/* ** $Id: lparser.c $ ** Lua Parser ** See Copyright Notice in lua.h */ #define lparser_c #define LUA_CORE #include "lprefix.h" #include #include #include "lua.h" #include "lcode.h" #include "ldebug.h" #include "ldo.h" #include "lfunc.h" #include "llex.h" #include "lmem.h" #include "lobject.h" #include "lopcodes.h" #include "lparser.h" #include "lstate.h" #include "lstring.h" #include "ltable.h" /* maximum number of local variables per function (must be smaller than 250, due to the bytecode format) */ #define MAXVARS 200 #define hasmultret(k) ((k) == VCALL || (k) == VVARARG) /* because all strings are unified by the scanner, the parser can use pointer equality for string equality */ #define eqstr(a,b) ((a) == (b)) /* ** nodes for block list (list of active blocks) */ typedef struct BlockCnt { struct BlockCnt *previous; /* chain */ int firstlabel; /* index of first label in this block */ int firstgoto; /* index of first pending goto in this block */ lu_byte nactvar; /* # active locals outside the block */ lu_byte upval; /* true if some variable in the block is an upvalue */ lu_byte isloop; /* true if 'block' is a loop */ lu_byte insidetbc; /* true if inside the scope of a to-be-closed var. */ } BlockCnt; /* ** prototypes for recursive non-terminal functions */ static void statement (LexState *ls); static void expr (LexState *ls, expdesc *v); static l_noret error_expected (LexState *ls, int token) { luaX_syntaxerror(ls, luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token))); } static l_noret errorlimit (FuncState *fs, int limit, const char *what) { lua_State *L = fs->ls->L; const char *msg; int line = fs->f->linedefined; const char *where = (line == 0) ? "main function" : luaO_pushfstring(L, "function at line %d", line); msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s", what, limit, where); luaX_syntaxerror(fs->ls, msg); } static void checklimit (FuncState *fs, int v, int l, const char *what) { if (v > l) errorlimit(fs, l, what); } /* ** Test whether next token is 'c'; if so, skip it. */ static int testnext (LexState *ls, int c) { if (ls->t.token == c) { luaX_next(ls); return 1; } else return 0; } /* ** Check that next token is 'c'. */ static void check (LexState *ls, int c) { if (ls->t.token != c) error_expected(ls, c); } /* ** Check that next token is 'c' and skip it. */ static void checknext (LexState *ls, int c) { check(ls, c); luaX_next(ls); } #define check_condition(ls,c,msg) { if (!(c)) luaX_syntaxerror(ls, msg); } /* ** Check that next token is 'what' and skip it. In case of error, ** raise an error that the expected 'what' should match a 'who' ** in line 'where' (if that is not the current line). */ static void check_match (LexState *ls, int what, int who, int where) { if (l_unlikely(!testnext(ls, what))) { if (where == ls->linenumber) /* all in the same line? */ error_expected(ls, what); /* do not need a complex message */ else { luaX_syntaxerror(ls, luaO_pushfstring(ls->L, "%s expected (to close %s at line %d)", luaX_token2str(ls, what), luaX_token2str(ls, who), where)); } } } static TString *str_checkname (LexState *ls) { TString *ts; check(ls, TK_NAME); ts = ls->t.seminfo.ts; luaX_next(ls); return ts; } static void init_exp (expdesc *e, expkind k, int i) { e->f = e->t = NO_JUMP; e->k = k; e->u.info = i; } static void codestring (expdesc *e, TString *s) { e->f = e->t = NO_JUMP; e->k = VKSTR; e->u.strval = s; } static void codename (LexState *ls, expdesc *e) { codestring(e, str_checkname(ls)); } /* ** Register a new local variable in the active 'Proto' (for debug ** information). */ static int registerlocalvar (LexState *ls, FuncState *fs, TString *varname) { Proto *f = fs->f; int oldsize = f->sizelocvars; luaM_growvector(ls->L, f->locvars, fs->ndebugvars, f->sizelocvars, LocVar, SHRT_MAX, "local variables"); while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL; f->locvars[fs->ndebugvars].varname = varname; f->locvars[fs->ndebugvars].startpc = fs->pc; luaC_objbarrier(ls->L, f, varname); return fs->ndebugvars++; } /* ** Create a new local variable with the given 'name' and given 'kind'. ** Return its index in the function. */ static int new_localvarkind (LexState *ls, TString *name, int kind) { lua_State *L = ls->L; FuncState *fs = ls->fs; Dyndata *dyd = ls->dyd; Vardesc *var; checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal, MAXVARS, "local variables"); luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1, dyd->actvar.size, Vardesc, USHRT_MAX, "local variables"); var = &dyd->actvar.arr[dyd->actvar.n++]; var->vd.kind = kind; /* default */ var->vd.name = name; return dyd->actvar.n - 1 - fs->firstlocal; } /* ** Create a new local variable with the given 'name' and regular kind. */ static int new_localvar (LexState *ls, TString *name) { return new_localvarkind(ls, name, VDKREG); } #define new_localvarliteral(ls,v) \ new_localvar(ls, \ luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char)) - 1)); /* ** Return the "variable description" (Vardesc) of a given variable. ** (Unless noted otherwise, all variables are referred to by their ** compiler indices.) */ static Vardesc *getlocalvardesc (FuncState *fs, int vidx) { return &fs->ls->dyd->actvar.arr[fs->firstlocal + vidx]; } /* ** Convert 'nvar', a compiler index level, to its corresponding ** register. For that, search for the highest variable below that level ** that is in a register and uses its register index ('ridx') plus one. */ static int reglevel (FuncState *fs, int nvar) { while (nvar-- > 0) { Vardesc *vd = getlocalvardesc(fs, nvar); /* get previous variable */ if (vd->vd.kind != RDKCTC) /* is in a register? */ return vd->vd.ridx + 1; } return 0; /* no variables in registers */ } /* ** Return the number of variables in the register stack for the given ** function. */ int luaY_nvarstack (FuncState *fs) { return reglevel(fs, fs->nactvar); } /* ** Get the debug-information entry for current variable 'vidx'. */ static LocVar *localdebuginfo (FuncState *fs, int vidx) { Vardesc *vd = getlocalvardesc(fs, vidx); if (vd->vd.kind == RDKCTC) return NULL; /* no debug info. for constants */ else { int idx = vd->vd.pidx; lua_assert(idx < fs->ndebugvars); return &fs->f->locvars[idx]; } } /* ** Create an expression representing variable 'vidx' */ static void init_var (FuncState *fs, expdesc *e, int vidx) { e->f = e->t = NO_JUMP; e->k = VLOCAL; e->u.var.vidx = vidx; e->u.var.ridx = getlocalvardesc(fs, vidx)->vd.ridx; } /* ** Raises an error if variable described by 'e' is read only */ static void check_readonly (LexState *ls, expdesc *e) { FuncState *fs = ls->fs; TString *varname = NULL; /* to be set if variable is const */ switch (e->k) { case VCONST: { varname = ls->dyd->actvar.arr[e->u.info].vd.name; break; } case VLOCAL: { Vardesc *vardesc = getlocalvardesc(fs, e->u.var.vidx); if (vardesc->vd.kind != VDKREG) /* not a regular variable? */ varname = vardesc->vd.name; break; } case VUPVAL: { Upvaldesc *up = &fs->f->upvalues[e->u.info]; if (up->kind != VDKREG) varname = up->name; break; } default: return; /* other cases cannot be read-only */ } if (varname) { const char *msg = luaO_pushfstring(ls->L, "attempt to assign to const variable '%s'", getstr(varname)); luaK_semerror(ls, msg); /* error */ } } /* ** Start the scope for the last 'nvars' created variables. */ static void adjustlocalvars (LexState *ls, int nvars) { FuncState *fs = ls->fs; int reglevel = luaY_nvarstack(fs); int i; for (i = 0; i < nvars; i++) { int vidx = fs->nactvar++; Vardesc *var = getlocalvardesc(fs, vidx); var->vd.ridx = reglevel++; var->vd.pidx = registerlocalvar(ls, fs, var->vd.name); } } /* ** Close the scope for all variables up to level 'tolevel'. ** (debug info.) */ static void removevars (FuncState *fs, int tolevel) { fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel); while (fs->nactvar > tolevel) { LocVar *var = localdebuginfo(fs, --fs->nactvar); if (var) /* does it have debug information? */ var->endpc = fs->pc; } } /* ** Search the upvalues of the function 'fs' for one ** with the given 'name'. */ static int searchupvalue (FuncState *fs, TString *name) { int i; Upvaldesc *up = fs->f->upvalues; for (i = 0; i < fs->nups; i++) { if (eqstr(up[i].name, name)) return i; } return -1; /* not found */ } static Upvaldesc *allocupvalue (FuncState *fs) { Proto *f = fs->f; int oldsize = f->sizeupvalues; checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues"); luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues, Upvaldesc, MAXUPVAL, "upvalues"); while (oldsize < f->sizeupvalues) f->upvalues[oldsize++].name = NULL; return &f->upvalues[fs->nups++]; } static int newupvalue (FuncState *fs, TString *name, expdesc *v) { Upvaldesc *up = allocupvalue(fs); FuncState *prev = fs->prev; if (v->k == VLOCAL) { up->instack = 1; up->idx = v->u.var.ridx; up->kind = getlocalvardesc(prev, v->u.var.vidx)->vd.kind; lua_assert(eqstr(name, getlocalvardesc(prev, v->u.var.vidx)->vd.name)); } else { up->instack = 0; up->idx = cast_byte(v->u.info); up->kind = prev->f->upvalues[v->u.info].kind; lua_assert(eqstr(name, prev->f->upvalues[v->u.info].name)); } up->name = name; luaC_objbarrier(fs->ls->L, fs->f, name); return fs->nups - 1; } /* ** Look for an active local variable with the name 'n' in the ** function 'fs'. If found, initialize 'var' with it and return ** its expression kind; otherwise return -1. */ static int searchvar (FuncState *fs, TString *n, expdesc *var) { int i; for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) { Vardesc *vd = getlocalvardesc(fs, i); if (eqstr(n, vd->vd.name)) { /* found? */ if (vd->vd.kind == RDKCTC) /* compile-time constant? */ init_exp(var, VCONST, fs->firstlocal + i); else /* real variable */ init_var(fs, var, i); return var->k; } } return -1; /* not found */ } /* ** Mark block where variable at given level was defined ** (to emit close instructions later). */ static void markupval (FuncState *fs, int level) { BlockCnt *bl = fs->bl; while (bl->nactvar > level) bl = bl->previous; bl->upval = 1; fs->needclose = 1; } /* ** Mark that current block has a to-be-closed variable. */ static void marktobeclosed (FuncState *fs) { BlockCnt *bl = fs->bl; bl->upval = 1; bl->insidetbc = 1; fs->needclose = 1; } /* ** Find a variable with the given name 'n'. If it is an upvalue, add ** this upvalue into all intermediate functions. If it is a global, set ** 'var' as 'void' as a flag. */ static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) { if (fs == NULL) /* no more levels? */ init_exp(var, VVOID, 0); /* default is global */ else { int v = searchvar(fs, n, var); /* look up locals at current level */ if (v >= 0) { /* found? */ if (v == VLOCAL && !base) markupval(fs, var->u.var.vidx); /* local will be used as an upval */ } else { /* not found as local at current level; try upvalues */ int idx = searchupvalue(fs, n); /* try existing upvalues */ if (idx < 0) { /* not found? */ singlevaraux(fs->prev, n, var, 0); /* try upper levels */ if (var->k == VLOCAL || var->k == VUPVAL) /* local or upvalue? */ idx = newupvalue(fs, n, var); /* will be a new upvalue */ else /* it is a global or a constant */ return; /* don't need to do anything at this level */ } init_exp(var, VUPVAL, idx); /* new or old upvalue */ } } } /* ** Find a variable with the given name 'n', handling global variables ** too. */ static void singlevar (LexState *ls, expdesc *var) { TString *varname = str_checkname(ls); FuncState *fs = ls->fs; singlevaraux(fs, varname, var, 1); if (var->k == VVOID) { /* global name? */ expdesc key; singlevaraux(fs, ls->envn, var, 1); /* get environment variable */ lua_assert(var->k != VVOID); /* this one must exist */ luaK_exp2anyregup(fs, var); /* but could be a constant */ codestring(&key, varname); /* key is variable name */ luaK_indexed(fs, var, &key); /* env[varname] */ } } /* ** Adjust the number of results from an expression list 'e' with 'nexps' ** expressions to 'nvars' values. */ static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) { FuncState *fs = ls->fs; int needed = nvars - nexps; /* extra values needed */ if (hasmultret(e->k)) { /* last expression has multiple returns? */ int extra = needed + 1; /* discount last expression itself */ if (extra < 0) extra = 0; luaK_setreturns(fs, e, extra); /* last exp. provides the difference */ } else { if (e->k != VVOID) /* at least one expression? */ luaK_exp2nextreg(fs, e); /* close last expression */ if (needed > 0) /* missing values? */ luaK_nil(fs, fs->freereg, needed); /* complete with nils */ } if (needed > 0) luaK_reserveregs(fs, needed); /* registers for extra values */ else /* adding 'needed' is actually a subtraction */ fs->freereg += needed; /* remove extra values */ } #define enterlevel(ls) luaE_incCstack(ls->L) #define leavelevel(ls) ((ls)->L->nCcalls--) /* ** Generates an error that a goto jumps into the scope of some ** local variable. */ static l_noret jumpscopeerror (LexState *ls, Labeldesc *gt) { TString *tsname = getlocalvardesc(ls->fs, gt->nactvar)->vd.name; const char *varname = getstr(tsname); const