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      1 /*
      2 ** $Id: lfunc.c,v 2.30 2012/10/03 12:36:46 roberto Exp $
      3 ** Auxiliary functions to manipulate prototypes and closures
      4 ** See Copyright Notice in lua.h
      5 */
      6 
      7 
      8 #include <stddef.h>
      9 
     10 #define lfunc_c
     11 #define LUA_CORE
     12 
     13 #include "lua.h"
     14 
     15 #include "lfunc.h"
     16 #include "lgc.h"
     17 #include "lmem.h"
     18 #include "lobject.h"
     19 #include "lstate.h"
     20 
     21 
     22 
     23 Closure *luaF_newCclosure (lua_State *L, int n) {
     24   Closure *c = &luaC_newobj(L, LUA_TCCL, sizeCclosure(n), NULL, 0)->cl;
     25   c->c.nupvalues = cast_byte(n);
     26   return c;
     27 }
     28 
     29 
     30 Closure *luaF_newLclosure (lua_State *L, int n) {
     31   Closure *c = &luaC_newobj(L, LUA_TLCL, sizeLclosure(n), NULL, 0)->cl;
     32   c->l.p = NULL;
     33   c->l.nupvalues = cast_byte(n);
     34   while (n--) c->l.upvals[n] = NULL;
     35   return c;
     36 }
     37 
     38 
     39 UpVal *luaF_newupval (lua_State *L) {
     40   UpVal *uv = &luaC_newobj(L, LUA_TUPVAL, sizeof(UpVal), NULL, 0)->uv;
     41   uv->v = &uv->u.value;
     42   setnilvalue(uv->v);
     43   return uv;
     44 }
     45 
     46 
     47 UpVal *luaF_findupval (lua_State *L, StkId level) {
     48   global_State *g = G(L);
     49   GCObject **pp = &L->openupval;
     50   UpVal *p;
     51   UpVal *uv;
     52   while (*pp != NULL && (p = gco2uv(*pp))->v >= level) {
     53     GCObject *o = obj2gco(p);
     54     lua_assert(p->v != &p->u.value);
     55     lua_assert(!isold(o) || isold(obj2gco(L)));
     56     if (p->v == level) {  /* found a corresponding upvalue? */
     57       if (isdead(g, o))  /* is it dead? */
     58         changewhite(o);  /* resurrect it */
     59       return p;
     60     }
     61     pp = &p->next;
     62   }
     63   /* not found: create a new one */
     64   uv = &luaC_newobj(L, LUA_TUPVAL, sizeof(UpVal), pp, 0)->uv;
     65   uv->v = level;  /* current value lives in the stack */
     66   uv->u.l.prev = &g->uvhead;  /* double link it in `uvhead' list */
     67   uv->u.l.next = g->uvhead.u.l.next;
     68   uv->u.l.next->u.l.prev = uv;
     69   g->uvhead.u.l.next = uv;
     70   lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
     71   return uv;
     72 }
     73 
     74 
     75 static void unlinkupval (UpVal *uv) {
     76   lua_assert(uv->u.l.next->u.l.prev == uv && uv->u.l.prev->u.l.next == uv);
     77   uv->u.l.next->u.l.prev = uv->u.l.prev;  /* remove from `uvhead' list */
     78   uv->u.l.prev->u.l.next = uv->u.l.next;
     79 }
     80 
     81 
     82 void luaF_freeupval (lua_State *L, UpVal *uv) {
     83   if (uv->v != &uv->u.value)  /* is it open? */
     84     unlinkupval(uv);  /* remove from open list */
     85   luaM_free(L, uv);  /* free upvalue */
     86 }
     87 
     88 
     89 void luaF_close (lua_State *L, StkId level) {
     90   UpVal *uv;
     91   global_State *g = G(L);
     92   while (L->openupval != NULL && (uv = gco2uv(L->openupval))->v >= level) {
     93     GCObject *o = obj2gco(uv);
     94     lua_assert(!isblack(o) && uv->v != &uv->u.value);
     95     L->openupval = uv->next;  /* remove from `open' list */
     96     if (isdead(g, o))
     97       luaF_freeupval(L, uv);  /* free upvalue */
     98     else {
     99       unlinkupval(uv);  /* remove upvalue from 'uvhead' list */
    100       setobj(L, &uv->u.value, uv->v);  /* move value to upvalue slot */
    101       uv->v = &uv->u.value;  /* now current value lives here */
    102       gch(o)->next = g->allgc;  /* link upvalue into 'allgc' list */
    103       g->allgc = o;
    104       luaC_checkupvalcolor(g, uv);
    105     }
    106   }
    107 }
    108 
    109 
    110 Proto *luaF_newproto (lua_State *L) {
    111   Proto *f = &luaC_newobj(L, LUA_TPROTO, sizeof(Proto), NULL, 0)->p;
    112   f->k = NULL;
    113   f->sizek = 0;
    114   f->p = NULL;
    115   f->sizep = 0;
    116   f->code = NULL;
    117   f->cache = NULL;
    118   f->sizecode = 0;
    119   f->lineinfo = NULL;
    120   f->sizelineinfo = 0;
    121   f->upvalues = NULL;
    122   f->sizeupvalues = 0;
    123   f->numparams = 0;
    124   f->is_vararg = 0;
    125   f->maxstacksize = 0;
    126   f->locvars = NULL;
    127   f->sizelocvars = 0;
    128   f->linedefined = 0;
    129   f->lastlinedefined = 0;
    130   f->source = NULL;
    131   return f;
    132 }
    133 
    134 
    135 void luaF_freeproto (lua_State *L, Proto *f) {
    136   luaM_freearray(L, f->code, f->sizecode);
    137   luaM_freearray(L, f->p, f->sizep);
    138   luaM_freearray(L, f->k, f->sizek);
    139   luaM_freearray(L, f->lineinfo, f->sizelineinfo);
    140   luaM_freearray(L, f->locvars, f->sizelocvars);
    141   luaM_freearray(L, f->upvalues, f->sizeupvalues);
    142   luaM_free(L, f);
    143 }
    144 
    145 
    146 /*
    147 ** Look for n-th local variable at line `line' in function `func'.
    148 ** Returns NULL if not found.
    149 */
    150 const char *luaF_getlocalname (const Proto *f, int local_number, int pc) {
    151   int i;
    152   for (i = 0; i<f->sizelocvars && f->locvars[i].startpc <= pc; i++) {
    153     if (pc < f->locvars[i].endpc) {  /* is variable active? */
    154       local_number--;
    155       if (local_number == 0)
    156         return getstr(f->locvars[i].varname);
    157     }
    158   }
    159   return NULL;  /* not found */
    160 }
    161 
    162