* variable is local */
  278.       if (!base)
  279.         markupval(fs, v);  /* local will be used as an upval */
  280.       return VLOCAL;
  281.     }
  282.     else {  /* not found as local at current level; try upvalues */
  283.       int idx = searchupvalue(fs, n);  /* try existing upvalues */
  284.       if (idx < 0) {  /* not found? */
  285.         if (singlevaraux(fs->prev, n, var, 0) == VVOID) /* try upper levels */
  286.           return VVOID;  /* not found; is a global */
  287.         /* else was LOCAL or UPVAL */
  288.         idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
  289.       }
  290.       init_exp(var, VUPVAL, idx);
  291.       return VUPVAL;
  292.     }
  293.   }
  294. }
  295.  
  296.  
  297. static void singlevar (LexState *ls, expdesc *var) {
  298.   TString *varname = str_checkname(ls);
  299.   FuncState *fs = ls->fs;
  300.   if (singlevaraux(fs, varname, var, 1) == VVOID) {  /* global name? */
  301.     expdesc key;
  302.     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
  303.     lua_assert(var->k == VLOCAL || var->k == VUPVAL);
  304.     codestring(ls, &key, varname);  /* key is variable name */
  305.     luaK_indexed(fs, var, &key);  /* env[varname] */
  306.   }
  307. }
  308.  
  309.  
  310. static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
  311.   FuncState *fs = ls->fs;
  312.   int extra = nvars - nexps;
  313.   if (hasmultret(e->k)) {
  314.     extra++;  /* includes call itself */
  315.     if (extra < 0) extra = 0;
  316.     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
  317.     if (extra > 1) luaK_reserveregs(fs, extra-1);
  318.   }
  319.   else {
  320.     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
  321.     if (extra > 0) {
  322.       int reg = fs->freereg;
  323.       luaK_reserveregs(fs, extra);
  324.       luaK_nil(fs, reg, extra);
  325.     }
  326.   }
  327. }
  328.  
  329.  
  330. static void enterlevel (LexState *ls) {
  331.   lua_State *L = ls->L;
  332.   ++L->nCcalls;
  333.   checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
  334. }
  335.  
  336.  
  337. #define leavelevel(ls)  ((ls)->L->nCcalls--)
  338.  
  339.  
  340. static void closegoto (LexState *ls, int g, Labeldesc *label) {
  341.   int i;
  342.   FuncState *fs = ls->fs;
  343.   Labellist *gl = &ls->dyd->gt;
  344.   Labeldesc *gt = &gl->arr[g];
  345.   lua_assert(eqstr(gt->name, label->name));
  346.   if (gt->nactvar < label->nactvar) {
  347.     TString *vname = getlocvar(fs, gt->nactvar)->varname;
  348.     const char *msg = luaO_pushfstring(ls->L,
  349.       "<goto %s> at line %d jumps into the scope of local " LUA_QS,
  350.       getstr(gt->name), gt->line, getstr(vname));
  351.     semerror(ls, msg);
  352.   }
  353.   luaK_patchlist(fs, gt->pc, label->pc);
  354.   /* remove goto from pending list */
  355.   for (i = g; i < gl->n - 1; i++)
  356.     gl->arr[i] = gl->arr[i + 1];
  357.   gl->n--;
  358. }
  359.  
  360.  
  361. /*
  362. ** try to close a goto with existing labels; this solves backward jumps
  363. */
  364. static int findlabel (LexState *ls, int g) {
  365.   int i;
  366.   BlockCnt *bl = ls->fs->bl;
  367.   Dyndata *dyd = ls->dyd;
  368.   Labeldesc *gt = &dyd->gt.arr[g];
  369.   /* check labels in current block for a match */
  370.   for (i = bl->firstlabel; i < dyd->label.n; i++) {
  371.     Labeldesc *lb = &dyd->label.arr[i];
  372.     if (eqstr(lb->name, gt->name)) {  /* correct label? */
  373.       if (gt->nactvar > lb->nactvar &&
  374.           (bl->upval || dyd->label.n > bl->firstlabel))
  375.         luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
  376.       closegoto(ls, g, lb);  /* close it */
  377.       return 1;
  378.     }
  379.   }
  380.   return 0;  /* label not found; cannot close goto */
  381. }
  382.  
  383.  
  384. static int newlabelentry (LexState *ls, Labellist *l, TString *name,
  385.                           int line, int pc) {
  386.   int n = l->n;
  387.   luaM_growvector(ls->L, l->arr, n, l->size,
  388.                   Labeldesc, SHRT_MAX, "labels/gotos");
  389.   l->arr[n].name = name;
  390.   l->arr[n].line = line;
  391.   l->arr[n].nactvar = ls->fs->nactvar;
  392.   l->arr[n].pc = pc;
  393.   l->n++;
  394.   return n;
  395. }
  396.  
  397.  
  398. /*
  399. ** check whether new label 'lb' matches any pending gotos in current
  400. ** block; solves forward jumps
  401. */
  402. static void findgotos (LexState *ls, Labeldesc *lb) {
  403.   Labellist *gl = &ls->dyd->gt;
  404.   int i = ls->fs->bl->firstgoto;
  405.   while (i < gl->n) {
  406.     if (eqstr(gl->arr[i].name, lb->name))
  407.       closegoto(ls, i, lb);
  408.     else
  409.       i++;
  410.   }
  411. }
  412.  
  413.  
  414. /*
  415. ** "export" pending gotos to outer level, to check them against
  416. ** outer labels; if the block being exited has upvalues, and
  417. ** the goto exits the scope of any variable (which can be the
  418. ** upvalue), close those variables being exited.
  419. */
  420. static void movegotosout (FuncState *fs, BlockCnt *bl) {
  421.   int i = bl->firstgoto;
  422.   Labellist *gl = &fs->ls->dyd->gt;
  423.   /* correct pending gotos to current block and try to close it
  424.      with visible labels */
  425.   while (i < gl->n) {
  426.     Labeldesc *gt = &gl->arr[i];
  427.     if (gt->nactvar > bl->nactvar) {
  428.       if (bl->upval)
  429.         luaK_patchclose(fs, gt->pc, bl->nactvar);
  430.       gt->nactvar = bl->nactvar;
  431.     }
  432.     if (!findlabel(fs->ls, i))
  433.       i++;  /* move to next one */
  434.   }
  435. }
  436.  
  437.  
