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  1. /*
  2. ** $Id: lparser.c,v 2.155.1.2 2017/04/29 18:11:40 roberto Exp $
  3. ** Lua Parser
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7. #define lparser_c
  8. #define LUA_CORE
  9.  
  10. #include "lprefix.h"
  11.  
  12.  
  13. #include <string.h>
  14.  
  15. #include "lua.h"
  16.  
  17. #include "lcode.h"
  18. #include "ldebug.h"
  19. #include "ldo.h"
  20. #include "lfunc.h"
  21. #include "llex.h"
  22. #include "lmem.h"
  23. #include "lobject.h"
  24. #include "lopcodes.h"
  25. #include "lparser.h"
  26. #include "lstate.h"
  27. #include "lstring.h"
  28. #include "ltable.h"
  29.  
  30.  
  31.  
  32. /* maximum number of local variables per function (must be smaller
  33.    than 250, due to the bytecode format) */
  34. #define MAXVARS         200
  35.  
  36.  
  37. #define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
  38.  
  39.  
  40. /* because all strings are unified by the scanner, the parser
  41.    can use pointer equality for string equality */
  42. #define eqstr(a,b)      ((a) == (b))
  43.  
  44.  
  45. /*
  46. ** nodes for block list (list of active blocks)
  47. */
  48. typedef struct BlockCnt {
  49.   struct BlockCnt *previous;  /* chain */
  50.   int firstlabel;  /* index of first label in this block */
  51.   int firstgoto;  /* index of first pending goto in this block */
  52.   lu_byte nactvar;  /* # active locals outside the block */
  53.   lu_byte upval;  /* true if some variable in the block is an upvalue */
  54.   lu_byte isloop;  /* true if 'block' is a loop */
  55. } BlockCnt;
  56.  
  57.  
  58.  
  59. /*
  60. ** prototypes for recursive non-terminal functions
  61. */
  62. static void statement (LexState *ls);
  63. static void expr (LexState *ls, expdesc *v);
  64.  
  65.  
  66. /* semantic error */
  67. static l_noret semerror (LexState *ls, const char *msg) {
  68.   ls->t.token = 0;  /* remove "near <token>" from final message */
  69.   luaX_syntaxerror(ls, msg);
  70. }
  71.  
  72.  
  73. static l_noret error_expected (LexState *ls, int token) {
  74.   luaX_syntaxerror(ls,
  75.       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
  76. }
  77.  
  78.  
  79. static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
  80.   lua_State *L = fs->ls->L;
  81.   const char *msg;
  82.   int line = fs->f->linedefined;
  83.   const char *where = (line == 0)
  84.                       ? "main function"
  85.                       : luaO_pushfstring(L, "function at line %d", line);
  86.   msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
  87.                              what, limit, where);
  88.   luaX_syntaxerror(fs->ls, msg);
  89. }
  90.  
  91.  
  92. static void checklimit (FuncState *fs, int v, int l, const char *what) {
  93.   if (v > l) errorlimit(fs, l, what);
  94. }
  95.  
  96.  
  97. static int testnext (LexState *ls, int c) {
  98.   if (ls->t.token == c) {
  99.     luaX_next(ls);
  100.     return 1;
  101.   }
  102.   else return 0;
  103. }
  104.  
  105.  
  106. static void check (LexState *ls, int c) {
  107.   if (ls->t.token != c)
  108.     error_expected(ls, c);
  109. }
  110.  
  111.  
  112. static void checknext (LexState *ls, int c) {
  113.   check(ls, c);
  114.   luaX_next(ls);
  115. }
  116.  
  117.  
  118. #define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
  119.  
  120.  
  121.  
  122. static void check_match (LexState *ls, int what, int who, int where) {
  123.   if (!testnext(ls, what)) {
  124.     if (where == ls->linenumber)
  125.       error_expected(ls, what);
  126.     else {
  127.       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
  128.              "%s expected (to close %s at line %d)",
  129.               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
  130.     }
  131.   }
  132. }
  133.  
  134.  
  135. static TString *str_checkname (LexState *ls) {
  136.   TString *ts;
  137.   check(ls, TK_NAME);
  138.   ts = ls->t.seminfo.ts;
  139.   luaX_next(ls);
  140.   return ts;
  141. }
  142.  
  143.  
  144. static void init_exp (expdesc *e, expkind k, int i) {
  145.   e->f = e->t = NO_JUMP;
  146.   e->k = k;
  147.   e->u.info = i;
  148. }
  149.  
  150.  
  151. static void codestring (LexState *ls, expdesc *e, TString *s) {
  152.   init_exp(e, VK, luaK_stringK(ls->fs, s));
  153. }
  154.  
  155.  
  156. static void checkname (LexState *ls, expdesc *e) {
  157.   codestring(ls, e, str_checkname(ls));
  158. }
  159.  
  160.  
  161. static int registerlocalvar (LexState *ls, TString *varname) {
  162.   FuncState *fs = ls->fs;
  163.   Proto *f = fs->f;
  164.   int oldsize = f->sizelocvars;
  165.   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
  166.                   LocVar, SHRT_MAX, "local variables");
  167.   while (oldsize < f->sizelocvars)
  168.     f->locvars[oldsize++].varname = NULL;
  169.   f->locvars[fs->nlocvars].varname = varname;
  170.   luaC_objbarrier(ls->L, f, varname);
  171.   return fs->nlocvars++;
  172. }
  173.  
  174.  
  175. static void new_localvar (LexState *ls, TString *name) {
  176.   FuncState *fs = ls->fs;
  177.   Dyndata *dyd = ls->dyd;
  178.   int reg = registerlocalvar(ls, name);
  179.   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
  180.                   MAXVARS, "local variables");
  181.   luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
  182.                   dyd->actvar.size, Vardesc, MAX_INT, "local variables");
  183.   dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
  184. }
  185.  
  186.  
  187. static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
  188.   new_localvar(ls, luaX_newstring(ls, name, sz));
  189. }
  190.  
  191. #define new_localvarliteral(ls,v) \
  192.         new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
  193.  
  194.  
  195. static LocVar *getlocvar (FuncState *fs, int i) {
  196.   int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
  197.   lua_assert(idx < fs->nlocvars);
  198.   return &fs->f->locvars[idx];
  199. }
  200.  
  201.  
  202. static void adjustlocalvars (LexState *ls, int nvars) {
  203.   FuncState *fs = ls->fs;
  204.   fs->nactvar = cast_byte(fs->nactvar + nvars);
  205.   for (; nvars; nvars--) {
  206.     getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
  207.   }
  208. }
  209.  
  210.  
  211. static void removevars (FuncState *fs, int tolevel) {
  212.   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
  213.   while (fs->nactvar > tolevel)
  214.     getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
  215. }
  216.  
  217.  
  218. static int searchupvalue (FuncState *fs, TString *name) {
  219.   int i;
  220.   Upvaldesc *up = fs->f->upvalues;
  221.   for (i = 0; i < fs->nups; i++) {
  222.     if (eqstr(up[i].name, name)) return i;
  223.   }
  224.   return -1;  /* not found */
  225. }
  226.  
  227.  
  228. static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
  229.   Proto *f = fs->f;
  230.   int oldsize = f->sizeupvalues;
  231.   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
  232.   luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
  233.                   Upvaldesc, MAXUPVAL, "upvalues");
  234.   while (oldsize < f->sizeupvalues)
  235.     f->upvalues[oldsize++].name = NULL;
  236.   f->upvalues[fs->nups].instack = (v->k == VLOCAL);
  237.   f->upvalues[fs->nups].idx = cast_byte(v->u.info);
  238.   f->upvalues[fs->nups].name = name;
  239.   luaC_objbarrier(fs->ls->L, f, name);
  240.   return fs->nups++;
  241. }
  242.  
  243.  