char *msg = " at line %d jumps into the scope of local '%s'"; msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line, varname); luaK_semerror(ls, msg); /* raise the error */ } /* ** Solves the goto at index 'g' to given 'label' and removes it ** from the list of pending gotos. ** If it jumps into the scope of some variable, raises an error. */ static void solvegoto (LexState *ls, int g, Labeldesc *label) { int i; Labellist *gl = &ls->dyd->gt; /* list of gotos */ Labeldesc *gt = &gl->arr[g]; /* goto to be resolved */ lua_assert(eqstr(gt->name, label->name)); if (l_unlikely(gt->nactvar < label->nactvar)) /* enter some scope? */ jumpscopeerror(ls, gt); luaK_patchlist(ls->fs, gt->pc, label->pc); for (i = g; i < gl->n - 1; i++) /* remove goto from pending list */ gl->arr[i] = gl->arr[i + 1]; gl->n--; } /* ** Search for an active label with the given name. */ static Labeldesc *findlabel (LexState *ls, TString *name) { int i; Dyndata *dyd = ls->dyd; /* check labels in current function for a match */ for (i = ls->fs->firstlabel; i < dyd->label.n; i++) { Labeldesc *lb = &dyd->label.arr[i]; if (eqstr(lb->name, name)) /* correct label? */ return lb; } return NULL; /* label not found */ } /* ** Adds a new label/goto in the corresponding list. */ static int newlabelentry (LexState *ls, Labellist *l, TString *name, int line, int pc) { int n = l->n; luaM_growvector(ls->L, l->arr, n, l->size, Labeldesc, SHRT_MAX, "labels/gotos"); l->arr[n].name = name; l->arr[n].line = line; l->arr[n].nactvar = ls->fs->nactvar; l->arr[n].close = 0; l->arr[n].pc = pc; l->n = n + 1; return n; } static int newgotoentry (LexState *ls, TString *name, int line, int pc) { return newlabelentry(ls, &ls->dyd->gt, name, line, pc); } /* ** Solves forward jumps. Check whether new label 'lb' matches any ** pending gotos in current block and solves them. Return true ** if any of the gotos need to close upvalues. */ static int solvegotos (LexState *ls, Labeldesc *lb) { Labellist *gl = &ls->dyd->gt; int i = ls->fs->bl->firstgoto; int needsclose = 0; while (i < gl->n) { if (eqstr(gl->arr[i].name, lb->name)) { needsclose |= gl->arr[i].close; solvegoto(ls, i, lb); /* will remove 'i' from the list */ } else i++; } return needsclose; } /* ** Create a new label with the given 'name' at the given 'line'. ** 'last' tells whether label is the last non-op statement in its ** block. Solves all pending gotos to this new label and adds ** a close instruction if necessary. ** Returns true iff it added a close instruction. */ static int createlabel (LexState *ls, TString *name, int line, int last) { FuncState *fs = ls->fs; Labellist *ll = &ls->dyd->label; int l = newlabelentry(ls, ll, name, line, luaK_getlabel(fs)); if (last) { /* label is last no-op statement in the block? */ /* assume that locals are already out of scope */ ll->arr[l].nactvar = fs->bl->nactvar; } if (solvegotos(ls, &ll->arr[l])) { /* need close? */ luaK_codeABC(fs, OP_CLOSE, luaY_nvarstack(fs), 0, 0); return 1; } return 0; } /* ** Adjust pending gotos to outer level of a block. */ static void movegotosout (FuncState *fs, BlockCnt *bl) { int i; Labellist *gl = &fs->ls->dyd->gt; /* correct pending gotos to current block */ for (i = bl->firstgoto; i < gl->n; i++) { /* for each pending goto */ Labeldesc *gt = &gl->arr[i]; /* leaving a variable scope? */ if (reglevel(fs, gt->nactvar) > reglevel(fs, bl->nactvar)) gt->close |= bl->upval; /* jump may need a close */ gt->nactvar = bl->nactvar; /* update goto level */ } } static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) { bl->isloop = isloop; bl->nactvar = fs->nactvar; bl->firstlabel = fs->ls->dyd->label.n; bl->firstgoto = fs->ls->dyd->gt.n; bl->upval = 0; bl->insidetbc = (fs->bl != NULL && fs->bl->insidetbc); bl->previous = fs->bl; fs->bl = bl; lua_assert(fs->freereg == luaY_nvarstack(fs)); } /* ** generates an error for an undefined 'goto'. */ static l_noret undefgoto (LexState *ls, Labeldesc *gt) { const char *msg; if (eqstr(gt->name, luaS_newliteral(ls->L, "break"))) { msg = "break outside loop at line %d"; msg = luaO_pushfstring(ls->L, msg, gt->line); } else { msg = "no visible label '%s' for at line %d"; msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line); } luaK_semerror(ls, msg); } static void leaveblock (FuncState *fs) { BlockCnt *bl = fs->bl; LexState *ls = fs->ls; int hasclose = 0; int stklevel = reglevel(fs, bl->nactvar); /* level outside the block */ removevars(fs, bl->nactvar); /* remove block locals */ lua_assert(bl->nactvar == fs->nactvar); /* back to level on entry */ if (bl->isloop) /* has to fix pending breaks? */ hasclose = createlabel(ls, luaS_newliteral(ls->L, "break"), 0, 0); if (!hasclose && bl->previous && bl->upval) /* still need a 'close'? */ luaK_codeABC(fs, OP_CLOSE, stklevel, 0, 0); fs->freereg = stklevel; /* free registers */ ls->dyd->label.n = bl->firstlabel; /* remove local labels */ fs->bl = bl->previous; /* current block now is previous one */ if (bl->previous) /* was it a nested block? */ movegotosout(fs, bl); /* update pending gotos to enclosing block */ else { if (bl->firstgoto < ls->dyd->gt.n) /* still pending gotos? */ undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]); /* error */ } } /* ** adds a new prototype into list of prototypes */ static Proto *addprototype (LexState *ls) { Proto *clp; lua_State *L = ls->L; FuncState *fs = ls->fs; Proto *f = fs->f; /* prototype of current function */ if (fs->np >= f->sizep) { int oldsize = f->sizep; luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions"); while (oldsize < f->sizep) f->p[oldsize++] = NULL; } f->p[fs->np++] = clp = luaF_newproto(L); luaC_objbarrier(L, f, clp); return clp; } /* ** codes instruction to create new closure in parent function. ** The OP_CLOSURE instruction uses the last available register, ** so that, if it invokes the GC, the GC knows which registers ** are in use at that time. */ static void codeclosure (LexState *ls, expdesc *v) { FuncState *fs = ls->fs->prev; init_exp(v, VRELOC, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1)); luaK_exp2nextreg(fs, v); /* fix it at the last register */ } static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) { Proto *f = fs->f; fs->prev = ls->fs; /* linked list of funcstates */ fs->ls = ls; ls->fs = fs; fs->pc = 0; fs->previousline = f->linedefined; fs->iwthabs = 0; fs->lasttarget = 0; fs->freereg = 0; fs->nk = 0; fs->nabslineinfo = 0; fs->np = 0; fs->nups = 0; fs->ndebugvars = 0; fs->nactvar = 0; fs->needclose = 0; fs->firstlocal = ls->dyd->actvar.n; fs->firstlabel = ls->dyd->label.n; fs->bl = NULL; f->source = ls->source; luaC_objbarrier(ls->L, f, f->source); f->maxstacksize = 2; /* registers 0/1 are always valid */ enterblock(fs, bl, 0); } static void close_func (LexState *ls) { lua_State *L = ls->L; FuncState *fs = ls->fs; Proto *f = fs->f; luaK_ret(fs, luaY_nvarstack(fs), 0); /* final return */ leaveblock(fs); lua_assert(fs->bl == NULL); luaK_finish(fs); luaM_shrinkvector(L, f->code, f->sizecode, fs->pc, Instruction); luaM_shrinkvector(L, f->lineinfo, f->sizelineinfo, fs->pc, ls_byte); luaM_shrinkvector(L, f->abslineinfo, f->sizeabslineinfo, fs->nabslineinfo, AbsLineInfo); luaM_shrinkvector(L, f->k, f->sizek, fs->nk, TValue); luaM_shrinkvector(L, f->p, f->sizep, fs->np, Proto *); luaM_shrinkvector(L, f->locvars, f->sizelocvars, fs->ndebugvars, LocVar); luaM_shrinkvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc); ls->fs = fs->prev; luaC_checkGC(L); } /*============================================================*/ /* GRAMMAR RULES */ /*============================================================*/ /* ** check whether current token is in the follow set of a block. ** 'until' closes syntactical blocks, but do not close scope, ** so it is handled in separate. */ static int block_follow (LexState *ls, int withuntil) { switch (ls->t.token) { case TK_ELSE: case TK_ELSEIF: case TK_END: case TK_EOS: return 1; case TK_UNTIL: return withuntil; default: return 0; } } static void statlist (LexState *ls) { /* statlist -> { stat [';'] } */ while (!block_follow(ls, 1)) { if (ls->t.token == TK_RETURN) { statement(ls); return; /* 'return' must be last statement */ } statement(ls); } } static void fieldsel (LexState *ls, expdesc *v) { /* fieldsel -> ['.' | ':'] NAME */ FuncState *fs = ls->fs; expdesc key; luaK_exp2anyregup(fs, v); luaX_next(ls); /* skip the dot or colon */ codename(ls, &key); luaK_indexed(fs, v, &key); } static void yindex (LexState *ls, expdesc *v) { /* index -> '[' expr ']' */ luaX_next(ls); /* skip the '[' */ expr(ls, v); luaK_exp2val(ls->fs, v); checknext(ls, ']'); } /* ** {====================================================================== ** Rules for Constructors ** ======================================================================= */ typedef struct ConsControl { expdesc v; /* last list item read */ expdesc *t; /* table descriptor */ int nh; /* total number of 'record' elements */ int na; /* number of array elements already stored */ int tostore; /* number of array elements pending to be stored */ int maxtostore; /* maximum number of pending elements */ } ConsControl; static void recfield (LexState *ls, ConsControl *cc) { /* recfield -> (NAME | '['exp']') = exp */ FuncState *fs = ls->fs; int reg = ls->fs->freereg; expdesc tab, key, val; if (ls->t.token == TK_NAME) { checklimit(fs, cc->nh, INT_MAX, "items in a constructor"); codename(ls, &key); } else /* ls->t.token == '[' */ yindex(ls, &key); cc->nh++; checknext(ls, '='); tab = *cc->t; luaK_indexed(fs, &tab, &key); expr(ls, &val); luaK_storevar(fs, &tab, &val); fs->freereg = reg; /* free registers */ } static void closelistfield (FuncState *fs, ConsControl *cc) { if (cc->v.k == VVOID) return; /* there is no list item */ luaK_exp2nextreg(fs, &cc->v); cc->v.k = VVOID; if (cc->tostore >= cc->maxtostore) { luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore); /* flush */ cc->na += cc->tostore; cc->tostore = 0; /* no more items pending */ } } static void lastlistfield (FuncState *fs, ConsControl *cc) { if (cc->tostore == 0) return; if (hasmultret(cc->v.k)) { luaK_setmultret(fs, &cc->v); luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET); cc->na--; /* do not count last expression (unknown number of elements) */ } else { if (cc->v.k != VVOID) luaK_exp2nextreg(fs, &cc->v); luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore); } cc->na += cc->tostore; } static void listfield (LexState *ls, ConsControl *cc) { /* listfield -> exp */ expr(ls, &cc->v); cc->tostore++; } static void field (LexState *ls, ConsControl *cc) { /* field -> listfield | recfield */ switch(ls->t.token) { case TK_NAME: { /* may be 'listfield' or 'recfield' */ if (luaX_lookahead(ls) != '=') /* expression? */ listfield(ls, cc); else recfield(ls, cc); break; } case '[': { recfield(ls, cc); break; } default: { listfield(ls, cc); break; } } } /* ** Compute a limit for how many registers a constructor can use before ** emitting a 'SETLIST' instruction, based on how many registers are ** available. */ static int maxtostore (FuncState *fs) { int numfreeregs = MAX_FSTACK - fs->freereg; if (numfreeregs >= 160) /* "lots" of registers? */ return numfreeregs / 5u; /* use up to 1/5 of them */ else if (numfreeregs >= 80) /* still "enough" registers? */ return 10; /* one 'SETLIST' instruction for each 10 values */ else /* save registers for potential more nesting */ return 1; } static void constructor (LexState *ls, expdesc *t) { /* constructor -> '{' [ field { sep field } [sep] ] '}' sep -> ',' | ';' */ FuncState *fs = ls->fs; int line = ls->linenumber; int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0); ConsControl cc; luaK_code(fs, 0); /* space for extra arg. */ cc.na = cc.nh = cc.tostore = 0; cc.t = t; init_exp(t, VNONRELOC, fs->freereg); /* table will be at stack top */ luaK_reserveregs(fs, 1); init_exp(&cc.v, VVOID, 0); /* no value (yet) */ checknext(ls, '{'); cc.maxtostore = maxtostore(fs); do { lua_assert(cc.v.k == VVOID || cc.tostore > 0); if (ls->t.token == '}') break; closelistfield(fs, &cc); field(ls, &cc); } while (testnext(ls, ',') || testnext(ls, ';')); check_match(ls, '}', '{', line); lastlistfield(fs, &cc); luaK_settablesize(fs, pc, t->u.info, cc.na, cc.nh); } /* }====================================================================== */ static void setvararg (FuncState *fs, int nparams) { fs->f->flag |= PF_ISVARARG; luaK_codeABC(fs, OP_VARARGPREP, nparams, 0, 0); } static void parlist (LexState *ls) { /* parlist -> [ {NAME ','} (NAME | '...') ] */ FuncState *fs = ls->fs; Proto *f = fs->f; int nparams = 0; int isvararg = 0; if (ls->t.token != ')') { /* is 'parlist' not empty? */ do { switch (ls->t.token) { case TK_NAME: { new_localvar(ls, str_checkname(ls)); nparams++; break; } case TK_DOTS: { luaX_next(ls); isvararg = 1; break; } default: luaX_syntaxerror(ls, " or '...' expected"); } } while (!isvararg && testnext(ls, ',')); } adjustlocalvars(ls, nparams); f->numparams = cast_byte(fs->nactvar); if (isvararg) setvararg(fs, f->numparams); /* declared