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  1. /*
  2. ** $Id: lparser.c $
  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 <limits.h>
  14. #include <string.h>
  15.  
  16. #include "lua.h"
  17.  
  18. #include "lcode.h"
  19. #include "ldebug.h"
  20. #include "ldo.h"
  21. #include "lfunc.h"
  22. #include "llex.h"
  23. #include "lmem.h"
  24. #include "lobject.h"
  25. #include "lopcodes.h"
  26. #include "lparser.h"
  27. #include "lstate.h"
  28. #include "lstring.h"
  29. #include "ltable.h"
  30.  
  31.  
  32.  
  33. /* maximum number of local variables per function (must be smaller
  34.    than 250, due to the bytecode format) */
  35. #define MAXVARS         200
  36.  
  37.  
  38. #define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
  39.  
  40.  
  41. /* because all strings are unified by the scanner, the parser
  42.    can use pointer equality for string equality */
  43. #define eqstr(a,b)      ((a) == (b))
  44.  
  45.  
  46. /*
  47. ** nodes for block list (list of active blocks)
  48. */
  49. typedef struct BlockCnt {
  50.   struct BlockCnt *previous;  /* chain */
  51.   int firstlabel;  /* index of first label in this block */
  52.   int firstgoto;  /* index of first pending goto in this block */
  53.   lu_byte nactvar;  /* # active locals outside the block */
  54.   lu_byte upval;  /* true if some variable in the block is an upvalue */
  55.   lu_byte isloop;  /* true if 'block' is a loop */
  56.   lu_byte insidetbc;  /* true if inside the scope of a to-be-closed var. */
  57. } BlockCnt;
  58.  
  59.  
  60.  
  61. /*
  62. ** prototypes for recursive non-terminal functions
  63. */
  64. static void statement (LexState *ls);
  65. static void expr (LexState *ls, expdesc *v);
  66.  
  67.  
  68. static l_noret error_expected (LexState *ls, int token) {
  69.   luaX_syntaxerror(ls,
  70.       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
  71. }
  72.  
  73.  
  74. static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
  75.   lua_State *L = fs->ls->L;
  76.   const char *msg;
  77.   int line = fs->f->linedefined;
  78.   const char *where = (line == 0)
  79.                       ? "main function"
  80.                       : luaO_pushfstring(L, "function at line %d", line);
  81.   msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
  82.                              what, limit, where);
  83.   luaX_syntaxerror(fs->ls, msg);
  84. }
  85.  
  86.  
  87. static void checklimit (FuncState *fs, int v, int l, const char *what) {
  88.   if (v > l) errorlimit(fs, l, what);
  89. }
  90.  
  91.  
  92. /*
  93. ** Test whether next token is 'c'; if so, skip it.
  94. */
  95. static int testnext (LexState *ls, int c) {
  96.   if (ls->t.token == c) {
  97.     luaX_next(ls);
  98.     return 1;
  99.   }
  100.   else return 0;
  101. }
  102.  
  103.  
  104. /*
  105. ** Check that next token is 'c'.
  106. */
  107. static void check (LexState *ls, int c) {
  108.   if (ls->t.token != c)
  109.     error_expected(ls, c);
  110. }
  111.  
  112.  
  113. /*
  114. ** Check that next token is 'c' and skip it.
  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. ** Check that next token is 'what' and skip it. In case of error,
  127. ** raise an error that the expected 'what' should match a 'who'
  128. ** in line 'where' (if that is not the current line).
  129. */
  130. static void check_match (LexState *ls, int what, int who, int where) {
  131.   if (l_unlikely(!testnext(ls, what))) {
  132.     if (where == ls->linenumber)  /* all in the same line? */
  133.       error_expected(ls, what);  /* do not need a complex message */
  134.     else {
  135.       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
  136.              "%s expected (to close %s at line %d)",
  137.               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
  138.     }
  139.   }
  140. }
  141.  
  142.  
  143. static TString *str_checkname (LexState *ls) {
  144.   TString *ts;
  145.   check(ls, TK_NAME);
  146.   ts = ls->t.seminfo.ts;
  147.   luaX_next(ls);
  148.   return ts;
  149. }
  150.  
  151.  
  152. static void init_exp (expdesc *e, expkind k, int i) {
  153.   e->f = e->t = NO_JUMP;
  154.   e->k = k;
  155.   e->u.info = i;
  156. }
  157.  
  158.  
  159. static void codestring (expdesc *e, TString *s) {
  160.   e->f = e->t = NO_JUMP;
  161.   e->k = VKSTR;
  162.   e->u.strval = s;
  163. }
  164.  
  165.  
  166. static void codename (LexState *ls, expdesc *e) {
  167.   codestring(e, str_checkname(ls));
  168. }
  169.  
  170.  
  171. /*
  172. ** Register a new local variable in the active 'Proto' (for debug
  173. ** information).
  174. */
  175. static int registerlocalvar (LexState *ls, FuncState *fs, TString *varname) {
  176.   Proto *f = fs->f;
  177.   int oldsize = f->sizelocvars;
  178.   luaM_growvector(ls->L, f->locvars, fs->ndebugvars, f->sizelocvars,
  179.                   LocVar, SHRT_MAX, "local variables");
  180.   while (oldsize < f->sizelocvars)
  181.     f->locvars[oldsize++].varname = NULL;
  182.   f->locvars[fs->ndebugvars].varname = varname;
  183.   f->locvars[fs->ndebugvars].startpc = fs->pc;
  184.   luaC_objbarrier(ls->L, f, varname);
  185.   return fs->ndebugvars++;
  186. }
  187.  
  188.  
  189. /*
  190. ** Create a new local variable with the given 'name'. Return its index
  191. ** in the function.
  192. */
  193. static int new_localvar (LexState *ls, TString *name) {
  194.   lua_State *L = ls->L;
  195.   FuncState *fs = ls->fs;
  196.   Dyndata *dyd = ls->dyd;
  197.   Vardesc *var;
  198.   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
  199.                  MAXVARS, "local variables");
  200.   luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1,
  201.                   dyd->actvar.size, Vardesc, USHRT_MAX, "local variables");
  202.   var = &dyd->actvar.arr[dyd->actvar.n++];
  203.   var->vd.kind = VDKREG;  /* default */
  204.   var->vd.name = name;
  205.   return dyd->actvar.n - 1 - fs->firstlocal;
  206. }
  207.  
  208. #define new_localvarliteral(ls,v) \
  209.     new_localvar(ls,  \
  210.       luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char)) - 1));
  211.  
  212.  
  213.  
  214. /*
  215. ** Return the "variable description" (Vardesc) of a given variable.
  216. ** (Unless noted otherwise, all variables are referred to by their
  217. ** compiler indices.)
  218. */
  219. static Vardesc *getlocalvardesc (FuncState *fs, int vidx) {
  220.   return &fs->ls->dyd->actvar.arr[fs->firstlocal + vidx];
  221. }
  222.  
  223.  
  224. /*
  225. ** Convert 'nvar', a compiler index level, to its corresponding
  226. ** register. For that, search for the highest variable below that level
  227. ** that is in a register and uses its register index ('ridx') plus one.
  228. */
  229. static int reglevel (FuncState *fs, int nvar) {
  230.   while (nvar-- > 0) {
  231.     Vardesc *vd = getlocalvardesc(fs, nvar);  /* get previous variable */
  232.     if (vd->vd.kind != RDKCTC)  /* is in a register? */
  233.       return vd->vd.ridx + 1;
  234.   }
  235.   return 0;  /* no variables in registers */
  236. }
  237.  
  238.  
  239. /*
  240. ** Return the number of variables in the register stack for the given
  241. ** function.
  242. */
  243. int luaY_nvarstack (FuncState *fs) {
  244.   return reglevel(fs, fs->nactvar);
  245. }
  246.  
  247.  
  248. /*
  249. ** Get the debug-information entry for current variable 'vidx'.
  250. */
  251. static LocVar *localdebuginfo (FuncState *fs, int vidx) {
  252.   Vardesc *vd = getlocalvardesc(fs,  vidx);
  253.   if (vd->vd.kind == RDKCTC)
  254.     return NULL;  /* no debug info. for constants */
  255.   else {
  256.     int idx = vd->vd.pidx;
  257.     lua_assert(idx < fs->ndebugvars);
  258.     return &fs->f->locvars[idx];
  259.   }
  260. }
  261.  
  262.  
  263. /*
  264. ** Create an expression representing variable 'vidx'
  265. */
  266. static void init_var (FuncState *fs, expdesc *e, int vidx) {
  267.   e->f = e->t = NO_JUMP;
  268.   e->k = VLOCAL;
  269.   e->u.var.vidx = vidx;
  270.   e->u.var.ridx = getlocalvardesc(fs, vidx)->vd.ridx;
  271. }
  272.  
  273.  
  274. /*
  275. ** Raises an error if variable described by 'e' is read only
  276. */
  277. static void check_readonly (LexState *ls, expdesc *e) {
  278.   FuncState *fs = ls->fs;
  279.   TString *varname = NULL;  /* to be set if variable is const */
  280.   switch (e->k) {
  281.     case VCONST: {
  282.       varname = ls->dyd->actvar.arr[e->u.info].vd.name;
  283.       break;
  284.     }
  285.     case VLOCAL: {
  286.       Vardesc *vardesc = getlocalvardesc(fs, e->u.var.vidx);
  287.       if (vardesc->vd.kind != VDKREG)  /* not a regular variable? */
  288.         varname = vardesc->vd.name;
  289.       break;
  290.     }
  291.     case VUPVAL: {
  292.       Upvaldesc *up = &fs->f->upvalues[e->u.info];
  293.       if (up->kind != VDKREG)
  294.         varname = up->name;
  295.       break;
  296.     }
  297.     default:
  298.       return;  /* other cases cannot be read-only */
  299.   }
  300.   if (varname) {
  301.     const char *msg = luaO_pushfstring(ls->L,
  302.        "attempt to assign to const variable '%s'", getstr(varname));
  303.     luaK_semerror(ls, msg);  /* error */
  304.   }
  305. }
  306.  