  244. static int searchvar (FuncState *fs, TString *n) {
  245.   int i;
  246.   for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
  247.     if (eqstr(n, getlocvar(fs, i)->varname))
  248.       return i;
  249.   }
  250.   return -1;  /* not found */
  251. }
  252.  
  253.  
  254. /*
  255.   Mark block where variable at given level was defined
  256.   (to emit close instructions later).
  257. */
  258. static void markupval (FuncState *fs, int level) {
  259.   BlockCnt *bl = fs->bl;
  260.   while (bl->nactvar > level)
  261.     bl = bl->previous;
  262.   bl->upval = 1;
  263. }
  264.  
  265.  
  266. /*
  267.   Find variable with given name 'n'. If it is an upvalue, add this
  268.   upvalue into all intermediate functions.
  269. */
  270. static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
  271.   if (fs == NULL)  /* no more levels? */
  272.     init_exp(var, VVOID, 0);  /* default is global */
  273.   else {
  274.     int v = searchvar(fs, n);  /* look up locals at current level */
  275.     if (v >= 0) {  /* found? */
  276.       init_exp(var, VLOCAL, v);  /* variable is local */
  277.       if (!base)
  278.         markupval(fs, v);  /* local will be used as an upval */
  279.     }
  280.     else {  /* not found as local at current level; try upvalues */
  281.       int idx = searchupvalue(fs, n);  /* try existing upvalues */
  282.       if (idx < 0) {  /* not found? */
  283.         singlevaraux(fs->prev, n, var, 0);  /* try upper levels */
  284.         if (var->k == VVOID)  /* not found? */
  285.           return;  /* it is a global */
  286.         /* else was LOCAL or UPVAL */
  287.         idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
  288.       }
  289.       init_exp(var, VUPVAL, idx);  /* new or old upvalue */
  290.     }
  291.   }
  292. }
  293.  
  294.  
  295. static void singlevar (LexState *ls, expdesc *var) {
  296.   TString *varname = str_checkname(ls);
  297.   FuncState *fs = ls->fs;
  298.   singlevaraux(fs, varname, var, 1);
  299.   if (var->k == VVOID) {  /* global name? */
  300.     expdesc key;
  301.     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
  302.     lua_assert(var->k != VVOID);  /* this one must exist */
  303.     codestring(ls, &key, varname);  /* key is variable name */
  304.     luaK_indexed(fs, var, &key);  /* env[varname] */
  305.   }
  306. }
  307.  
  308.  
  309. static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
  310.   FuncState *fs = ls->fs;
  311.   int extra = nvars - nexps;
  312.   if (hasmultret(e->k)) {
  313.     extra++;  /* includes call itself */
  314.     if (extra < 0) extra = 0;
  315.     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
  316.     if (extra > 1) luaK_reserveregs(fs, extra-1);
  317.   }
  318.   else {
  319.     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
  320.     if (extra > 0) {
  321.       int reg = fs->freereg;
  322.       luaK_reserveregs(fs, extra);
  323.       luaK_nil(fs, reg, extra);
  324.     }
  325.   }
  326.   if (nexps > nvars)
  327.     ls->fs->freereg -= nexps - nvars;  /* remove extra values */
  328. }
  329.  
  330.  
  331. static void enterlevel (LexState *ls) {
  332.   lua_State *L = ls->L;
  333.   ++L->nCcalls;
  334.   checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
  335. }
  336.  
  337.  
  338. #define leavelevel(ls)  ((ls)->L->nCcalls--)
  339.  
  340.  
  341. static void closegoto (LexState *ls, int g, Labeldesc *label) {
  342.   int i;
  343.   FuncState *fs = ls->fs;
  344.   Labellist *gl = &ls->dyd->gt;
  345.   Labeldesc *gt = &gl->arr[g];
  346.   lua_assert(eqstr(gt->name, label->name));
  347.   if (gt->nactvar < label->nactvar) {
  348.     TString *vname = getlocvar(fs, gt->nactvar)->varname;
  349.     const char *msg = luaO_pushfstring(ls->L,
  350.       "<goto %s> at line %d jumps into the scope of local '%s'",
  351.       getstr(gt->name), gt->line, getstr(vname));
  352.     semerror(ls, msg);
  353.   }
  354.   luaK_patchlist(fs, gt->pc, label->pc);
  355.   /* remove goto from pending list */
  356.   for (i = g; i < gl->n - 1; i++)
  357.     gl->arr[i] = gl->arr[i + 1];
  358.   gl->n--;
  359. }
  360.  
  361.  
  362. /*
  363. ** try to close a goto with existing labels; this solves backward jumps
  364. */
  365. static int findlabel (LexState *ls, int g) {
  366.   int i;
  367.   BlockCnt *bl = ls->fs->bl;
  368.   Dyndata *dyd = ls->dyd;
  369.   Labeldesc *gt = &dyd->gt.arr[g];
  370.   /* check labels in current block for a match */
  371.   for (i = bl->firstlabel; i < dyd->label.n; i++) {
  372.     Labeldesc *lb = &dyd->label.arr[i];
  373.     if (eqstr(lb->name, gt->name)) {  /* correct label? */
  374.       if (gt->nactvar > lb->nactvar &&
  375.           (bl->upval || dyd->label.n > bl->firstlabel))
  376.         luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
  377.       closegoto(ls, g, lb);  /* close it */
  378.       return 1;
  379.     }
  380.   }
  381.   return 0;  /* label not found; cannot close goto */
  382. }
  383.  
  384.  
  385. static int newlabelentry (LexState *ls, Labellist *l, TString *name,
  386.                           int line, int pc) {
  387.   int n = l->n;
  388.   luaM_growvector(ls->L, l->arr, n, l->size,
  389.                   Labeldesc, SHRT_MAX, "labels/gotos");
  390.   l->arr[n].name = name;
  391.   l->arr[n].line = line;
  392.   l->arr[n].nactvar = ls->fs->nactvar;
  393.   l->arr[n].pc = pc;
  394.   l->n = n + 1;
  395.   return n;
  396. }
  397.  
  398.  
  399. /*
  400. ** check whether new label 'lb' matches any pending gotos in current
  401. ** block; solves forward jumps
  402. */
  403. static void findgotos (LexState *ls, Labeldesc *lb) {
  404.   Labellist *gl = &ls->dyd->gt;
  405.   int i = ls->fs->bl->firstgoto;
  406.   while (i < gl->n) {
  407.     if (eqstr(gl->arr[i].name, lb->name))
  408.       closegoto(ls, i, lb);
  409.     else
  410.       i++;
  411.   }
  412. }
  413.  
  414.  
  415. /*
  416. ** export pending gotos to outer level, to check them against
  417. ** outer labels; if the block being exited has upvalues, and
  418. ** the goto exits the scope of any variable (which can be the
  419. ** upvalue), close those variables being exited.
  420. */
  421. static void movegotosout (FuncState *fs, BlockCnt *bl) {
  422.   int i = bl->firstgoto;
  423.   Labellist *gl = &fs->ls->dyd->gt;
  424.   /* correct pending gotos to current block and try to close it
  425.      with visible labels */
  426.   while (i < gl->n) {
  427.     Labeldesc *gt = &gl->arr[i];
  428.     if (gt->nactvar > bl->nactvar) {
  429.       if (bl->upval)
  430.         luaK_patchclose(fs, gt->pc, bl->nactvar);
  431.       gt->nactvar = bl->nactvar;
  432.     }
  433.     if (!findlabel(fs->ls, i))
  434.       i++;  /* move to next one */
  435.   }
  436. }
  437.  
  438.  
  439. static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
  440.   bl->isloop = isloop;
  441.   bl->nactvar = fs->nactvar;
  442.   bl->firstlabel = fs->ls->dyd->label.n;
  443.   bl->firstgoto = fs->ls->dyd->gt.n;
  444.   bl->upval = 0;
  445.   bl->previous = fs->bl;
  446.   fs->bl = bl;
  447.   lua_assert(fs->freereg == fs->nactvar);
  448. }
  449.  
