#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") != )){
throw runtime_error("open lua file error");
}
system("pause");
return ;
}
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 == || L->hookmask & LUA_MASKLINE)) {
traceexec(L, pc);
if (L->status == LUA_YIELD) { /* did hook yield? */
L->savedpc = pc - ;
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+, 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+, 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) - ;
if (b != ) 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 >= ) L->top = L->ci->top;
base = L->base;
continue;
}
default: {
return; /* yield */
}
}
}
case OP_TAILCALL: {
int b = GETARG_B(i);
if (b != ) L->top = ra+b; /* else previous instruction set top */
L->savedpc = pc;
lua_assert(GETARG_C(i) - == 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 - ; /* previous frame */
int aux;
StkId func = ci->func;
StkId pfunc = (ci+)->func; /* previous function index */
if (L->openupval) luaF_close(L, ci->base);
L->base = ci->base = ci->func + ((ci+)->base - pfunc);
for (aux = ; 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 != ) L->top = ra+b-;
if (L->openupval) luaF_close(L, base);
L->savedpc = pc;
b = luaD_poscall(L, ra);
if (--nexeccalls == ) /* 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 - )) == OP_CALL);
goto reentry;
}
}
case OP_FORLOOP: {
lua_Number step = nvalue(ra+);
lua_Number idx = luai_numadd(nvalue(ra), step); /* increment index */
lua_Number limit = nvalue(ra+);
if (luai_numlt(, 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+, idx); /* ...and external index */
}
continue;
}
case OP_FORPREP: {
const TValue *init = ra;
const TValue *plimit = ra+;
const TValue *pstep = ra+;
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+))
luaG_runerror(L, LUA_QL("for") " limit must be a number");
else if (!tonumber(pstep, ra+))
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 + ; /* call base */
setobjs2s(L, cb+, ra+);
setobjs2s(L, cb+, ra+);
setobjs2s(L, cb, ra);
L->top = cb+; /* func. + 2 args (state and index) */
Protect(luaD_call(L, cb, GETARG_C(i)));
L->top = L->ci->top;
cb = RA(i) + ; /* previous call may change the stack */
if (!ttisnil(cb)) { /* continue loop? */
setobjs2s(L, cb-, 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 == ) {
n = cast_int(L->top - ra) - ;
L->top = L->ci->top;
}
if (c == ) c = cast_int(*pc++);
runtime_check(L, ttistable(ra));
h = hvalue(ra);
last = ((c-)*LFIELDS_PER_FLUSH) + n;
if (last > h->sizearray) /* needs more space? */
luaH_resizearray(L, h, last); /* pre-alloc it at once */
for (; n > ; 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=; 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) - ;
int j;
CallInfo *ci = L->ci;
int n = cast_int(ci->base - ci->func) - cl->p->numparams - ;
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 = ; j < b; j++) {
if (j < n) {
setobjs2s(L, ra + j, ci->base - n + j);
}
else {
setnilvalue(ra + j);
}
}
continue;
}
}
}
}