freelist.h

//
//  CRF++ -- Yet Another CRF toolkit
//
//  $Id: freelist.h 1588 2007-02-12 09:03:39Z taku $;
//
//  Copyright(C) 2005-2007 Taku Kudo <taku@chasen.org>
//
#ifndef CRFPP_FREELIST_H_
#define CRFPP_FREELIST_H_

#include <vector>
#include <cstring>

namespace CRFPP {
template <class T>
class Length {
 public:
  size_t operator()(const T *str) const { return 1; }
};

class charLength {
 public:
  size_t operator()(const char *str) const  { return strlen(str) + 1; }
};

template <class T, class LengthFunc = Length<T> >
class FreeList {
 private:
  std::vector <T *> freeList;
  size_t pi;
  size_t li;
  size_t size;

 public:
  void free() { li = pi = 0; }

  T* alloc(size_t len = 1) {
    if ((pi + len) >= size) {
      li++;
      pi = 0;
    }
    if (li == freeList.size()) {
      freeList.push_back(new T[size]);
    }
    T* r = freeList[li] + pi;
    pi += len;
    return r;
  }

  T* dup(T *src, size_t len = 0) {
    if (!len) len = LengthFunc () (src);
    T *p = alloc(len);
    if (src == 0) memset (p, 0, len * sizeof (T));
    else        memcpy(p, src, len * sizeof(T));
    return p;
  }

  void set_size(size_t n) { size = n; }

  explicit FreeList(size_t _size): pi(0), li(0), size(_size) {}
  explicit FreeList(): pi(0), li(0), size(0) {}

  virtual ~FreeList() {
    for (li = 0; li < freeList.size(); ++li) {
      delete [] freeList[li];
    }
  }
};

typedef FreeList<char, charLength> StrFreeList;
}
#endif