  450.  
  451. /*
  452. ** create a label named 'break' to resolve break statements
  453. */
  454. static void breaklabel (LexState *ls) {
  455.   TString *n = luaS_new(ls->L, "break");
  456.   int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
  457.   findgotos(ls, &ls->dyd->label.arr[l]);
  458. }
  459.  
  460. /*
  461. ** generates an error for an undefined 'goto'; choose appropriate
  462. ** message when label name is a reserved word (which can only be 'break')
  463. */
  464. static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
  465.   const char *msg = isreserved(gt->name)
  466.                     ? "<%s> at line %d not inside a loop"
  467.                     : "no visible label '%s' for <goto> at line %d";
  468.   msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
  469.   semerror(ls, msg);
  470. }
  471.  
  472.  
  473. static void leaveblock (FuncState *fs) {
  474.   BlockCnt *bl = fs->bl;
  475.   LexState *ls = fs->ls;
  476.   if (bl->previous && bl->upval) {
  477.     /* create a 'jump to here' to close upvalues */
  478.     int j = luaK_jump(fs);
  479.     luaK_patchclose(fs, j, bl->nactvar);
  480.     luaK_patchtohere(fs, j);
  481.   }
  482.   if (bl->isloop)
  483.     breaklabel(ls);  /* close pending breaks */
  484.   fs->bl = bl->previous;
  485.   removevars(fs, bl->nactvar);
  486.   lua_assert(bl->nactvar == fs->nactvar);
  487.   fs->freereg = fs->nactvar;  /* free registers */
  488.   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
  489.   if (bl->previous)  /* inner block? */
  490.     movegotosout(fs, bl);  /* update pending gotos to outer block */
  491.   else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
  492.     undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
  493. }
  494.  
  495.  
  496. /*
  497. ** adds a new prototype into list of prototypes
  498. */
  499. static Proto *addprototype (LexState *ls) {
  500.   Proto *clp;
  501.   lua_State *L = ls->L;
  502.   FuncState *fs = ls->fs;
  503.   Proto *f = fs->f;  /* prototype of current function */
  504.   if (fs->np >= f->sizep) {
  505.     int oldsize = f->sizep;
  506.     luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
  507.     while (oldsize < f->sizep)
  508.       f->p[oldsize++] = NULL;
  509.   }
  510.   f->p[fs->np++] = clp = luaF_newproto(L);
  511.   luaC_objbarrier(L, f, clp);
  512.   return clp;
  513. }
  514.  
  515.  
  516. /*
  517. ** codes instruction to create new closure in parent function.
  518. ** The OP_CLOSURE instruction must use the last available register,
  519. ** so that, if it invokes the GC, the GC knows which registers
  520. ** are in use at that time.
  521. */
  522. static void codeclosure (LexState *ls, expdesc *v) {
  523.   FuncState *fs = ls->fs->prev;
  524.   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
  525.   luaK_exp2nextreg(fs, v);  /* fix it at the last register */
  526. }
  527.  
  528.  
  529. static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
  530.   Proto *f;
  531.   fs->prev = ls->fs;  /* linked list of funcstates */
  532.   fs->ls = ls;
  533.   ls->fs = fs;
  534.   fs->pc = 0;
  535.   fs->lasttarget = 0;
  536.   fs->jpc = NO_JUMP;
  537.   fs->freereg = 0;
  538.   fs->nk = 0;
  539.   fs->np = 0;
  540.   fs->nups = 0;
  541.   fs->nlocvars = 0;
  542.   fs->nactvar = 0;
  543.   fs->firstlocal = ls->dyd->actvar.n;
  544.   fs->bl = NULL;
  545.   f = fs->f;
  546.   f->source = ls->source;
  547.   luaC_objbarrier(ls->L, f, f->source);
  548.   f->maxstacksize = 2;  /* registers 0/1 are always valid */
  549.   enterblock(fs, bl, 0);
  550. }
  551.  
  552.  
  553. static void close_func (LexState *ls) {
  554.   lua_State *L = ls->L;
  555.   FuncState *fs = ls->fs;
  556.   Proto *f = fs->f;
  557.   luaK_ret(fs, 0, 0);  /* final return */
  558.   leaveblock(fs);
  559.   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
  560.   f->sizecode = fs->pc;
  561.   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
  562.   f->sizelineinfo = fs->pc;
  563.   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
  564.   f->sizek = fs->nk;
  565.   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
  566.   f->sizep = fs->np;
  567.   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
  568.   f->sizelocvars = fs->nlocvars;
  569.   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
  570.   f->sizeupvalues = fs->nups;
  571.   lua_assert(fs->bl == NULL);
  572.   ls->fs = fs->prev;
  573.   luaC_checkGC(L);
  574. }
  575.  
  576.  
  577.  
  578. /*============================================================*/
  579. /* GRAMMAR RULES */
  580. /*============================================================*/
  581.  
  582.  
  583. /*
  584. ** check whether current token is in the follow set of a block.
  585. ** 'until' closes syntactical blocks, but do not close scope,
  586. ** so it is handled in separate.
  587. */
  588. static int block_follow (LexState *ls, int withuntil) {
  589.   switch (ls->t.token) {
  590.     case TK_ELSE: case TK_ELSEIF:
  591.     case TK_END: case TK_EOS:
  592.       return 1;
  593.     case TK_UNTIL: return withuntil;
  594.     default: return 0;
  595.   }
  596. }
  597.  
  598.  
  599. static void statlist (LexState *ls) {
  600.   /* statlist -> { stat [';'] } */
  601.   while (!block_follow(ls, 1)) {
  602.     if (ls->t.token == TK_RETURN) {
  603.       statement(ls);
  604.       return;  /* 'return' must be last statement */
  605.     }
  606.     statement(ls);
  607.   }
  608. }
  609.  
  610.  
  611. static void fieldsel (LexState *ls, expdesc *v) {
  612.   /* fieldsel -> ['.' | ':'] NAME */
  613.   FuncState *fs = ls->fs;
  614.   expdesc key;
  615.   luaK_exp2anyregup(fs, v);
  616.   luaX_next(ls);  /* skip the dot or colon */
  617.   checkname(ls, &key);
  618.   luaK_indexed(fs, v, &key);
  619. }
  620.  
  621.  
  622. static void yindex (LexState *ls, expdesc *v) {
  623.   /* index -> '[' expr ']' */
  624.   luaX_next(ls);  /* skip the '[' */
  625.   expr(ls, v);
  626.   luaK_exp2val(ls->fs, v);
  627.   checknext(ls, ']');
  628. }
  629.  
  630.  
  631. /*
  632. ** {======================================================================
  633. ** Rules for Constructors
  634. ** =======================================================================
  635. */
  636.  
  637.  
  638. struct ConsControl {
  639.   expdesc v;  /* last list item read */
  640.   expdesc *t;  /* table descriptor */
  641.   int nh;  /* total number of 'record' elements */
  642.   int na;  /* total number of array elements */
  643.   int tostore;  /* number of array elements pending to be stored */
  644. };
  645.  
  646.  
  647. static void recfield (LexState *ls, struct ConsControl *cc) {
  648.   /* recfield -> (NAME | '['exp1']') = exp1 */
  649.   FuncState *fs = ls->fs;
  650.   int reg = ls->fs->freereg;
  651.   expdesc key, val;
  652.   int rkkey;
  653.   if (ls->t.token == TK_NAME) {
  654.     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
  655.     checkname(ls, &key);
  656.   }
  657.   else  /* ls->t.token == '[' */
  658.     yindex(ls, &key);
  659.   cc->nh++;
  660.   checknext(ls, '=');
  661.   rkkey = luaK_exp2RK(fs, &key);
  662.   expr(ls, &val);
  663.   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
  664.   fs->freereg = reg;  /* free registers */
  665. }
  666.  