  438. static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
  439.   bl->isloop = isloop;
  440.   bl->nactvar = fs->nactvar;
  441.   bl->firstlabel = fs->ls->dyd->label.n;
  442.   bl->firstgoto = fs->ls->dyd->gt.n;
  443.   bl->upval = 0;
  444.   bl->previous = fs->bl;
  445.   fs->bl = bl;
  446.   lua_assert(fs->freereg == fs->nactvar);
  447. }
  448.  
  449.  
  450. /*
  451. ** create a label named "break" to resolve break statements
  452. */
  453. static void breaklabel (LexState *ls) {
  454.   TString *n = luaS_new(ls->L, "break");
  455.   int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
  456.   findgotos(ls, &ls->dyd->label.arr[l]);
  457. }
  458.  
  459. /*
  460. ** generates an error for an undefined 'goto'; choose appropriate
  461. ** message when label name is a reserved word (which can only be 'break')
  462. */
  463. static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
  464.   const char *msg = (gt->name->tsv.reserved > 0)
  465.                     ? "<%s> at line %d not inside a loop"
  466.                     : "no visible label " LUA_QS " for <goto> at line %d";
  467.   msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
  468.   semerror(ls, msg);
  469. }
  470.  
  471.  
  472. static void leaveblock (FuncState *fs) {
  473.   BlockCnt *bl = fs->bl;
  474.   LexState *ls = fs->ls;
  475.   if (bl->previous && bl->upval) {
  476.     /* create a 'jump to here' to close upvalues */
  477.     int j = luaK_jump(fs);
  478.     luaK_patchclose(fs, j, bl->nactvar);
  479.     luaK_patchtohere(fs, j);
  480.   }
  481.   if (bl->isloop)
  482.     breaklabel(ls);  /* close pending breaks */
  483.   fs->bl = bl->previous;
  484.   removevars(fs, bl->nactvar);
  485.   lua_assert(bl->nactvar == fs->nactvar);
  486.   fs->freereg = fs->nactvar;  /* free registers */
  487.   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
  488.   if (bl->previous)  /* inner block? */
  489.     movegotosout(fs, bl);  /* update pending gotos to outer block */
  490.   else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
  491.     undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
  492. }
  493.  
  494.  
  495. /*
  496. ** adds prototype being created into its parent list of prototypes
  497. ** and codes instruction to create new closure
  498. */
  499. static void codeclosure (LexState *ls, Proto *clp, expdesc *v) {
  500.   FuncState *fs = ls->fs->prev;
  501.   Proto *f = fs->f;  /* prototype of function creating new closure */
  502.   if (fs->np >= f->sizep) {
  503.     int oldsize = f->sizep;
  504.     luaM_growvector(ls->L, f->p, fs->np, f->sizep, Proto *,
  505.                     MAXARG_Bx, "functions");
  506.     while (oldsize < f->sizep) f->p[oldsize++] = NULL;
  507.   }
  508.   f->p[fs->np++] = clp;
  509.   luaC_objbarrier(ls->L, f, clp);
  510.   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np-1));
  511.   luaK_exp2nextreg(fs, v);  /* fix it at stack top (for GC) */
  512. }
  513.  
  514.  
  515. static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
  516.   lua_State *L = ls->L;
  517.   Proto *f;
  518.   fs->prev = ls->fs;  /* linked list of funcstates */
  519.   fs->ls = ls;
  520.   ls->fs = fs;
  521.   fs->pc = 0;
  522.   fs->lasttarget = 0;
  523.   fs->jpc = NO_JUMP;
  524.   fs->freereg = 0;
  525.   fs->nk = 0;
  526.   fs->np = 0;
  527.   fs->nups = 0;
  528.   fs->nlocvars = 0;
  529.   fs->nactvar = 0;
  530.   fs->firstlocal = ls->dyd->actvar.n;
  531.   fs->bl = NULL;
  532.   f = luaF_newproto(L);
  533.   fs->f = f;
  534.   f->source = ls->source;
  535.   f->maxstacksize = 2;  /* registers 0/1 are always valid */
  536.   /* anchor prototype (to avoid being collected) */
  537.   setptvalue2s(L, L->top, f);
  538.   incr_top(L);
  539.   fs->h = luaH_new(L);
  540.   /* anchor table of constants (to avoid being collected) */
  541.   sethvalue2s(L, L->top, fs->h);
  542.   incr_top(L);
  543.   enterblock(fs, bl, 0);
  544. }
  545.  
  546.  
  547. static void close_func (LexState *ls) {
  548.   lua_State *L = ls->L;
  549.   FuncState *fs = ls->fs;
  550.   Proto *f = fs->f;
  551.   luaK_ret(fs, 0, 0);  /* final return */
  552.   leaveblock(fs);
  553.   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
  554.   f->sizecode = fs->pc;
  555.   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
  556.   f->sizelineinfo = fs->pc;
  557.   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
  558.   f->sizek = fs->nk;
  559.   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
  560.   f->sizep = fs->np;
  561.   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
  562.   f->sizelocvars = fs->nlocvars;
  563.   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
  564.   f->sizeupvalues = fs->nups;
  565.   lua_assert(fs->bl == NULL);
  566.   ls->fs = fs->prev;
  567.   /* last token read was anchored in defunct function; must re-anchor it */
  568.   anchor_token(ls);
  569.   L->top--;  /* pop table of constants */
  570.   luaC_checkGC(L);
  571.   L->top--;  /* pop prototype (after possible collection) */
  572. }
  573.  
  574.  
  575. /*
  576. ** opens the main function, which is a regular vararg function with an
  577. ** upvalue named LUA_ENV
  578. */
  579. static void open_mainfunc (LexState *ls, FuncState *fs, BlockCnt *bl) {
  580.   expdesc v;
  581.   open_func(ls, fs, bl);
  582.   fs->f->is_vararg = 1;  /* main function is always vararg */
  583.   init_exp(&v, VLOCAL, 0);
  584.   newupvalue(fs, ls->envn, &v);  /* create environment upvalue */
  585. }
  586.  
  587.  
  588.  
  589. /*============================================================*/
  590. /* GRAMMAR RULES */
  591. /*============================================================*/
  592.  
  593.  
  594. /*
  595. ** check whether current token is in the follow set of a block.
  596. ** 'until' closes syntactical blocks, but do not close scope,
  597. ** so it handled in separate.
  598. */
  599. static int block_follow (LexState *ls, int withuntil) {
  600.   switch (ls->t.token) {
  601.     case TK_ELSE: case TK_ELSEIF:
  602.     case TK_END: case TK_EOS:
  603.       return 1;
  604.     case TK_UNTIL: return withuntil;
  605.     default: return 0;
  606.   }
  607. }
  608.  
  609.  