  307.  
  308. /*
  309. ** Start the scope for the last 'nvars' created variables.
  310. */
  311. static void adjustlocalvars (LexState *ls, int nvars) {
  312.   FuncState *fs = ls->fs;
  313.   int reglevel = luaY_nvarstack(fs);
  314.   int i;
  315.   for (i = 0; i < nvars; i++) {
  316.     int vidx = fs->nactvar++;
  317.     Vardesc *var = getlocalvardesc(fs, vidx);
  318.     var->vd.ridx = reglevel++;
  319.     var->vd.pidx = registerlocalvar(ls, fs, var->vd.name);
  320.   }
  321. }
  322.  
  323.  
  324. /*
  325. ** Close the scope for all variables up to level 'tolevel'.
  326. ** (debug info.)
  327. */
  328. static void removevars (FuncState *fs, int tolevel) {
  329.   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
  330.   while (fs->nactvar > tolevel) {
  331.     LocVar *var = localdebuginfo(fs, --fs->nactvar);
  332.     if (var)  /* does it have debug information? */
  333.       var->endpc = fs->pc;
  334.   }
  335. }
  336.  
  337.  
  338. /*
  339. ** Search the upvalues of the function 'fs' for one
  340. ** with the given 'name'.
  341. */
  342. static int searchupvalue (FuncState *fs, TString *name) {
  343.   int i;
  344.   Upvaldesc *up = fs->f->upvalues;
  345.   for (i = 0; i < fs->nups; i++) {
  346.     if (eqstr(up[i].name, name)) return i;
  347.   }
  348.   return -1;  /* not found */
  349. }
  350.  
  351.  
  352. static Upvaldesc *allocupvalue (FuncState *fs) {
  353.   Proto *f = fs->f;
  354.   int oldsize = f->sizeupvalues;
  355.   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
  356.   luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
  357.                   Upvaldesc, MAXUPVAL, "upvalues");
  358.   while (oldsize < f->sizeupvalues)
  359.     f->upvalues[oldsize++].name = NULL;
  360.   return &f->upvalues[fs->nups++];
  361. }
  362.  
  363.  
  364. static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
  365.   Upvaldesc *up = allocupvalue(fs);
  366.   FuncState *prev = fs->prev;
  367.   if (v->k == VLOCAL) {
  368.     up->instack = 1;
  369.     up->idx = v->u.var.ridx;
  370.     up->kind = getlocalvardesc(prev, v->u.var.vidx)->vd.kind;
  371.     lua_assert(eqstr(name, getlocalvardesc(prev, v->u.var.vidx)->vd.name));
  372.   }
  373.   else {
  374.     up->instack = 0;
  375.     up->idx = cast_byte(v->u.info);
  376.     up->kind = prev->f->upvalues[v->u.info].kind;
  377.     lua_assert(eqstr(name, prev->f->upvalues[v->u.info].name));
  378.   }
  379.   up->name = name;
  380.   luaC_objbarrier(fs->ls->L, fs->f, name);
  381.   return fs->nups - 1;
  382. }
  383.  
  384.  
  385. /*
  386. ** Look for an active local variable with the name 'n' in the
  387. ** function 'fs'. If found, initialize 'var' with it and return
  388. ** its expression kind; otherwise return -1.
  389. */
  390. static int searchvar (FuncState *fs, TString *n, expdesc *var) {
  391.   int i;
  392.   for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
  393.     Vardesc *vd = getlocalvardesc(fs, i);
  394.     if (eqstr(n, vd->vd.name)) {  /* found? */
  395.       if (vd->vd.kind == RDKCTC)  /* compile-time constant? */
  396.         init_exp(var, VCONST, fs->firstlocal + i);
  397.       else  /* real variable */
  398.         init_var(fs, var, i);
  399.       return var->k;
  400.     }
  401.   }
  402.   return -1;  /* not found */
  403. }
  404.  
  405.  
  406. /*
  407. ** Mark block where variable at given level was defined
  408. ** (to emit close instructions later).
  409. */
  410. static void markupval (FuncState *fs, int level) {
  411.   BlockCnt *bl = fs->bl;
  412.   while (bl->nactvar > level)
  413.     bl = bl->previous;
  414.   bl->upval = 1;
  415.   fs->needclose = 1;
  416. }
  417.  
  418.  
  419. /*
  420. ** Mark that current block has a to-be-closed variable.
  421. */
  422. static void marktobeclosed (FuncState *fs) {
  423.   BlockCnt *bl = fs->bl;
  424.   bl->upval = 1;
  425.   bl->insidetbc = 1;
  426.   fs->needclose = 1;
  427. }
  428.  
  429.  
  430. /*
  431. ** Find a variable with the given name 'n'. If it is an upvalue, add
  432. ** this upvalue into all intermediate functions. If it is a global, set
  433. ** 'var' as 'void' as a flag.
  434. */
  435. static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
  436.   if (fs == NULL)  /* no more levels? */
  437.     init_exp(var, VVOID, 0);  /* default is global */
  438.   else {
  439.     int v = searchvar(fs, n, var);  /* look up locals at current level */
  440.     if (v >= 0) {  /* found? */
  441.       if (v == VLOCAL && !base)
  442.         markupval(fs, var->u.var.vidx);  /* local will be used as an upval */
  443.     }
  444.     else {  /* not found as local at current level; try upvalues */
  445.       int idx = searchupvalue(fs, n);  /* try existing upvalues */
  446.       if (idx < 0) {  /* not found? */
  447.         singlevaraux(fs->prev, n, var, 0);  /* try upper levels */
  448.         if (var->k == VLOCAL || var->k == VUPVAL)  /* local or upvalue? */
  449.           idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
  450.         else  /* it is a global or a constant */
  451.           return;  /* don't need to do anything at this level */
  452.       }
  453.       init_exp(var, VUPVAL, idx);  /* new or old upvalue */
  454.     }
  455.   }
  456. }
  457.  
  458.  
  459. /*
  460. ** Find a variable with the given name 'n', handling global variables
  461. ** too.
  462. */
  463. static void singlevar (LexState *ls, expdesc *var) {
  464.   TString *varname = str_checkname(ls);
  465.   FuncState *fs = ls->fs;
  466.   singlevaraux(fs, varname, var, 1);
  467.   if (var->k == VVOID) {  /* global name? */
  468.     expdesc key;
  469.     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
  470.     lua_assert(var->k != VVOID);  /* this one must exist */
  471.     codestring(&key, varname);  /* key is variable name */
  472.     luaK_indexed(fs, var, &key);  /* env[varname] */
  473.   }
  474. }
  475.  
  476.  
  477. /*
  478. ** Adjust the number of results from an expression list 'e' with 'nexps'
  479. ** expressions to 'nvars' values.
  480. */
  481. static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
  482.   FuncState *fs = ls->fs;
  483.   int needed = nvars - nexps;  /* extra values needed */
  484.   if (hasmultret(e->k)) {  /* last expression has multiple returns? */
  485.     int extra = needed + 1;  /* discount last expression itself */
  486.     if (extra < 0)
  487.       extra = 0;
  488.     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
  489.   }
  490.   else {
  491.     if (e->k != VVOID)  /* at least one expression? */
  492.       luaK_exp2nextreg(fs, e);  /* close last expression */
  493.     if (needed > 0)  /* missing values? */
  494.       luaK_nil(fs, fs->freereg, needed);  /* complete with nils */
  495.   }
  496.   if (needed > 0)
  497.     luaK_reserveregs(fs, needed);  /* registers for extra values */
  498.   else  /* adding 'needed' is actually a subtraction */
  499.     fs->freereg += needed;  /* remove extra values */
  500. }
  501.  
  502.  
  503. #define enterlevel(ls)  luaE_incCstack(ls->L)
  504.  
  505.  
  506. #define leavelevel(ls) ((ls)->L->nCcalls--)
  507.  
  508.  
  509. /*
  510. ** Generates an error that a goto jumps into the scope of some
  511. ** local variable.
  512. */
  513. static l_noret jumpscopeerror (LexState *ls, Labeldesc *gt) {
  514.   const char *varname = getstr(getlocalvardesc(ls->fs, gt->nactvar)->vd.name);
  515.   const char *msg = "<goto %s> at line %d jumps into the scope of local '%s'";
  516.   msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line, varname);
  517.   luaK_semerror(ls, msg);  /* raise the error */
  518. }
  519.  
  520.  
  521. /*
  522. ** Solves the goto at index 'g' to given 'label' and removes it
  523. ** from the list of pending goto's.
  524. ** If it jumps into the scope of some variable, raises an error.
  525. */
  526. static void solvegoto (LexState *ls, int g, Labeldesc *label) {
  527.   int i;
  528.   Labellist *gl = &ls->dyd->gt;  /* list of goto's */
  529.   Labeldesc *gt = &gl->arr[g];  /* goto to be resolved */
  530.   lua_assert(eqstr(gt->name, label->name));
  531.   if (l_unlikely(gt->nactvar < label->nactvar))  /* enter some scope? */
  532.     jumpscopeerror(ls, gt);
  533.   luaK_patchlist(ls->fs, gt->pc, label->pc);
  534.   for (i = g; i < gl->n - 1; i++)  /* remove goto from pending list */
  535.     gl->arr[i] = gl->arr[i + 1];
  536.   gl->n--;
  537. }
  538.  
  539.  
  540. /*
  541. ** Search for an active label with the given name.
  542. */
  543. static Labeldesc *findlabel (LexState *ls, TString *name) {
  544.   int i;
  545.   Dyndata *dyd = ls->dyd;
  546.   /* check labels in current function for a match */
  547.   for (i = ls->fs->firstlabel; i < dyd->label.n; i++) {
  548.     Labeldesc *lb = &dyd->label.arr[i];
  549.     if (eqstr(lb->name, name))  /* correct label? */
  550.       return lb;
  551.   }
  552.   return NULL;  /* label not found */
  553. }
  554.  