  667.  
  668. static void closelistfield (FuncState *fs, struct ConsControl *cc) {
  669.   if (cc->v.k == VVOID) return;  /* there is no list item */
  670.   luaK_exp2nextreg(fs, &cc->v);
  671.   cc->v.k = VVOID;
  672.   if (cc->tostore == LFIELDS_PER_FLUSH) {
  673.     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
  674.     cc->tostore = 0;  /* no more items pending */
  675.   }
  676. }
  677.  
  678.  
  679. static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
  680.   if (cc->tostore == 0) return;
  681.   if (hasmultret(cc->v.k)) {
  682.     luaK_setmultret(fs, &cc->v);
  683.     luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
  684.     cc->na--;  /* do not count last expression (unknown number of elements) */
  685.   }
  686.   else {
  687.     if (cc->v.k != VVOID)
  688.       luaK_exp2nextreg(fs, &cc->v);
  689.     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
  690.   }
  691. }
  692.  
  693.  
  694. static void listfield (LexState *ls, struct ConsControl *cc) {
  695.   /* listfield -> exp */
  696.   expr(ls, &cc->v);
  697.   checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
  698.   cc->na++;
  699.   cc->tostore++;
  700. }
  701.  
  702.  
  703. static void field (LexState *ls, struct ConsControl *cc) {
  704.   /* field -> listfield | recfield */
  705.   switch(ls->t.token) {
  706.     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
  707.       if (luaX_lookahead(ls) != '=')  /* expression? */
  708.         listfield(ls, cc);
  709.       else
  710.         recfield(ls, cc);
  711.       break;
  712.     }
  713.     case '[': {
  714.       recfield(ls, cc);
  715.       break;
  716.     }
  717.     default: {
  718.       listfield(ls, cc);
  719.       break;
  720.     }
  721.   }
  722. }
  723.  
  724.  
  725. static void constructor (LexState *ls, expdesc *t) {
  726.   /* constructor -> '{' [ field { sep field } [sep] ] '}'
  727.      sep -> ',' | ';' */
  728.   FuncState *fs = ls->fs;
  729.   int line = ls->linenumber;
  730.   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
  731.   struct ConsControl cc;
  732.   cc.na = cc.nh = cc.tostore = 0;
  733.   cc.t = t;
  734.   init_exp(t, VRELOCABLE, pc);
  735.   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
  736.   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
  737.   checknext(ls, '{');
  738.   do {
  739.     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
  740.     if (ls->t.token == '}') break;
  741.     closelistfield(fs, &cc);
  742.     field(ls, &cc);
  743.   } while (testnext(ls, ',') || testnext(ls, ';'));
  744.   check_match(ls, '}', '{', line);
  745.   lastlistfield(fs, &cc);
  746.   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
  747.   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
  748. }
  749.  
  750. /* }====================================================================== */
  751.  
  752.  
  753.  
  754. static void parlist (LexState *ls) {
  755.   /* parlist -> [ param { ',' param } ] */
  756.   FuncState *fs = ls->fs;
  757.   Proto *f = fs->f;
  758.   int nparams = 0;
  759.   f->is_vararg = 0;
  760.   if (ls->t.token != ')') {  /* is 'parlist' not empty? */
  761.     do {
  762.       switch (ls->t.token) {
  763.         case TK_NAME: {  /* param -> NAME */
  764.           new_localvar(ls, str_checkname(ls));
  765.           nparams++;
  766.           break;
  767.         }
  768.         case TK_DOTS: {  /* param -> '...' */
  769.           luaX_next(ls);
  770.           f->is_vararg = 1;  /* declared vararg */
  771.           break;
  772.         }
  773.         default: luaX_syntaxerror(ls, "<name> or '...' expected");
  774.       }
  775.     } while (!f->is_vararg && testnext(ls, ','));
  776.   }
  777.   adjustlocalvars(ls, nparams);
  778.   f->numparams = cast_byte(fs->nactvar);
  779.   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
  780. }
  781.  
  782.  
  783. static void body (LexState *ls, expdesc *e, int ismethod, int line) {
  784.   /* body ->  '(' parlist ')' block END */
  785.   FuncState new_fs;
  786.   BlockCnt bl;
  787.   new_fs.f = addprototype(ls);
  788.   new_fs.f->linedefined = line;
  789.   open_func(ls, &new_fs, &bl);
  790.   checknext(ls, '(');
  791.   if (ismethod) {
  792.     new_localvarliteral(ls, "self");  /* create 'self' parameter */
  793.     adjustlocalvars(ls, 1);
  794.   }
  795.   parlist(ls);
  796.   checknext(ls, ')');
  797.   statlist(ls);
  798.   new_fs.f->lastlinedefined = ls->linenumber;
  799.   check_match(ls, TK_END, TK_FUNCTION, line);
  800.   codeclosure(ls, e);
  801.   close_func(ls);
  802. }
  803.  
  804.  
  805. static int explist (LexState *ls, expdesc *v) {
  806.   /* explist -> expr { ',' expr } */
  807.   int n = 1;  /* at least one expression */
  808.   expr(ls, v);
  809.   while (testnext(ls, ',')) {
  810.     luaK_exp2nextreg(ls->fs, v);
  811.     expr(ls, v);
  812.     n++;
  813.   }
  814.   return n;
  815. }
  816.  
  817.  
  818. static void funcargs (LexState *ls, expdesc *f, int line) {
  819.   FuncState *fs = ls->fs;
  820.   expdesc args;
  821.   int base, nparams;
  822.   switch (ls->t.token) {
  823.     case '(': {  /* funcargs -> '(' [ explist ] ')' */
  824.       luaX_next(ls);
  825.       if (ls->t.token == ')')  /* arg list is empty? */
  826.         args.k = VVOID;
  827.       else {
  828.         explist(ls, &args);
  829.         luaK_setmultret(fs, &args);
  830.       }
  831.       check_match(ls, ')', '(', line);
  832.       break;
  833.     }
  834.     case '{': {  /* funcargs -> constructor */
  835.       constructor(ls, &args);
  836.       break;
  837.     }
  838.     case TK_STRING: {  /* funcargs -> STRING */
  839.       codestring(ls, &args, ls->t.seminfo.ts);
  840.       luaX_next(ls);  /* must use 'seminfo' before 'next' */
  841.       break;
  842.     }
  843.     default: {
  844.       luaX_syntaxerror(ls, "function arguments expected");
  845.     }
  846.   }
  847.   lua_assert(f->k == VNONRELOC);
  848.   base = f->u.info;  /* base register for call */
  849.   if (hasmultret(args.k))
  850.     nparams = LUA_MULTRET;  /* open call */
  851.   else {
  852.     if (args.k != VVOID)
  853.       luaK_exp2nextreg(fs, &args);  /* close last argument */
  854.     nparams = fs->freereg - (base+1);
  855.   }
  856.   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
  857.   luaK_fixline(fs, line);
  858.   fs->freereg = base+1;  /* call remove function and arguments and leaves
  859.                             (unless changed) one result */
  860. }
  861.  
  862.  
  863.  
  864.  
  865. /*
  866. ** {======================================================================
  867. ** Expression parsing
  868. ** =======================================================================
  869. */
  870.  
  871.  
  872. static void primaryexp (LexState *ls, expdesc *v) {
  873.   /* primaryexp -> NAME | '(' expr ')' */
  874.   switch (ls->t.token) {
  875.     case '(': {
  876.       int line = ls->linenumber;
  877.       luaX_next(ls);
  878.       expr(ls, v);
  879.       check_match(ls, ')', '(', line);
  880.       luaK_dischargevars(ls->fs, v);
  881.       return;
  882.     }
  883.     case TK_NAME: {
  884.       singlevar(ls, v);
  885.       return;
  886.     }
  887.     default: {
  888.       luaX_syntaxerror(ls, "unexpected symbol");
  889.     }
  890.   }
  891. }
  892.  