  610. static void statlist (LexState *ls) {
  611.   /* statlist -> { stat [`;'] } */
  612.   while (!block_follow(ls, 1)) {
  613.     if (ls->t.token == TK_RETURN) {
  614.       statement(ls);
  615.       return;  /* 'return' must be last statement */
  616.     }
  617.     statement(ls);
  618.   }
  619. }
  620.  
  621.  
  622. static void fieldsel (LexState *ls, expdesc *v) {
  623.   /* fieldsel -> ['.' | ':'] NAME */
  624.   FuncState *fs = ls->fs;
  625.   expdesc key;
  626.   luaK_exp2anyregup(fs, v);
  627.   luaX_next(ls);  /* skip the dot or colon */
  628.   checkname(ls, &key);
  629.   luaK_indexed(fs, v, &key);
  630. }
  631.  
  632.  
  633. static void yindex (LexState *ls, expdesc *v) {
  634.   /* index -> '[' expr ']' */
  635.   luaX_next(ls);  /* skip the '[' */
  636.   expr(ls, v);
  637.   luaK_exp2val(ls->fs, v);
  638.   checknext(ls, ']');
  639. }
  640.  
  641.  
  642. /*
  643. ** {======================================================================
  644. ** Rules for Constructors
  645. ** =======================================================================
  646. */
  647.  
  648.  
  649. struct ConsControl {
  650.   expdesc v;  /* last list item read */
  651.   expdesc *t;  /* table descriptor */
  652.   int nh;  /* total number of `record' elements */
  653.   int na;  /* total number of array elements */
  654.   int tostore;  /* number of array elements pending to be stored */
  655. };
  656.  
  657.  
  658. static void recfield (LexState *ls, struct ConsControl *cc) {
  659.   /* recfield -> (NAME | `['exp1`]') = exp1 */
  660.   FuncState *fs = ls->fs;
  661.   int reg = ls->fs->freereg;
  662.   expdesc key, val;
  663.   int rkkey;
  664.   if (ls->t.token == TK_NAME) {
  665.     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
  666.     checkname(ls, &key);
  667.   }
  668.   else  /* ls->t.token == '[' */
  669.     yindex(ls, &key);
  670.   cc->nh++;
  671.   checknext(ls, '=');
  672.   rkkey = luaK_exp2RK(fs, &key);
  673.   expr(ls, &val);
  674.   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
  675.   fs->freereg = reg;  /* free registers */
  676. }
  677.  
  678.  
  679. static void closelistfield (FuncState *fs, struct ConsControl *cc) {
  680.   if (cc->v.k == VVOID) return;  /* there is no list item */
  681.   luaK_exp2nextreg(fs, &cc->v);
  682.   cc->v.k = VVOID;
  683.   if (cc->tostore == LFIELDS_PER_FLUSH) {
  684.     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
  685.     cc->tostore = 0;  /* no more items pending */
  686.   }
  687. }
  688.  
  689.  
  690. static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
  691.   if (cc->tostore == 0) return;
  692.   if (hasmultret(cc->v.k)) {
  693.     luaK_setmultret(fs, &cc->v);
  694.     luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
  695.     cc->na--;  /* do not count last expression (unknown number of elements) */
  696.   }
  697.   else {
  698.     if (cc->v.k != VVOID)
  699.       luaK_exp2nextreg(fs, &cc->v);
  700.     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
  701.   }
  702. }
  703.  
  704.  
  705. static void listfield (LexState *ls, struct ConsControl *cc) {
  706.   /* listfield -> exp */
  707.   expr(ls, &cc->v);
  708.   checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
  709.   cc->na++;
  710.   cc->tostore++;
  711. }
  712.  
  713.  
  714. static void field (LexState *ls, struct ConsControl *cc) {
  715.   /* field -> listfield | recfield */
  716.   switch(ls->t.token) {
  717.     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
  718.       if (luaX_lookahead(ls) != '=')  /* expression? */
  719.         listfield(ls, cc);
  720.       else
  721.         recfield(ls, cc);
  722.       break;
  723.     }
  724.     case '[': {
  725.       recfield(ls, cc);
  726.       break;
  727.     }
  728.     default: {
  729.       listfield(ls, cc);
  730.       break;
  731.     }
  732.   }
  733. }
  734.  
  735.  
  736. static void constructor (LexState *ls, expdesc *t) {
  737.   /* constructor -> '{' [ field { sep field } [sep] ] '}'
  738.      sep -> ',' | ';' */
  739.   FuncState *fs = ls->fs;
  740.   int line = ls->linenumber;
  741.   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
  742.   struct ConsControl cc;
  743.   cc.na = cc.nh = cc.tostore = 0;
  744.   cc.t = t;
  745.   init_exp(t, VRELOCABLE, pc);
  746.   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
  747.   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
  748.   checknext(ls, '{');
  749.   do {
  750.     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
  751.     if (ls->t.token == '}') break;
  752.     closelistfield(fs, &cc);
  753.     field(ls, &cc);
  754.   } while (testnext(ls, ',') || testnext(ls, ';'));
  755.   check_match(ls, '}', '{', line);
  756.   lastlistfield(fs, &cc);
  757.   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
  758.   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
  759. }
  760.  
  761. /* }====================================================================== */
  762.  
  763.  
  764.  
  765. static void parlist (LexState *ls) {
  766.   /* parlist -> [ param { `,' param } ] */
  767.   FuncState *fs = ls->fs;
  768.   Proto *f = fs->f;
  769.   int nparams = 0;
  770.   f->is_vararg = 0;
  771.   if (ls->t.token != ')') {  /* is `parlist' not empty? */
  772.     do {
  773.       switch (ls->t.token) {
  774.         case TK_NAME: {  /* param -> NAME */
  775.           new_localvar(ls, str_checkname(ls));
  776.           nparams++;
  777.           break;
  778.         }
  779.         case TK_DOTS: {  /* param -> `...' */
  780.           luaX_next(ls);
  781.           f->is_vararg = 1;
  782.           break;
  783.         }
  784.         default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");
  785.       }
  786.     } while (!f->is_vararg && testnext(ls, ','));
  787.   }
  788.   adjustlocalvars(ls, nparams);
  789.   f->numparams = cast_byte(fs->nactvar);
  790.   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
  791. }
  792.  
  793.  