  555.  
  556. /*
  557. ** Adds a new label/goto in the corresponding list.
  558. */
  559. static int newlabelentry (LexState *ls, Labellist *l, TString *name,
  560.                           int line, int pc) {
  561.   int n = l->n;
  562.   luaM_growvector(ls->L, l->arr, n, l->size,
  563.                   Labeldesc, SHRT_MAX, "labels/gotos");
  564.   l->arr[n].name = name;
  565.   l->arr[n].line = line;
  566.   l->arr[n].nactvar = ls->fs->nactvar;
  567.   l->arr[n].close = 0;
  568.   l->arr[n].pc = pc;
  569.   l->n = n + 1;
  570.   return n;
  571. }
  572.  
  573.  
  574. static int newgotoentry (LexState *ls, TString *name, int line, int pc) {
  575.   return newlabelentry(ls, &ls->dyd->gt, name, line, pc);
  576. }
  577.  
  578.  
  579. /*
  580. ** Solves forward jumps. Check whether new label 'lb' matches any
  581. ** pending gotos in current block and solves them. Return true
  582. ** if any of the goto's need to close upvalues.
  583. */
  584. static int solvegotos (LexState *ls, Labeldesc *lb) {
  585.   Labellist *gl = &ls->dyd->gt;
  586.   int i = ls->fs->bl->firstgoto;
  587.   int needsclose = 0;
  588.   while (i < gl->n) {
  589.     if (eqstr(gl->arr[i].name, lb->name)) {
  590.       needsclose |= gl->arr[i].close;
  591.       solvegoto(ls, i, lb);  /* will remove 'i' from the list */
  592.     }
  593.     else
  594.       i++;
  595.   }
  596.   return needsclose;
  597. }
  598.  
  599.  
  600. /*
  601. ** Create a new label with the given 'name' at the given 'line'.
  602. ** 'last' tells whether label is the last non-op statement in its
  603. ** block. Solves all pending goto's to this new label and adds
  604. ** a close instruction if necessary.
  605. ** Returns true iff it added a close instruction.
  606. */
  607. static int createlabel (LexState *ls, TString *name, int line,
  608.                         int last) {
  609.   FuncState *fs = ls->fs;
  610.   Labellist *ll = &ls->dyd->label;
  611.   int l = newlabelentry(ls, ll, name, line, luaK_getlabel(fs));
  612.   if (last) {  /* label is last no-op statement in the block? */
  613.     /* assume that locals are already out of scope */
  614.     ll->arr[l].nactvar = fs->bl->nactvar;
  615.   }
  616.   if (solvegotos(ls, &ll->arr[l])) {  /* need close? */
  617.     luaK_codeABC(fs, OP_CLOSE, luaY_nvarstack(fs), 0, 0);
  618.     return 1;
  619.   }
  620.   return 0;
  621. }
  622.  
  623.  
  624. /*
  625. ** Adjust pending gotos to outer level of a block.
  626. */
  627. static void movegotosout (FuncState *fs, BlockCnt *bl) {
  628.   int i;
  629.   Labellist *gl = &fs->ls->dyd->gt;
  630.   /* correct pending gotos to current block */
  631.   for (i = bl->firstgoto; i < gl->n; i++) {  /* for each pending goto */
  632.     Labeldesc *gt = &gl->arr[i];
  633.     /* leaving a variable scope? */
  634.     if (reglevel(fs, gt->nactvar) > reglevel(fs, bl->nactvar))
  635.       gt->close |= bl->upval;  /* jump may need a close */
  636.     gt->nactvar = bl->nactvar;  /* update goto level */
  637.   }
  638. }
  639.  
  640.  
  641. static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
  642.   bl->isloop = isloop;
  643.   bl->nactvar = fs->nactvar;
  644.   bl->firstlabel = fs->ls->dyd->label.n;
  645.   bl->firstgoto = fs->ls->dyd->gt.n;
  646.   bl->upval = 0;
  647.   bl->insidetbc = (fs->bl != NULL && fs->bl->insidetbc);
  648.   bl->previous = fs->bl;
  649.   fs->bl = bl;
  650.   lua_assert(fs->freereg == luaY_nvarstack(fs));
  651. }
  652.  
  653.  
  654. /*
  655. ** generates an error for an undefined 'goto'.
  656. */
  657. static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
  658.   const char *msg;
  659.   if (eqstr(gt->name, luaS_newliteral(ls->L, "break"))) {
  660.     msg = "break outside loop at line %d";
  661.     msg = luaO_pushfstring(ls->L, msg, gt->line);
  662.   }
  663.   else {
  664.     msg = "no visible label '%s' for <goto> at line %d";
  665.     msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
  666.   }
  667.   luaK_semerror(ls, msg);
  668. }
  669.  
  670.  
  671. static void leaveblock (FuncState *fs) {
  672.   BlockCnt *bl = fs->bl;
  673.   LexState *ls = fs->ls;
  674.   int hasclose = 0;
  675.   int stklevel = reglevel(fs, bl->nactvar);  /* level outside the block */
  676.   if (bl->isloop)  /* fix pending breaks? */
  677.     hasclose = createlabel(ls, luaS_newliteral(ls->L, "break"), 0, 0);
  678.   if (!hasclose && bl->previous && bl->upval)
  679.     luaK_codeABC(fs, OP_CLOSE, stklevel, 0, 0);
  680.   fs->bl = bl->previous;
  681.   removevars(fs, bl->nactvar);
  682.   lua_assert(bl->nactvar == fs->nactvar);
  683.   fs->freereg = stklevel;  /* free registers */
  684.   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
  685.   if (bl->previous)  /* inner block? */
  686.     movegotosout(fs, bl);  /* update pending gotos to outer block */
  687.   else {
  688.     if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
  689.       undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
  690.   }
  691. }
  692.  
  693.  
  694. /*
  695. ** adds a new prototype into list of prototypes
  696. */
  697. static Proto *addprototype (LexState *ls) {
  698.   Proto *clp;
  699.   lua_State *L = ls->L;
  700.   FuncState *fs = ls->fs;
  701.   Proto *f = fs->f;  /* prototype of current function */
  702.   if (fs->np >= f->sizep) {
  703.     int oldsize = f->sizep;
  704.     luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
  705.     while (oldsize < f->sizep)
  706.       f->p[oldsize++] = NULL;
  707.   }
  708.   f->p[fs->np++] = clp = luaF_newproto(L);
  709.   luaC_objbarrier(L, f, clp);
  710.   return clp;
  711. }
  712.  
  713.  
  714. /*
  715. ** codes instruction to create new closure in parent function.
  716. ** The OP_CLOSURE instruction uses the last available register,
  717. ** so that, if it invokes the GC, the GC knows which registers
  718. ** are in use at that time.
  719.  
  720. */
  721. static void codeclosure (LexState *ls, expdesc *v) {
  722.   FuncState *fs = ls->fs->prev;
  723.   init_exp(v, VRELOC, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
  724.   luaK_exp2nextreg(fs, v);  /* fix it at the last register */
  725. }
  726.  
  727.  
  728. static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
  729.   Proto *f = fs->f;
  730.   fs->prev = ls->fs;  /* linked list of funcstates */
  731.   fs->ls = ls;
  732.   ls->fs = fs;
  733.   fs->pc = 0;
  734.   fs->previousline = f->linedefined;
  735.   fs->iwthabs = 0;
  736.   fs->lasttarget = 0;
  737.   fs->freereg = 0;
  738.   fs->nk = 0;
  739.   fs->nabslineinfo = 0;
  740.   fs->np = 0;
  741.   fs->nups = 0;
  742.   fs->ndebugvars = 0;
  743.   fs->nactvar = 0;
  744.   fs->needclose = 0;
  745.   fs->firstlocal = ls->dyd->actvar.n;
  746.   fs->firstlabel = ls->dyd->label.n;
  747.   fs->bl = NULL;
  748.   f->source = ls->source;
  749.   luaC_objbarrier(ls->L, f, f->source);
  750.   f->maxstacksize = 2;  /* registers 0/1 are always valid */
  751.   enterblock(fs, bl, 0);
  752. }
  753.  
  754.  
  755. static void close_func (LexState *ls) {
  756.   lua_State *L = ls->L;
  757.   FuncState *fs = ls->fs;
  758.   Proto *f = fs->f;
  759.   luaK_ret(fs, luaY_nvarstack(fs), 0);  /* final return */
  760.   leaveblock(fs);
  761.   lua_assert(fs->bl == NULL);
  762.   luaK_finish(fs);
  763.   luaM_shrinkvector(L, f->code, f->sizecode, fs->pc, Instruction);
  764.   luaM_shrinkvector(L, f->lineinfo, f->sizelineinfo, fs->pc, ls_byte);
  765.   luaM_shrinkvector(L, f->abslineinfo, f->sizeabslineinfo,
  766.                        fs->nabslineinfo, AbsLineInfo);
  767.   luaM_shrinkvector(L, f->k, f->sizek, fs->nk, TValue);
  768.   luaM_shrinkvector(L, f->p, f->sizep, fs->np, Proto *);
  769.   luaM_shrinkvector(L, f->locvars, f->sizelocvars, fs->ndebugvars, LocVar);
  770.   luaM_shrinkvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
  771.   ls->fs = fs->prev;
  772.   luaC_checkGC(L);
  773. }
  774.  
  775.  
  776.  
  777. /*============================================================*/
  778. /* GRAMMAR RULES */
  779. /*============================================================*/
  780.  
  781.  
  782. /*
  783. ** check whether current token is in the follow set of a block.
  784. ** 'until' closes syntactical blocks, but do not close scope,
  785. ** so it is handled in separate.