  893.  
  894. static void suffixedexp (LexState *ls, expdesc *v) {
  895.   /* suffixedexp ->
  896.        primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
  897.   FuncState *fs = ls->fs;
  898.   int line = ls->linenumber;
  899.   primaryexp(ls, v);
  900.   for (;;) {
  901.     switch (ls->t.token) {
  902.       case '.': {  /* fieldsel */
  903.         fieldsel(ls, v);
  904.         break;
  905.       }
  906.       case '[': {  /* '[' exp1 ']' */
  907.         expdesc key;
  908.         luaK_exp2anyregup(fs, v);
  909.         yindex(ls, &key);
  910.         luaK_indexed(fs, v, &key);
  911.         break;
  912.       }
  913.       case ':': {  /* ':' NAME funcargs */
  914.         expdesc key;
  915.         luaX_next(ls);
  916.         checkname(ls, &key);
  917.         luaK_self(fs, v, &key);
  918.         funcargs(ls, v, line);
  919.         break;
  920.       }
  921.       case '(': case TK_STRING: case '{': {  /* funcargs */
  922.         luaK_exp2nextreg(fs, v);
  923.         funcargs(ls, v, line);
  924.         break;
  925.       }
  926.       default: return;
  927.     }
  928.   }
  929. }
  930.  
  931.  
  932. static void simpleexp (LexState *ls, expdesc *v) {
  933.   /* simpleexp -> FLT | INT | STRING | NIL | TRUE | FALSE | ... |
  934.                   constructor | FUNCTION body | suffixedexp */
  935.   switch (ls->t.token) {
  936.     case TK_FLT: {
  937.       init_exp(v, VKFLT, 0);
  938.       v->u.nval = ls->t.seminfo.r;
  939.       break;
  940.     }
  941.     case TK_INT: {
  942.       init_exp(v, VKINT, 0);
  943.       v->u.ival = ls->t.seminfo.i;
  944.       break;
  945.     }
  946.     case TK_STRING: {
  947.       codestring(ls, v, ls->t.seminfo.ts);
  948.       break;
  949.     }
  950.     case TK_NIL: {
  951.       init_exp(v, VNIL, 0);
  952.       break;
  953.     }
  954.     case TK_TRUE: {
  955.       init_exp(v, VTRUE, 0);
  956.       break;
  957.     }
  958.     case TK_FALSE: {
  959.       init_exp(v, VFALSE, 0);
  960.       break;
  961.     }
  962.     case TK_DOTS: {  /* vararg */
  963.       FuncState *fs = ls->fs;
  964.       check_condition(ls, fs->f->is_vararg,
  965.                       "cannot use '...' outside a vararg function");
  966.       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
  967.       break;
  968.     }
  969.     case '{': {  /* constructor */
  970.       constructor(ls, v);
  971.       return;
  972.     }
  973.     case TK_FUNCTION: {
  974.       luaX_next(ls);
  975.       body(ls, v, 0, ls->linenumber);
  976.       return;
  977.     }
  978.     default: {
  979.       suffixedexp(ls, v);
  980.       return;
  981.     }
  982.   }
  983.   luaX_next(ls);
  984. }
  985.  
  986.  
  987. static UnOpr getunopr (int op) {
  988.   switch (op) {
  989.     case TK_NOT: return OPR_NOT;
  990.     case '-': return OPR_MINUS;
  991.     case '~': return OPR_BNOT;
  992.     case '#': return OPR_LEN;
  993.     default: return OPR_NOUNOPR;
  994.   }
  995. }
  996.  
  997.  
  998. static BinOpr getbinopr (int op) {
  999.   switch (op) {
  1000.     case '+': return OPR_ADD;
  1001.     case '-': return OPR_SUB;
  1002.     case '*': return OPR_MUL;
  1003.     case '%': return OPR_MOD;
  1004.     case '^': return OPR_POW;
  1005.     case '/': return OPR_DIV;
  1006.     case TK_IDIV: return OPR_IDIV;
  1007.     case '&': return OPR_BAND;
  1008.     case '|': return OPR_BOR;
  1009.     case '~': return OPR_BXOR;
  1010.     case TK_SHL: return OPR_SHL;
  1011.     case TK_SHR: return OPR_SHR;
  1012.     case TK_CONCAT: return OPR_CONCAT;
  1013.     case TK_NE: return OPR_NE;
  1014.     case TK_EQ: return OPR_EQ;
  1015.     case '<': return OPR_LT;
  1016.     case TK_LE: return OPR_LE;
  1017.     case '>': return OPR_GT;
  1018.     case TK_GE: return OPR_GE;
  1019.     case TK_AND: return OPR_AND;
  1020.     case TK_OR: return OPR_OR;
  1021.     default: return OPR_NOBINOPR;
  1022.   }
  1023. }
  1024.  
  1025.  
  1026. static const struct {
  1027.   lu_byte left;  /* left priority for each binary operator */
  1028.   lu_byte right; /* right priority */
  1029. } priority[] = {  /* ORDER OPR */
  1030.    {10, 10}, {10, 10},           /* '+' '-' */
  1031.    {11, 11}, {11, 11},           /* '*' '%' */
  1032.    {14, 13},                  /* '^' (right associative) */
  1033.    {11, 11}, {11, 11},           /* '/' '//' */
  1034.    {6, 6}, {4, 4}, {5, 5},   /* '&' '|' '~' */
  1035.    {7, 7}, {7, 7},           /* '<<' '>>' */
  1036.    {9, 8},                   /* '..' (right associative) */
  1037.    {3, 3}, {3, 3}, {3, 3},   /* ==, <, <= */
  1038.    {3, 3}, {3, 3}, {3, 3},   /* ~=, >, >= */
  1039.    {2, 2}, {1, 1}            /* and, or */
  1040. };
  1041.  
  1042. #define UNARY_PRIORITY  12  /* priority for unary operators */
  1043.  
  1044.  
  1045. /*
  1046. ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
  1047. ** where 'binop' is any binary operator with a priority higher than 'limit'
  1048. */
  1049. static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
  1050.   BinOpr op;
  1051.   UnOpr uop;
  1052.   enterlevel(ls);
  1053.   uop = getunopr(ls->t.token);
  1054.   if (uop != OPR_NOUNOPR) {
  1055.     int line = ls->linenumber;
  1056.     luaX_next(ls);
  1057.     subexpr(ls, v, UNARY_PRIORITY);
  1058.     luaK_prefix(ls->fs, uop, v, line);
  1059.   }
  1060.   else simpleexp(ls, v);
  1061.   /* expand while operators have priorities higher than 'limit' */
  1062.   op = getbinopr(ls->t.token);
  1063.   while (op != OPR_NOBINOPR && priority[op].left > limit) {
  1064.     expdesc v2;
  1065.     BinOpr nextop;
  1066.     int line = ls->linenumber;
  1067.     luaX_next(ls);
  1068.     luaK_infix(ls->fs, op, v);
  1069.     /* read sub-expression with higher priority */
  1070.     nextop = subexpr(ls, &v2, priority[op].right);
  1071.     luaK_posfix(ls->fs, op, v, &v2, line);
  1072.     op = nextop;
  1073.   }
  1074.   leavelevel(ls);
  1075.   return op;  /* return first untreated operator */
  1076. }
  1077.  
  1078.  
  1079. static void expr (LexState *ls, expdesc *v) {
  1080.   subexpr(ls, v, 0);
  1081. }
  1082.  
  1083. /* }==================================================================== */
  1084.  
  1085.  
  1086.  