  794. static void body (LexState *ls, expdesc *e, int ismethod, int line) {
  795.   /* body ->  `(' parlist `)' block END */
  796.   FuncState new_fs;
  797.   BlockCnt bl;
  798.   open_func(ls, &new_fs, &bl);
  799.   new_fs.f->linedefined = line;
  800.   checknext(ls, '(');
  801.   if (ismethod) {
  802.     new_localvarliteral(ls, "self");  /* create 'self' parameter */
  803.     adjustlocalvars(ls, 1);
  804.   }
  805.   parlist(ls);
  806.   checknext(ls, ')');
  807.   statlist(ls);
  808.   new_fs.f->lastlinedefined = ls->linenumber;
  809.   check_match(ls, TK_END, TK_FUNCTION, line);
  810.   codeclosure(ls, new_fs.f, e);
  811.   close_func(ls);
  812. }
  813.  
  814.  
  815. static int explist (LexState *ls, expdesc *v) {
  816.   /* explist -> expr { `,' expr } */
  817.   int n = 1;  /* at least one expression */
  818.   expr(ls, v);
  819.   while (testnext(ls, ',')) {
  820.     luaK_exp2nextreg(ls->fs, v);
  821.     expr(ls, v);
  822.     n++;
  823.   }
  824.   return n;
  825. }
  826.  
  827.  
  828. static void funcargs (LexState *ls, expdesc *f, int line) {
  829.   FuncState *fs = ls->fs;
  830.   expdesc args;
  831.   int base, nparams;
  832.   switch (ls->t.token) {
  833.     case '(': {  /* funcargs -> `(' [ explist ] `)' */
  834.       luaX_next(ls);
  835.       if (ls->t.token == ')')  /* arg list is empty? */
  836.         args.k = VVOID;
  837.       else {
  838.         explist(ls, &args);
  839.         luaK_setmultret(fs, &args);
  840.       }
  841.       check_match(ls, ')', '(', line);
  842.       break;
  843.     }
  844.     case '{': {  /* funcargs -> constructor */
  845.       constructor(ls, &args);
  846.       break;
  847.     }
  848.     case TK_STRING: {  /* funcargs -> STRING */
  849.       codestring(ls, &args, ls->t.seminfo.ts);
  850.       luaX_next(ls);  /* must use `seminfo' before `next' */
  851.       break;
  852.     }
  853.     default: {
  854.       luaX_syntaxerror(ls, "function arguments expected");
  855.     }
  856.   }
  857.   lua_assert(f->k == VNONRELOC);
  858.   base = f->u.info;  /* base register for call */
  859.   if (hasmultret(args.k))
  860.     nparams = LUA_MULTRET;  /* open call */
  861.   else {
  862.     if (args.k != VVOID)
  863.       luaK_exp2nextreg(fs, &args);  /* close last argument */
  864.     nparams = fs->freereg - (base+1);
  865.   }
  866.   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
  867.   luaK_fixline(fs, line);
  868.   fs->freereg = base+1;  /* call remove function and arguments and leaves
  869.                             (unless changed) one result */
  870. }
  871.  
  872.  
  873.  
  874.  
  875. /*
  876. ** {======================================================================
  877. ** Expression parsing
  878. ** =======================================================================
  879. */
  880.  
  881.  
  882. static void prefixexp (LexState *ls, expdesc *v) {
  883.   /* prefixexp -> NAME | '(' expr ')' */
  884.   switch (ls->t.token) {
  885.     case '(': {
  886.       int line = ls->linenumber;
  887.       luaX_next(ls);
  888.       expr(ls, v);
  889.       check_match(ls, ')', '(', line);
  890.       luaK_dischargevars(ls->fs, v);
  891.       return;
  892.     }
  893.     case TK_NAME: {
  894.       singlevar(ls, v);
  895.       return;
  896.     }
  897.     default: {
  898.       luaX_syntaxerror(ls, "unexpected symbol");
  899.     }
  900.   }
  901. }
  902.  
  903.  
  904. static void primaryexp (LexState *ls, expdesc *v) {
  905.   /* primaryexp ->
  906.         prefixexp { `.' NAME | `[' exp `]' | `:' NAME funcargs | funcargs } */
  907.   FuncState *fs = ls->fs;
  908.   int line = ls->linenumber;
  909.   prefixexp(ls, v);
  910.   for (;;) {
  911.     switch (ls->t.token) {
  912.       case '.': {  /* fieldsel */
  913.         fieldsel(ls, v);
  914.         break;
  915.       }
  916.       case '[': {  /* `[' exp1 `]' */
  917.         expdesc key;
  918.         luaK_exp2anyregup(fs, v);
  919.         yindex(ls, &key);
  920.         luaK_indexed(fs, v, &key);
  921.         break;
  922.       }
  923.       case ':': {  /* `:' NAME funcargs */
  924.         expdesc key;
  925.         luaX_next(ls);
  926.         checkname(ls, &key);
  927.         luaK_self(fs, v, &key);
  928.         funcargs(ls, v, line);
  929.         break;
  930.       }
  931.       case '(': case TK_STRING: case '{': {  /* funcargs */
  932.         luaK_exp2nextreg(fs, v);
  933.         funcargs(ls, v, line);
  934.         break;
  935.       }
  936.       default: return;
  937.     }
  938.   }
  939. }
  940.  
  941.  
  942. static void simpleexp (LexState *ls, expdesc *v) {
  943.   /* simpleexp -> NUMBER | STRING | NIL | TRUE | FALSE | ... |
  944.                   constructor | FUNCTION body | primaryexp */
  945.   switch (ls->t.token) {
  946.     case TK_NUMBER: {
  947.       init_exp(v, VKNUM, 0);
  948.       v->u.nval = ls->t.seminfo.r;
  949.       break;
  950.     }
  951.     case TK_STRING: {
  952.       codestring(ls, v, ls->t.seminfo.ts);
  953.       break;
  954.     }
  955.     case TK_NIL: {
  956.       init_exp(v, VNIL, 0);
  957.       break;
  958.     }
  959.     case TK_TRUE: {
  960.       init_exp(v, VTRUE, 0);
  961.       break;
  962.     }
  963.     case TK_FALSE: {
  964.       init_exp(v, VFALSE, 0);
  965.       break;
  966.     }
  967.     case TK_DOTS: {  /* vararg */
  968.       FuncState *fs = ls->fs;
  969.       check_condition(ls, fs->f->is_vararg,
  970.                       "cannot use " LUA_QL("...") " outside a vararg function");
  971.       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
  972.       break;
  973.     }
  974.     case '{': {  /* constructor */
  975.       constructor(ls, v);
  976.       return;
  977.     }
  978.     case TK_FUNCTION: {
  979.       luaX_next(ls);
  980.       body(ls, v, 0, ls->linenumber);
  981.       return;
  982.     }
  983.     default: {
  984.       primaryexp(ls, v);
  985.       return;
  986.     }
  987.   }
  988.   luaX_next(ls);
  989. }
  990.  