  786. */
  787. static int block_follow (LexState *ls, int withuntil) {
  788.   switch (ls->t.token) {
  789.     case TK_ELSE: case TK_ELSEIF:
  790.     case TK_END: case TK_EOS:
  791.       return 1;
  792.     case TK_UNTIL: return withuntil;
  793.     default: return 0;
  794.   }
  795. }
  796.  
  797.  
  798. static void statlist (LexState *ls) {
  799.   /* statlist -> { stat [';'] } */
  800.   while (!block_follow(ls, 1)) {
  801.     if (ls->t.token == TK_RETURN) {
  802.       statement(ls);
  803.       return;  /* 'return' must be last statement */
  804.     }
  805.     statement(ls);
  806.   }
  807. }
  808.  
  809.  
  810. static void fieldsel (LexState *ls, expdesc *v) {
  811.   /* fieldsel -> ['.' | ':'] NAME */
  812.   FuncState *fs = ls->fs;
  813.   expdesc key;
  814.   luaK_exp2anyregup(fs, v);
  815.   luaX_next(ls);  /* skip the dot or colon */
  816.   codename(ls, &key);
  817.   luaK_indexed(fs, v, &key);
  818. }
  819.  
  820.  
  821. static void yindex (LexState *ls, expdesc *v) {
  822.   /* index -> '[' expr ']' */
  823.   luaX_next(ls);  /* skip the '[' */
  824.   expr(ls, v);
  825.   luaK_exp2val(ls->fs, v);
  826.   checknext(ls, ']');
  827. }
  828.  
  829.  
  830. /*
  831. ** {======================================================================
  832. ** Rules for Constructors
  833. ** =======================================================================
  834. */
  835.  
  836.  
  837. typedef struct ConsControl {
  838.   expdesc v;  /* last list item read */
  839.   expdesc *t;  /* table descriptor */
  840.   int nh;  /* total number of 'record' elements */
  841.   int na;  /* number of array elements already stored */
  842.   int tostore;  /* number of array elements pending to be stored */
  843. } ConsControl;
  844.  
  845.  
  846. static void recfield (LexState *ls, ConsControl *cc) {
  847.   /* recfield -> (NAME | '['exp']') = exp */
  848.   FuncState *fs = ls->fs;
  849.   int reg = ls->fs->freereg;
  850.   expdesc tab, key, val;
  851.   if (ls->t.token == TK_NAME) {
  852.     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
  853.     codename(ls, &key);
  854.   }
  855.   else  /* ls->t.token == '[' */
  856.     yindex(ls, &key);
  857.   cc->nh++;
  858.   checknext(ls, '=');
  859.   tab = *cc->t;
  860.   luaK_indexed(fs, &tab, &key);
  861.   expr(ls, &val);
  862.   luaK_storevar(fs, &tab, &val);
  863.   fs->freereg = reg;  /* free registers */
  864. }
  865.  
  866.  
  867. static void closelistfield (FuncState *fs, ConsControl *cc) {
  868.   if (cc->v.k == VVOID) return;  /* there is no list item */
  869.   luaK_exp2nextreg(fs, &cc->v);
  870.   cc->v.k = VVOID;
  871.   if (cc->tostore == LFIELDS_PER_FLUSH) {
  872.     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
  873.     cc->na += cc->tostore;
  874.     cc->tostore = 0;  /* no more items pending */
  875.   }
  876. }
  877.  
  878.  
  879. static void lastlistfield (FuncState *fs, ConsControl *cc) {
  880.   if (cc->tostore == 0) return;
  881.   if (hasmultret(cc->v.k)) {
  882.     luaK_setmultret(fs, &cc->v);
  883.     luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
  884.     cc->na--;  /* do not count last expression (unknown number of elements) */
  885.   }
  886.   else {
  887.     if (cc->v.k != VVOID)
  888.       luaK_exp2nextreg(fs, &cc->v);
  889.     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
  890.   }
  891.   cc->na += cc->tostore;
  892. }
  893.  
  894.  
  895. static void listfield (LexState *ls, ConsControl *cc) {
  896.   /* listfield -> exp */
  897.   expr(ls, &cc->v);
  898.   cc->tostore++;
  899. }
  900.  
  901.  
  902. static void field (LexState *ls, ConsControl *cc) {
  903.   /* field -> listfield | recfield */
  904.   switch(ls->t.token) {
  905.     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
  906.       if (luaX_lookahead(ls) != '=')  /* expression? */
  907.         listfield(ls, cc);
  908.       else
  909.         recfield(ls, cc);
  910.       break;
  911.     }
  912.     case '[': {
  913.       recfield(ls, cc);
  914.       break;
  915.     }
  916.     default: {
  917.       listfield(ls, cc);
  918.       break;
  919.     }
  920.   }
  921. }
  922.  
  923.  
  924. static void constructor (LexState *ls, expdesc *t) {
  925.   /* constructor -> '{' [ field { sep field } [sep] ] '}'
  926.      sep -> ',' | ';' */
  927.   FuncState *fs = ls->fs;
  928.   int line = ls->linenumber;
  929.   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
  930.   ConsControl cc;
  931.   luaK_code(fs, 0);  /* space for extra arg. */
  932.   cc.na = cc.nh = cc.tostore = 0;
  933.   cc.t = t;
  934.   init_exp(t, VNONRELOC, fs->freereg);  /* table will be at stack top */
  935.   luaK_reserveregs(fs, 1);
  936.   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
  937.   checknext(ls, '{');
  938.   do {
  939.     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
  940.     if (ls->t.token == '}') break;
  941.     closelistfield(fs, &cc);
  942.     field(ls, &cc);
  943.   } while (testnext(ls, ',') || testnext(ls, ';'));
  944.   check_match(ls, '}', '{', line);
  945.   lastlistfield(fs, &cc);
  946.   luaK_settablesize(fs, pc, t->u.info, cc.na, cc.nh);
  947. }
  948.  
  949. /* }====================================================================== */
  950.  
  951.  
  952. static void setvararg (FuncState *fs, int nparams) {
  953.   fs->f->is_vararg = 1;
  954.   luaK_codeABC(fs, OP_VARARGPREP, nparams, 0, 0);
  955. }
  956.  
  957.  
  958. static void parlist (LexState *ls) {
  959.   /* parlist -> [ {NAME ','} (NAME | '...') ] */
  960.   FuncState *fs = ls->fs;
  961.   Proto *f = fs->f;
  962.   int nparams = 0;
  963.   int isvararg = 0;
  964.   if (ls->t.token != ')') {  /* is 'parlist' not empty? */
  965.     do {
  966.       switch (ls->t.token) {
  967.         case TK_NAME: {
  968.           new_localvar(ls, str_checkname(ls));
  969.           nparams++;
  970.           break;
  971.         }
  972.         case TK_DOTS: {
  973.           luaX_next(ls);
  974.           isvararg = 1;
  975.           break;
  976.         }
  977.         default: luaX_syntaxerror(ls, "<name> or '...' expected");
  978.       }
  979.     } while (!isvararg && testnext(ls, ','));
  980.   }
  981.   adjustlocalvars(ls, nparams);
  982.   f->numparams = cast_byte(fs->nactvar);
  983.   if (isvararg)
  984.     setvararg(fs, f->numparams);  /* declared vararg */
  985.   luaK_reserveregs(fs, fs->nactvar);  /* reserve registers for parameters */
  986. }
  987.  
  988.  
  989. static void body (LexState *ls, expdesc *e, int ismethod, int line) {
  990.   /* body ->  '(' parlist ')' block END */
  991.   FuncState new_fs;
  992.   BlockCnt bl;
  993.   new_fs.f = addprototype(ls);
  994.   new_fs.f->linedefined = line;
  995.   open_func(ls, &new_fs, &bl);
  996.   checknext(ls, '(');
  997.   if (ismethod) {
  998.     new_localvarliteral(ls, "self");  /* create 'self' parameter */
  999.     adjustlocalvars(ls, 1);
  1000.   }
  1001.   parlist(ls);
  1002.   checknext(ls, ')');
  1003.   statlist(ls);
  1004.   new_fs.f->lastlinedefined = ls->linenumber;
  1005.   check_match(ls, TK_END, TK_FUNCTION, line);
  1006.   codeclosure(ls, e);
  1007.   close_func(ls);
  1008. }
  1009.  
  1010.  
  1011. static int explist (LexState *ls, expdesc *v) {
  1012.   /* explist -> expr { ',' expr } */
  1013.   int n = 1;  /* at least one expression */
  1014.   expr(ls, v);
  1015.   while (testnext(ls, ',')) {
  1016.     luaK_exp2nextreg(ls->fs, v);
  1017.     expr(ls, v);
  1018.     n++;
  1019.   }
  1020.   return n;
  1021. }
  1022.  
  1023.  
  1024. static void funcargs (LexState *ls, expdesc *f, int line) {
  1025.   FuncState *fs = ls->fs;
  1026.   expdesc args;
  1027.   int base, nparams;
  1028.   switch (ls->t.token) {
  1029.     case '(': {  /* funcargs -> '(' [ explist ] ')' */
  1030.       luaX_next(ls);
  1031.       if (ls->t.token == ')')  /* arg list is empty? */
  1032.         args.k = VVOID;
  1033.       else {
  1034.         explist(ls, &args);
  1035.         if (hasmultret(args.k))
  1036.           luaK_setmultret(fs, &args);
  1037.       }
  1038.       check_match(ls, ')', '(', line);
  1039.       break;
  1040.     }
  1041.     case '{': {  /* funcargs -> constructor */
  1042.       constructor(ls, &args);
  1043.       break;
  1044.     }
  1045.     case TK_STRING: {  /* funcargs -> STRING */
  1046.       codestring(&args, ls->t.seminfo.ts);
  1047.       luaX_next(ls);  /* must use 'seminfo' before 'next' */
  1048.       break;
  1049.     }
  1050.     default: {
  1051.       luaX_syntaxerror(ls, "function arguments expected");
  1052.     }
  1053.   }
  1054.   lua_assert(f->k == VNONRELOC);
  1055.   base = f->u.info;  /* base register for call */
  1056.   if (hasmultret(args.k))
  1057.     nparams = LUA_MULTRET;  /* open call */
  1058.   else {
  1059.     if (args.k != VVOID)
  1060.       luaK_exp2nextreg(fs, &args);  /* close last argument */
  1061.     nparams = fs->freereg - (base+1);
  1062.   }
  1063.   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
  1064.   luaK_fixline(fs, line);
  1065.   fs->freereg = base+1;  /* call remove function and arguments and leaves
  1066.                             (unless changed) one result */
  1067. }
  1068.  
