/*
 * shstr.C
 */

#include <cstring>
#include <cstdlib>

#include <glib.h>

#include <tr1/unordered_set>

#include "shstr.h"
#include "util.h"

typedef std::tr1::unordered_set<const char *, str_hash, str_equal> HT;

static HT ht;

static const char *makevec (const char *s)
{
  int len = strlen (s);

  const char *v = (const char *)(2 + (int *)g_slice_alloc (sizeof (int) * 2 + len + 1));

  shstr::length (v) = len;
  shstr::refcnt (v) = 1;

  memcpy ((char *)v, s, len + 1);

  return v;
}

const char *shstr::null = makevec ("<nil>");

// what weird misoptimisation is this again?
const shstr undead_name ("undead");

const char *
shstr::find (const char *s)
{
  if (!s)
    return s;

  HT::iterator i = ht.find (s);

  return i != ht.end ()
    ? *i
    : 0;
}

const char *
shstr::intern (const char *s)
{
  if (!s)
    return null;

  if (const char *found = find (s))
    {
      ++refcnt (found);
      return found;
    }

  s = makevec (s);
  ht.insert (s);
  return s;
}

// periodically test refcounts == 0 for a few strings
// this is the ONLY thing that erases stuff from ht. keep it that way.
void
shstr::gc ()
{
  static const char *curpos;

  HT::iterator i = curpos ? ht.find (curpos) : ht.begin ();

  if (i == ht.end ())
    i = ht.begin ();

  // go through all strings roughly once every 4 minutes
  int n = ht.size () / 256 + 16000;

  for (;;)
    {
      if (i == ht.end ())
        {
          curpos = 0;
          return;
        }
      else if (!--n)
        break;
      else if (!refcnt (*i))
        {
          HT::iterator o = i++;
          const char *s = *o;
          ht.erase (o);

          int len = length (s);

          //printf ("GC %4d %3d %d >%s<%d\n", (int)ht.size (), n, shstr::refcnt (s), s, shstr::length (s));
          g_slice_free1 (sizeof (int) * 2 + length (s) + 1, -2 + (int *)s);
        }
      else
        ++i;
    }

  curpos = *i;
}

//TODO: this should of course not be here
/* buf_overflow() - we don't want to exceed the buffer size of 
 * buf1 by adding on buf2! Returns true if overflow will occur.
 */

int 
buf_overflow (const char *buf1, const char *buf2, int bufsize)
{
    int len1 = 0, len2 = 0;

    if (buf1)
        len1 = strlen (buf1);
    if (buf2)
        len2 = strlen (buf2);
    if ((len1 + len2) >= bufsize)
        return 1;
    return 0;
}