vararg */ luaK_reserveregs(fs, fs->nactvar); /* reserve registers for parameters */ } static void body (LexState *ls, expdesc *e, int ismethod, int line) { /* body -> '(' parlist ')' block END */ FuncState new_fs; BlockCnt bl; new_fs.f = addprototype(ls); new_fs.f->linedefined = line; open_func(ls, &new_fs, &bl); checknext(ls, '('); if (ismethod) { new_localvarliteral(ls, "self"); /* create 'self' parameter */ adjustlocalvars(ls, 1); } parlist(ls); checknext(ls, ')'); statlist(ls); new_fs.f->lastlinedefined = ls->linenumber; check_match(ls, TK_END, TK_FUNCTION, line); codeclosure(ls, e); close_func(ls); } static int explist (LexState *ls, expdesc *v) { /* explist -> expr { ',' expr } */ int n = 1; /* at least one expression */ expr(ls, v); while (testnext(ls, ',')) { luaK_exp2nextreg(ls->fs, v); expr(ls, v); n++; } return n; } static void funcargs (LexState *ls, expdesc *f) { FuncState *fs = ls->fs; expdesc args; int base, nparams; int line = ls->linenumber; switch (ls->t.token) { case '(': { /* funcargs -> '(' [ explist ] ')' */ luaX_next(ls); if (ls->t.token == ')') /* arg list is empty? */ args.k = VVOID; else { explist(ls, &args); if (hasmultret(args.k)) luaK_setmultret(fs, &args); } check_match(ls, ')', '(', line); break; } case '{': { /* funcargs -> constructor */ constructor(ls, &args); break; } case TK_STRING: { /* funcargs -> STRING */ codestring(&args, ls->t.seminfo.ts); luaX_next(ls); /* must use 'seminfo' before 'next' */ break; } default: { luaX_syntaxerror(ls, "function arguments expected"); } } lua_assert(f->k == VNONRELOC); base = f->u.info; /* base register for call */ if (hasmultret(args.k)) nparams = LUA_MULTRET; /* open call */ else { if (args.k != VVOID) luaK_exp2nextreg(fs, &args); /* close last argument */ nparams = fs->freereg - (base+1); } init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2)); luaK_fixline(fs, line); fs->freereg = base+1; /* call removes function and arguments and leaves one result (unless changed later) */ } /* ** {====================================================================== ** Expression parsing ** ======================================================================= */ static void primaryexp (LexState *ls, expdesc *v) { /* primaryexp -> NAME | '(' expr ')' */ switch (ls->t.token) { case '(': { int line = ls->linenumber; luaX_next(ls); expr(ls, v); check_match(ls, ')', '(', line); luaK_dischargevars(ls->fs, v); return; } case TK_NAME: { singlevar(ls, v); return; } default: { luaX_syntaxerror(ls, "unexpected symbol"); } } } static void suffixedexp (LexState *ls, expdesc *v) { /* suffixedexp -> primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */ FuncState *fs = ls->fs; primaryexp(ls, v); for (;;) { switch (ls->t.token) { case '.': { /* fieldsel */ fieldsel(ls, v); break; } case '[': { /* '[' exp ']' */ expdesc key; luaK_exp2anyregup(fs, v); yindex(ls, &key); luaK_indexed(fs, v, &key); break; } case ':': { /* ':' NAME funcargs */ expdesc key; luaX_next(ls); codename(ls, &key); luaK_self(fs, v, &key); funcargs(ls, v); break; } case '(': case TK_STRING: case '{': { /* funcargs */ luaK_exp2nextreg(fs, v); funcargs(ls, v); break; } default: return; } } } static void simpleexp (LexState *ls, expdesc *v) { /* simpleexp -> FLT | INT | STRING | NIL | TRUE | FALSE | ... | constructor | FUNCTION body | suffixedexp */ switch (ls->t.token) { case TK_FLT: { init_exp(v, VKFLT, 0); v->u.nval = ls->t.seminfo.r; break; } case TK_INT: { init_exp(v, VKINT, 0); v->u.ival = ls->t.seminfo.i; break; } case TK_STRING: { codestring(v, ls->t.seminfo.ts); break; } case TK_NIL: { init_exp(v, VNIL, 0); break; } case TK_TRUE: { init_exp(v, VTRUE, 0); break; } case TK_FALSE: { init_exp(v, VFALSE, 0); break; } case TK_DOTS: { /* vararg */ FuncState *fs = ls->fs; check_condition(ls, fs->f->flag & PF_ISVARARG, "cannot use '...' outside a vararg function"); init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 0, 1)); break; } case '{': { /* constructor */ constructor(ls, v); return; } case TK_FUNCTION: { luaX_next(ls); body(ls, v, 0, ls->linenumber); return; } default: { suffixedexp(ls, v); return; } } luaX_next(ls); } static UnOpr getunopr (int op) { switch (op) { case TK_NOT: return OPR_NOT; case '-': return OPR_MINUS; case '~': return OPR_BNOT; case '#': return OPR_LEN; default: return OPR_NOUNOPR; } } static BinOpr getbinopr (int op) { switch (op) { case '+': return OPR_ADD; case '-': return OPR_SUB; case '*': return OPR_MUL; case '%': return OPR_MOD; case '^': return OPR_POW; case '/': return OPR_DIV; case TK_IDIV: return OPR_IDIV; case '&': return OPR_BAND; case '|': return OPR_BOR; case '~': return OPR_BXOR; case TK_SHL: return OPR_SHL; case TK_SHR: return OPR_SHR; case TK_CONCAT: return OPR_CONCAT; case TK_NE: return OPR_NE; case TK_EQ: return OPR_EQ; case '<': return OPR_LT; case TK_LE: return OPR_LE; case '>': return OPR_GT; case TK_GE: return OPR_GE; case TK_AND: return OPR_AND; case TK_OR: return OPR_OR; default: return OPR_NOBINOPR; } } /* ** Priority table for binary operators. */ static const struct { lu_byte left; /* left priority for each binary operator */ lu_byte right; /* right priority */ } priority[] = { /* ORDER OPR */ {10, 10}, {10, 10}, /* '+' '-' */ {11, 11}, {11, 11}, /* '*' '%' */ {14, 13}, /* '^' (right associative) */ {11, 11}, {11, 11}, /* '/' '//' */ {6, 6}, {4, 4}, {5, 5}, /* '&' '|' '~' */ {7, 7}, {7, 7}, /* '<<' '>>' */ {9, 8}, /* '..' (right associative) */ {3, 3}, {3, 3}, {3, 3}, /* ==, <, <= */ {3, 3}, {3, 3}, {3, 3}, /* ~=, >, >= */ {2, 2}, {1, 1} /* and, or */ }; #define UNARY_PRIORITY 12 /* priority for unary operators */ /* ** subexpr -> (simpleexp | unop subexpr) { binop subexpr } ** where 'binop' is any binary operator with a priority higher than 'limit' */ static BinOpr subexpr (LexState *ls, expdesc *v, int limit) { BinOpr op; UnOpr uop; enterlevel(ls); uop = getunopr(ls->t.token); if (uop != OPR_NOUNOPR) { /* prefix (unary) operator? */ int line = ls->linenumber; luaX_next(ls); /* skip operator */ subexpr(ls, v, UNARY_PRIORITY); luaK_prefix(ls->fs, uop, v, line); } else simpleexp(ls, v); /* expand while operators have priorities higher than 'limit' */ op = getbinopr(ls->t.token); while (op != OPR_NOBINOPR && priority[op].left > limit) { expdesc v2; BinOpr nextop; int line = ls->linenumber; luaX_next(ls); /* skip operator */ luaK_infix(ls->fs, op, v); /* read sub-expression with higher priority */ nextop = subexpr(ls, &v2, priority[op].right); luaK_posfix(ls->fs, op, v, &v2, line); op = nextop; } leavelevel(ls); return op; /* return first untreated operator */ } static void expr (LexState *ls, expdesc *v) { subexpr(ls, v, 0); } /* }==================================================================== */ /* ** {====================================================================== ** Rules for Statements ** ======================================================================= */ static void block (LexState *ls) { /* block -> statlist */ FuncState *fs = ls->fs; BlockCnt bl; enterblock(fs, &bl, 0); statlist(ls); leaveblock(fs); } /* ** structure to chain all variables in the left-hand side of an ** assignment */ struct LHS_assign { struct LHS_assign *prev; expdesc v; /* variable (global, local, upvalue, or indexed) */ }; /* ** check whether, in an assignment to an upvalue/local variable, the ** upvalue/local variable is begin used in a previous assignment to a ** table. If so, save original upvalue/local value in a safe place and ** use this safe copy in the previous assignment. */ static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) { FuncState *fs = ls->fs; int extra = fs->freereg; /* eventual position to save local variable */ int conflict = 0; for (; lh; lh = lh->prev) { /* check all previous assignments */ if (vkisindexed(lh->v.k)) { /* assignment to table field? */ if (lh->v.k == VINDEXUP) { /* is table an upvalue? */ if (v->k == VUPVAL && lh->v.u.ind.t == v->u.info) { conflict = 1; /* table is the upvalue being assigned now */ lh->v.k = VINDEXSTR; lh->v.u.ind.t = extra; /* assignment will use safe copy */ } } else { /* table is a register */ if (v->k == VLOCAL && lh->v.u.ind.t == v->u.var.ridx) { conflict = 1; /* table is the local being assigned now */ lh->v.u.ind.t = extra; /* assignment will use safe copy */ } /* is index the local being assigned? */ if (lh->v.k == VINDEXED && v->k == VLOCAL && lh->v.u.ind.idx == v->u.var.ridx) { conflict = 1; lh->v.u.ind.idx = extra; /* previous assignment will use safe copy */ } } } } if (conflict) { /* copy upvalue/local value to a temporary (in position 'extra') */ if (v->k == VLOCAL) luaK_codeABC(fs, OP_MOVE, extra, v->u.var.ridx, 0); else luaK_codeABC(fs, OP_GETUPVAL, extra, v->u.info, 0); luaK_reserveregs(fs, 1); } } /* ** Parse and compile a multiple assignment. The first "variable" ** (a 'suffixedexp') was already read by the caller. ** ** assignment -> suffixedexp restassign ** restassign -> ',' suffixedexp restassign | '=' explist */ static void restassign (LexState *ls, struct LHS_assign *lh, int nvars) { expdesc e; check_condition(ls, vkisvar(lh->v.k), "syntax error"); check_readonly(ls, &lh->v); if (testnext(ls, ',')) { /* restassign -> ',' suffixedexp restassign */ struct LHS_assign nv; nv.prev = lh; suffixedexp(ls, &nv.v); if (!vkisindexed(nv.v.k)) check_conflict(ls, lh, &nv.v); enterlevel(ls); /* control recursion depth */ restassign(ls, &nv, nvars+1); leavelevel(ls); } else { /* restassign -> '=' explist */ int nexps; checknext(ls, '='); nexps = explist(ls, &e); if (nexps != nvars) adjust_assign(ls, nvars, nexps, &e); else { luaK_setoneret(ls->fs, &e); /* close last expression */ luaK_storevar(ls->fs, &lh->v, &e); return; /* avoid default */ } } init_exp(&e, VNONRELOC, ls->fs->freereg-1); /* default assignment */ luaK_storevar(ls->fs, &lh->v, &e); } static int cond (LexState *ls) { /* cond -> exp */ expdesc v; expr(ls, &v); /* read condition */ if (v.k == VNIL) v.k = VFALSE; /* 'falses' are all equal here */ luaK_goiftrue(ls->fs, &v); return v.f; } static void gotostat (LexState *ls) { FuncState *fs = ls->fs; int line = ls->linenumber; TString *name = str_checkname(ls); /* label's name */ Labeldesc *lb = findlabel(ls, name); if (lb == NULL) /* no label? */ /* forward jump; will be resolved when the label is declared */ newgotoentry(ls, name, line, luaK_jump(fs)); else { /* found a label */ /* backward jump; will be resolved here */ int lblevel = reglevel(fs, lb->nactvar); /* label level */ if (luaY_nvarstack(fs) > lblevel) /* leaving the scope of a variable? */ luaK_codeABC(fs, OP_CLOSE, lblevel, 0, 0); /* create jump and link it to the label */ luaK_patchlist(fs, luaK_jump(fs), lb->pc); } } /* ** Break statement. Semantically equivalent to "goto break". */ static void breakstat (LexState *ls) { int line = ls->linenumber; luaX_next(ls); /* skip break */ newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, luaK_jump(ls->fs)); } /* ** Check whether there is already a label with the given 'name'. */ static void checkrepeated (LexState *ls, TString *name) { Labeldesc *lb = findlabel(ls, name); if (l_unlikely(lb != NULL)) { /* already defined? */ const char *msg = "label '%s' already defined on line %d"; msg = luaO_pushfstring(ls->L, msg, getstr(name), lb->line); luaK_semerror(ls, msg); /* error */ } } static void labelstat (LexState *ls, TString *name, int line) { /* label -> '::' NAME '::' */ checknext(ls, TK_DBCOLON); /* skip double colon */ while (ls->t.token == ';' || ls->t.token == TK_DBCOLON) statement(ls); /* skip other no-op statements */ checkrepeated(ls, name); /* check for repeated labels */ createlabel(ls, name, line, block_follow(ls, 0)); } static void whilestat (LexState *ls, int line) { /* whilestat -> WHILE cond DO block END */ FuncState *fs = ls->fs; int whileinit; int condexit; BlockCnt bl; luaX_next(ls); /* skip WHILE */ whileinit = luaK_getlabel(fs); condexit = cond(ls); enterblock(fs, &bl, 1); checknext(ls, TK_DO); block(ls); luaK_jumpto(fs, whileinit); check_match(ls, TK_END, TK_WHILE, line); leaveblock(fs); luaK_patchtohere(fs, condexit); /* false conditions finish the loop */ } static void repeatstat (LexState *ls, int line) { /* repeatstat -> REPEAT block UNTIL cond */ int condexit; FuncState *fs = ls->fs; int repeat_init = luaK_getlabel(fs); BlockCnt bl1, bl2; enterblock(fs, &bl1, 1); /* loop block */ enterblock(fs, &bl2, 0); /* scope block */ luaX_next(ls); /* skip REPEAT */ statlist(ls); check_match(ls, TK_UNTIL, TK_REPEAT, line); condexit = cond(ls); /* read condition (inside scope block) */ leaveblock(fs); /* finish scope */ if (bl2.upval) { /* upvalues? */ int exit = luaK_jump(fs); /* normal exit must jump over fix */ luaK_patchtohere(fs, condexit); /* repetition must close upvalues */ luaK_codeABC(fs, OP_CLOSE, reglevel(fs, bl2.nactvar), 0, 0); condexit = luaK_jump(fs); /* repeat after closing upvalues */ luaK_patchtohere(fs, exit); /* normal exit comes to here */ } luaK_patchlist(fs, condexit, repeat_init); /* close the loop */ leaveblock(fs); /* finish loop */ } /* ** Read an expression and generate code to put its results in next ** stack slot. ** */ static void exp1 (LexState *ls) { expdesc e; expr(ls, &e); luaK_exp2nextreg(ls->fs, &e); lua_assert(e.k == VNONRELOC); } /* ** Fix for instruction at position 'pc' to jump to 'dest'. ** (Jump addresses are relative in Lua). 