/*

** $Id: lfunc.c $

** Auxiliary functions to manipulate prototypes and closures

** See Copyright Notice in lua.h

*/

#define lfunc_c

#define LUA_CORE

#include "lprefix.h"

#include <stddef.h>

#include "lua.h"

#include "ldebug.h"

#include "ldo.h"

#include "lfunc.h"

#include "lgc.h"

#include "lmem.h"

#include "lobject.h"

#include "lstate.h"

CClosure *luaF_newCclosure (lua_State *L, int nupvals) {

  GCObject *o = luaC_newobj(L, LUA_VCCL, sizeCclosure(nupvals));

  CClosure *c = gco2ccl(o);

  c->nupvalues = cast_byte(nupvals);

  return c;

}

LClosure *luaF_newLclosure (lua_State *L, int nupvals) {

  GCObject *o = luaC_newobj(L, LUA_VLCL, sizeLclosure(nupvals));

  LClosure *c = gco2lcl(o);

  c->p = NULL;

  c->nupvalues = cast_byte(nupvals);

  while (nupvals--) c->upvals[nupvals] = NULL;

  return c;

}

/*

** fill a closure with new closed upvalues

*/

void luaF_initupvals (lua_State *L, LClosure *cl) {

  int i;

  for (i = 0; i < cl->nupvalues; i++) {

    GCObject *o = luaC_newobj(L, LUA_VUPVAL, sizeof(UpVal));

    UpVal *uv = gco2upv(o);

    uv->v.p = &uv->u.value;  /* make it closed */

    setnilvalue(uv->v.p);

    cl->upvals[i] = uv;

    luaC_objbarrier(L, cl, uv);

  }

}

/*

** Create a new upvalue at the given level, and link it to the list of

** open upvalues of 'L' after entry 'prev'.

**/

static UpVal *newupval (lua_State *L, StkId level, UpVal **prev) {

  GCObject *o = luaC_newobj(L, LUA_VUPVAL, sizeof(UpVal));

  UpVal *uv = gco2upv(o);

  UpVal *next = *prev;

  uv->v.p = s2v(level);  /* current value lives in the stack */

  uv->u.open.next = next;  /* link it to list of open upvalues */

  uv->u.open.previous = prev;

  if (next)

    next->u.open.previous = &uv->u.open.next;

  *prev = uv;

  if (!isintwups(L)) {  /* thread not in list of threads with upvalues? */

    L->twups = G(L)->twups;  /* link it to the list */

    G(L)->twups = L;

  }

  return uv;

}

/*

** Find and reuse, or create if it does not exist, an upvalue

** at the given level.

*/

UpVal *luaF_findupval (lua_State *L, StkId level) {

  UpVal **pp = &L->openupval;

  UpVal *p;

  lua_assert(isintwups(L) || L->openupval == NULL);

  while ((p = *pp) != NULL && uplevel(p) >= level) {  /* search for it */

    lua_assert(!isdead(G(L), p));

    if (uplevel(p) == level)  /* corresponding upvalue? */

      return p;  /* return it */

    pp = &p->u.open.next;

  }

  /* not found: create a new upvalue after 'pp' */

  return newupval(L, level, pp);

}

/*

** Call closing method for object 'obj' with error message 'err'. The

** boolean 'yy' controls whether the call is yieldable.

** (This function assumes EXTRA_STACK.)

*/

static void callclosemethod (lua_State *L, TValue *obj, TValue *err, int yy) {

  StkId top = L->top.p;

  const TValue *tm = luaT_gettmbyobj(L, obj, TM_CLOSE);

  setobj2s(L, top, tm);  /* will call metamethod... */

  setobj2s(L, top + 1, obj);  /* with 'self' as the 1st argument */

  setobj2s(L, top + 2, err);  /* and error msg. as 2nd argument */

  L->top.p = top + 3;  /* add function and arguments */

  if (yy)

    luaD_call(L, top, 0);

  else

    luaD_callnoyield(L, top, 0);

}

/*

** Check whether object at given level has a close metamethod and raise

** an error if not.

*/

static void checkclosemth (lua_State *L, StkId level) {

  const TValue *tm = luaT_gettmbyobj(L, s2v(level), TM_CLOSE);

  if (ttisnil(tm)) {  /* no metamethod? */

    int idx = cast_int(level - L->ci->func.p);  /* variable index */

    const char *vname = luaG_findlocal(L, L->ci, idx, NULL);

    if (vname == NULL) vname = "?";

    luaG_runerror(L, "variable '%s' got a non-closable value", vname);