  991.  
  992. static UnOpr getunopr (int op) {
  993.   switch (op) {
  994.     case TK_NOT: return OPR_NOT;
  995.     case '-': return OPR_MINUS;
  996.     case '#': return OPR_LEN;
  997.     default: return OPR_NOUNOPR;
  998.   }
  999. }
  1000.  
  1001.  
  1002. static BinOpr getbinopr (int op) {
  1003.   switch (op) {
  1004.     case '+': return OPR_ADD;
  1005.     case '-': return OPR_SUB;
  1006.     case '*': return OPR_MUL;
  1007.     case '/': return OPR_DIV;
  1008.     case '%': return OPR_MOD;
  1009.     case '^': return OPR_POW;
  1010.     case TK_CONCAT: return OPR_CONCAT;
  1011.     case TK_NE: return OPR_NE;
  1012.     case TK_EQ: return OPR_EQ;
  1013.     case '<': return OPR_LT;
  1014.     case TK_LE: return OPR_LE;
  1015.     case '>': return OPR_GT;
  1016.     case TK_GE: return OPR_GE;
  1017.     case TK_AND: return OPR_AND;
  1018.     case TK_OR: return OPR_OR;
  1019.     default: return OPR_NOBINOPR;
  1020.   }
  1021. }
  1022.  
  1023.  
  1024. static const struct {
  1025.   lu_byte left;  /* left priority for each binary operator */
  1026.   lu_byte right; /* right priority */
  1027. } priority[] = {  /* ORDER OPR */
  1028.    {6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `*' `/' `%' */
  1029.    {10, 9}, {5, 4},                 /* ^, .. (right associative) */
  1030.    {3, 3}, {3, 3}, {3, 3},          /* ==, <, <= */
  1031.    {3, 3}, {3, 3}, {3, 3},          /* ~=, >, >= */
  1032.    {2, 2}, {1, 1}                   /* and, or */
  1033. };
  1034.  
  1035. #define UNARY_PRIORITY  8  /* priority for unary operators */
  1036.  
  1037.  
  1038. /*
  1039. ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
  1040. ** where `binop' is any binary operator with a priority higher than `limit'
  1041. */
  1042. static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
  1043.   BinOpr op;
  1044.   UnOpr uop;
  1045.   enterlevel(ls);
  1046.   uop = getunopr(ls->t.token);
  1047.   if (uop != OPR_NOUNOPR) {
  1048.     int line = ls->linenumber;
  1049.     luaX_next(ls);
  1050.     subexpr(ls, v, UNARY_PRIORITY);
  1051.     luaK_prefix(ls->fs, uop, v, line);
  1052.   }
  1053.   else simpleexp(ls, v);
  1054.   /* expand while operators have priorities higher than `limit' */
  1055.   op = getbinopr(ls->t.token);
  1056.   while (op != OPR_NOBINOPR && priority[op].left > limit) {
  1057.     expdesc v2;
  1058.     BinOpr nextop;
  1059.     int line = ls->linenumber;
  1060.     luaX_next(ls);
  1061.     luaK_infix(ls->fs, op, v);
  1062.     /* read sub-expression with higher priority */
  1063.     nextop = subexpr(ls, &v2, priority[op].right);
  1064.     luaK_posfix(ls->fs, op, v, &v2, line);
  1065.     op = nextop;
  1066.   }
  1067.   leavelevel(ls);
  1068.   return op;  /* return first untreated operator */
  1069. }
  1070.  
  1071.  
  1072. static void expr (LexState *ls, expdesc *v) {
  1073.   subexpr(ls, v, 0);
  1074. }
  1075.  
  1076. /* }==================================================================== */
  1077.  
  1078.  
  1079.  
  1080. /*
  1081. ** {======================================================================
  1082. ** Rules for Statements
  1083. ** =======================================================================
  1084. */
  1085.  
  1086.  
  1087. static void block (LexState *ls) {
  1088.   /* block -> statlist */
  1089.   FuncState *fs = ls->fs;
  1090.   BlockCnt bl;
  1091.   enterblock(fs, &bl, 0);
  1092.   statlist(ls);
  1093.   leaveblock(fs);
  1094. }
  1095.  
  1096.  
  1097. /*
  1098. ** structure to chain all variables in the left-hand side of an
  1099. ** assignment
  1100. */
  1101. struct LHS_assign {
  1102.   struct LHS_assign *prev;
  1103.   expdesc v;  /* variable (global, local, upvalue, or indexed) */
  1104. };
  1105.  
  1106.  
  1107. /*
  1108. ** check whether, in an assignment to an upvalue/local variable, the
  1109. ** upvalue/local variable is begin used in a previous assignment to a
  1110. ** table. If so, save original upvalue/local value in a safe place and
  1111. ** use this safe copy in the previous assignment.
  1112. */
  1113. static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
  1114.   FuncState *fs = ls->fs;
  1115.   int extra = fs->freereg;  /* eventual position to save local variable */
  1116.   int conflict = 0;
  1117.   for (; lh; lh = lh->prev) {  /* check all previous assignments */
  1118.     if (lh->v.k == VINDEXED) {  /* assigning to a table? */
  1119.       /* table is the upvalue/local being assigned now? */
  1120.       if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
  1121.         conflict = 1;
  1122.         lh->v.u.ind.vt = VLOCAL;
  1123.         lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
  1124.       }
  1125.       /* index is the local being assigned? (index cannot be upvalue) */
  1126.       if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
  1127.         conflict = 1;
  1128.         lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
  1129.       }
  1130.     }
  1131.   }
  1132.   if (conflict) {
  1133.     /* copy upvalue/local value to a temporary (in position 'extra') */
  1134.     OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
  1135.     luaK_codeABC(fs, op, extra, v->u.info, 0);
  1136.     luaK_reserveregs(fs, 1);
  1137.   }
  1138. }
  1139.  
  1140.  
