/* ** $Id: lparser.c,v 1.206 2003/02/18 16:02:56 roberto Exp roberto $ ** Lua Parser ** See Copyright Notice in lua.h */ #include #define lparser_c #include "lua.h" #include "lcode.h" #include "ldebug.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" #define getlocvar(fs, i) ((fs)->f->locvars[(fs)->actvar[i]]) #define enterlevel(ls) if (++(ls)->nestlevel > LUA_MAXPARSERLEVEL) \ luaX_syntaxerror(ls, "too many syntax levels"); #define leavelevel(ls) ((ls)->nestlevel--) /* ** nodes for block list (list of active blocks) */ typedef struct BlockCnt { struct BlockCnt *previous; /* chain */ int breaklist; /* list of jumps out of this loop */ int nactvar; /* # active local variables outside the breakable structure */ int upval; /* true if some variable in the block is an upvalue */ int isbreakable; /* true if `block' is a loop */ } BlockCnt; /* ** prototypes for recursive non-terminal functions */ static void chunk (LexState *ls); static void expr (LexState *ls, expdesc *v); static void next (LexState *ls) { ls->lastline = ls->linenumber; if (ls->lookahead.token != TK_EOS) { /* is there a look-ahead token? */ ls->t = ls->lookahead; /* use this one */ ls->lookahead.token = TK_EOS; /* and discharge it */ } else ls->t.token = luaX_lex(ls, &ls->t.seminfo); /* read next token */ } static void lookahead (LexState *ls) { lua_assert(ls->lookahead.token == TK_EOS); ls->lookahead.token = luaX_lex(ls, &ls->lookahead.seminfo); } static void error_expected (LexState *ls, int token) { luaX_syntaxerror(ls, luaO_pushfstring(ls->L, "`%s' expected", luaX_token2str(ls, token))); } static int testnext (LexState *ls, int c) { if (ls->t.token == c) { next(ls); return 1; } else return 0; } static void check (LexState *ls, int c) { if (!testnext(ls, c)) error_expected(ls, c); } #define check_condition(ls,c,msg) { if (!(c)) luaX_syntaxerror(ls, msg); } static void check_match (LexState *ls, int what, int who, int where) { if (!testnext(ls, what)) { if (where == ls->linenumber) error_expected(ls, what); 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_condition(ls, (ls->t.token == TK_NAME), " expected"); ts = ls->t.seminfo.ts; next(ls); return ts; } static void init_exp (expdesc *e, expkind k, int i) { e->f = e->t = NO_JUMP; e->k = k; e->info = i; } static void codestring (LexState *ls, expdesc *e, TString *s) { init_exp(e, VK, luaK_stringK(ls->fs, s)); } static void checkname(LexState *ls, expdesc *e) { codestring(ls, e, str_checkname(ls)); } static int luaI_registerlocalvar (LexState *ls, TString *varname) { FuncState *fs = ls->fs; Proto *f = fs->f; luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars, LocVar, MAX_INT, ""); f->locvars[fs->nlocvars].varname = varname; return fs->nlocvars++; } static void new_localvar (LexState *ls, TString *name, int n) { FuncState *fs = ls->fs; luaX_checklimit(ls, fs->nactvar+n+1, MAXVARS, "local variables"); fs->actvar[fs->nactvar+n] = luaI_registerlocalvar(ls, name); } static void adjustlocalvars (LexState *ls, int nvars) { FuncState *fs = ls->fs; fs->nactvar += nvars; for (; nvars; nvars--) { getlocvar(fs, fs->nactvar - nvars).startpc = fs->pc; } } static void removevars (LexState *ls, int tolevel) { FuncState *fs = ls->fs; while (fs->nactvar > tolevel) getlocvar(fs, --fs->nactvar).endpc = fs->pc; } static void new_localvarstr (LexState *ls, const char *name, int n) { new_localvar(ls, luaS_new(ls->L, name), n); } static void create_local (LexState *ls, const char *name) { new_localvarstr(ls, name, 0); adjustlocalvars(ls, 1); } static int indexupvalue (FuncState *fs, TString *name, expdesc *v) { int i; Proto *f = fs->f; for (i=0; inups; i++) { if (fs->upvalues[i].k == v->k && fs->upvalues[i].info == v->info) { lua_assert(fs->f->upvalues[i] == name); return i; } } /* new one */ luaX_checklimit(fs->ls, f->nups + 1, MAXUPVALUES, "upvalues"); luaM_growvector(fs->L, fs->f->upvalues, f->nups, fs->f->sizeupvalues, TString *, MAX_INT, ""); fs->f->upvalues[f->nups] = name; fs->upvalues[f->nups] = *v; return f->nups++; } static int searchvar (FuncState *fs, TString *n) { int i; for (i=fs->nactvar-1; i >= 0; i--) { if (n == getlocvar(fs, i).varname) return i; } return -1; /* not found */ } static void markupval (FuncState *fs, int level) { BlockCnt *bl = fs->bl; while (bl && bl->nactvar > level) bl = bl->previous; if (bl) bl->upval = 1; } static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) { if (fs == NULL) /* no more levels? */ init_exp(var, VGLOBAL, NO_REG); /* default is global variable */ else { int v = searchvar(fs, n); /* look up at current level */ if (v >= 0) { init_exp(var, VLOCAL, v); if (!base) markupval(fs, v); /* local will be used as an upval */ } else { /* not found at current level; try upper one */ singlevaraux(fs->prev, n, var, 0); if (var->k == VGLOBAL) { if (base) var->info = luaK_stringK(fs, n); /* info points to global name */ } else { /* LOCAL or UPVAL */ var->info = indexupvalue(fs, n, var); var->k = VUPVAL; /* upvalue in this level */ } } } } static TString *singlevar (LexState *ls, expdesc *var, int base) { TString *varname = str_checkname(ls); singlevaraux(ls->fs, varname, var, base); return varname; } static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) { FuncState *fs = ls->fs; int extra = nvars - nexps; if (e->k == VCALL) { extra++; /* includes call itself */ if (extra <= 0) extra = 0; else luaK_reserveregs(fs, extra-1); luaK_setcallreturns(fs, e, extra); /* call provides the difference */ } else { if (e->k != VVOID) luaK_exp2nextreg(fs, e); /* close last expression */ if (extra > 0) { int reg = fs->freereg; luaK_reserveregs(fs, extra); luaK_nil(fs, reg, extra); } } } static void code_params (LexState *ls, int nparams, int dots) { FuncState *fs = ls->fs; adjustlocalvars(ls, nparams); luaX_checklimit(ls, fs->nactvar, MAXPARAMS, "parameters"); fs->f->numparams = cast(lu_byte, fs->nactvar); fs->f->is_vararg = cast(lu_byte, dots); if (dots) create_local(ls, "arg"); luaK_reserveregs(fs, fs->nactvar); /* reserve register for parameters */ } static void enterblock (FuncState *fs, BlockCnt *bl, int isbreakable) { bl->breaklist = NO_JUMP; bl->isbreakable = isbreakable; bl->nactvar = fs->nactvar; bl->upval = 0; bl->previous = fs->bl; fs->bl = bl; lua_assert(fs->freereg == fs->nactvar); } static void leaveblock (FuncState *fs) { BlockCnt *bl = fs->bl; fs->bl = bl->previous; removevars(fs->ls, bl->nactvar); if (bl->upval) luaK_codeABC(fs, OP_CLOSE, bl->nactvar, 0, 0); lua_assert(bl->nactvar == fs->nactvar); fs->freereg = fs->nactvar; /* free registers */ luaK_patchtohere(fs, bl->breaklist); } static void pushclosure (LexState *ls, FuncState *func, expdesc *v) { FuncState *fs = ls->fs; Proto *f = fs->f; int i; luaM_growvector(ls->L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "constant table overflow"); f->p[fs->np++] = func->f; init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np-1)); for (i=0; if->nups; i++) { OpCode o = (func->upvalues[i].k == VLOCAL) ? OP_MOVE : OP_GETUPVAL; luaK_codeABC(fs, o, 0, func->upvalues[i].info, 0); } } static void open_func (LexState *ls, FuncState *fs) { Proto *f = luaF_newproto(ls->L); fs->f = f; fs->prev = ls->fs; /* linked list of funcstates */ fs->ls = ls; fs->L = ls->L; ls->fs = fs; fs->pc = 0; fs->lasttarget = 0; fs->jpc = NO_JUMP; fs->freereg = 0; fs->nk = 