  }

}

/*

** Prepare and call a closing method.

** If status is CLOSEKTOP, the call to the closing method will be pushed

** at the top of the stack. Otherwise, values can be pushed right after

** the 'level' of the upvalue being closed, as everything after that

** won't be used again.

*/

static void prepcallclosemth (lua_State *L, StkId level, int status, int yy) {

  TValue *uv = s2v(level);  /* value being closed */

  TValue *errobj;

  if (status == CLOSEKTOP)

    errobj = &G(L)->nilvalue;  /* error object is nil */

  else {  /* 'luaD_seterrorobj' will set top to level + 2 */

    errobj = s2v(level + 1);  /* error object goes after 'uv' */

    luaD_seterrorobj(L, status, level + 1);  /* set error object */

  }

  callclosemethod(L, uv, errobj, yy);

}

/*

** Maximum value for deltas in 'tbclist', dependent on the type

** of delta. (This macro assumes that an 'L' is in scope where it

** is used.)

*/

#define MAXDELTA  \

  ((256ul << ((sizeof(L->stack.p->tbclist.delta) - 1) * 8)) - 1)

/*

** Insert a variable in the list of to-be-closed variables.

*/

void luaF_newtbcupval (lua_State *L, StkId level) {

  lua_assert(level > L->tbclist.p);

  if (l_isfalse(s2v(level)))

    return;  /* false doesn't need to be closed */

  checkclosemth(L, level);  /* value must have a close method */

  while (cast_uint(level - L->tbclist.p) > MAXDELTA) {

    L->tbclist.p += MAXDELTA;  /* create a dummy node at maximum delta */

    L->tbclist.p->tbclist.delta = 0;

  }

  level->tbclist.delta = cast(unsigned short, level - L->tbclist.p);

  L->tbclist.p = level;

}

void luaF_unlinkupval (UpVal *uv) {

  lua_assert(upisopen(uv));

  *uv->u.open.previous = uv->u.open.next;

  if (uv->u.open.next)

    uv->u.open.next->u.open.previous = uv->u.open.previous;

}

/*

** Close all upvalues up to the given stack level.

*/

void luaF_closeupval (lua_State *L, StkId level) {

  UpVal *uv;

  StkId upl;  /* stack index pointed by 'uv' */

  while ((uv = L->openupval) != NULL && (upl = uplevel(uv)) >= level) {

    TValue *slot = &uv->u.value;  /* new position for value */

    lua_assert(uplevel(uv) < L->top.p);

    luaF_unlinkupval(uv);  /* remove upvalue from 'openupval' list */

    setobj(L, slot, uv->v.p);  /* move value to upvalue slot */

    uv->v.p = slot;  /* now current value lives here */

    if (!iswhite(uv)) {  /* neither white nor dead? */

      nw2black(uv);  /* closed upvalues cannot be gray */

      luaC_barrier(L, uv, slot);

    }

  }

}

/*

** Remove first element from the tbclist plus its dummy nodes.

*/

static void poptbclist (lua_State *L) {

  StkId tbc = L->tbclist.p;

  lua_assert(tbc->tbclist.delta > 0);  /* first element cannot be dummy */

  tbc -= tbc->tbclist.delta;

  while (tbc > L->stack.p && tbc->tbclist.delta == 0)

    tbc -= MAXDELTA;  /* remove dummy nodes */

  L->tbclist.p = tbc;

}

/*

** Close all upvalues and to-be-closed variables up to the given stack

** level. Return restored 'level'.

*/

StkId luaF_close (lua_State *L, StkId level, int status, int yy) {

  ptrdiff_t levelrel = savestack(L, level);

  luaF_closeupval(L, level);  /* first, close the upvalues */

  while (L->tbclist.p >= level) {  /* traverse tbc's down to that level */

    StkId tbc = L->tbclist.p;  /* get variable index */

    poptbclist(L);  /* remove it from list */

    prepcallclosemth(L, tbc, status, yy);  /* close variable */

    level = restorestack(L, levelrel);

  }

  return level;

}

Proto *luaF_newproto (lua_State *L) {

  GCObject *o = luaC_newobj(L, LUA_VPROTO, sizeof(Proto));

  Proto *f = gco2p(o);

  f->k = NULL;

  f->sizek = 0;

  f->p = NULL;

  f->sizep = 0;

  f->code = NULL;

  f->sizecode = 0;

  f->lineinfo = NULL;

  f->sizelineinfo = 0;

  f->abslineinfo = NULL;

  f->sizeabslineinfo = 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->abslineinfo, f->sizeabslineinfo);

  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 */

}