标签：lua
先看table.insert调用的C函数:
static int tinsert (lua_State *L) {
int e = aux_getn(L, 1) + 1; /* first empty element */
int pos; /* where to insert new element */
switch (lua_gettop(L)) {
case 2: { /* called with only 2 arguments */
pos = e; /* insert new element at the end */
break;
}
case 3: {
int i;
pos = luaL_checkint(L, 2); /* 2nd argument is the position */
luaL_argcheck(L, 1 <= pos && pos <= e, 2, "position out of bounds");
for (i = e; i > pos; i--) { /* move up elements */
lua_rawgeti(L, 1, i-1);
lua_rawseti(L, 1, i); /* t[i] = t[i-1] */
}
break;
}
default: {
return luaL_error(L, "wrong number of arguments to " LUA_QL("insert"));
}
}
lua_rawseti(L, 1, pos); /* t[pos] = v */
return 0;
}
LUA_API void lua_rawseti (lua_State *L, int idx, int n) {
StkId t;
lua_lock(L);
api_checknelems(L, 1);
t = index2addr(L, idx);
api_check(L, ttistable(t), "table expected");
luaH_setint(L, hvalue(t), n, L->top - 1);
luaC_barrierback(L, gcvalue(t), L->top-1);
L->top--;
lua_unlock(L);
}最终调用luaH_setint函数:
void luaH_setint (lua_State *L, Table *t, int key, TValue *value) {
const TValue *p = luaH_getint(t, key);
TValue *cell;
if (p != luaO_nilobject)
cell = cast(TValue *, p);
else {
TValue k;
setnvalue(&k, cast_num(key));
cell = luaH_newkey(L, t, &k);
}
setobj2t(L, cell, value);
}此孙数key为table.insert要插入的pos,就是int e = aux_getn(L, 1) + 1的e,value就是要插入的值,看luaH_getint:/*
** search function for integers
*/
const TValue *luaH_getint (Table *t, int key) {
/* (1 <= key && key <= t->sizearray) */
if (cast(unsigned int, key-1) < cast(unsigned int, t->sizearray))
return &t->array[key-1];
else {
lua_Number nk = cast_num(key);
Node *n = hashnum(t, nk);
do { /* check whether `key' is somewhere in the chain */
if (ttisnumber(gkey(n)) && luai_numeq(nvalue(gkey(n)), nk))
return gval(n); /* that's it */
else n = gnext(n);
} while (n);
return luaO_nilobject;
}
}从此函数的注释可以知道，就是查找一个整形key是否存在(包括数组和hash).假如此key存在，刚赋值，不存在，刚新newkey，看luaH_newkey函数:TValue *luaH_newkey (lua_State *L, Table *t, const TValue *key) {
Node *mp;
if (ttisnil(key)) luaG_runerror(L, "table index is nil");
else if (ttisnumber(key) && luai_numisnan(L, nvalue(key)))
luaG_runerror(L, "table index is NaN");
mp = mainposition(t, key);
if (!ttisnil(gval(mp)) || isdummy(mp)) { /* main position is taken? */
Node *othern;
Node *n = getfreepos(t); /* get a free place */
if (n == NULL) { /* cannot find a free place? */
rehash(L, t, key); /* grow table */
/* whatever called 'newkey' take care of TM cache and GC barrier */
return luaH_set(L, t, key); /* insert key into grown table */
}
lua_assert(!isdummy(n));
othern = mainposition(t, gkey(mp));
if (othern != mp) { /* is colliding node out of its main position? */
/* yes; move colliding node into free position */
while (gnext(othern) != mp) othern = gnext(othern); /* find previous */
gnext(othern) = n; /* redo the chain with `n' in place of `mp' */
*n = *mp; /* copy colliding node into free pos. (mp->next also goes) */
gnext(mp) = NULL; /* now `mp' is free */
setnilvalue(gval(mp));
}
else { /* colliding node is in its own main position */
/* new node will go into free position */
gnext(n) = gnext(mp); /* chain new position */
gnext(mp) = n;
mp = n;
}
}
setobj2t(L, gkey(mp), key);
luaC_barrierback(L, obj2gco(t), key);
lua_assert(ttisnil(gval(mp)));
return gval(mp);
}
此函数就是把刚才要插入的key放到hash部分，如果hash已满刚rehash(rehash函数有点复杂，有空再写)，到这里，就知道table.insert的值有可能进入到hash，这就是为什么再讲一点，table的构告是由指令OP_NEWTABLE执行,初始化数组操作是由OP_SETLIST执行(赋值时元素个数是由语法解析生成的)，key value赋值是由OP_SETTABLE执行再加上table.insert和table.remove这两 个函数就组成了table所有的外部操作了。
标签：lua
原文地址：http://blog.csdn.net/ball32109/article/details/44906001
