text: /*
  ** $Id: lfunc.c,v 1.2 2007/09/13 03:59:24 dengzhihui 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 nelems, Table *e) {
    Closure *c = cast(Closure *, luaM_malloc(L, sizeCclosure(nelems)));
    luaC_link(L, obj2gco(c), LUA_TFUNCTION);
    c->c.isC = 1;
    c->c.env = e;
    c->c.nupvalues = cast_byte(nelems);
    return c;
  }
  
  
  Closure *luaF_newLclosure (lua_State *L, int nelems, Table *e) {
    Closure *c = cast(Closure *, luaM_malloc(L, sizeLclosure(nelems)));
    luaC_link(L, obj2gco(c), LUA_TFUNCTION);
    c->l.isC = 0;
    c->l.env = e;
    c->l.nupvalues = cast_byte(nelems);
    while (nelems--) c->l.upvals[nelems] = NULL;
    return c;
  }
  
  
  UpVal *luaF_newupval (lua_State *L) {
    UpVal *uv = luaM_new(L, UpVal);
    luaC_link(L, obj2gco(uv), LUA_TUPVAL);
    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 ((p = ngcotouv(*pp)) != NULL && p->v >= level) {
      lua_assert(p->v != &p->u.value);
      if (p->v == level) {  /* found a corresponding upvalue? */
        if (isdead(g, obj2gco(p)))  /* is it dead? */
          changewhite(obj2gco(p));  /* ressurect it */
        return p;
      }
      pp = &p->next;
    }
    uv = luaM_new(L, UpVal);  /* not found: create a new one */
    uv->tt = LUA_TUPVAL;
    uv->marked = luaC_white(g);
    uv->v = level;  /* current value lives in the stack */
    uv->next = *pp;  /* chain it in the proper position */
    *pp = obj2gco(uv);
    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 ((uv = ngcotouv(L->openupval)) != NULL && uv->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);
        setobj(L, &uv->u.value, uv->v);
        uv->v = &uv->u.value;  /* now current value lives here */
        luaC_linkupval(L, uv);  /* link upvalue into `gcroot' list */
      }
    }
  }
  
  
  Proto *luaF_newproto (lua_State *L) {
    Proto *f = luaM_new(L, Proto);
    luaC_link(L, obj2gco(f), LUA_TPROTO);
    f->k = NULL;
    f->sizek = 0;
    f->p = NULL;
    f->sizep = 0;
    f->code = NULL;
    f->sizecode = 0;
    f->sizelineinfo = 0;
    f->sizeupvalues = 0;
    f->nups = 0;
    f->upvalues = NULL;
    f->numparams = 0;
    f->is_vararg = 0;
    f->maxstacksize = 0;
    f->lineinfo = NULL;
    f->sizelocvars = 0;
    f->locvars = NULL;
    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, Instruction);
    luaM_freearray(L, f->p, f->sizep, Proto *);
    luaM_freearray(L, f->k, f->sizek, TValue);
    luaM_freearray(L, f->lineinfo, f->sizelineinfo, int);
    luaM_freearray(L, f->locvars, f->sizelocvars, struct LocVar);
    luaM_freearray(L, f->upvalues, f->sizeupvalues, TString *);
    luaM_free(L, f);
  }
  
  
  void luaF_freeclosure (lua_State *L, Closure *c) {
    int size = (c->c.isC) ? sizeCclosure(c->c.nupvalues) :
                            sizeLclosure(c->l.nupvalues);
    luaM_freemem(L, c, size);
  }
  
  
  /*
  ** 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 */
  }
  
  