0; fs->h = luaH_new(ls->L, 0, 0); fs->np = 0; fs->nlocvars = 0; fs->nactvar = 0; fs->bl = NULL; f->source = ls->source; f->maxstacksize = 2; /* registers 0/1 are always valid */ } static void close_func (LexState *ls) { lua_State *L = ls->L; FuncState *fs = ls->fs; Proto *f = fs->f; removevars(ls, 0); luaK_codeABC(fs, OP_RETURN, 0, 1, 0); /* final return */ luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction); f->sizecode = fs->pc; luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int); f->sizelineinfo = fs->pc; luaM_reallocvector(L, f->k, f->sizek, fs->nk, TObject); f->sizek = fs->nk; luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *); f->sizep = fs->np; luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar); f->sizelocvars = fs->nlocvars; luaM_reallocvector(L, f->upvalues, f->sizeupvalues, f->nups, TString *); f->sizeupvalues = f->nups; lua_assert(luaG_checkcode(f)); lua_assert(fs->bl == NULL); ls->fs = fs->prev; } Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff) { struct LexState lexstate; struct FuncState funcstate; lexstate.buff = buff; lexstate.nestlevel = 0; luaX_setinput(L, &lexstate, z, luaS_new(L, zname(z))); open_func(&lexstate, &funcstate); next(&lexstate); /* read first token */ chunk(&lexstate); check_condition(&lexstate, (lexstate.t.token == TK_EOS), " expected"); close_func(&lexstate); lua_assert(funcstate.prev == NULL); lua_assert(funcstate.f->nups == 0); lua_assert(lexstate.nestlevel == 0); return funcstate.f; } /*============================================================*/ /* GRAMMAR RULES */ /*============================================================*/ static void luaY_field (LexState *ls, expdesc *v) { /* field -> ['.' | ':'] NAME */ FuncState *fs = ls->fs; expdesc key; luaK_exp2anyreg(fs, v); next(ls); /* skip the dot or colon */ checkname(ls, &key); luaK_indexed(fs, v, &key); } static void luaY_index (LexState *ls, expdesc *v) { /* index -> '[' expr ']' */ next(ls); /* skip the '[' */ expr(ls, v); luaK_exp2val(ls->fs, v); check(ls, ']'); } /* ** {====================================================================== ** Rules for Constructors ** ======================================================================= */ struct ConsControl { expdesc v; /* last list item read */ expdesc *t; /* table descriptor */ int nh; /* total number of `record' elements */ int na; /* total number of array elements */ int tostore; /* number of array elements pending to be stored */ }; static void recfield (LexState *ls, struct ConsControl *cc) { /* recfield -> (NAME | `['exp1`]') = exp1 */ FuncState *fs = ls->fs; int reg = ls->fs->freereg; expdesc key, val; if (ls->t.token == TK_NAME) { luaX_checklimit(ls, cc->nh, MAX_INT, "items in a constructor"); cc->nh++; checkname(ls, &key); } else /* ls->t.token == '[' */ luaY_index(ls, &key); check(ls, '='); luaK_exp2RK(fs, &key); expr(ls, &val); luaK_codeABC(fs, OP_SETTABLE, cc->t->info, luaK_exp2RK(fs, &key), luaK_exp2RK(fs, &val)); fs->freereg = reg; /* free registers */ } static void closelistfield (FuncState *fs, struct 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 == LFIELDS_PER_FLUSH) { luaK_codeABx(fs, OP_SETLIST, cc->t->info, cc->na-1); /* flush */ cc->tostore = 0; /* no more items pending */ fs->freereg = cc->t->info + 1; /* free registers */ } } static void lastlistfield (FuncState *fs, struct ConsControl *cc) { if (cc->tostore == 0) return; if (cc->v.k == VCALL) { luaK_setcallreturns(fs, &cc->v, LUA_MULTRET); luaK_codeABx(fs, OP_SETLISTO, cc->t->info, cc->na-1); } else { if (cc->v.k != VVOID) luaK_exp2nextreg(fs, &cc->v); luaK_codeABx(fs, OP_SETLIST, cc->t->info, cc->na-1); } fs->freereg = cc->t->info + 1; /* free registers */ } static void listfield (LexState *ls, struct ConsControl *cc) { expr(ls, &cc->v); luaX_checklimit(ls, cc->na, MAXARG_Bx, "items in a constructor"); cc->na++; cc->tostore++; } static void constructor (LexState *ls, expdesc *t) { /* constructor -> ?? */ FuncState *fs = ls->fs; int line = ls->linenumber; int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0); struct ConsControl cc; cc.na = cc.nh = cc.tostore = 0; cc.t = t; init_exp(t, VRELOCABLE, pc); init_exp(&cc.v, VVOID, 0); /* no value (yet) */ luaK_exp2nextreg(ls->fs, t); /* fix it at stack top (for gc) */ check(ls, '{'); do { lua_assert(cc.v.k == VVOID || cc.tostore > 0); testnext(ls, ';'); /* compatibility only */ if (ls->t.token == '}') break; closelistfield(fs, &cc); switch(ls->t.token) { case TK_NAME: { /* may be listfields or recfields */ lookahead(ls); if (ls->lookahead.token != '=') /* expression? */ listfield(ls, &cc); else recfield(ls, &cc); break; } case '[': { /* constructor_item -> recfield */ recfield(ls, &cc); break; } default: { /* constructor_part -> listfield */ listfield(ls, &cc); break; } } } while (testnext(ls, ',') || testnext(ls, ';')); check_match(ls, '}', '{', line); lastlistfield(fs, &cc); SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */ SETARG_C(fs->f->code[pc], luaO_log2(cc.nh)+1); /* set initial table size */ } /* }====================================================================== */ static void parlist (LexState *ls) { /* parlist -> [ param { `,' param } ] */ int nparams = 0; int dots = 0; if (ls->t.token != ')') { /* is `parlist' not empty? */ do { switch (ls->t.token) { case TK_DOTS: dots = 1; next(ls); break; case TK_NAME: new_localvar(ls, str_checkname(ls), nparams++); break; default: luaX_syntaxerror(ls, " or `...' expected"); } } while (!dots && testnext(ls, ',')); } code_params(ls, nparams, dots); } static void body (LexState *ls, expdesc *e, int needself, int line) { /* body -> `(' parlist `)' chunk END */ FuncState new_fs; open_func(ls, &new_fs); new_fs.f->lineDefined = line; check(ls, '('); if (needself) create_local(ls, "self"); parlist(ls); check(ls, ')'); chunk(ls); check_match(ls, TK_END, TK_FUNCTION, line); close_func(ls); pushclosure(ls, &new_fs, e); } static int explist1 (LexState *ls, expdesc *v) { /* explist1 -> 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 -> `(' [ explist1 ] `)' */ if (line != ls->lastline) luaX_syntaxerror(ls,"ambiguous syntax (function call x new statement)"); next(ls); if (ls->t.token == ')') /* arg list is empty? */ args.k = VVOID; else { explist1(ls, &args); luaK_setcallreturns(fs, &args, LUA_MULTRET); } check_match(ls, ')', '(', line); break; } case '{': { /* funcargs -> constructor */ constructor(ls, &args); break; } case TK_STRING: { /* funcargs -> STRING */ codestring(ls, &args, ls->t.seminfo.ts); next(ls); /* must use `seminfo' before `next' */ break; } default: { luaX_syntaxerror(ls, "function arguments expected"); return; } } lua_assert(f->k == VNONRELOC); base = f->info; /* base register for call */ if (args.k == VCALL) 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 remove function and arguments and leaves (unless changed) one result */ } /* ** {====================================================================== ** Expression parsing ** ======================================================================= */ static void prefixexp (LexState *ls, expdesc *v) { /* prefixexp -> NAME | '(' expr ')' */ switch (ls->t.token) { case '(': { int line = ls->linenumber; next(ls); expr(ls, v); check_match(ls, ')', '(', line); luaK_dischargevars(ls->fs, v); return; } case