  1141. static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
  1142.   expdesc e;
  1143.   check_condition(ls, vkisvar(lh->v.k), "syntax error");
  1144.   if (testnext(ls, ',')) {  /* assignment -> `,' primaryexp assignment */
  1145.     struct LHS_assign nv;
  1146.     nv.prev = lh;
  1147.     primaryexp(ls, &nv.v);
  1148.     if (nv.v.k != VINDEXED)
  1149.       check_conflict(ls, lh, &nv.v);
  1150.     checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
  1151.                     "C levels");
  1152.     assignment(ls, &nv, nvars+1);
  1153.   }
  1154.   else {  /* assignment -> `=' explist */
  1155.     int nexps;
  1156.     checknext(ls, '=');
  1157.     nexps = explist(ls, &e);
  1158.     if (nexps != nvars) {
  1159.       adjust_assign(ls, nvars, nexps, &e);
  1160.       if (nexps > nvars)
  1161.         ls->fs->freereg -= nexps - nvars;  /* remove extra values */
  1162.     }
  1163.     else {
  1164.       luaK_setoneret(ls->fs, &e);  /* close last expression */
  1165.       luaK_storevar(ls->fs, &lh->v, &e);
  1166.       return;  /* avoid default */
  1167.     }
  1168.   }
  1169.   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
  1170.   luaK_storevar(ls->fs, &lh->v, &e);
  1171. }
  1172.  
  1173.  
  1174. static int cond (LexState *ls) {
  1175.   /* cond -> exp */
  1176.   expdesc v;
  1177.   expr(ls, &v);  /* read condition */
  1178.   if (v.k == VNIL) v.k = VFALSE;  /* `falses' are all equal here */
  1179.   luaK_goiftrue(ls->fs, &v);
  1180.   return v.f;
  1181. }
  1182.  
  1183.  
  1184. static void gotostat (LexState *ls, int pc) {
  1185.   int line = ls->linenumber;
  1186.   TString *label;
  1187.   int g;
  1188.   if (testnext(ls, TK_GOTO))
  1189.     label = str_checkname(ls);
  1190.   else {
  1191.     luaX_next(ls);  /* skip break */
  1192.     label = luaS_new(ls->L, "break");
  1193.   }
  1194.   g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
  1195.   findlabel(ls, g);  /* close it if label already defined */
  1196. }
  1197.  
  1198.  
  1199. /* check for repeated labels on the same block */
  1200. static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
  1201.   int i;
  1202.   for (i = fs->bl->firstlabel; i < ll->n; i++) {
  1203.     if (eqstr(label, ll->arr[i].name)) {
  1204.       const char *msg = luaO_pushfstring(fs->ls->L,
  1205.                           "label " LUA_QS " already defined on line %d",
  1206.                           getstr(label), ll->arr[i].line);
  1207.       semerror(fs->ls, msg);
  1208.     }
  1209.   }
  1210. }
  1211.  
  1212.  
  1213. static void labelstat (LexState *ls, TString *label, int line) {
  1214.   /* label -> '::' NAME '::' */
  1215.   FuncState *fs = ls->fs;
  1216.   Labellist *ll = &ls->dyd->label;
  1217.   int l;  /* index of new label being created */
  1218.   checkrepeated(fs, ll, label);  /* check for repeated labels */
  1219.   checknext(ls, TK_DBCOLON);  /* skip double colon */
  1220.   /* create new entry for this label */
  1221.   l = newlabelentry(ls, ll, label, line, fs->pc);
  1222.   /* skip other no-op statements */
  1223.   while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
  1224.     statement(ls);
  1225.   if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
  1226.     /* assume that locals are already out of scope */
  1227.     ll->arr[l].nactvar = fs->bl->nactvar;
  1228.   }
  1229.   findgotos(ls, &ll->arr[l]);
  1230. }
  1231.  
  1232.  
  1233. static void whilestat (LexState *ls, int line) {
  1234.   /* whilestat -> WHILE cond DO block END */
  1235.   FuncState *fs = ls->fs;
  1236.   int whileinit;
  1237.   int condexit;
  1238.   BlockCnt bl;
  1239.   luaX_next(ls);  /* skip WHILE */
  1240.   whileinit = luaK_getlabel(fs);
  1241.   condexit = cond(ls);
  1242.   enterblock(fs, &bl, 1);
  1243.   checknext(ls, TK_DO);
  1244.   block(ls);
  1245.   luaK_jumpto(fs, whileinit);
  1246.   check_match(ls, TK_END, TK_WHILE, line);
  1247.   leaveblock(fs);
  1248.   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
  1249. }
  1250.  
  1251.  
  1252. static void repeatstat (LexState *ls, int line) {
  1253.   /* repeatstat -> REPEAT block UNTIL cond */
  1254.   int condexit;
  1255.   FuncState *fs = ls->fs;
  1256.   int repeat_init = luaK_getlabel(fs);
  1257.   BlockCnt bl1, bl2;
  1258.   enterblock(fs, &bl1, 1);  /* loop block */
  1259.   enterblock(fs, &bl2, 0);  /* scope block */
  1260.   luaX_next(ls);  /* skip REPEAT */
  1261.   statlist(ls);
  1262.   check_match(ls, TK_UNTIL, TK_REPEAT, line);
  1263.   condexit = cond(ls);  /* read condition (inside scope block) */
  1264.   if (bl2.upval)  /* upvalues? */
  1265.     luaK_patchclose(fs, condexit, bl2.nactvar);
  1266.   leaveblock(fs);  /* finish scope */
  1267.   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
  1268.   leaveblock(fs);  /* finish loop */
  1269. }
  1270.  
  1271.  
  1272. static int exp1 (LexState *ls) {
  1273.   expdesc e;
  1274.   int reg;
  1275.   expr(ls, &e);
  1276.   luaK_exp2nextreg(ls->fs, &e);
  1277.   lua_assert(e.k == VNONRELOC);
  1278.   reg = e.u.info;
  1279.   return reg;
  1280. }
  1281.  
  1282.  
  1283. static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
  1284.   /* forbody -> DO block */
  1285.   BlockCnt bl;
  1286.   FuncState *fs = ls->fs;
  1287.   int prep, endfor;
  1288.   adjustlocalvars(ls, 3);  /* control variables */
  1289.   checknext(ls, TK_DO);
  1290.   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
  1291.   enterblock(fs, &bl, 0);  /* scope for declared variables */
  1292.   adjustlocalvars(ls, nvars);
  1293.   luaK_reserveregs(fs, nvars);
  1294.   block(ls);
  1295.   leaveblock(fs);  /* end of scope for declared variables */
  1296.   luaK_patchtohere(fs, prep);
  1297.   if (isnum)  /* numeric for? */
  1298.     endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
  1299.   else {  /* generic for */
  1300.     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
  1301.     luaK_fixline(fs, line);
  1302.     endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
  1303.   }
  1304.   luaK_patchlist(fs, endfor, prep + 1);
  1305.   luaK_fixline(fs, line);
  1306. }
  1307.  
  1308.  
