本文转自:http://www.cnblogs.com/zxh1210603696/p/4458473.html
#include "lua.hpp" #include <iostream> using namespace std; #pragma comment(lib, "lua5.1.lib") struct lua_guard{ lua_State *pL; lua_guard(lua_State *s) :pL(s){} ~lua_guard(){ lua_close(pL); } }; int main(){ lua_guard g(lua_open()); luaL_openlibs(g.pL); int err; if ((err = luaL_dofile(g.pL, "mylua.lua") != 0)){ throw runtime_error("open lua file error"); } system("pause"); return 0; }
首先利用lua提供的函数luaL_dofile来执行一个lua脚本。
可以看到有两个过程,首先luaL_loadfile函数将lua文件加载进来然后进行词法语法语义分析,得到一个closure函数放入栈中,接着调用lua_pcall函数来执行栈顶的closure。
我们先来看看第一个过程:
首先在luaL_loadfile中真正加载lua文件的是lua_load函数
在lua_load中调用了luaD_protectedparser来进行parse过程
在luaD_protectedparser中又调用了f_parser
在f_parser中根据一些选择来分别处理不同的情况,我们示例中会跑到luaY_parser函数中去,在luaY_parser中会调用luaX_next进行分析,这个函数会首先读取源文件中的第一个token
最后在luaX_next中调用了llex,llex是真正切出token的例程
在读取了第一个token后luaX_next返回,相关的词法信息保存在了lexstate中,接着luaY_parser调用chunk函数来递归的生成一个chunk块
在chunk中循环读取下一个token并根据token的类型一层一层的递归的生成chunk,将chunks根据层次组合成tree,位于root的是最外层chunk
在分析完lua脚本后会返回到f_parser,在f_parser中接着调用luaF_newLclosure来将分析结果包裹成一个closure然后push到lua栈中
接下来分析第二个过程:
当第一个过程完成后lua栈顶存放着一个closure,luaL_dofile中调用lua_pcall让其来调用这个closure:
在lua_pcall中调用了f_call
f_call中又接着调用了luaD_call,传入了被调用的closure和参数个数
最后在luaD_call中调用了luaV_execute来执行closure中的opcode
luaV_execute既是lua虚拟机执行opcode的函数,其中可以看到一个无限循环,利用switch (GET_OPCODE(i))来根据不同的opcode进行不同的过程
void luaV_execute (lua_State *L, int nexeccalls) { LClosure *cl; StkId base; TValue *k; const Instruction *pc; reentry: /* entry point */ lua_assert(isLua(L->ci)); pc = L->savedpc; cl = &clvalue(L->ci->func)->l; base = L->base; k = cl->p->k; /* main loop of interpreter */ for (;;) { const Instruction i = *pc++; StkId ra; if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) && (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) { traceexec(L, pc); if (L->status == LUA_YIELD) { /* did hook yield? */ L->savedpc = pc - 1; return; } base = L->base; } /* warning!! several calls may realloc the stack and invalidate `ra' */ ra = RA(i); lua_assert(base == L->base && L->base == L->ci->base); lua_assert(base <= L->top && L->top <= L->stack + L->stacksize); lua_assert(L->top == L->ci->top || luaG_checkopenop(i)); switch (GET_OPCODE(i)) { case OP_MOVE: { setobjs2s(L, ra, RB(i)); continue; } case OP_LOADK: { setobj2s(L, ra, KBx(i)); continue; } case OP_LOADBOOL: { setbvalue(ra, GETARG_B(i)); if (GETARG_C(i)) pc++; /* skip next instruction (if C) */ continue; } case OP_LOADNIL: { TValue *rb = RB(i); do { setnilvalue(rb--); } while (rb >= ra); continue; } case OP_GETUPVAL: { int b = GETARG_B(i); setobj2s(L, ra, cl->upvals[b]->v); continue; } case OP_GETGLOBAL: { TValue g; TValue *rb = KBx(i); sethvalue(L, &g, cl->env); lua_assert(ttisstring(rb)); Protect(luaV_gettable(L, &g, rb, ra)); continue; } case OP_GETTABLE: { Protect(luaV_gettable(L, RB(i), RKC(i), ra)); continue; } case OP_SETGLOBAL: { TValue g; sethvalue(L, &g, cl->env); lua_assert(ttisstring(KBx(i))); Protect(luaV_settable(L, &g, KBx(i), ra)); continue; } case OP_SETUPVAL: { UpVal *uv = cl->upvals[GETARG_B(i)]; setobj(L, uv->v, ra); luaC_barrier(L, uv, ra); continue; } case OP_SETTABLE: { Protect(luaV_settable(L, ra, RKB(i), RKC(i))); continue; } case OP_NEWTABLE: { int b = GETARG_B(i); int c = GETARG_C(i); sethvalue(L, ra, luaH_new(L, luaO_fb2int(b), luaO_fb2int(c))); Protect(luaC_checkGC(L)); continue; } case