TK_NAME: { singlevar(ls, v, 1); return; } #ifdef LUA_COMPATUPSYNTAX case '%': { /* for compatibility only */ TString *varname; int line = ls->linenumber; next(ls); /* skip `%' */ varname = singlevar(ls, v, 1); if (v->k != VUPVAL) luaX_errorline(ls, "global upvalues are obsolete", getstr(varname), line); return; } #endif default: { luaX_syntaxerror(ls, "unexpected symbol"); return; } } } static void primaryexp (LexState *ls, expdesc *v) { /* primaryexp -> prefixexp { `.' NAME | `[' exp `]' | `:' NAME funcargs | funcargs } */ FuncState *fs = ls->fs; prefixexp(ls, v); for (;;) { switch (ls->t.token) { case '.': { /* field */ luaY_field(ls, v); break; } case '[': { /* `[' exp1 `]' */ expdesc key; luaK_exp2anyreg(fs, v); luaY_index(ls, &key); luaK_indexed(fs, v, &key); break; } case ':': { /* `:' NAME funcargs */ expdesc key; next(ls); checkname(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 -> NUMBER | STRING | NIL | constructor | FUNCTION body | primaryexp */ switch (ls->t.token) { case TK_NUMBER: { init_exp(v, VK, luaK_numberK(ls->fs, ls->t.seminfo.r)); next(ls); /* must use `seminfo' before `next' */ break; } case TK_STRING: { codestring(ls, v, ls->t.seminfo.ts); next(ls); /* must use `seminfo' before `next' */ break; } case TK_NIL: { init_exp(v, VNIL, 0); next(ls); break; } case TK_TRUE: { init_exp(v, VTRUE, 0); next(ls); break; } case TK_FALSE: { init_exp(v, VFALSE, 0); next(ls); break; } case '{': { /* constructor */ constructor(ls, v); break; } case TK_FUNCTION: { next(ls); body(ls, v, 0, ls->linenumber); break; } default: { primaryexp(ls, v); break; } } } static UnOpr getunopr (int op) { switch (op) { case TK_NOT: return OPR_NOT; case '-': return OPR_MINUS; default: return OPR_NOUNOPR; } } static BinOpr getbinopr (int op) { switch (op) { case '+': return OPR_ADD; case '-': return OPR_SUB; case '*': return OPR_MULT; case '/': return OPR_DIV; case '^': return OPR_POW; case TK_CONCAT: return OPR_CONCAT; case TK_NE: return OPR_NE; case TK_EQ: return OPR_EQ; case '<': return OPR_LT; case TK_LE: return OPR_LE; case '>': return OPR_GT; case TK_GE: return OPR_GE; case TK_AND: return OPR_AND; case TK_OR: return OPR_OR; default: return OPR_NOBINOPR; } } static const struct { lu_byte left; /* left priority for each binary operator */ lu_byte right; /* right priority */ } priority[] = { /* ORDER OPR */ {6, 6}, {6, 6}, {7, 7}, {7, 7}, /* arithmetic */ {10, 9}, {5, 4}, /* power and concat (right associative) */ {3, 3}, {3, 3}, /* equality */ {3, 3}, {3, 3}, {3, 3}, {3, 3}, /* order */ {2, 2}, {1, 1} /* logical (and/or) */ }; #define UNARY_PRIORITY 8 /* priority for unary operators */ /* ** subexpr -> (simplexep | unop subexpr) { binop subexpr } ** where `binop' is any binary operator with a priority higher than `limit' */ static BinOpr subexpr (LexState *ls, expdesc *v, int limit) { BinOpr op; UnOpr uop; enterlevel(ls); uop = getunopr(ls->t.token); if (uop != OPR_NOUNOPR) { next(ls); subexpr(ls, v, UNARY_PRIORITY); luaK_prefix(ls->fs, uop, v); } else simpleexp(ls, v); /* expand while operators have priorities higher than `limit' */ op = getbinopr(ls->t.token); while (op != OPR_NOBINOPR && cast(int, priority[op].left) > limit) { expdesc v2; BinOpr nextop; next(ls); luaK_infix(ls->fs, op, v); /* read sub-expression with higher priority */ nextop = subexpr(ls, &v2, cast(int, priority[op].right)); luaK_posfix(ls->fs, op, v, &v2); op = nextop; } leavelevel(ls); return op; /* return first untreated operator */ } static void expr (LexState *ls, expdesc *v) { subexpr(ls, v, -1); } /* }==================================================================== */ /* ** {====================================================================== ** Rules for Statements ** ======================================================================= */ static int block_follow (int token) { switch (token) { case TK_ELSE: case TK_ELSEIF: case TK_END: case TK_UNTIL: case TK_EOS: return 1; default: return 0; } } static void block (LexState *ls) { /* block -> chunk */ FuncState *fs = ls->fs; BlockCnt bl; enterblock(fs, &bl, 0); chunk(ls); lua_assert(bl.breaklist == NO_JUMP); 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 a local variable, the local variable ** is needed in a previous assignment (to a table). If so, save original ** 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) { if (lh->v.k == VINDEXED) { if (lh->v.info == v->info) { /* conflict? */ conflict = 1; lh->v.info = extra; /* previous assignment will use safe copy */ } if (lh->v.aux == v->info) { /* conflict? */ conflict = 1; lh->v.aux = extra; /* previous assignment will use safe copy */ } } } if (conflict) { luaK_codeABC(fs, OP_MOVE, fs->freereg, v->info, 0); /* make copy */ luaK_reserveregs(fs, 1); } } static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) { expdesc e; check_condition(ls, VLOCAL <= lh->v.k && lh->v.k <= VINDEXED, "syntax error"); if (testnext(ls, ',')) { /* assignment -> `,' primaryexp assignment */ struct LHS_assign nv; nv.prev = lh; primaryexp(ls, &nv.v); if (nv.v.k == VLOCAL) check_conflict(ls, lh, &nv.v); assignment(ls, &nv, nvars+1); } else { /* assignment -> `=' explist1 */ int nexps; check(ls, '='); nexps = explist1(ls, &e); if (nexps != nvars) { adjust_assign(ls, nvars, nexps, &e); if (nexps > nvars) ls->fs->freereg -= nexps - nvars; /* remove extra values */ } else { luaK_setcallreturns(ls->fs, &e, 1); /* 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 void cond (LexState *ls, expdesc *v) { /* cond -> exp */ expr(ls, v); /* read condition */ if (v->k == VNIL) v->k = VFALSE; /* `falses' are all equal here */ luaK_goiftrue(ls->fs, v); luaK_patchtohere(ls->fs, v->t); } /* ** The while statement optimizes its code by coding the condition ** after its body (and thus avoiding one jump in the loop). */ /* ** maximum size of expressions for optimizing `while' code */ #ifndef MAXEXPWHILE #define MAXEXPWHILE 100 #endif /* ** the call `luaK_goiffalse' may grow the size of an expression by ** at most this: */ #define EXTRAEXP 5 static void whilestat (LexState *ls, int line) { /* whilestat -> WHILE cond DO block END */ Instruction codeexp[MAXEXPWHILE + EXTRAEXP]; int lineexp = 0; int i; int sizeexp; FuncState *fs = ls->fs; int whileinit, blockinit, expinit; expdesc v; BlockCnt bl; next(ls); /* skip WHILE */ whileinit = luaK_jump(fs); /* jump to condition (which will be moved) */ expinit = luaK_getlabel(fs); expr(ls, &v); /* parse condition */ if (v.k == VK) v.k = VTRUE; /* `trues' are all equal here */ lineexp = ls->linenumber; luaK_goiffalse(fs, &v); luaK_concat(fs, &v.f, fs->jpc); fs->jpc = NO_JUMP; sizeexp = fs->pc - expinit; /* size of expression code */ if (sizeexp > MAXEXPWHILE) luaX_syntaxerror(ls, "`while' condition too complex"); for (i = 0; i < sizeexp; i++) /* save `exp' code */ codeexp[i] = fs->f->code[expinit + i]; fs->pc = expinit; /* remove `exp' code */ enterblock(fs, &bl, 1); check(ls, TK_DO); blockinit = luaK_getlabel(fs); block(ls); luaK_patchtohere(fs, whileinit); /* initial jump jumps to here */ /* move `exp' back to code */ if (v.t != NO_JUMP) v.t += fs->pc - expinit; if (v.f != NO_JUMP) v.f += fs->pc - expinit; for (i=0; i REPEAT block UNTIL cond */ FuncState *fs = ls->fs; int repeat_init = luaK_getlabel(fs); expdesc v; BlockCnt bl; enterblock(fs, &bl, 