  1309. static void fornum (LexState *ls, TString *varname, int line) {
  1310.   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
  1311.   FuncState *fs = ls->fs;
  1312.   int base = fs->freereg;
  1313.   new_localvarliteral(ls, "(for index)");
  1314.   new_localvarliteral(ls, "(for limit)");
  1315.   new_localvarliteral(ls, "(for step)");
  1316.   new_localvar(ls, varname);
  1317.   checknext(ls, '=');
  1318.   exp1(ls);  /* initial value */
  1319.   checknext(ls, ',');
  1320.   exp1(ls);  /* limit */
  1321.   if (testnext(ls, ','))
  1322.     exp1(ls);  /* optional step */
  1323.   else {  /* default step = 1 */
  1324.     luaK_codek(fs, fs->freereg, luaK_numberK(fs, 1));
  1325.     luaK_reserveregs(fs, 1);
  1326.   }
  1327.   forbody(ls, base, line, 1, 1);
  1328. }
  1329.  
  1330.  
  1331. static void forlist (LexState *ls, TString *indexname) {
  1332.   /* forlist -> NAME {,NAME} IN explist forbody */
  1333.   FuncState *fs = ls->fs;
  1334.   expdesc e;
  1335.   int nvars = 4;  /* gen, state, control, plus at least one declared var */
  1336.   int line;
  1337.   int base = fs->freereg;
  1338.   /* create control variables */
  1339.   new_localvarliteral(ls, "(for generator)");
  1340.   new_localvarliteral(ls, "(for state)");
  1341.   new_localvarliteral(ls, "(for control)");
  1342.   /* create declared variables */
  1343.   new_localvar(ls, indexname);
  1344.   while (testnext(ls, ',')) {
  1345.     new_localvar(ls, str_checkname(ls));
  1346.     nvars++;
  1347.   }
  1348.   checknext(ls, TK_IN);
  1349.   line = ls->linenumber;
  1350.   adjust_assign(ls, 3, explist(ls, &e), &e);
  1351.   luaK_checkstack(fs, 3);  /* extra space to call generator */
  1352.   forbody(ls, base, line, nvars - 3, 0);
  1353. }
  1354.  
  1355.  
  1356. static void forstat (LexState *ls, int line) {
  1357.   /* forstat -> FOR (fornum | forlist) END */
  1358.   FuncState *fs = ls->fs;
  1359.   TString *varname;
  1360.   BlockCnt bl;
  1361.   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
  1362.   luaX_next(ls);  /* skip `for' */
  1363.   varname = str_checkname(ls);  /* first variable name */
  1364.   switch (ls->t.token) {
  1365.     case '=': fornum(ls, varname, line); break;
  1366.     case ',': case TK_IN: forlist(ls, varname); break;
  1367.     default: luaX_syntaxerror(ls, LUA_QL("=") " or " LUA_QL("in") " expected");
  1368.   }
  1369.   check_match(ls, TK_END, TK_FOR, line);
  1370.   leaveblock(fs);  /* loop scope (`break' jumps to this point) */
  1371. }
  1372.  
  1373.  
  1374. static void test_then_block (LexState *ls, int *escapelist) {
  1375.   /* test_then_block -> [IF | ELSEIF] cond THEN block */
  1376.   BlockCnt bl;
  1377.   FuncState *fs = ls->fs;
  1378.   expdesc v;
  1379.   int jf;  /* instruction to skip 'then' code (if condition is false) */
  1380.   luaX_next(ls);  /* skip IF or ELSEIF */
  1381.   expr(ls, &v);  /* read condition */
  1382.   checknext(ls, TK_THEN);
  1383.   if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
  1384.     luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
  1385.     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
  1386.     gotostat(ls, v.t);  /* handle goto/break */
  1387.     if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
  1388.       leaveblock(fs);
  1389.       return;  /* and that is it */
  1390.     }
  1391.     else  /* must skip over 'then' part if condition is false */
  1392.       jf = luaK_jump(fs);
  1393.   }
  1394.   else {  /* regular case (not goto/break) */
  1395.     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
  1396.     enterblock(fs, &bl, 0);
  1397.     jf = v.f;
  1398.   }
  1399.   statlist(ls);  /* `then' part */
  1400.   leaveblock(fs);
  1401.   if (ls->t.token == TK_ELSE ||
  1402.       ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
  1403.     luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
  1404.   luaK_patchtohere(fs, jf);
  1405. }
  1406.  
  1407.  
  1408. static void ifstat (LexState *ls, int line) {
  1409.   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
  1410.   FuncState *fs = ls->fs;
  1411.   int escapelist = NO_JUMP;  /* exit list for finished parts */
  1412.   test_then_block(ls, &escapelist);  /* IF cond THEN block */
  1413.   while (ls->t.token == TK_ELSEIF)
  1414.     test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
  1415.   if (testnext(ls, TK_ELSE))
  1416.     block(ls);  /* `else' part */
  1417.   check_match(ls, TK_END, TK_IF, line);
  1418.   luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
  1419. }
  1420.  
  1421.  
  1422. static void localfunc (LexState *ls) {
  1423.   expdesc b;
  1424.   FuncState *fs = ls->fs;
  1425.   new_localvar(ls, str_checkname(ls));  /* new local variable */
  1426.   adjustlocalvars(ls, 1);  /* enter its scope */
  1427.   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
  1428.   /* debug information will only see the variable after this point! */
  1429.   getlocvar(fs, b.u.info)->startpc = fs->pc;
  1430. }
  1431.  
  1432.  
  1433. static void localstat (LexState *ls) {
  1434.   /* stat -> LOCAL NAME {`,' NAME} [`=' explist] */
  1435.   int nvars = 0;
  1436.   int nexps;
  1437.   expdesc e;
  1438.   do {
  1439.     new_localvar(ls, str_checkname(ls));
  1440.     nvars++;
  1441.   } while (testnext(ls, ','));
  1442.   if (testnext(ls, '='))
  1443.     nexps = explist(ls, &e);
  1444.   else {
  1445.     e.k = VVOID;
  1446.     nexps = 0;
  1447.   }
  1448.   adjust_assign(ls, nvars, nexps, &e);
  1449.   adjustlocalvars(ls, nvars);
  1450. }
  1451.  
  1452.  
  1453. static int funcname (LexState *ls, expdesc *v) {
  1454.   /* funcname -> NAME {fieldsel} [`:' NAME] */
  1455.   int ismethod = 0;
  1456.   singlevar(ls, v);
  1457.   while (ls->t.token == '.')
  1458.     fieldsel(ls, v);
  1459.   if (ls->t.token == ':') {
  1460.     ismethod = 1;
  1461.     fieldsel(ls, v);
  1462.   }
  1463.   return ismethod;
  1464. }
  1465.  