  1087. /*
  1088. ** {======================================================================
  1089. ** Rules for Statements
  1090. ** =======================================================================
  1091. */
  1092.  
  1093.  
  1094. static void block (LexState *ls) {
  1095.   /* block -> statlist */
  1096.   FuncState *fs = ls->fs;
  1097.   BlockCnt bl;
  1098.   enterblock(fs, &bl, 0);
  1099.   statlist(ls);
  1100.   leaveblock(fs);
  1101. }
  1102.  
  1103.  
  1104. /*
  1105. ** structure to chain all variables in the left-hand side of an
  1106. ** assignment
  1107. */
  1108. struct LHS_assign {
  1109.   struct LHS_assign *prev;
  1110.   expdesc v;  /* variable (global, local, upvalue, or indexed) */
  1111. };
  1112.  
  1113.  
  1114. /*
  1115. ** check whether, in an assignment to an upvalue/local variable, the
  1116. ** upvalue/local variable is begin used in a previous assignment to a
  1117. ** table. If so, save original upvalue/local value in a safe place and
  1118. ** use this safe copy in the previous assignment.
  1119. */
  1120. static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
  1121.   FuncState *fs = ls->fs;
  1122.   int extra = fs->freereg;  /* eventual position to save local variable */
  1123.   int conflict = 0;
  1124.   for (; lh; lh = lh->prev) {  /* check all previous assignments */
  1125.     if (lh->v.k == VINDEXED) {  /* assigning to a table? */
  1126.       /* table is the upvalue/local being assigned now? */
  1127.       if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
  1128.         conflict = 1;
  1129.         lh->v.u.ind.vt = VLOCAL;
  1130.         lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
  1131.       }
  1132.       /* index is the local being assigned? (index cannot be upvalue) */
  1133.       if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
  1134.         conflict = 1;
  1135.         lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
  1136.       }
  1137.     }
  1138.   }
  1139.   if (conflict) {
  1140.     /* copy upvalue/local value to a temporary (in position 'extra') */
  1141.     OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
  1142.     luaK_codeABC(fs, op, extra, v->u.info, 0);
  1143.     luaK_reserveregs(fs, 1);
  1144.   }
  1145. }
  1146.  
  1147.  
  1148. static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
  1149.   expdesc e;
  1150.   check_condition(ls, vkisvar(lh->v.k), "syntax error");
  1151.   if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
  1152.     struct LHS_assign nv;
  1153.     nv.prev = lh;
  1154.     suffixedexp(ls, &nv.v);
  1155.     if (nv.v.k != VINDEXED)
  1156.       check_conflict(ls, lh, &nv.v);
  1157.     checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
  1158.                     "C levels");
  1159.     assignment(ls, &nv, nvars+1);
  1160.   }
  1161.   else {  /* assignment -> '=' explist */
  1162.     int nexps;
  1163.     checknext(ls, '=');
  1164.     nexps = explist(ls, &e);
  1165.     if (nexps != nvars)
  1166.       adjust_assign(ls, nvars, nexps, &e);
  1167.     else {
  1168.       luaK_setoneret(ls->fs, &e);  /* close last expression */
  1169.       luaK_storevar(ls->fs, &lh->v, &e);
  1170.       return;  /* avoid default */
  1171.     }
  1172.   }
  1173.   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
  1174.   luaK_storevar(ls->fs, &lh->v, &e);
  1175. }
  1176.  
  1177.  
  1178. static int cond (LexState *ls) {
  1179.   /* cond -> exp */
  1180.   expdesc v;
  1181.   expr(ls, &v);  /* read condition */
  1182.   if (v.k == VNIL) v.k = VFALSE;  /* 'falses' are all equal here */
  1183.   luaK_goiftrue(ls->fs, &v);
  1184.   return v.f;
  1185. }
  1186.  
  1187.  
  1188. static void gotostat (LexState *ls, int pc) {
  1189.   int line = ls->linenumber;
  1190.   TString *label;
  1191.   int g;
  1192.   if (testnext(ls, TK_GOTO))
  1193.     label = str_checkname(ls);
  1194.   else {
  1195.     luaX_next(ls);  /* skip break */
  1196.     label = luaS_new(ls->L, "break");
  1197.   }
  1198.   g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
  1199.   findlabel(ls, g);  /* close it if label already defined */
  1200. }
  1201.  
  1202.  
  1203. /* check for repeated labels on the same block */
  1204. static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
  1205.   int i;
  1206.   for (i = fs->bl->firstlabel; i < ll->n; i++) {
  1207.     if (eqstr(label, ll->arr[i].name)) {
  1208.       const char *msg = luaO_pushfstring(fs->ls->L,
  1209.                           "label '%s' already defined on line %d",
  1210.                           getstr(label), ll->arr[i].line);
  1211.       semerror(fs->ls, msg);
  1212.     }
  1213.   }
  1214. }
  1215.  
  1216.  
  1217. /* skip no-op statements */
  1218. static void skipnoopstat (LexState *ls) {
  1219.   while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
  1220.     statement(ls);
  1221. }
  1222.  
  1223.  
  1224. static void labelstat (LexState *ls, TString *label, int line) {
  1225.   /* label -> '::' NAME '::' */
  1226.   FuncState *fs = ls->fs;
  1227.   Labellist *ll = &ls->dyd->label;
  1228.   int l;  /* index of new label being created */
  1229.   checkrepeated(fs, ll, label);  /* check for repeated labels */
  1230.   checknext(ls, TK_DBCOLON);  /* skip double colon */
  1231.   /* create new entry for this label */
  1232.   l = newlabelentry(ls, ll, label, line, luaK_getlabel(fs));
  1233.   skipnoopstat(ls);  /* skip other no-op statements */
  1234.   if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
  1235.     /* assume that locals are already out of scope */
  1236.     ll->arr[l].nactvar = fs->bl->nactvar;
  1237.   }
  1238.   findgotos(ls, &ll->arr[l]);
  1239. }
  1240.  
  1241.  
  1242. static void whilestat (LexState *ls, int line) {
  1243.   /* whilestat -> WHILE cond DO block END */
  1244.   FuncState *fs = ls->fs;
  1245.   int whileinit;
  1246.   int condexit;
  1247.   BlockCnt bl;
  1248.   luaX_next(ls);  /* skip WHILE */
  1249.   whileinit = luaK_getlabel(fs);
  1250.   condexit = cond(ls);
  1251.   enterblock(fs, &bl, 1);
  1252.   checknext(ls, TK_DO);
  1253.   block(ls);
  1254.   luaK_jumpto(fs, whileinit);
  1255.   check_match(ls, TK_END, TK_WHILE, line);
  1256.   leaveblock(fs);
  1257.   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
  1258. }
  1259.  
  1260.  
  1261. static void repeatstat (LexState *ls, int line) {
  1262.   /* repeatstat -> REPEAT block UNTIL cond */
  1263.   int condexit;
  1264.   FuncState *fs = ls->fs;
  1265.   int repeat_init = luaK_getlabel(fs);
  1266.   BlockCnt bl1, bl2;
  1267.   enterblock(fs, &bl1, 1);  /* loop block */
  1268.   enterblock(fs, &bl2, 0);  /* scope block */
  1269.   luaX_next(ls);  /* skip REPEAT */
  1270.   statlist(ls);
  1271.   check_match(ls, TK_UNTIL, TK_REPEAT, line);
  1272.   condexit = cond(ls);  /* read condition (inside scope block) */
  1273.   if (bl2.upval)  /* upvalues? */
  1274.     luaK_patchclose(fs, condexit, bl2.nactvar);
  1275.   leaveblock(fs);  /* finish scope */
  1276.   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
  1277.   leaveblock(fs);  /* finish loop */
  1278. }
  1279.  
  1280.  