  1069.  
  1070.  
  1071.  
  1072. /*
  1073. ** {======================================================================
  1074. ** Expression parsing
  1075. ** =======================================================================
  1076. */
  1077.  
  1078.  
  1079. static void primaryexp (LexState *ls, expdesc *v) {
  1080.   /* primaryexp -> NAME | '(' expr ')' */
  1081.   switch (ls->t.token) {
  1082.     case '(': {
  1083.       int line = ls->linenumber;
  1084.       luaX_next(ls);
  1085.       expr(ls, v);
  1086.       check_match(ls, ')', '(', line);
  1087.       luaK_dischargevars(ls->fs, v);
  1088.       return;
  1089.     }
  1090.     case TK_NAME: {
  1091.       singlevar(ls, v);
  1092.       return;
  1093.     }
  1094.     default: {
  1095.       luaX_syntaxerror(ls, "unexpected symbol");
  1096.     }
  1097.   }
  1098. }
  1099.  
  1100.  
  1101. static void suffixedexp (LexState *ls, expdesc *v) {
  1102.   /* suffixedexp ->
  1103.        primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
  1104.   FuncState *fs = ls->fs;
  1105.   int line = ls->linenumber;
  1106.   primaryexp(ls, v);
  1107.   for (;;) {
  1108.     switch (ls->t.token) {
  1109.       case '.': {  /* fieldsel */
  1110.         fieldsel(ls, v);
  1111.         break;
  1112.       }
  1113.       case '[': {  /* '[' exp ']' */
  1114.         expdesc key;
  1115.         luaK_exp2anyregup(fs, v);
  1116.         yindex(ls, &key);
  1117.         luaK_indexed(fs, v, &key);
  1118.         break;
  1119.       }
  1120.       case ':': {  /* ':' NAME funcargs */
  1121.         expdesc key;
  1122.         luaX_next(ls);
  1123.         codename(ls, &key);
  1124.         luaK_self(fs, v, &key);
  1125.         funcargs(ls, v, line);
  1126.         break;
  1127.       }
  1128.       case '(': case TK_STRING: case '{': {  /* funcargs */
  1129.         luaK_exp2nextreg(fs, v);
  1130.         funcargs(ls, v, line);
  1131.         break;
  1132.       }
  1133.       default: return;
  1134.     }
  1135.   }
  1136. }
  1137.  
  1138.  
  1139. static void simpleexp (LexState *ls, expdesc *v) {
  1140.   /* simpleexp -> FLT | INT | STRING | NIL | TRUE | FALSE | ... |
  1141.                   constructor | FUNCTION body | suffixedexp */
  1142.   switch (ls->t.token) {
  1143.     case TK_FLT: {
  1144.       init_exp(v, VKFLT, 0);
  1145.       v->u.nval = ls->t.seminfo.r;
  1146.       break;
  1147.     }
  1148.     case TK_INT: {
  1149.       init_exp(v, VKINT, 0);
  1150.       v->u.ival = ls->t.seminfo.i;
  1151.       break;
  1152.     }
  1153.     case TK_STRING: {
  1154.       codestring(v, ls->t.seminfo.ts);
  1155.       break;
  1156.     }
  1157.     case TK_NIL: {
  1158.       init_exp(v, VNIL, 0);
  1159.       break;
  1160.     }
  1161.     case TK_TRUE: {
  1162.       init_exp(v, VTRUE, 0);
  1163.       break;
  1164.     }
  1165.     case TK_FALSE: {
  1166.       init_exp(v, VFALSE, 0);
  1167.       break;
  1168.     }
  1169.     case TK_DOTS: {  /* vararg */
  1170.       FuncState *fs = ls->fs;
  1171.       check_condition(ls, fs->f->is_vararg,
  1172.                       "cannot use '...' outside a vararg function");
  1173.       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 0, 1));
  1174.       break;
  1175.     }
  1176.     case '{': {  /* constructor */
  1177.       constructor(ls, v);
  1178.       return;
  1179.     }
  1180.     case TK_FUNCTION: {
  1181.       luaX_next(ls);
  1182.       body(ls, v, 0, ls->linenumber);
  1183.       return;
  1184.     }
  1185.     default: {
  1186.       suffixedexp(ls, v);
  1187.       return;
  1188.     }
  1189.   }
  1190.   luaX_next(ls);
  1191. }
  1192.  
  1193.  
  1194. static UnOpr getunopr (int op) {
  1195.   switch (op) {
  1196.     case TK_NOT: return OPR_NOT;
  1197.     case '-': return OPR_MINUS;
  1198.     case '~': return OPR_BNOT;
  1199.     case '#': return OPR_LEN;
  1200.     default: return OPR_NOUNOPR;
  1201.   }
  1202. }
  1203.  
  1204.  
  1205. static BinOpr getbinopr (int op) {
  1206.   switch (op) {
  1207.     case '+': return OPR_ADD;
  1208.     case '-': return OPR_SUB;
  1209.     case '*': return OPR_MUL;
  1210.     case '%': return OPR_MOD;
  1211.     case '^': return OPR_POW;
  1212.     case '/': return OPR_DIV;
  1213.     case TK_IDIV: return OPR_IDIV;
  1214.     case '&': return OPR_BAND;
  1215.     case '|': return OPR_BOR;
  1216.     case '~': return OPR_BXOR;
  1217.     case TK_SHL: return OPR_SHL;
  1218.     case TK_SHR: return OPR_SHR;
  1219.     case TK_CONCAT: return OPR_CONCAT;
  1220.     case TK_NE: return OPR_NE;
  1221.     case TK_EQ: return OPR_EQ;
  1222.     case '<': return OPR_LT;
  1223.     case TK_LE: return OPR_LE;
  1224.     case '>': return OPR_GT;
  1225.     case TK_GE: return OPR_GE;
  1226.     case TK_AND: return OPR_AND;
  1227.     case TK_OR: return OPR_OR;
  1228.     default: return OPR_NOBINOPR;
  1229.   }
  1230. }
  1231.  
  1232.  
  1233. /*
  1234. ** Priority table for binary operators.
  1235. */
  1236. static const struct {
  1237.   lu_byte left;  /* left priority for each binary operator */
  1238.   lu_byte right; /* right priority */
  1239. } priority[] = {  /* ORDER OPR */
  1240.    {10, 10}, {10, 10},           /* '+' '-' */
  1241.    {11, 11}, {11, 11},           /* '*' '%' */
  1242.    {14, 13},                  /* '^' (right associative) */
  1243.    {11, 11}, {11, 11},           /* '/' '//' */
  1244.    {6, 6}, {4, 4}, {5, 5},   /* '&' '|' '~' */
  1245.    {7, 7}, {7, 7},           /* '<<' '>>' */
  1246.    {9, 8},                   /* '..' (right associative) */
  1247.    {3, 3}, {3, 3}, {3, 3},   /* ==, <, <= */
  1248.    {3, 3}, {3, 3}, {3, 3},   /* ~=, >, >= */
  1249.    {2, 2}, {1, 1}            /* and, or */
  1250. };
  1251.  
  1252. #define UNARY_PRIORITY  12  /* priority for unary operators */
  1253.  
  1254.  
  1255. /*
  1256. ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
  1257. ** where 'binop' is any binary operator with a priority higher than 'limit'
  1258. */
  1259. static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
  1260.   BinOpr op;
  1261.   UnOpr uop;
  1262.   enterlevel(ls);
  1263.   uop = getunopr(ls->t.token);
  1264.   if (uop != OPR_NOUNOPR) {  /* prefix (unary) operator? */
  1265.     int line = ls->linenumber;
  1266.     luaX_next(ls);  /* skip operator */
  1267.     subexpr(ls, v, UNARY_PRIORITY);
  1268.     luaK_prefix(ls->fs, uop, v, line);
  1269.   }
  1270.   else simpleexp(ls, v);
  1271.   /* expand while operators have priorities higher than 'limit' */
  1272.   op = getbinopr(ls->t.token);
  1273.   while (op != OPR_NOBINOPR && priority[op].left > limit) {
  1274.     expdesc v2;
  1275.     BinOpr nextop;
  1276.     int line = ls->linenumber;
  1277.     luaX_next(ls);  /* skip operator */
  1278.     luaK_infix(ls->fs, op, v);
  1279.     /* read sub-expression with higher priority */
  1280.     nextop = subexpr(ls, &v2, priority[op].right);
  1281.     luaK_posfix(ls->fs, op, v, &v2, line);
  1282.     op = nextop;
  1283.   }
  1284.   leavelevel(ls);
  1285.   return op;  /* return first untreated operator */
  1286. }
  1287.  
  1288.  
  1289. static void expr (LexState *ls, expdesc *v) {
  1290.   subexpr(ls, v, 0);
  1291. }
  1292.  
  1293. /* }==================================================================== */
  1294.  
  1295.  
  1296.  
  1297. /*
  1298. ** {======================================================================
  1299. ** Rules for Statements
  1300. ** =======================================================================
  1301. */
  1302.  
  1303.  
  1304. static void block (LexState *ls) {
  1305.   /* block -> statlist */
  1306.   FuncState *fs = ls->fs;
  1307.   BlockCnt bl;
  1308.   enterblock(fs, &bl, 0);
  1309.   statlist(ls);
  1310.   leaveblock(fs);
  1311. }
  1312.  