  1466.  
  1467. static void funcstat (LexState *ls, int line) {
  1468.   /* funcstat -> FUNCTION funcname body */
  1469.   int ismethod;
  1470.   expdesc v, b;
  1471.   luaX_next(ls);  /* skip FUNCTION */
  1472.   ismethod = funcname(ls, &v);
  1473.   body(ls, &b, ismethod, line);
  1474.   luaK_storevar(ls->fs, &v, &b);
  1475.   luaK_fixline(ls->fs, line);  /* definition `happens' in the first line */
  1476. }
  1477.  
  1478.  
  1479. static void exprstat (LexState *ls) {
  1480.   /* stat -> func | assignment */
  1481.   FuncState *fs = ls->fs;
  1482.   struct LHS_assign v;
  1483.   primaryexp(ls, &v.v);
  1484.   if (v.v.k == VCALL)  /* stat -> func */
  1485.     SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */
  1486.   else {  /* stat -> assignment */
  1487.     v.prev = NULL;
  1488.     assignment(ls, &v, 1);
  1489.   }
  1490. }
  1491.  
  1492.  
  1493. static void retstat (LexState *ls) {
  1494.   /* stat -> RETURN [explist] [';'] */
  1495.   FuncState *fs = ls->fs;
  1496.   expdesc e;
  1497.   int first, nret;  /* registers with returned values */
  1498.   if (block_follow(ls, 1) || ls->t.token == ';')
  1499.     first = nret = 0;  /* return no values */
  1500.   else {
  1501.     nret = explist(ls, &e);  /* optional return values */
  1502.     if (hasmultret(e.k)) {
  1503.       luaK_setmultret(fs, &e);
  1504.       if (e.k == VCALL && nret == 1) {  /* tail call? */
  1505.         SET_OPCODE(getcode(fs,&e), OP_TAILCALL);
  1506.         lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);
  1507.       }
  1508.       first = fs->nactvar;
  1509.       nret = LUA_MULTRET;  /* return all values */
  1510.     }
  1511.     else {
  1512.       if (nret == 1)  /* only one single value? */
  1513.         first = luaK_exp2anyreg(fs, &e);
  1514.       else {
  1515.         luaK_exp2nextreg(fs, &e);  /* values must go to the `stack' */
  1516.         first = fs->nactvar;  /* return all `active' values */
  1517.         lua_assert(nret == fs->freereg - first);
  1518.       }
  1519.     }
  1520.   }
  1521.   luaK_ret(fs, first, nret);
  1522.   testnext(ls, ';');  /* skip optional semicolon */
  1523. }
  1524.  
  1525.  
  1526. static void statement (LexState *ls) {
  1527.   int line = ls->linenumber;  /* may be needed for error messages */
  1528.   enterlevel(ls);
  1529.   switch (ls->t.token) {
  1530.     case ';': {  /* stat -> ';' (empty statement) */
  1531.       luaX_next(ls);  /* skip ';' */
  1532.       break;
  1533.     }
  1534.     case TK_IF: {  /* stat -> ifstat */
  1535.       ifstat(ls, line);
  1536.       break;
  1537.     }
  1538.     case TK_WHILE: {  /* stat -> whilestat */
  1539.       whilestat(ls, line);
  1540.       break;
  1541.     }
  1542.     case TK_DO: {  /* stat -> DO block END */
  1543.       luaX_next(ls);  /* skip DO */
  1544.       block(ls);
  1545.       check_match(ls, TK_END, TK_DO, line);
  1546.       break;
  1547.     }
  1548.     case TK_FOR: {  /* stat -> forstat */
  1549.       forstat(ls, line);
  1550.       break;
  1551.     }
  1552.     case TK_REPEAT: {  /* stat -> repeatstat */
  1553.       repeatstat(ls, line);
  1554.       break;
  1555.     }
  1556.     case TK_FUNCTION: {  /* stat -> funcstat */
  1557.       funcstat(ls, line);
  1558.       break;
  1559.     }
  1560.     case TK_LOCAL: {  /* stat -> localstat */
  1561.       luaX_next(ls);  /* skip LOCAL */
  1562.       if (testnext(ls, TK_FUNCTION))  /* local function? */
  1563.         localfunc(ls);
  1564.       else
  1565.         localstat(ls);
  1566.       break;
  1567.     }
  1568.     case TK_DBCOLON: {  /* stat -> label */
  1569.       luaX_next(ls);  /* skip double colon */
  1570.       labelstat(ls, str_checkname(ls), line);
  1571.       break;
  1572.     }
  1573.     case TK_RETURN: {  /* stat -> retstat */
  1574.       luaX_next(ls);  /* skip RETURN */
  1575.       retstat(ls);
  1576.       break;
  1577.     }
  1578.     case TK_BREAK:   /* stat -> breakstat */
  1579.     case TK_GOTO: {  /* stat -> 'goto' NAME */
  1580.       gotostat(ls, luaK_jump(ls->fs));
  1581.       break;
  1582.     }
  1583.     default: {  /* stat -> func | assignment */
  1584.       exprstat(ls);
  1585.       break;
  1586.     }
  1587.   }
  1588.   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
  1589.              ls->fs->freereg >= ls->fs->nactvar);
  1590.   ls->fs->freereg = ls->fs->nactvar;  /* free registers */
  1591.   leavelevel(ls);
  1592. }
  1593.  
  1594. /* }====================================================================== */
  1595.  
  1596.  
  1597. Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
  1598.                     Dyndata *dyd, const char *name, int firstchar) {
  1599.   LexState lexstate;
  1600.   FuncState funcstate;
  1601.   BlockCnt bl;
  1602.   TString *tname = luaS_new(L, name);
  1603.   setsvalue2s(L, L->top, tname);  /* push name to protect it */
  1604.   incr_top(L);
  1605.   lexstate.buff = buff;
  1606.   lexstate.dyd = dyd;
  1607.   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
  1608.   luaX_setinput(L, &lexstate, z, tname, firstchar);
  1609.   open_mainfunc(&lexstate, &funcstate, &bl);
  1610.   luaX_next(&lexstate);  /* read first token */
  1611.   statlist(&lexstate);  /* main body */
  1612.   check(&lexstate, TK_EOS);
  1613.   close_func(&lexstate);
  1614.   L->top--;  /* pop name */
  1615.   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
  1616.   /* all scopes should be correctly finished */
  1617.   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
  1618.   return funcstate.f;
  1619. }
  1620.  
  1621.