OP_SELF: { StkId rb = RB(i); setobjs2s(L, ra+1, rb); Protect(luaV_gettable(L, rb, RKC(i), ra)); continue; } case OP_ADD: { arith_op(luai_numadd, TM_ADD); continue; } case OP_SUB: { arith_op(luai_numsub, TM_SUB); continue; } case OP_MUL: { arith_op(luai_nummul, TM_MUL); continue; } case OP_DIV: { arith_op(luai_numdiv, TM_DIV); continue; } case OP_MOD: { arith_op(luai_nummod, TM_MOD); continue; } case OP_POW: { arith_op(luai_numpow, TM_POW); continue; } case OP_UNM: { TValue *rb = RB(i); if (ttisnumber(rb)) { lua_Number nb = nvalue(rb); setnvalue(ra, luai_numunm(nb)); } else { Protect(Arith(L, ra, rb, rb, TM_UNM)); } continue; } case OP_NOT: { int res = l_isfalse(RB(i)); /* next assignment may change this value */ setbvalue(ra, res); continue; } case OP_LEN: { const TValue *rb = RB(i); switch (ttype(rb)) { case LUA_TTABLE: { setnvalue(ra, cast_num(luaH_getn(hvalue(rb)))); break; } case LUA_TSTRING: { setnvalue(ra, cast_num(tsvalue(rb)->len)); break; } default: { /* try metamethod */ Protect( if (!call_binTM(L, rb, luaO_nilobject, ra, TM_LEN)) luaG_typeerror(L, rb, "get length of"); ) } } continue; } case OP_CONCAT: { int b = GETARG_B(i); int c = GETARG_C(i); Protect(luaV_concat(L, c-b+1, c); luaC_checkGC(L)); setobjs2s(L, RA(i), base+b); continue; } case OP_JMP: { dojump(L, pc, GETARG_sBx(i)); continue; } case OP_EQ: { TValue *rb = RKB(i); TValue *rc = RKC(i); Protect( if (equalobj(L, rb, rc) == GETARG_A(i)) dojump(L, pc, GETARG_sBx(*pc)); ) pc++; continue; } case OP_LT: { Protect( if (luaV_lessthan(L, RKB(i), RKC(i)) == GETARG_A(i)) dojump(L, pc, GETARG_sBx(*pc)); ) pc++; continue; } case OP_LE: { Protect( if (lessequal(L, RKB(i), RKC(i)) == GETARG_A(i)) dojump(L, pc, GETARG_sBx(*pc)); ) pc++; continue; } case OP_TEST: { if (l_isfalse(ra) != GETARG_C(i)) dojump(L, pc, GETARG_sBx(*pc)); pc++; continue; } case OP_TESTSET: { TValue *rb = RB(i); if (l_isfalse(rb) != GETARG_C(i)) { setobjs2s(L, ra, rb); dojump(L, pc, GETARG_sBx(*pc)); } pc++; continue; } case OP_CALL: { int b = GETARG_B(i); int nresults = GETARG_C(i) - 1; if (b != 0) L->top = ra+b; /* else previous instruction set top */ L->savedpc = pc; switch (luaD_precall(L, ra, nresults)) { case PCRLUA: { nexeccalls++; goto reentry; /* restart luaV_execute over new Lua function */ } case PCRC: { /* it was a C function (`precall' called it); adjust results */ if (nresults >= 0) L->top = L->ci->top; base = L->base; continue; } default: { return; /* yield */ } } } case OP_TAILCALL: { int b = GETARG_B(i); if (b != 0) L->top = ra+b; /* else previous instruction set top */ L->savedpc = pc; lua_assert(GETARG_C(i) - 1 == LUA_MULTRET); switch (luaD_precall(L, ra, LUA_MULTRET)) { case PCRLUA: { /* tail call: put new frame in place of previous one */ CallInfo *ci = L->ci - 1; /* previous frame */ int aux; StkId func = ci->func; StkId pfunc = (ci+1)->func; /* previous function index */ if (L->openupval) luaF_close(L, ci->base); L->base = ci->base = ci->func + ((ci+1)->base - pfunc); for (aux = 0; pfunc+aux < L->top; aux++) /* move frame down */ setobjs2s(L, func+aux, pfunc+aux); ci->top = L->top = func+aux; /* correct top */ lua_assert(L->top == L->base + clvalue(func)->l.p->maxstacksize); ci->savedpc = L->savedpc; ci->tailcalls++; /* one more call lost */ L->ci--; /* remove new