  1313.  
  1314. /*
  1315. ** structure to chain all variables in the left-hand side of an
  1316. ** assignment
  1317. */
  1318. struct LHS_assign {
  1319.   struct LHS_assign *prev;
  1320.   expdesc v;  /* variable (global, local, upvalue, or indexed) */
  1321. };
  1322.  
  1323.  
  1324. /*
  1325. ** check whether, in an assignment to an upvalue/local variable, the
  1326. ** upvalue/local variable is begin used in a previous assignment to a
  1327. ** table. If so, save original upvalue/local value in a safe place and
  1328. ** use this safe copy in the previous assignment.
  1329. */
  1330. static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
  1331.   FuncState *fs = ls->fs;
  1332.   int extra = fs->freereg;  /* eventual position to save local variable */
  1333.   int conflict = 0;
  1334.   for (; lh; lh = lh->prev) {  /* check all previous assignments */
  1335.     if (vkisindexed(lh->v.k)) {  /* assignment to table field? */
  1336.       if (lh->v.k == VINDEXUP) {  /* is table an upvalue? */
  1337.         if (v->k == VUPVAL && lh->v.u.ind.t == v->u.info) {
  1338.           conflict = 1;  /* table is the upvalue being assigned now */
  1339.           lh->v.k = VINDEXSTR;
  1340.           lh->v.u.ind.t = extra;  /* assignment will use safe copy */
  1341.         }
  1342.       }
  1343.       else {  /* table is a register */
  1344.         if (v->k == VLOCAL && lh->v.u.ind.t == v->u.var.ridx) {
  1345.           conflict = 1;  /* table is the local being assigned now */
  1346.           lh->v.u.ind.t = extra;  /* assignment will use safe copy */
  1347.         }
  1348.         /* is index the local being assigned? */
  1349.         if (lh->v.k == VINDEXED && v->k == VLOCAL &&
  1350.             lh->v.u.ind.idx == v->u.var.ridx) {
  1351.           conflict = 1;
  1352.           lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
  1353.         }
  1354.       }
  1355.     }
  1356.   }
  1357.   if (conflict) {
  1358.     /* copy upvalue/local value to a temporary (in position 'extra') */
  1359.     if (v->k == VLOCAL)
  1360.       luaK_codeABC(fs, OP_MOVE, extra, v->u.var.ridx, 0);
  1361.     else
  1362.       luaK_codeABC(fs, OP_GETUPVAL, extra, v->u.info, 0);
  1363.     luaK_reserveregs(fs, 1);
  1364.   }
  1365. }
  1366.  
  1367. /*
  1368. ** Parse and compile a multiple assignment. The first "variable"
  1369. ** (a 'suffixedexp') was already read by the caller.
  1370. **
  1371. ** assignment -> suffixedexp restassign
  1372. ** restassign -> ',' suffixedexp restassign | '=' explist
  1373. */
  1374. static void restassign (LexState *ls, struct LHS_assign *lh, int nvars) {
  1375.   expdesc e;
  1376.   check_condition(ls, vkisvar(lh->v.k), "syntax error");
  1377.   check_readonly(ls, &lh->v);
  1378.   if (testnext(ls, ',')) {  /* restassign -> ',' suffixedexp restassign */
  1379.     struct LHS_assign nv;
  1380.     nv.prev = lh;
  1381.     suffixedexp(ls, &nv.v);
  1382.     if (!vkisindexed(nv.v.k))
  1383.       check_conflict(ls, lh, &nv.v);
  1384.     enterlevel(ls);  /* control recursion depth */
  1385.     restassign(ls, &nv, nvars+1);
  1386.     leavelevel(ls);
  1387.   }
  1388.   else {  /* restassign -> '=' explist */
  1389.     int nexps;
  1390.     checknext(ls, '=');
  1391.     nexps = explist(ls, &e);
  1392.     if (nexps != nvars)
  1393.       adjust_assign(ls, nvars, nexps, &e);
  1394.     else {
  1395.       luaK_setoneret(ls->fs, &e);  /* close last expression */
  1396.       luaK_storevar(ls->fs, &lh->v, &e);
  1397.       return;  /* avoid default */
  1398.     }
  1399.   }
  1400.   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
  1401.   luaK_storevar(ls->fs, &lh->v, &e);
  1402. }
  1403.  
  1404.  
  1405. static int cond (LexState *ls) {
  1406.   /* cond -> exp */
  1407.   expdesc v;
  1408.   expr(ls, &v);  /* read condition */
  1409.   if (v.k == VNIL) v.k = VFALSE;  /* 'falses' are all equal here */
  1410.   luaK_goiftrue(ls->fs, &v);
  1411.   return v.f;
  1412. }
  1413.  
  1414.  
  1415. static void gotostat (LexState *ls) {
  1416.   FuncState *fs = ls->fs;
  1417.   int line = ls->linenumber;
  1418.   TString *name = str_checkname(ls);  /* label's name */
  1419.   Labeldesc *lb = findlabel(ls, name);
  1420.   if (lb == NULL)  /* no label? */
  1421.     /* forward jump; will be resolved when the label is declared */
  1422.     newgotoentry(ls, name, line, luaK_jump(fs));
  1423.   else {  /* found a label */
  1424.     /* backward jump; will be resolved here */
  1425.     int lblevel = reglevel(fs, lb->nactvar);  /* label level */
  1426.     if (luaY_nvarstack(fs) > lblevel)  /* leaving the scope of a variable? */
  1427.       luaK_codeABC(fs, OP_CLOSE, lblevel, 0, 0);
  1428.     /* create jump and link it to the label */
  1429.     luaK_patchlist(fs, luaK_jump(fs), lb->pc);
  1430.   }
  1431. }
  1432.  
  1433.  
  1434. /*
  1435. ** Break statement. Semantically equivalent to "goto break".
  1436. */
  1437. static void breakstat (LexState *ls) {
  1438.   int line = ls->linenumber;
  1439.   luaX_next(ls);  /* skip break */
  1440.   newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, luaK_jump(ls->fs));
  1441. }
  1442.  
  1443.  
  1444. /*
  1445. ** Check whether there is already a label with the given 'name'.
  1446. */
  1447. static void checkrepeated (LexState *ls, TString *name) {
  1448.   Labeldesc *lb = findlabel(ls, name);
  1449.   if (l_unlikely(lb != NULL)) {  /* already defined? */
  1450.     const char *msg = "label '%s' already defined on line %d";
  1451.     msg = luaO_pushfstring(ls->L, msg, getstr(name), lb->line);
  1452.     luaK_semerror(ls, msg);  /* error */
  1453.   }
  1454. }
  1455.  
  1456.  
  1457. static void labelstat (LexState *ls, TString *name, int line) {
  1458.   /* label -> '::' NAME '::' */
  1459.   checknext(ls, TK_DBCOLON);  /* skip double colon */
  1460.   while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
  1461.     statement(ls);  /* skip other no-op statements */
  1462.   checkrepeated(ls, name);  /* check for repeated labels */
  1463.   createlabel(ls, name, line, block_follow(ls, 0));
  1464. }
  1465.  
  1466.  
  1467. static void whilestat (LexState *ls, int line) {
  1468.   /* whilestat -> WHILE cond DO block END */
  1469.   FuncState *fs = ls->fs;
  1470.   int whileinit;
  1471.   int condexit;
  1472.   BlockCnt bl;
  1473.   luaX_next(ls);  /* skip WHILE */
  1474.   whileinit = luaK_getlabel(fs);
  1475.   condexit = cond(ls);
  1476.   enterblock(fs, &bl, 1);
  1477.   checknext(ls, TK_DO);
  1478.   block(ls);
  1479.   luaK_jumpto(fs, whileinit);
  1480.   check_match(ls, TK_END, TK_WHILE, line);
  1481.   leaveblock(fs);
  1482.   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
  1483. }
  1484.  
  1485.  
  1486. static void repeatstat (LexState *ls, int line) {
  1487.   /* repeatstat -> REPEAT block UNTIL cond */
  1488.   int condexit;
  1489.   FuncState *fs = ls->fs;
  1490.   int repeat_init = luaK_getlabel(fs);
  1491.   BlockCnt bl1, bl2;
  1492.   enterblock(fs, &bl1, 1);  /* loop block */
  1493.   enterblock(fs, &bl2, 0);  /* scope block */
  1494.   luaX_next(ls);  /* skip REPEAT */
  1495.   statlist(ls);
  1496.   check_match(ls, TK_UNTIL, TK_REPEAT, line);
  1497.   condexit = cond(ls);  /* read condition (inside scope block) */
  1498.   leaveblock(fs);  /* finish scope */
  1499.   if (bl2.upval) {  /* upvalues? */
  1500.     int exit = luaK_jump(fs);  /* normal exit must jump over fix */
  1501.     luaK_patchtohere(fs, condexit);  /* repetition must close upvalues */
  1502.     luaK_codeABC(fs, OP_CLOSE, reglevel(fs, bl2.nactvar), 0, 0);
  1503.     condexit = luaK_jump(fs);  /* repeat after closing upvalues */
  1504.     luaK_patchtohere(fs, exit);  /* normal exit comes to here */
  1505.   }
  1506.   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
  1507.   leaveblock(fs);  /* finish loop */
  1508. }
  1509.  
  1510.  
  1511. /*
  1512. ** Read an expression and generate code to put its results in next
  1513. ** stack slot.
  1514. **
  1515. */
  1516. static void exp1 (LexState *ls) {
  1517.   expdesc e;
  1518.   expr(ls, &e);
  1519.   luaK_exp2nextreg(ls->fs, &e);
  1520.   lua_assert(e.k == VNONRELOC);
  1521. }
  1522.  
  1523.  
  1524. /*
  1525. ** Fix for instruction at position 'pc' to jump to 'dest'.
  1526. ** (Jump addresses are relative in Lua). 'back' true means
  1527. ** a back jump.