  1281. static int exp1 (LexState *ls) {
  1282.   expdesc e;
  1283.   int reg;
  1284.   expr(ls, &e);
  1285.   luaK_exp2nextreg(ls->fs, &e);
  1286.   lua_assert(e.k == VNONRELOC);
  1287.   reg = e.u.info;
  1288.   return reg;
  1289. }
  1290.  
  1291.  
  1292. static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
  1293.   /* forbody -> DO block */
  1294.   BlockCnt bl;
  1295.   FuncState *fs = ls->fs;
  1296.   int prep, endfor;
  1297.   adjustlocalvars(ls, 3);  /* control variables */
  1298.   checknext(ls, TK_DO);
  1299.   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
  1300.   enterblock(fs, &bl, 0);  /* scope for declared variables */
  1301.   adjustlocalvars(ls, nvars);
  1302.   luaK_reserveregs(fs, nvars);
  1303.   block(ls);
  1304.   leaveblock(fs);  /* end of scope for declared variables */
  1305.   luaK_patchtohere(fs, prep);
  1306.   if (isnum)  /* numeric for? */
  1307.     endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
  1308.   else {  /* generic for */
  1309.     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
  1310.     luaK_fixline(fs, line);
  1311.     endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
  1312.   }
  1313.   luaK_patchlist(fs, endfor, prep + 1);
  1314.   luaK_fixline(fs, line);
  1315. }
  1316.  
  1317.  
  1318. static void fornum (LexState *ls, TString *varname, int line) {
  1319.   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
  1320.   FuncState *fs = ls->fs;
  1321.   int base = fs->freereg;
  1322.   new_localvarliteral(ls, "(for index)");
  1323.   new_localvarliteral(ls, "(for limit)");
  1324.   new_localvarliteral(ls, "(for step)");
  1325.   new_localvar(ls, varname);
  1326.   checknext(ls, '=');
  1327.   exp1(ls);  /* initial value */
  1328.   checknext(ls, ',');
  1329.   exp1(ls);  /* limit */
  1330.   if (testnext(ls, ','))
  1331.     exp1(ls);  /* optional step */
  1332.   else {  /* default step = 1 */
  1333.     luaK_codek(fs, fs->freereg, luaK_intK(fs, 1));
  1334.     luaK_reserveregs(fs, 1);
  1335.   }
  1336.   forbody(ls, base, line, 1, 1);
  1337. }
  1338.  
  1339.  
  1340. static void forlist (LexState *ls, TString *indexname) {
  1341.   /* forlist -> NAME {,NAME} IN explist forbody */
  1342.   FuncState *fs = ls->fs;
  1343.   expdesc e;
  1344.   int nvars = 4;  /* gen, state, control, plus at least one declared var */
  1345.   int line;
  1346.   int base = fs->freereg;
  1347.   /* create control variables */
  1348.   new_localvarliteral(ls, "(for generator)");
  1349.   new_localvarliteral(ls, "(for state)");
  1350.   new_localvarliteral(ls, "(for control)");
  1351.   /* create declared variables */
  1352.   new_localvar(ls, indexname);
  1353.   while (testnext(ls, ',')) {
  1354.     new_localvar(ls, str_checkname(ls));
  1355.     nvars++;
  1356.   }
  1357.   checknext(ls, TK_IN);
  1358.   line = ls->linenumber;
  1359.   adjust_assign(ls, 3, explist(ls, &e), &e);
  1360.   luaK_checkstack(fs, 3);  /* extra space to call generator */
  1361.   forbody(ls, base, line, nvars - 3, 0);
  1362. }
  1363.  
  1364.  
  1365. static void forstat (LexState *ls, int line) {
  1366.   /* forstat -> FOR (fornum | forlist) END */
  1367.   FuncState *fs = ls->fs;
  1368.   TString *varname;
  1369.   BlockCnt bl;
  1370.   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
  1371.   luaX_next(ls);  /* skip 'for' */
  1372.   varname = str_checkname(ls);  /* first variable name */
  1373.   switch (ls->t.token) {
  1374.     case '=': fornum(ls, varname, line); break;
  1375.     case ',': case TK_IN: forlist(ls, varname); break;
  1376.     default: luaX_syntaxerror(ls, "'=' or 'in' expected");
  1377.   }
  1378.   check_match(ls, TK_END, TK_FOR, line);
  1379.   leaveblock(fs);  /* loop scope ('break' jumps to this point) */
  1380. }
  1381.  
  1382.  
  1383. static void test_then_block (LexState *ls, int *escapelist) {
  1384.   /* test_then_block -> [IF | ELSEIF] cond THEN block */
  1385.   BlockCnt bl;
  1386.   FuncState *fs = ls->fs;
  1387.   expdesc v;
  1388.   int jf;  /* instruction to skip 'then' code (if condition is false) */
  1389.   luaX_next(ls);  /* skip IF or ELSEIF */
  1390.   expr(ls, &v);  /* read condition */
  1391.   checknext(ls, TK_THEN);
  1392.   if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
  1393.     luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
  1394.     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
  1395.     gotostat(ls, v.t);  /* handle goto/break */
  1396.     while (testnext(ls, ';')) {}  /* skip colons */
  1397.     if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
  1398.       leaveblock(fs);
  1399.       return;  /* and that is it */
  1400.     }
  1401.     else  /* must skip over 'then' part if condition is false */
  1402.       jf = luaK_jump(fs);
  1403.   }
  1404.   else {  /* regular case (not goto/break) */
  1405.     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
  1406.     enterblock(fs, &bl, 0);
  1407.     jf = v.f;
  1408.   }
  1409.   statlist(ls);  /* 'then' part */
  1410.   leaveblock(fs);
  1411.   if (ls->t.token == TK_ELSE ||
  1412.       ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
  1413.     luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
  1414.   luaK_patchtohere(fs, jf);
  1415. }
  1416.  
  1417.  
  1418. static void ifstat (LexState *ls, int line) {
  1419.   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
  1420.   FuncState *fs = ls->fs;
  1421.   int escapelist = NO_JUMP;  /* exit list for finished parts */
  1422.   test_then_block(ls, &escapelist);  /* IF cond THEN block */
  1423.   while (ls->t.token == TK_ELSEIF)
  1424.     test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
  1425.   if (testnext(ls, TK_ELSE))
  1426.     block(ls);  /* 'else' part */
  1427.   check_match(ls, TK_END, TK_IF, line);
  1428.   luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
  1429. }
  1430.  
  1431.  
  1432. static void localfunc (LexState *ls) {
  1433.   expdesc b;
  1434.   FuncState *fs = ls->fs;
  1435.   new_localvar(ls, str_checkname(ls));  /* new local variable */
  1436.   adjustlocalvars(ls, 1);  /* enter its scope */
  1437.   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
  1438.   /* debug information will only see the variable after this point! */
  1439.   getlocvar(fs, b.u.info)->startpc = fs->pc;
  1440. }
  1441.  
  1442.  
  1443. static void localstat (LexState *ls) {
  1444.   /* stat -> LOCAL NAME {',' NAME} ['=' explist] */
  1445.   int nvars = 0;
  1446.   int nexps;
  1447.   expdesc e;
  1448.   do {
  1449.     new_localvar(ls, str_checkname(ls));
  1450.     nvars++;
  1451.   } while (testnext(ls, ','));
  1452.   if (testnext(ls, '='))
  1453.     nexps = explist(ls, &e);
  1454.   else {
  1455.     e.k = VVOID;
  1456.     nexps = 0;
  1457.   }
  1458.   adjust_assign(ls, nvars, nexps, &e);
  1459.   adjustlocalvars(ls, nvars);
  1460. }
  1461.  
  1462.  
  1463. static int funcname (LexState *ls, expdesc *v) {
  1464.   /* funcname -> NAME {fieldsel} [':' NAME] */
  1465.   int ismethod = 0;
  1466.   singlevar(ls, v);
  1467.   while (ls->t.token == '.')