1); next(ls); block(ls); check_match(ls, TK_UNTIL, TK_REPEAT, line); cond(ls, &v); luaK_patchlist(fs, v.f, repeat_init); leaveblock(fs); } static int exp1 (LexState *ls) { expdesc e; int k; expr(ls, &e); k = e.k; luaK_exp2nextreg(ls->fs, &e); return k; } static void forbody (LexState *ls, int base, int line, int nvars, int isnum) { BlockCnt bl; FuncState *fs = ls->fs; int prep, endfor; adjustlocalvars(ls, nvars); /* scope for all variables */ check(ls, TK_DO); enterblock(fs, &bl, 1); /* loop block */ prep = luaK_getlabel(fs); block(ls); luaK_patchtohere(fs, prep-1); endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) : luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars - 3); luaK_fixline(fs, line); /* pretend that `OP_FOR' starts the loop */ luaK_patchlist(fs, (isnum) ? endfor : luaK_jump(fs), prep); leaveblock(fs); } static void fornum (LexState *ls, TString *varname, int line) { /* fornum -> NAME = exp1,exp1[,exp1] DO body */ FuncState *fs = ls->fs; int base = fs->freereg; new_localvar(ls, varname, 0); new_localvarstr(ls, "(for limit)", 1); new_localvarstr(ls, "(for step)", 2); check(ls, '='); exp1(ls); /* initial value */ check(ls, ','); exp1(ls); /* limit */ if (testnext(ls, ',')) exp1(ls); /* optional step */ else { /* default step = 1 */ luaK_codeABx(fs, OP_LOADK, fs->freereg, luaK_numberK(fs, 1)); luaK_reserveregs(fs, 1); } luaK_codeABC(fs, OP_SUB, fs->freereg - 3, fs->freereg - 3, fs->freereg - 1); luaK_jump(fs); forbody(ls, base, line, 3, 1); } static void forlist (LexState *ls, TString *indexname) { /* forlist -> NAME {,NAME} IN explist1 DO body */ FuncState *fs = ls->fs; expdesc e; int nvars = 0; int line; int base = fs->freereg; new_localvarstr(ls, "(for generator)", nvars++); new_localvarstr(ls, "(for state)", nvars++); new_localvar(ls, indexname, nvars++); while (testnext(ls, ',')) new_localvar(ls, str_checkname(ls), nvars++); check(ls, TK_IN); line = ls->linenumber; adjust_assign(ls, nvars, explist1(ls, &e), &e); luaK_checkstack(fs, 3); /* extra space to call generator */ luaK_codeAsBx(fs, OP_TFORPREP, base, NO_JUMP); forbody(ls, base, line, nvars, 0); } static void forstat (LexState *ls, int line) { /* forstat -> fornum | forlist */ FuncState *fs = ls->fs; TString *varname; BlockCnt bl; enterblock(fs, &bl, 0); /* block to control variable scope */ 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); } static void test_then_block (LexState *ls, expdesc *v) { /* test_then_block -> [IF | ELSEIF] cond THEN block */ next(ls); /* skip IF or ELSEIF */ cond(ls, v); check(ls, TK_THEN); block(ls); /* `then' part */ } static void ifstat (LexState *ls, int line) { /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */ FuncState *fs = ls->fs; expdesc v; int escapelist = NO_JUMP; test_then_block(ls, &v); /* IF cond THEN block */ while (ls->t.token == TK_ELSEIF) { luaK_concat(fs, &escapelist, luaK_jump(fs)); luaK_patchtohere(fs, v.f); test_then_block(ls, &v); /* ELSEIF cond THEN block */ } if (ls->t.token == TK_ELSE) { luaK_concat(fs, &escapelist, luaK_jump(fs)); luaK_patchtohere(fs, v.f); next(ls); /* skip ELSE (after patch, for correct line info) */ block(ls); /* `else' part */ } else luaK_concat(fs, &escapelist, v.f); luaK_patchtohere(fs, escapelist); check_match(ls, TK_END, TK_IF, line); } static void localfunc (LexState *ls) { expdesc v, b; new_localvar(ls, str_checkname(ls), 0); init_exp(&v, VLOCAL, ls->fs->freereg++); adjustlocalvars(ls, 1); body(ls, &b, 0, ls->linenumber); luaK_storevar(ls->fs, &v, &b); } static void localstat (LexState *ls) { /* stat -> LOCAL NAME {`,' NAME} [`=' explist1] */ int nvars = 0; int nexps; expdesc e; do { new_localvar(ls, str_checkname(ls), nvars++); } while (testnext(ls, ',')); if (testnext(ls, '=')) nexps = explist1(ls, &e); else { e.k = VVOID; nexps = 0; } adjust_assign(ls, nvars, nexps, &e); adjustlocalvars(ls, nvars); } static int funcname (LexState *ls, expdesc *v) { /* funcname -> NAME {field} [`:' NAME] */ int needself = 0; singlevar(ls, v, 1); while (ls->t.token == '.') luaY_field(ls, v); if (ls->t.token == ':') { needself = 1; luaY_field(ls, v); } return needself; } static void funcstat (LexState *ls, int line) { /* funcstat -> FUNCTION funcname body */ int needself; expdesc v, b; next(ls); /* skip FUNCTION */ needself = funcname(ls, &v); body(ls, &b, needself, line); 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; primaryexp(ls, &v.v); if (v.v.k == VCALL) { /* stat -> func */ luaK_setcallreturns(fs, &v.v, 0); /* call statement uses no results */ } else { /* stat -> assignment */ v.prev = NULL; assignment(ls, &v, 1); } } static void retstat (LexState *ls) { /* stat -> RETURN explist */ FuncState *fs = ls->fs; expdesc e; int first, nret; /* registers with returned values */ next(ls); /* skip RETURN */ if (block_follow(ls->t.token) || ls->t.token == ';') first = nret = 0; /* return no values */ else { nret = explist1(ls, &e); /* optional return values */ if (e.k == VCALL) { luaK_setcallreturns(fs, &e, LUA_MULTRET); if (nret == 1) { /* tail call? */ SET_OPCODE(getcode(fs,&e), OP_TAILCALL); lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar); } first = fs->nactvar; nret = LUA_MULTRET; /* return all values */ } else { if (nret == 1) /* only one single value? */ first = luaK_exp2anyreg(fs, &e); else { luaK_exp2nextreg(fs, &e); /* values must go to the `stack' */ first = fs->nactvar; /* return all `active' values */ lua_assert(nret == fs->freereg - first); } } } luaK_codeABC(fs, OP_RETURN, first, nret+1, 0); } static void breakstat (LexState *ls) { /* stat -> BREAK [NAME] */ FuncState *fs = ls->fs; BlockCnt *bl = fs->bl; int upval = 0; next(ls); /* skip BREAK */ while (bl && !bl->isbreakable) { upval |= bl->upval; bl = bl->previous; } if (!bl) luaX_syntaxerror(ls, "no loop to break"); if (upval) luaK_codeABC(fs, OP_CLOSE, bl->nactvar, 0, 0); luaK_concat(fs, &bl->breaklist, luaK_jump(fs)); } static int statement (LexState *ls) { int line = ls->linenumber; /* may be needed for error messages */ switch (ls->t.token) { case TK_IF: { /* stat -> ifstat */ ifstat(ls, line); return 0; } case TK_WHILE: { /* stat -> whilestat */ whilestat(ls, line); return 0; } case TK_DO: { /* stat -> DO block END */ next(ls); /* skip DO */ block(ls); check_match(ls, TK_END, TK_DO, line); return 0; } case TK_FOR: { /* stat -> forstat */ forstat(ls, line); return 0; } case TK_REPEAT: { /* stat -> repeatstat */ repeatstat(ls, line); return 0; } case TK_FUNCTION: { funcstat(ls, line); /* stat -> funcstat */ return 0; } case TK_LOCAL: { /* stat -> localstat */ next(ls); /* skip LOCAL */ if (testnext(ls, TK_FUNCTION)) /* local function? */ localfunc(ls); else localstat(ls); return 0; } case TK_RETURN: { /* stat -> retstat */ retstat(ls); return 1; /* must be last statement */ } case TK_BREAK: { /* stat -> breakstat */ breakstat(ls); return 1; /* must be last statement */ } default: { exprstat(ls); return 0; /* to avoid warnings */ } } } static void chunk (LexState *ls) { /* chunk -> { stat [`;'] } */ int islast = 0; enterlevel(ls); while (!islast && !block_follow(ls->t.token)) { islast = statement(ls); testnext(ls, ';'); lua_assert(ls->fs->freereg >= ls->fs->nactvar); ls->fs->freereg = ls->fs->nactvar; /* free registers */ } leavelevel(ls); } /* }====================================================================== */