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/*
** $Id: lfunc.c,v 2.30.1.1 2013/04/12 18:48:47 roberto Exp $
** Auxiliary functions to manipulate prototypes and closures
** See Copyright Notice in lua.h
*/
#include <stddef.h>
#define lfunc_c
#define LUA_CORE
#include "lua.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
// saw 创建 c closure，用在 LUA API lua_pushcclosure
Closure *luaF_newCclosure (lua_State *L, int n) {
Closure *c = &luaC_newobj(L, LUA_TCCL, sizeCclosure(n), NULL, 0)->cl;
c->c.nupvalues = cast_byte(n);
return c;
}
// saw 创建 lua closure
Closure *luaF_newLclosure (lua_State *L, int n) {
Closure *c = &luaC_newobj(L, LUA_TLCL, sizeLclosure(n), NULL, 0)->cl;
c->l.p = NULL;
c->l.nupvalues = cast_byte(n);
while (n--) c->l.upvals[n] = NULL;
return c;
}
// saw 创建upvalue结构，不是栈上变量关联的upvalue
UpVal *luaF_newupval (lua_State *L) {
UpVal *uv = &luaC_newobj(L, LUA_TUPVAL, sizeof(UpVal), NULL, 0)->uv;
uv->v = &uv->u.value;
setnilvalue(uv->v);
return uv;
}
// saw 找到栈上变量对应的upvalue，如果么有的话创建一个并返回UpVal结构
UpVal *luaF_findupval (lua_State *L, StkId level) {
global_State *g = G(L);
GCObject **pp = &L->openupval; // 没有退出栈的时候 upvalue链表
UpVal *p;
UpVal *uv;
while (*pp != NULL && (p = gco2uv(*pp))->v >= level) {
GCObject *o = obj2gco(p);
lua_assert(p->v != &p->u.value);
lua_assert(!isold(o) || isold(obj2gco(L)));
if (p->v == level) { /* found a corresponding upvalue? */
if (isdead(g, o)) /* is it dead? */
changewhite(o); /* resurrect it */
return p;
}
pp = &p->next;
}
/* not found: create a new one */
uv = &luaC_newobj(L, LUA_TUPVAL, sizeof(UpVal), pp, 0)->uv;
uv->v = level; /* current value lives in the stack */
uv->u.l.prev = &g->uvhead; /* double link it in `uvhead' list */
uv->u.l.next = g->uvhead.u.l.next;
uv->u.l.next->u.l.prev = uv;
g->uvhead.u.l.next = uv;
lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
return uv;
}
static void unlinkupval (UpVal *uv) {
lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
uv->u.l.next->u.l.prev = uv->u.l.prev; /* remove from `uvhead' list */
uv->u.l.prev->u.l.next = uv->u.l.next;
}
// saw 退出栈的时候将关联的upvalue关闭，从
void luaF_freeupval (lua_State *L, UpVal *uv) {
if (uv->v != &uv->u.value) /* is it open? */
unlinkupval(uv); /* remove from open list */
luaM_free(L, uv); /* free upvalue */
}
// saw 如果退出了栈，某些upvalue被闭包引用，需要close这些 upvalue:
// 如果没有被引用，直接销毁
// 如果被引用了，先从 L->openupval 中删除，
void luaF_close (lua_State *L, StkId level) {
UpVal *uv;
global_State *g = G(L);
while (L->openupval != NULL && (uv = gco2uv(L->openupval))->v >= level) {
GCObject *o = obj2gco(uv);
lua_assert(!isblack(o) && uv->v != &uv->u.value);
L->openupval = uv->next; /* remove from `open' list */
if (isdead(g, o))
luaF_freeupval(L, uv); /* free upvalue */ // 没有被引用的话直接释放
else {
// 先将upvalue从L->openupval中移除，给下面用
unlinkupval(uv); /* remove upvalue from 'uvhead' list */
// 移动栈里面保存的值
setobj(L, &uv->u.value, uv->v); /* move value to upvalue slot */
// 修改pointer指到自己的值的地址
uv->v = &uv->u.value; /* now current value lives here */
gch(o)->next = g->allgc; /* link upvalue into 'allgc' list */
g->allgc = o;
luaC_checkupvalcolor(g, uv);
}
}
}
Proto *luaF_newproto (lua_State *L) {
Proto *f = &luaC_newobj(L, LUA_TPROTO, sizeof(Proto), NULL, 0)->p;
f->k = NULL;
f->sizek = 0;
f->p = NULL;
f->sizep = 0;
f->code = NULL;
f->cache = NULL;
f->sizecode = 0;
f->lineinfo = NULL;
f->sizelineinfo = 0;
f->upvalues = NULL;
f->sizeupvalues = 0;
f->numparams = 0;
f->is_vararg = 0;
f->maxstacksize = 0;
f->locvars = NULL;
f->sizelocvars = 0;
f->linedefined = 0;
f->lastlinedefined = 0;
f->source = NULL;
return f;
}
// saw 释放函数原型
void luaF_freeproto (lua_State *L, Proto *f) {
luaM_freearray(L, f->code, f->sizecode);
luaM_freearray(L, f->p, f->sizep);
luaM_freearray(L, f->k, f->sizek);
luaM_freearray(L, f->lineinfo, f->sizelineinfo);
luaM_freearray(L, f->locvars, f->sizelocvars);
luaM_freearray(L, f->upvalues, f->sizeupvalues);
luaM_free(L, f);
}
/*
** Look for n-th local variable at line `line' in function `func'.
** Returns NULL if not found.
*/
const char *luaF_getlocalname (const Proto *f, int local_number, int pc) {
int i;
for (i = 0; i<f->sizelocvars && f->locvars[i].startpc <= pc; i++) {
if (pc < f->locvars[i].endpc) { /* is variable active? */
local_number--;
if (local_number == 0)
return getstr(f->locvars[i].varname);
}
}
return NULL; /* not found */
}
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