  1468.     fieldsel(ls, v);
  1469.   if (ls->t.token == ':') {
  1470.     ismethod = 1;
  1471.     fieldsel(ls, v);
  1472.   }
  1473.   return ismethod;
  1474. }
  1475.  
  1476.  
  1477. static void funcstat (LexState *ls, int line) {
  1478.   /* funcstat -> FUNCTION funcname body */
  1479.   int ismethod;
  1480.   expdesc v, b;
  1481.   luaX_next(ls);  /* skip FUNCTION */
  1482.   ismethod = funcname(ls, &v);
  1483.   body(ls, &b, ismethod, line);
  1484.   luaK_storevar(ls->fs, &v, &b);
  1485.   luaK_fixline(ls->fs, line);  /* definition "happens" in the first line */
  1486. }
  1487.  
  1488.  
  1489. static void exprstat (LexState *ls) {
  1490.   /* stat -> func | assignment */
  1491.   FuncState *fs = ls->fs;
  1492.   struct LHS_assign v;
  1493.   suffixedexp(ls, &v.v);
  1494.   if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
  1495.     v.prev = NULL;
  1496.     assignment(ls, &v, 1);
  1497.   }
  1498.   else {  /* stat -> func */
  1499.     check_condition(ls, v.v.k == VCALL, "syntax error");
  1500.     SETARG_C(getinstruction(fs, &v.v), 1);  /* call statement uses no results */
  1501.   }
  1502. }
  1503.  
  1504.  
  1505. static void retstat (LexState *ls) {
  1506.   /* stat -> RETURN [explist] [';'] */
  1507.   FuncState *fs = ls->fs;
  1508.   expdesc e;
  1509.   int first, nret;  /* registers with returned values */
  1510.   if (block_follow(ls, 1) || ls->t.token == ';')
  1511.     first = nret = 0;  /* return no values */
  1512.   else {
  1513.     nret = explist(ls, &e);  /* optional return values */
  1514.     if (hasmultret(e.k)) {
  1515.       luaK_setmultret(fs, &e);
  1516.       if (e.k == VCALL && nret == 1) {  /* tail call? */
  1517.         SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL);
  1518.         lua_assert(GETARG_A(getinstruction(fs,&e)) == fs->nactvar);
  1519.       }
  1520.       first = fs->nactvar;
  1521.       nret = LUA_MULTRET;  /* return all values */
  1522.     }
  1523.     else {
  1524.       if (nret == 1)  /* only one single value? */
  1525.         first = luaK_exp2anyreg(fs, &e);
  1526.       else {
  1527.         luaK_exp2nextreg(fs, &e);  /* values must go to the stack */
  1528.         first = fs->nactvar;  /* return all active values */
  1529.         lua_assert(nret == fs->freereg - first);
  1530.       }
  1531.     }
  1532.   }
  1533.   luaK_ret(fs, first, nret);
  1534.   testnext(ls, ';');  /* skip optional semicolon */
  1535. }
  1536.  
  1537.  
  1538. static void statement (LexState *ls) {
  1539.   int line = ls->linenumber;  /* may be needed for error messages */
  1540.   enterlevel(ls);
  1541.   switch (ls->t.token) {
  1542.     case ';': {  /* stat -> ';' (empty statement) */
  1543.       luaX_next(ls);  /* skip ';' */
  1544.       break;
  1545.     }
  1546.     case TK_IF: {  /* stat -> ifstat */
  1547.       ifstat(ls, line);
  1548.       break;
  1549.     }
  1550.     case TK_WHILE: {  /* stat -> whilestat */
  1551.       whilestat(ls, line);
  1552.       break;
  1553.     }
  1554.     case TK_DO: {  /* stat -> DO block END */
  1555.       luaX_next(ls);  /* skip DO */
  1556.       block(ls);
  1557.       check_match(ls, TK_END, TK_DO, line);
  1558.       break;
  1559.     }
  1560.     case TK_FOR: {  /* stat -> forstat */
  1561.       forstat(ls, line);
  1562.       break;
  1563.     }
  1564.     case TK_REPEAT: {  /* stat -> repeatstat */
  1565.       repeatstat(ls, line);
  1566.       break;
  1567.     }
  1568.     case TK_FUNCTION: {  /* stat -> funcstat */
  1569.       funcstat(ls, line);
  1570.       break;
  1571.     }
  1572.     case TK_LOCAL: {  /* stat -> localstat */
  1573.       luaX_next(ls);  /* skip LOCAL */
  1574.       if (testnext(ls, TK_FUNCTION))  /* local function? */
  1575.         localfunc(ls);
  1576.       else
  1577.         localstat(ls);
  1578.       break;
  1579.     }
  1580.     case TK_DBCOLON: {  /* stat -> label */
  1581.       luaX_next(ls);  /* skip double colon */
  1582.       labelstat(ls, str_checkname(ls), line);
  1583.       break;
  1584.     }
  1585.     case TK_RETURN: {  /* stat -> retstat */
  1586.       luaX_next(ls);  /* skip RETURN */
  1587.       retstat(ls);
  1588.       break;
  1589.     }
  1590.     case TK_BREAK:   /* stat -> breakstat */
  1591.     case TK_GOTO: {  /* stat -> 'goto' NAME */
  1592.       gotostat(ls, luaK_jump(ls->fs));
  1593.       break;
  1594.     }
  1595.     default: {  /* stat -> func | assignment */
  1596.       exprstat(ls);
  1597.       break;
  1598.     }
  1599.   }
  1600.   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
  1601.              ls->fs->freereg >= ls->fs->nactvar);
  1602.   ls->fs->freereg = ls->fs->nactvar;  /* free registers */
  1603.   leavelevel(ls);
  1604. }
  1605.  
  1606. /* }====================================================================== */
  1607.  
  1608.  
  1609. /*
  1610. ** compiles the main function, which is a regular vararg function with an
  1611. ** upvalue named LUA_ENV
  1612. */
  1613. static void mainfunc (LexState *ls, FuncState *fs) {
  1614.   BlockCnt bl;
  1615.   expdesc v;
  1616.   open_func(ls, fs, &bl);
  1617.   fs->f->is_vararg = 1;  /* main function is always declared vararg */
  1618.   init_exp(&v, VLOCAL, 0);  /* create and... */
  1619.   newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
  1620.   luaC_objbarrier(ls->L, fs->f, ls->envn);
  1621.   luaX_next(ls);  /* read first token */
  1622.   statlist(ls);  /* parse main body */
  1623.   check(ls, TK_EOS);
  1624.   close_func(ls);
  1625. }
  1626.  
  1627.  
  1628. LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
  1629.                        Dyndata *dyd, const char *name, int firstchar) {
  1630.   LexState lexstate;
  1631.   FuncState funcstate;
  1632.   LClosure *cl = luaF_newLclosure(L, 1);  /* create main closure */
  1633.   setclLvalue(L, L->top, cl);  /* anchor it (to avoid being collected) */
  1634.   luaD_inctop(L);
  1635.   lexstate.h = luaH_new(L);  /* create table for scanner */
  1636.   sethvalue(L, L->top, lexstate.h);  /* anchor it */
  1637.   luaD_inctop(L);
  1638.   funcstate.f = cl->p = luaF_newproto(L);
  1639.   luaC_objbarrier(L, cl, cl->p);
  1640.   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
  1641.   lua_assert(iswhite(funcstate.f));  /* do not need barrier here */
  1642.   lexstate.buff = buff;
  1643.   lexstate.dyd = dyd;
  1644.   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
  1645.   luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
  1646.   mainfunc(&lexstate, &funcstate);
  1647.   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
  1648.   /* all scopes should be correctly finished */
  1649.   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
  1650.   L->top--;  /* remove scanner's table */
  1651.   return cl;  /* closure is on the stack, too */
  1652. }
  1653.  
  1654.