/* ** $Id: lparser.c,v 2.42.1.3 2007/12/28 15:32:23 roberto Exp $ ** Lua Parser ** See Copyright Notice in lua.h */ #include <string.h> #define lparser_c #define LUA_CORE #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" #define hasmultret(k) ((k) == VCALL || (k) == VVARARG) #define getlocvar(fs, i) ((fs)->f->locvars[(fs)->actvar[i]]) #define luaY_checklimit(fs,v,l,m) if ((v)>(l)) errorlimit(fs,l,m) /* ** nodes for block list (list of active blocks) */ typedef struct BlockCnt { struct BlockCnt *previous; /* chain */ int breaklist; /* list of jumps out of this loop */ lu_byte nactvar; /* # active locals outside the breakable structure */ lu_byte upval; /* true if some variable in the block is an upvalue */ lu_byte 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 anchor_token (LexState *ls) { if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) { TString *ts = ls->t.seminfo.ts; luaX_newstring(ls, getstr(ts), ts->tsv.len); } } static void error_expected (LexState *ls, int token) { luaX_syntaxerror(ls, luaO_pushfstring(ls->L, LUA_QS " expected", luaX_token2str(ls, token))); } static void errorlimit (FuncState *fs, int limit, const char *what) { const char *msg = (fs->f->linedefined == 0) ? luaO_pushfstring(fs->L, "main function has more than %d %s", limit, what) : luaO_pushfstring(fs->L, "function at line %d has more than %d %s", fs->f->linedefined, limit, what); luaX_lexerror(fs->ls, msg, 0); } static int testnext (LexState *ls, int c) { if (ls->t.token == c) { luaX_next(ls); return 1; } else return 0; } static void check (LexState *ls, int c) { if (ls->t.token != c) error_expected(ls, c); } 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); } 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, LUA_QS " expected (to close " LUA_QS " 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.s.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 registerlocalvar (LexState *ls, TString *varname) { FuncState *fs = ls->fs; Proto *f = fs->f; int oldsize = f->sizelocvars; luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars, LocVar, SHRT_MAX, "too many local variables"); while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL; f->locvars[fs->nlocvars].varname = varname; luaC_objbarrier(ls->L, f, varname); return fs->nlocvars++; } #define new_localvarliteral(ls,v,n) \ new_localvar(ls, luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char))-1), n) static void new_localvar (LexState *ls, TString *name, int n) { FuncState *fs = ls->fs; luaY_checklimit(fs, fs->nactvar+n+1, LUAI_MAXVARS, "local variables"); fs->actvar[fs->nactvar+n] = cast(unsigned short, registerlocalvar(ls, name)); } static void adjustlocalvars (LexState *ls, int nvars) { FuncState *fs = ls->fs; fs->nactvar = cast_byte(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 int indexupvalue (FuncState *fs, TString *name, expdesc *v) { int i; Proto *f = fs->f; int oldsize = f->sizeupvalues; for (i=0; i<f->nups; i++) { if (fs->upvalues[i].k == v->k && fs->upvalues[i].info == v->u.s.info) { lua_assert(f->upvalues[i] == name); return i; } } /* new one */ luaY_checklimit(fs, f->nups + 1, LUAI_MAXUPVALUES, "upvalues"); luaM_growvector(fs->L, f->upvalues, f->nups, f->sizeupvalues, TString *, MAX_INT, ""); while (oldsize < f->sizeupvalues) f->upvalues[oldsize++] = NULL; f->upvalues[f->nups] = name; luaC_objbarrier(fs->L, f, name); lua_assert(v->k == VLOCAL || v->k == VUPVAL); fs->upvalues[f->nups].k = cast_byte(v->k); fs->upvalues[f->nups].info = cast_byte(v->u.s.info); 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 int 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 */ return VGLOBAL; } 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 */ return VLOCAL; } else { /* not found at current level; try upper one */ if (singlevaraux(fs->prev, n, var, 0) == VGLOBAL) return VGLOBAL; var->u.s.info = indexupvalue(fs, n, var); /* else was LOCAL or UPVAL */ var->k = VUPVAL; /* upvalue in this level */ return VUPVAL; } } } static void singlevar (LexState *ls, expdesc *var) { TString *varname = str_checkname(ls); FuncState *fs = ls->fs; if (singlevaraux(fs, varname, var, 1) == VGLOBAL) var->u.s.info = luaK_stringK(fs, varname); /* info points to global name */ } static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) { FuncState *fs = ls->fs; int extra = nvars - nexps; if (hasmultret(e->k)) { extra++; /* includes call itself */ if (extra < 0) extra = 0; luaK_setreturns(fs, e, extra); /* last exp. provides the difference */ if (extra > 1) luaK_reserveregs(fs, extra-1); } 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 enterlevel (LexState *ls) { if (++ls->L->nCcalls > LUAI_MAXCCALLS) luaX_lexerror(ls, "chunk has too many syntax levels", 0); } #define leavelevel(ls) ((ls)->L->nCcalls--) static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte 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); /* a block either controls scope or breaks (never both) */ lua_assert(!bl->isbreakable || !bl->upval); 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 oldsize = f->sizep; int i; luaM_growvector(ls->L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "constant table overflow"); while (oldsize < f->sizep) f->p[oldsize++] = NULL; f->p[fs->np++] = func->f; luaC_objbarrier(ls->L, f, func->f); init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np-1)); for (i=0; i<func->f->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) { lua_State *L = ls->L; Proto *f = luaF_newproto(L); fs->f = f; fs->prev = ls->fs; /* linked list of funcstates */ fs->ls = ls; fs->L = L; ls->fs = fs; fs->pc = 0; fs->lasttarget = -1; fs->jpc = NO_JUMP; fs->freereg = 0; fs->nk = 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 */ fs->h = luaH_new(L, 0, 0); /* anchor table of constants and prototype (to avoid being collected) */ sethvalue2s(L, L->top, fs->h); incr_top(L); setptvalue2s(L, L->top, f); incr_top(L); } static void close_func (LexState *ls) { lua_State *L = ls->L; FuncState *fs = ls->fs; Proto *f = fs->f; removevars(ls, 0); luaK_ret(fs, 0, 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, TValue); 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; L->top -= 2; /* remove table and prototype from the stack */ /* last token read was anchored in defunct function; must reanchor it */ if (fs) anchor_token(ls); } Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff, const char *name) { struct LexState lexstate; struct FuncState funcstate; lexstate.buff = buff; luaX_setinput(L, &lexstate, z, luaS_new(L, name)); open_func(&lexstate, &funcstate); funcstate.f->is_vararg = VARARG_ISVARARG; /* main func. is always vararg */ luaX_next(&lexstate); /* read first token */ chunk(&lexstate); check(&lexstate, TK_EOS); close_func(&lexstate); lua_assert(funcstate.prev == NULL); lua_assert(funcstate.f->nups == 0); lua_assert(lexstate.fs == NULL); return funcstate.f; } /*============================================================*/ /* GRAMMAR RULES */ /*============================================================*/ static void field (LexState *ls, expdesc *v) { /* field -> ['.' | ':'] NAME */ FuncState *fs = ls->fs; expdesc key; luaK_exp2anyreg(fs, v); luaX_next(ls); /* skip the dot or colon */ checkname(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 ** ======================================================================= */ 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; int rkkey; if (ls->t.token == TK_NAME) { luaY_checklimit(fs, cc->nh, MAX_INT, "items in a constructor"); checkname(ls, &key); } else /* ls->t.token == '[' */ yindex(ls, &key); cc->nh++; checknext(ls, '='); rkkey = luaK_exp2RK(fs, &key); expr(ls, &val); luaK_codeABC(fs, OP_SETTABLE, cc->t->u.s.info, rkkey, 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_setlist(fs, cc->t->u.s.info, cc->na, cc->tostore); /* flush */ cc->tostore = 0; /* no more items pending */ } } static void lastlistfield (FuncState *fs, struct ConsControl *cc) { if (cc->tostore == 0) return; if (hasmultret(cc->v.k)) { luaK_setmultret(fs, &cc->v); luaK_setlist(fs, cc->t->u.s.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.s.info, cc->na, cc->tostore); } } static void listfield (LexState *ls, struct ConsControl *cc) { expr(ls, &cc->v); luaY_checklimit(ls->fs, cc->na, MAX_INT, "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) */ checknext(ls, '{'); do { lua_assert(cc.v.k == VVOID || cc.tostore > 0); if (ls->t.token == '}') break; closelistfield(fs, &cc); switch(ls->t.token) { case TK_NAME: { /* may be listfields or recfields */ luaX_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_int2fb(cc.nh)); /* set initial table size */ } /* }====================================================================== */ static void parlist (LexState *ls) { /* parlist -> [ param { `,' param } ] */ FuncState *fs = ls->fs; Proto *f = fs->f; int nparams = 0; f->is_vararg = 0; if (ls->t.token != ')') { /* is `parlist' not empty? */ do { switch (ls->t.token) { case TK_NAME: { /* param -> NAME */ new_localvar(ls, str_checkname(ls), nparams++); break; } case TK_DOTS: { /* param -> `...' */ luaX_next(ls); #if defined(LUA_COMPAT_VARARG) /* use `arg' as default name */ new_localvarliteral(ls, "arg", nparams++); f->is_vararg = VARARG_HASARG | VARARG_NEEDSARG; #endif f->is_vararg |= VARARG_ISVARARG; break; } default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected"); } } while (!f->is_vararg && testnext(ls, ',')); } adjustlocalvars(ls, nparams); f->numparams = cast_byte(fs->nactvar - (f->is_vararg & VARARG_HASARG)); luaK_reserveregs(fs, fs->nactvar); /* reserve register for parameters */ } 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; checknext(ls, '('); if (needself) { new_localvarliteral(ls, "self", 0); adjustlocalvars(ls, 1); } parlist(ls); checknext(ls, ')'); chunk(ls); new_fs.f->lastlinedefined = ls->linenumber; 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)"); luaX_next(ls); if (ls->t.token == ')') /* arg list is empty? */ args.k = VVOID; else { explist1(ls, &args); luaK_setmultret(fs, &args); } check_match(ls, ')', '(', line); break; } case '{': { /* funcargs -> constructor */ constructor(ls, &args); break; } case TK_STRING: { /* funcargs -> STRING */ codestring(ls, &args, ls->t.seminfo.ts); luaX_next(ls); /* must use `seminfo' before `next' */ break; } default: { luaX_syntaxerror(ls, "function arguments expected"); return; } } lua_assert(f->k == VNONRELOC); base = f->u.s.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 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; 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"); 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 */ field(ls, v); break; } case '[': { /* `[' exp1 `]' */ expdesc key; luaK_exp2anyreg(fs, v); yindex(ls, &key); luaK_indexed(fs, v, &key); break; } case ':': { /* `:' NAME funcargs */ expdesc key; luaX_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 | true | false | ... | constructor | FUNCTION body | primaryexp */ switch (ls->t.token) { case TK_NUMBER: { init_exp(v, VKNUM, 0); v->u.nval = ls->t.seminfo.r; break; } case TK_STRING: { codestring(ls, 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->is_vararg, "cannot use " LUA_QL("...") " outside a vararg function"); fs->f->is_vararg &= ~VARARG_NEEDSARG; /* don't need 'arg' */ init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0)); break; } case '{': { /* constructor */ constructor(ls, v); return; } case TK_FUNCTION: { luaX_next(ls); body(ls, v, 0, ls->linenumber); return; } default: { primaryexp(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_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_DIV; case '%': return OPR_MOD; 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}, {7, 7}, /* `+' `-' `/' `%' */ {10, 9}, {5, 4}, /* power and concat (right associative) */ {3, 3}, {3, 3}, /* equality and inequality */ {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 -> (simpleexp | unop subexpr) { binop subexpr } ** where `binop' is any binary operator with a priority higher than `limit' */ static BinOpr subexpr (LexState *ls, expdesc *v, unsigned int limit) { BinOpr op; UnOpr uop; enterlevel(ls); uop = getunopr(ls->t.token); if (uop != OPR_NOUNOPR) { luaX_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 && priority[op].left > limit) { expdesc v2; BinOpr nextop; luaX_next(ls); 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); 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 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.u.s.info == v->u.s.info) { /* conflict? */ conflict = 1; lh->v.u.s.info = extra; /* previous assignment will use safe copy */ } if (lh->v.u.s.aux == v->u.s.info) { /* conflict? */ conflict = 1; lh->v.u.s.aux = extra; /* previous assignment will use safe copy */ } } } if (conflict) { luaK_codeABC(fs, OP_MOVE, fs->freereg, v->u.s.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); luaY_checklimit(ls->fs, nvars, LUAI_MAXCCALLS - ls->L->nCcalls, "variables in assignment"); assignment(ls, &nv, nvars+1); } else { /* assignment -> `=' explist1 */ int nexps; checknext(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_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 breakstat (LexState *ls) { FuncState *fs = ls->fs; BlockCnt *bl = fs->bl; int upval = 0; 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 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_patchlist(fs, luaK_jump(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 */ chunk(ls); check_match(ls, TK_UNTIL, TK_REPEAT, line); condexit = cond(ls); /* read condition (inside scope block) */ if (!bl2.upval) { /* no upvalues? */ leaveblock(fs); /* finish scope */ luaK_patchlist(ls->fs, condexit, repeat_init); /* close the loop */ } else { /* complete semantics when there are upvalues */ breakstat(ls); /* if condition then break */ luaK_patchtohere(ls->fs, condexit); /* else... */ leaveblock(fs); /* finish scope... */ luaK_patchlist(ls->fs, luaK_jump(fs), repeat_init); /* and repeat */ } leaveblock(fs); /* finish loop */ } 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) { /* forbody -> DO block */ BlockCnt bl; FuncState *fs = ls->fs; int prep, endfor; adjustlocalvars(ls, 3); /* control variables */ checknext(ls, TK_DO); prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs); 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 */ luaK_patchtohere(fs, prep); endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) : luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars); luaK_fixline(fs, line); /* pretend that `OP_FOR' starts the loop */ luaK_patchlist(fs, (isnum ? endfor : luaK_jump(fs)), prep + 1); } static void fornum (LexState *ls, TString *varname, int line) { /* fornum -> NAME = exp1,exp1[,exp1] forbody */ FuncState *fs = ls->fs; int base = fs->freereg; new_localvarliteral(ls, "(for index)", 0); new_localvarliteral(ls, "(for limit)", 1); new_localvarliteral(ls, "(for step)", 2); new_localvar(ls, varname, 3); checknext(ls, '='); exp1(ls); /* initial value */ checknext(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); } forbody(ls, base, line, 1, 1); } static void forlist (LexState *ls, TString *indexname) { /* forlist -> NAME {,NAME} IN explist1 forbody */ FuncState *fs = ls->fs; expdesc e; int nvars = 0; int line; int base = fs->freereg; /* create control variables */ new_localvarliteral(ls, "(for generator)", nvars++); new_localvarliteral(ls, "(for state)", nvars++); new_localvarliteral(ls, "(for control)", nvars++); /* create declared variables */ new_localvar(ls, indexname, nvars++); while (testnext(ls, ',')) new_localvar(ls, str_checkname(ls), nvars++); checknext(ls, TK_IN); line = ls->linenumber; adjust_assign(ls, 3, explist1(ls, &e), &e); luaK_checkstack(fs, 3); /* extra space to call generator */ forbody(ls, base, line, nvars - 3, 0); } 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, LUA_QL("=") " or " LUA_QL("in") " expected"); } check_match(ls, TK_END, TK_FOR, line); leaveblock(fs); /* loop scope (`break' jumps to this point) */ } static int test_then_block (LexState *ls) { /* test_then_block -> [IF | ELSEIF] cond THEN block */ int condexit; luaX_next(ls); /* skip IF or ELSEIF */ condexit = cond(ls); checknext(ls, TK_THEN); block(ls); /* `then' part */ return condexit; } static void ifstat (LexState *ls, int line) { /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */ FuncState *fs = ls->fs; int flist; int escapelist = NO_JUMP; flist = test_then_block(ls); /* IF cond THEN block */ while (ls->t.token == TK_ELSEIF) { luaK_concat(fs, &escapelist, luaK_jump(fs)); luaK_patchtohere(fs, flist); flist = test_then_block(ls); /* ELSEIF cond THEN block */ } if (ls->t.token == TK_ELSE) { luaK_concat(fs, &escapelist, luaK_jump(fs)); luaK_patchtohere(fs, flist); luaX_next(ls); /* skip ELSE (after patch, for correct line info) */ block(ls); /* `else' part */ } else luaK_concat(fs, &escapelist, flist); luaK_patchtohere(fs, escapelist); check_match(ls, TK_END, TK_IF, line); } static void localfunc (LexState *ls) { expdesc v, b; FuncState *fs = ls->fs; new_localvar(ls, str_checkname(ls), 0); init_exp(&v, VLOCAL, fs->freereg); luaK_reserveregs(fs, 1); adjustlocalvars(ls, 1); body(ls, &b, 0, ls->linenumber); luaK_storevar(fs, &v, &b); /* debug information will only see the variable after this point! */ getlocvar(fs, fs->nactvar - 1).startpc = fs->pc; } 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); while (ls->t.token == '.') field(ls, v); if (ls->t.token == ':') { needself = 1; field(ls, v); } return needself; } static void funcstat (LexState *ls, int line) { /* funcstat -> FUNCTION funcname body */ int needself; expdesc v, b; luaX_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 */ SETARG_C(getcode(fs, &v.v), 1); /* 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 */ luaX_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 (hasmultret(e.k)) { luaK_setmultret(fs, &e); if (e.k == VCALL && 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_ret(fs, first, nret); } 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 */ luaX_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 */ luaX_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 */ luaX_next(ls); /* skip BREAK */ 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->f->maxstacksize >= ls->fs->freereg && ls->fs->freereg >= ls->fs->nactvar); ls->fs->freereg = ls->fs->nactvar; /* free registers */ } leavelevel(ls); } /* }====================================================================== */