  1528. */
  1529. static void fixforjump (FuncState *fs, int pc, int dest, int back) {
  1530.   Instruction *jmp = &fs->f->code[pc];
  1531.   int offset = dest - (pc + 1);
  1532.   if (back)
  1533.     offset = -offset;
  1534.   if (l_unlikely(offset > MAXARG_Bx))
  1535.     luaX_syntaxerror(fs->ls, "control structure too long");
  1536.   SETARG_Bx(*jmp, offset);
  1537. }
  1538.  
  1539.  
  1540. /*
  1541. ** Generate code for a 'for' loop.
  1542. */
  1543. static void forbody (LexState *ls, int base, int line, int nvars, int isgen) {
  1544.   /* forbody -> DO block */
  1545.   static const OpCode forprep[2] = {OP_FORPREP, OP_TFORPREP};
  1546.   static const OpCode forloop[2] = {OP_FORLOOP, OP_TFORLOOP};
  1547.   BlockCnt bl;
  1548.   FuncState *fs = ls->fs;
  1549.   int prep, endfor;
  1550.   checknext(ls, TK_DO);
  1551.   prep = luaK_codeABx(fs, forprep[isgen], base, 0);
  1552.   enterblock(fs, &bl, 0);  /* scope for declared variables */
  1553.   adjustlocalvars(ls, nvars);
  1554.   luaK_reserveregs(fs, nvars);
  1555.   block(ls);
  1556.   leaveblock(fs);  /* end of scope for declared variables */
  1557.   fixforjump(fs, prep, luaK_getlabel(fs), 0);
  1558.   if (isgen) {  /* generic for? */
  1559.     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
  1560.     luaK_fixline(fs, line);
  1561.   }
  1562.   endfor = luaK_codeABx(fs, forloop[isgen], base, 0);
  1563.   fixforjump(fs, endfor, prep + 1, 1);
  1564.   luaK_fixline(fs, line);
  1565. }
  1566.  
  1567.  
  1568. static void fornum (LexState *ls, TString *varname, int line) {
  1569.   /* fornum -> NAME = exp,exp[,exp] forbody */
  1570.   FuncState *fs = ls->fs;
  1571.   int base = fs->freereg;
  1572.   new_localvarliteral(ls, "(for state)");
  1573.   new_localvarliteral(ls, "(for state)");
  1574.   new_localvarliteral(ls, "(for state)");
  1575.   new_localvar(ls, varname);
  1576.   checknext(ls, '=');
  1577.   exp1(ls);  /* initial value */
  1578.   checknext(ls, ',');
  1579.   exp1(ls);  /* limit */
  1580.   if (testnext(ls, ','))
  1581.     exp1(ls);  /* optional step */
  1582.   else {  /* default step = 1 */
  1583.     luaK_int(fs, fs->freereg, 1);
  1584.     luaK_reserveregs(fs, 1);
  1585.   }
  1586.   adjustlocalvars(ls, 3);  /* control variables */
  1587.   forbody(ls, base, line, 1, 0);
  1588. }
  1589.  
  1590.  
  1591. static void forlist (LexState *ls, TString *indexname) {
  1592.   /* forlist -> NAME {,NAME} IN explist forbody */
  1593.   FuncState *fs = ls->fs;
  1594.   expdesc e;
  1595.   int nvars = 5;  /* gen, state, control, toclose, 'indexname' */
  1596.   int line;
  1597.   int base = fs->freereg;
  1598.   /* create control variables */
  1599.   new_localvarliteral(ls, "(for state)");
  1600.   new_localvarliteral(ls, "(for state)");
  1601.   new_localvarliteral(ls, "(for state)");
  1602.   new_localvarliteral(ls, "(for state)");
  1603.   /* create declared variables */
  1604.   new_localvar(ls, indexname);
  1605.   while (testnext(ls, ',')) {
  1606.     new_localvar(ls, str_checkname(ls));
  1607.     nvars++;
  1608.   }
  1609.   checknext(ls, TK_IN);
  1610.   line = ls->linenumber;
  1611.   adjust_assign(ls, 4, explist(ls, &e), &e);
  1612.   adjustlocalvars(ls, 4);  /* control variables */
  1613.   marktobeclosed(fs);  /* last control var. must be closed */
  1614.   luaK_checkstack(fs, 3);  /* extra space to call generator */
  1615.   forbody(ls, base, line, nvars - 4, 1);
  1616. }
  1617.  
  1618.  
  1619. static void forstat (LexState *ls, int line) {
  1620.   /* forstat -> FOR (fornum | forlist) END */
  1621.   FuncState *fs = ls->fs;
  1622.   TString *varname;
  1623.   BlockCnt bl;
  1624.   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
  1625.   luaX_next(ls);  /* skip 'for' */
  1626.   varname = str_checkname(ls);  /* first variable name */
  1627.   switch (ls->t.token) {
  1628.     case '=': fornum(ls, varname, line); break;
  1629.     case ',': case TK_IN: forlist(ls, varname); break;
  1630.     default: luaX_syntaxerror(ls, "'=' or 'in' expected");
  1631.   }
  1632.   check_match(ls, TK_END, TK_FOR, line);
  1633.   leaveblock(fs);  /* loop scope ('break' jumps to this point) */
  1634. }
  1635.  
  1636.  
  1637. static void test_then_block (LexState *ls, int *escapelist) {
  1638.   /* test_then_block -> [IF | ELSEIF] cond THEN block */
  1639.   BlockCnt bl;
  1640.   FuncState *fs = ls->fs;
  1641.   expdesc v;
  1642.   int jf;  /* instruction to skip 'then' code (if condition is false) */
  1643.   luaX_next(ls);  /* skip IF or ELSEIF */
  1644.   expr(ls, &v);  /* read condition */
  1645.   checknext(ls, TK_THEN);
  1646.   if (ls->t.token == TK_BREAK) {  /* 'if x then break' ? */
  1647.     int line = ls->linenumber;
  1648.     luaK_goiffalse(ls->fs, &v);  /* will jump if condition is true */
  1649.     luaX_next(ls);  /* skip 'break' */
  1650.     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
  1651.     newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, v.t);
  1652.     while (testnext(ls, ';')) {}  /* skip semicolons */
  1653.     if (block_follow(ls, 0)) {  /* jump is the entire block? */
  1654.       leaveblock(fs);
  1655.       return;  /* and that is it */
  1656.     }
  1657.     else  /* must skip over 'then' part if condition is false */
  1658.       jf = luaK_jump(fs);
  1659.   }
  1660.   else {  /* regular case (not a break) */
  1661.     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
  1662.     enterblock(fs, &bl, 0);
  1663.     jf = v.f;
  1664.   }
  1665.   statlist(ls);  /* 'then' part */
  1666.   leaveblock(fs);
  1667.   if (ls->t.token == TK_ELSE ||
  1668.       ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
  1669.     luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
  1670.   luaK_patchtohere(fs, jf);
  1671. }
  1672.  
  1673.  
  1674. static void ifstat (LexState *ls, int line) {
  1675.   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
  1676.   FuncState *fs = ls->fs;
  1677.   int escapelist = NO_JUMP;  /* exit list for finished parts */
  1678.   test_then_block(ls, &escapelist);  /* IF cond THEN block */
  1679.   while (ls->t.token == TK_ELSEIF)
  1680.     test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
  1681.   if (testnext(ls, TK_ELSE))
  1682.     block(ls);  /* 'else' part */
  1683.   check_match(ls, TK_END, TK_IF, line);
  1684.   luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
  1685. }
  1686.  
  1687.  
  1688. static void localfunc (LexState *ls) {
  1689.   expdesc b;
  1690.   FuncState *fs = ls->fs;
  1691.   int fvar = fs->nactvar;  /* function's variable index */
  1692.   new_localvar(ls, str_checkname(ls));  /* new local variable */
  1693.   adjustlocalvars(ls, 1);  /* enter its scope */
  1694.   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
  1695.   /* debug information will only see the variable after this point! */
  1696.   localdebuginfo(fs, fvar)->startpc = fs->pc;
  1697. }
  1698.  
  1699.  
  1700. static int getlocalattribute (LexState *ls) {
  1701.   /* ATTRIB -> ['<' Name '>'] */
  1702.   if (testnext(ls, '<')) {
  1703.     const char *attr = getstr(str_checkname(ls));
  1704.     checknext(ls, '>');
  1705.     if (strcmp(attr, "const") == 0)
  1706.       return RDKCONST;  /* read-only variable */
  1707.     else if (strcmp(attr, "close") == 0)
  1708.       return RDKTOCLOSE;  /* to-be-closed variable */
  1709.     else
  1710.       luaK_semerror(ls,
  1711.         luaO_pushfstring(ls->L, "unknown attribute '%s'", attr));
  1712.   }
  1713.   return VDKREG;  /* regular variable */
  1714. }
  1715.  
  1716.  
  1717. static void checktoclose (FuncState *fs, int level) {
  1718.   if (level != -1) {  /* is there a to-be-closed variable? */
  1719.     marktobeclosed(fs);
  1720.     luaK_codeABC(fs, OP_TBC, reglevel(fs, level), 0, 0);
  1721.   }
  1722. }
  1723.  
  1724.  