'back' true means ** a back jump. */ static void fixforjump (FuncState *fs, int pc, int dest, int back) { Instruction *jmp = &fs->f->code[pc]; int offset = dest - (pc + 1); if (back) offset = -offset; if (l_unlikely(offset > MAXARG_Bx)) luaX_syntaxerror(fs->ls, "control structure too long"); SETARG_Bx(*jmp, offset); } /* ** Generate code for a 'for' loop. */ static void forbody (LexState *ls, int base, int line, int nvars, int isgen) { /* forbody -> DO block */ static const OpCode forprep[2] = {OP_FORPREP, OP_TFORPREP}; static const OpCode forloop[2] = {OP_FORLOOP, OP_TFORLOOP}; BlockCnt bl; FuncState *fs = ls->fs; int prep, endfor; checknext(ls, TK_DO); prep = luaK_codeABx(fs, forprep[isgen], base, 0); fs->freereg--; /* both 'forprep' remove one register from the stack */ enterblock(fs, &bl, 0); /* scope for declared variables */ adjustlocalvars(ls, nvars); luaK_reserveregs(fs, nvars); block(ls); leaveblock(fs); /* end of scope for declared variables */ fixforjump(fs, prep, luaK_getlabel(fs), 0); if (isgen) { /* generic for? */ luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars); luaK_fixline(fs, line); } endfor = luaK_codeABx(fs, forloop[isgen], base, 0); fixforjump(fs, endfor, prep + 1, 1); luaK_fixline(fs, line); } static void fornum (LexState *ls, TString *varname, int line) { /* fornum -> NAME = exp,exp[,exp] forbody */ FuncState *fs = ls->fs; int base = fs->freereg; new_localvarliteral(ls, "(for state)"); new_localvarliteral(ls, "(for state)"); new_localvarkind(ls, varname, RDKCONST); /* control variable */ checknext(ls, '='); exp1(ls); /* initial value */ checknext(ls, ','); exp1(ls); /* limit */ if (testnext(ls, ',')) exp1(ls); /* optional step */ else { /* default step = 1 */ luaK_int(fs, fs->freereg, 1); luaK_reserveregs(fs, 1); } adjustlocalvars(ls, 2); /* start scope for internal variables */ forbody(ls, base, line, 1, 0); } static void forlist (LexState *ls, TString *indexname) { /* forlist -> NAME {,NAME} IN explist forbody */ FuncState *fs = ls->fs; expdesc e; int nvars = 4; /* function, state, closing, control */ int line; int base = fs->freereg; /* create internal variables */ new_localvarliteral(ls, "(for state)"); /* iterator function */ new_localvarliteral(ls, "(for state)"); /* state */ new_localvarliteral(ls, "(for state)"); /* closing var. (after swap) */ new_localvarkind(ls, indexname, RDKCONST); /* control variable */ /* other declared variables */ while (testnext(ls, ',')) { new_localvar(ls, str_checkname(ls)); nvars++; } checknext(ls, TK_IN); line = ls->linenumber; adjust_assign(ls, 4, explist(ls, &e), &e); adjustlocalvars(ls, 3); /* start scope for internal variables */ marktobeclosed(fs); /* last internal var. must be closed */ luaK_checkstack(fs, 2); /* extra space to call iterator */ forbody(ls, base, line, nvars - 3, 1); } static void forstat (LexState *ls, int line) { /* forstat -> FOR (fornum | forlist) END */ FuncState *fs = ls->fs; TString *varname; BlockCnt bl; enterblock(fs, &bl, 1); /* scope for loop and control variables */ luaX_next(ls); /* skip 'for' */ varname = str_checkname(ls); /* first variable name */ switch (ls->t.token) { case '=': fornum(ls, varname, line); break; case ',': case TK_IN: forlist(ls, varname); break; default: luaX_syntaxerror(ls, "'=' or 'in' expected"); } check_match(ls, TK_END, TK_FOR, line); leaveblock(fs); /* loop scope ('break' jumps to this point) */ } static void test_then_block (LexState *ls, int *escapelist) { /* test_then_block -> [IF | ELSEIF] cond THEN block */ BlockCnt bl; FuncState *fs = ls->fs; expdesc v; int jf; /* instruction to skip 'then' code (if condition is false) */ luaX_next(ls); /* skip IF or ELSEIF */ expr(ls, &v); /* read condition */ checknext(ls, TK_THEN); if (ls->t.token == TK_BREAK) { /* 'if x then break' ? */ int line = ls->linenumber; luaK_goiffalse(ls->fs, &v); /* will jump if condition is true */ luaX_next(ls); /* skip 'break' */ enterblock(fs, &bl, 0); /* must enter block before 'goto' */ newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, v.t); while (testnext(ls, ';')) {} /* skip semicolons */ if (block_follow(ls, 0)) { /* jump is the entire block? */ leaveblock(fs); return; /* and that is it */ } else /* must skip over 'then' part if condition is false */ jf = luaK_jump(fs); } else { /* regular case (not a break) */ luaK_goiftrue(ls->fs, &v); /* skip over block if condition is false */ enterblock(fs, &bl, 0); jf = v.f; } statlist(ls); /* 'then' part */ leaveblock(fs); if (ls->t.token == TK_ELSE || ls->t.token == TK_ELSEIF) /* followed by 'else'/'elseif'? */ luaK_concat(fs, escapelist, luaK_jump(fs)); /* must jump over it */ luaK_patchtohere(fs, jf); } static void ifstat (LexState *ls, int line) { /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */ FuncState *fs = ls->fs; int escapelist = NO_JUMP; /* exit list for finished parts */ test_then_block(ls, &escapelist); /* IF cond THEN block */ while (ls->t.token == TK_ELSEIF) test_then_block(ls, &escapelist); /* ELSEIF cond THEN block */ if (testnext(ls, TK_ELSE)) block(ls); /* 'else' part */ check_match(ls, TK_END, TK_IF, line); luaK_patchtohere(fs, escapelist); /* patch escape list to 'if' end */ } static void localfunc (LexState *ls) { expdesc b; FuncState *fs = ls->fs; int fvar = fs->nactvar; /* function's variable index */ new_localvar(ls, str_checkname(ls)); /* new local variable */ adjustlocalvars(ls, 1); /* enter its scope */ body(ls, &b, 0, ls->linenumber); /* function created in next register */ /* debug information will only see the variable after this point! */ localdebuginfo(fs, fvar)->startpc = fs->pc; } static int getlocalattribute (LexState *ls) { /* ATTRIB -> ['<' Name '>'] */ if (testnext(ls, '<')) { TString *ts = str_checkname(ls); const char *attr = getstr(ts); checknext(ls, '>'); if (strcmp(attr, "const") == 0) return RDKCONST; /* read-only variable */ else if (strcmp(attr, "close") == 0) return RDKTOCLOSE; /* to-be-closed variable */ else luaK_semerror(ls, luaO_pushfstring(ls->L, "unknown attribute '%s'", attr)); } return VDKREG; /* regular variable */ } static void checktoclose (FuncState *fs, int level) { if (level != -1) { /* is there a to-be-closed variable? */ marktobeclosed(fs); luaK_codeABC(fs, OP_TBC, reglevel(fs, level), 0, 0); } } static void localstat (LexState *ls) { /* stat -> LOCAL NAME ATTRIB { ',' NAME ATTRIB } ['=' explist] */ FuncState *fs = ls->fs; int toclose = -1; /* index of to-be-closed variable (if any) */ Vardesc *var; /* last variable */ int vidx; /* index of last variable */ int nvars = 0; int nexps; expdesc e; do { TString *vname = str_checkname(ls); int kind = getlocalattribute(ls); vidx = new_localvarkind(ls, vname, kind); if (kind == RDKTOCLOSE) { /* to-be-closed? */ if (toclose != -1) /* one already present? */ luaK_semerror(ls, "multiple to-be-closed variables in local list"); toclose = fs->nactvar + nvars; } nvars++; } while (testnext(ls, ',')); if (testnext(ls, '=')) nexps = explist(ls, &e); else { e.k = VVOID; nexps = 0; } var = getlocalvardesc(fs, vidx); /* get last variable */ if (nvars == nexps && /* no adjustments? */ var->vd.kind == RDKCONST && /* last variable is const? */ luaK_exp2const(fs, &e, &var->k)) { /* compile-time constant? */ var->vd.kind = RDKCTC; /* variable is a compile-time constant */ adjustlocalvars(ls, nvars - 1); /* exclude last variable */ fs->nactvar++; /* but count it */ } else { adjust_assign(ls, nvars, nexps, &e); adjustlocalvars(ls, nvars); } checktoclose(fs, toclose); } static int funcname (LexState *ls, expdesc *v) { /* funcname -> NAME {fieldsel} [':' NAME] */ int ismethod = 0; singlevar(ls, v); while (ls->t.token == '.') fieldsel(ls, v); if (ls->t.token == ':') { ismethod = 1; fieldsel(ls, v); } return ismethod; } static void funcstat (LexState *ls, int line) { /* funcstat -> FUNCTION funcname body */ int ismethod; expdesc v, b; luaX_next(ls); /* skip FUNCTION */ ismethod = funcname(ls, &v); body(ls, &b, ismethod, line); check_readonly(ls, &v); luaK_storevar(ls->fs, &v, &b); luaK_fixline(ls->fs, line); /* definition "happens" in the first line */ } static void exprstat (LexState *ls) { /* stat -> func | assignment */ FuncState *fs = ls->fs; struct LHS_assign v; suffixedexp(ls, &v.v); if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */ v.prev = NULL; restassign(ls, &v, 1); } else { /* stat -> func */ Instruction *inst; check_condition(ls, v.v.k == VCALL, "syntax error"); inst = &getinstruction(fs, &v.v); SETARG_C(*inst, 1); /* call statement uses no results */ } } static void retstat (LexState *ls) { /* stat -> RETURN [explist] [';'] */ FuncState *fs = ls->fs; expdesc e; int nret; /* number of values being returned */ int first = luaY_nvarstack(fs); /* first slot to be returned */ if (block_follow(ls, 1) || ls->t.token == ';') nret = 0; /* return no values */ else { nret = explist(ls, &e); /* optional return values */ if (hasmultret(e.k)) { luaK_setmultret(fs, &e); if (e.k == VCALL && nret == 1 && !fs->bl->insidetbc) { /* tail call? */ SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL); lua_assert(GETARG_A(getinstruction(fs,&e)) == luaY_nvarstack(fs)); } nret = LUA_MULTRET; /* return all values */ } else { if (nret == 1) /* only one single value? */ first = luaK_exp2anyreg(fs, &e); /* can use original slot */ else { /* values must go to the top of the stack */ luaK_exp2nextreg(fs, &e); lua_assert(nret == fs->freereg - first); } } } luaK_ret(fs, first, nret); testnext(ls, ';'); /* skip optional semicolon */ } static void statement (LexState *ls) { int line = ls->linenumber; /* may be needed for error messages */ enterlevel(ls); switch (ls->t.token) { case ';': { /* stat -> ';' (empty statement) */ luaX_next(ls); /* skip ';' */ break; } case TK_IF: { /* stat -> ifstat */ ifstat(ls, line); break; } case TK_WHILE: { /* stat -> whilestat */ whilestat(ls, line); break; } case TK_DO: { /* stat -> DO block END */ luaX_next(ls); /* skip DO */ block(ls); check_match(ls, TK_END, TK_DO, line); break; } case TK_FOR: { /* stat -> forstat */ forstat(ls, line); break; } case TK_REPEAT: { /* stat -> repeatstat */ repeatstat(ls, line); break; } case TK_FUNCTION: { /* stat -> funcstat */ funcstat(ls, line); break; } case TK_LOCAL: { /* stat -> localstat */ luaX_next(ls); /* skip LOCAL */ if (testnext(ls, TK_FUNCTION)) /* local function? */ localfunc(ls); else localstat(ls); break; } case TK_DBCOLON: { /* stat -> label */ luaX_next(ls); /* skip double colon */ labelstat(ls, str_checkname(ls), line); break; } case TK_RETURN: { /* stat -> retstat */ luaX_next(ls); /* skip RETURN */ retstat(ls); break; } case TK_BREAK: { /* stat -> breakstat */ breakstat(ls); break; } case TK_GOTO: { /* stat -> 'goto' NAME */ luaX_next(ls); /* skip 'goto' */ gotostat(ls); break; } default: { /* stat -> func | assignment */ exprstat(ls); break; } } lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg && ls->fs->freereg >= luaY_nvarstack(ls->fs)); ls->fs->freereg = luaY_nvarstack(ls->fs); /* free registers */ leavelevel(ls); } /* }====================================================================== */ /* ** compiles the main function, which is a regular vararg function with an ** upvalue named LUA_ENV */ static void mainfunc (LexState *ls, FuncState *fs) { BlockCnt bl; Upvaldesc *env; open_func(ls, fs, &bl); setvararg(fs, 0); /* main function is always declared vararg */ env = allocupvalue(fs); /* ...set environment upvalue */ env->instack = 1; env->idx = 0; env->kind = VDKREG; env->name = ls->envn; luaC_objbarrier(ls->L, fs->f, env->name); luaX_next(ls); /* read first token */ statlist(ls); /* parse main body */ check(ls, TK_EOS); close_func(ls); } LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff, Dyndata *dyd, const char *name, int firstchar) { LexState lexstate; FuncState funcstate; LClosure *cl = luaF_newLclosure(L, 1); /* create main closure */ setclLvalue2s(L, L->top.p, cl); /* anchor it (to avoid being collected) */ luaD_inctop(L); lexstate.h = luaH_new(L); /* create table for scanner */ sethvalue2s(L, L->top.p, lexstate.h); /* anchor it */ luaD_inctop(L); funcstate.f = cl->p = luaF_newproto(L); luaC_objbarrier(L, cl, cl->p); funcstate.f->source = luaS_new(L, name); /* create and anchor TString */ luaC_objbarrier(L, funcstate.f, funcstate.f->source); lexstate.buff = buff; lexstate.dyd = dyd; dyd->actvar.n = dyd->gt.n = dyd->label.n = 0; luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar); mainfunc(&lexstate, &funcstate); lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs); /* all scopes should be correctly finished */ lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0); L->top.p--; /* remove scanner's table */ return cl; /* closure is on the stack, too */ }