/*
** $Id: lfunc.c,v 2.30 2012/10/03 12:36:46 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"



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;
}


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;
}


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;
}


UpVal *luaF_findupval(lua_State *L, StkId level) {
    global_State *g = G(L);
    GCObject **pp = &L->openupval;
    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;
}


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 */
}


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 */
        else {
            unlinkupval(uv);  /* remove upvalue from 'uvhead' list */
            setobj(L, &uv->u.value, uv->v);  /* move value to upvalue slot */
            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;
}


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 */
}