frame */ goto reentry; } case PCRC: { /* it was a C function (`precall' called it) */ base = L->base; continue; } default: { return; /* yield */ } } } case OP_RETURN: { int b = GETARG_B(i); if (b != 0) L->top = ra+b-1; if (L->openupval) luaF_close(L, base); L->savedpc = pc; b = luaD_poscall(L, ra); if (--nexeccalls == 0) /* was previous function running `here'? */ return; /* no: return */ else { /* yes: continue its execution */ if (b) L->top = L->ci->top; lua_assert(isLua(L->ci)); lua_assert(GET_OPCODE(*((L->ci)->savedpc - 1)) == OP_CALL); goto reentry; } } case OP_FORLOOP: { lua_Number step = nvalue(ra+2); lua_Number idx = luai_numadd(nvalue(ra), step); /* increment index */ lua_Number limit = nvalue(ra+1); if (luai_numlt(0, step) ? luai_numle(idx, limit) : luai_numle(limit, idx)) { dojump(L, pc, GETARG_sBx(i)); /* jump back */ setnvalue(ra, idx); /* update internal index... */ setnvalue(ra+3, idx); /* ...and external index */ } continue; } case OP_FORPREP: { const TValue *init = ra; const TValue *plimit = ra+1; const TValue *pstep = ra+2; L->savedpc = pc; /* next steps may throw errors */ if (!tonumber(init, ra)) luaG_runerror(L, LUA_QL("for") " initial value must be a number"); else if (!tonumber(plimit, ra+1)) luaG_runerror(L, LUA_QL("for") " limit must be a number"); else if (!tonumber(pstep, ra+2)) luaG_runerror(L, LUA_QL("for") " step must be a number"); setnvalue(ra, luai_numsub(nvalue(ra), nvalue(pstep))); dojump(L, pc, GETARG_sBx(i)); continue; } case OP_TFORLOOP: { StkId cb = ra + 3; /* call base */ setobjs2s(L, cb+2, ra+2); setobjs2s(L, cb+1, ra+1); setobjs2s(L, cb, ra); L->top = cb+3; /* func. + 2 args (state and index) */ Protect(luaD_call(L, cb, GETARG_C(i))); L->top = L->ci->top; cb = RA(i) + 3; /* previous call may change the stack */ if (!ttisnil(cb)) { /* continue loop? */ setobjs2s(L, cb-1, cb); /* save control variable */ dojump(L, pc, GETARG_sBx(*pc)); /* jump back */ } pc++; continue; } case OP_SETLIST: { int n = GETARG_B(i); int c = GETARG_C(i); int last; Table *h; if (n == 0) { n = cast_int(L->top - ra) - 1; L->top = L->ci->top; } if (c == 0) c = cast_int(*pc++); runtime_check(L, ttistable(ra)); h = hvalue(ra); last = ((c-1)*LFIELDS_PER_FLUSH) + n; if (last > h->sizearray) /* needs more space? */ luaH_resizearray(L, h, last); /* pre-alloc it at once */ for (; n > 0; n--) { TValue *val = ra+n; setobj2t(L, luaH_setnum(L, h, last--), val); luaC_barriert(L, h, val); } continue; } case OP_CLOSE: { luaF_close(L, ra); continue; } case OP_CLOSURE: { Proto *p; Closure *ncl; int nup, j; p = cl->p->p[GETARG_Bx(i)]; nup = p->nups; ncl = luaF_newLclosure(L, nup, cl->env); ncl->l.p = p; for (j=0; j<nup; j++, pc++) { if (GET_OPCODE(*pc) == OP_GETUPVAL) ncl->l.upvals[j] = cl->upvals[GETARG_B(*pc)]; else { lua_assert(GET_OPCODE(*pc) == OP_MOVE); ncl->l.upvals[j] = luaF_findupval(L, base + GETARG_B(*pc)); } } setclvalue(L, ra, ncl); Protect(luaC_checkGC(L)); continue; } case OP_VARARG: { int b = GETARG_B(i) - 1; int j; CallInfo *ci = L->ci; int n = cast_int(ci->base - ci->func) - cl->p->numparams - 1; if (b == LUA_MULTRET) { Protect(luaD_checkstack(L, n)); ra = RA(i); /* previous call may change the stack */ b = n; L->top = ra + n; } for (j = 0; j < b; j++) { if (j < n) { setobjs2s(L, ra + j, ci->base - n + j); } else { setnilvalue(ra + j); } } continue; } } } }