  1725. static void localstat (LexState *ls) {
  1726.   /* stat -> LOCAL NAME ATTRIB { ',' NAME ATTRIB } ['=' explist] */
  1727.   FuncState *fs = ls->fs;
  1728.   int toclose = -1;  /* index of to-be-closed variable (if any) */
  1729.   Vardesc *var;  /* last variable */
  1730.   int vidx, kind;  /* index and kind of last variable */
  1731.   int nvars = 0;
  1732.   int nexps;
  1733.   expdesc e;
  1734.   do {
  1735.     vidx = new_localvar(ls, str_checkname(ls));
  1736.     kind = getlocalattribute(ls);
  1737.     getlocalvardesc(fs, vidx)->vd.kind = kind;
  1738.     if (kind == RDKTOCLOSE) {  /* to-be-closed? */
  1739.       if (toclose != -1)  /* one already present? */
  1740.         luaK_semerror(ls, "multiple to-be-closed variables in local list");
  1741.       toclose = fs->nactvar + nvars;
  1742.     }
  1743.     nvars++;
  1744.   } while (testnext(ls, ','));
  1745.   if (testnext(ls, '='))
  1746.     nexps = explist(ls, &e);
  1747.   else {
  1748.     e.k = VVOID;
  1749.     nexps = 0;
  1750.   }
  1751.   var = getlocalvardesc(fs, vidx);  /* get last variable */
  1752.   if (nvars == nexps &&  /* no adjustments? */
  1753.       var->vd.kind == RDKCONST &&  /* last variable is const? */
  1754.       luaK_exp2const(fs, &e, &var->k)) {  /* compile-time constant? */
  1755.     var->vd.kind = RDKCTC;  /* variable is a compile-time constant */
  1756.     adjustlocalvars(ls, nvars - 1);  /* exclude last variable */
  1757.     fs->nactvar++;  /* but count it */
  1758.   }
  1759.   else {
  1760.     adjust_assign(ls, nvars, nexps, &e);
  1761.     adjustlocalvars(ls, nvars);
  1762.   }
  1763.   checktoclose(fs, toclose);
  1764. }
  1765.  
  1766.  
  1767. static int funcname (LexState *ls, expdesc *v) {
  1768.   /* funcname -> NAME {fieldsel} [':' NAME] */
  1769.   int ismethod = 0;
  1770.   singlevar(ls, v);
  1771.   while (ls->t.token == '.')
  1772.     fieldsel(ls, v);
  1773.   if (ls->t.token == ':') {
  1774.     ismethod = 1;
  1775.     fieldsel(ls, v);
  1776.   }
  1777.   return ismethod;
  1778. }
  1779.  
  1780.  
  1781. static void funcstat (LexState *ls, int line) {
  1782.   /* funcstat -> FUNCTION funcname body */
  1783.   int ismethod;
  1784.   expdesc v, b;
  1785.   luaX_next(ls);  /* skip FUNCTION */
  1786.   ismethod = funcname(ls, &v);
  1787.   body(ls, &b, ismethod, line);
  1788.   check_readonly(ls, &v);
  1789.   luaK_storevar(ls->fs, &v, &b);
  1790.   luaK_fixline(ls->fs, line);  /* definition "happens" in the first line */
  1791. }
  1792.  
  1793.  
  1794. static void exprstat (LexState *ls) {
  1795.   /* stat -> func | assignment */
  1796.   FuncState *fs = ls->fs;
  1797.   struct LHS_assign v;
  1798.   suffixedexp(ls, &v.v);
  1799.   if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
  1800.     v.prev = NULL;
  1801.     restassign(ls, &v, 1);
  1802.   }
  1803.   else {  /* stat -> func */
  1804.     Instruction *inst;
  1805.     check_condition(ls, v.v.k == VCALL, "syntax error");
  1806.     inst = &getinstruction(fs, &v.v);
  1807.     SETARG_C(*inst, 1);  /* call statement uses no results */
  1808.   }
  1809. }
  1810.  
  1811.  
  1812. static void retstat (LexState *ls) {
  1813.   /* stat -> RETURN [explist] [';'] */
  1814.   FuncState *fs = ls->fs;
  1815.   expdesc e;
  1816.   int nret;  /* number of values being returned */
  1817.   int first = luaY_nvarstack(fs);  /* first slot to be returned */
  1818.   if (block_follow(ls, 1) || ls->t.token == ';')
  1819.     nret = 0;  /* return no values */
  1820.   else {
  1821.     nret = explist(ls, &e);  /* optional return values */
  1822.     if (hasmultret(e.k)) {
  1823.       luaK_setmultret(fs, &e);
  1824.       if (e.k == VCALL && nret == 1 && !fs->bl->insidetbc) {  /* tail call? */
  1825.         SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL);
  1826.         lua_assert(GETARG_A(getinstruction(fs,&e)) == luaY_nvarstack(fs));
  1827.       }
  1828.       nret = LUA_MULTRET;  /* return all values */
  1829.     }
  1830.     else {
  1831.       if (nret == 1)  /* only one single value? */
  1832.         first = luaK_exp2anyreg(fs, &e);  /* can use original slot */
  1833.       else {  /* values must go to the top of the stack */
  1834.         luaK_exp2nextreg(fs, &e);
  1835.         lua_assert(nret == fs->freereg - first);
  1836.       }
  1837.     }
  1838.   }
  1839.   luaK_ret(fs, first, nret);
  1840.   testnext(ls, ';');  /* skip optional semicolon */
  1841. }
  1842.  
  1843.  
  1844. static void statement (LexState *ls) {
  1845.   int line = ls->linenumber;  /* may be needed for error messages */
  1846.   enterlevel(ls);
  1847.   switch (ls->t.token) {
  1848.     case ';': {  /* stat -> ';' (empty statement) */
  1849.       luaX_next(ls);  /* skip ';' */
  1850.       break;
  1851.     }
  1852.     case TK_IF: {  /* stat -> ifstat */
  1853.       ifstat(ls, line);
  1854.       break;
  1855.     }
  1856.     case TK_WHILE: {  /* stat -> whilestat */
  1857.       whilestat(ls, line);
  1858.       break;
  1859.     }
  1860.     case TK_DO: {  /* stat -> DO block END */
  1861.       luaX_next(ls);  /* skip DO */
  1862.       block(ls);
  1863.       check_match(ls, TK_END, TK_DO, line);
  1864.       break;
  1865.     }
  1866.     case TK_FOR: {  /* stat -> forstat */
  1867.       forstat(ls, line);
  1868.       break;
  1869.     }
  1870.     case TK_REPEAT: {  /* stat -> repeatstat */
  1871.       repeatstat(ls, line);
  1872.       break;
  1873.     }
  1874.     case TK_FUNCTION: {  /* stat -> funcstat */
  1875.       funcstat(ls, line);
  1876.       break;
  1877.     }
  1878.     case TK_LOCAL: {  /* stat -> localstat */
  1879.       luaX_next(ls);  /* skip LOCAL */
  1880.       if (testnext(ls, TK_FUNCTION))  /* local function? */
  1881.         localfunc(ls);
  1882.       else
  1883.         localstat(ls);
  1884.       break;
  1885.     }
  1886.     case TK_DBCOLON: {  /* stat -> label */
  1887.       luaX_next(ls);  /* skip double colon */
  1888.       labelstat(ls, str_checkname(ls), line);
  1889.       break;
  1890.     }
  1891.     case TK_RETURN: {  /* stat -> retstat */
  1892.       luaX_next(ls);  /* skip RETURN */
  1893.       retstat(ls);
  1894.       break;
  1895.     }
  1896.     case TK_BREAK: {  /* stat -> breakstat */
  1897.       breakstat(ls);
  1898.       break;
  1899.     }
  1900.     case TK_GOTO: {  /* stat -> 'goto' NAME */
  1901.       luaX_next(ls);  /* skip 'goto' */
  1902.       gotostat(ls);
  1903.       break;
  1904.     }
  1905.     default: {  /* stat -> func | assignment */
  1906.       exprstat(ls);
  1907.       break;
  1908.     }
  1909.   }
  1910.   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
  1911.              ls->fs->freereg >= luaY_nvarstack(ls->fs));
  1912.   ls->fs->freereg = luaY_nvarstack(ls->fs);  /* free registers */
  1913.   leavelevel(ls);
  1914. }
  1915.  
  1916. /* }====================================================================== */
  1917.  
  1918.  
  1919. /*
  1920. ** compiles the main function, which is a regular vararg function with an
  1921. ** upvalue named LUA_ENV
  1922. */
  1923. static void mainfunc (LexState *ls, FuncState *fs) {
  1924.   BlockCnt bl;
  1925.   Upvaldesc *env;
  1926.   open_func(ls, fs, &bl);
  1927.   setvararg(fs, 0);  /* main function is always declared vararg */
  1928.   env = allocupvalue(fs);  /* ...set environment upvalue */
  1929.   env->instack = 1;
  1930.   env->idx = 0;
  1931.   env->kind = VDKREG;
  1932.   env->name = ls->envn;
  1933.   luaC_objbarrier(ls->L, fs->f, env->name);
  1934.   luaX_next(ls);  /* read first token */
  1935.   statlist(ls);  /* parse main body */
  1936.   check(ls, TK_EOS);
  1937.   close_func(ls);
  1938. }
  1939.  
  1940.  
  1941. LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
  1942.                        Dyndata *dyd, const char *name, int firstchar) {
  1943.   LexState lexstate;
  1944.   FuncState funcstate;
  1945.   LClosure *cl = luaF_newLclosure(L, 1);  /* create main closure */
  1946.   setclLvalue2s(L, L->top, cl);  /* anchor it (to avoid being collected) */
  1947.   luaD_inctop(L);
  1948.   lexstate.h = luaH_new(L);  /* create table for scanner */
  1949.   sethvalue2s(L, L->top, lexstate.h);  /* anchor it */
  1950.   luaD_inctop(L);
  1951.   funcstate.f = cl->p = luaF_newproto(L);
  1952.   luaC_objbarrier(L, cl, cl->p);
  1953.   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
  1954.   luaC_objbarrier(L, funcstate.f, funcstate.f->source);
  1955.   lexstate.buff = buff;
  1956.   lexstate.dyd = dyd;
  1957.   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
  1958.   luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
  1959.   mainfunc(&lexstate, &funcstate);
  1960.   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
  1961.   /* all scopes should be correctly finished */
  1962.   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
  1963.   L->top--;  /* remove scanner's table */
  1964.   return cl;  /* closure is on the stack, too */
  1965. }
  1966.  
  1967.