c_cpp/lib/klib/cpp/khash.hpp

   1 #ifndef KHASH_HPP
   2 #define KHASH_HPP
   3
   4 #include <memory>
   5 #include <functional>
   6 #include <cstdlib> // for malloc() etc
   7 #include <cstring> // for memset()
   8
   9 #include <stdint.h> // for uint32_t
  10
  11 namespace klib {
  12
  13 #ifndef kroundup32 // FIXME: doesn't work for 64-bit integers
  14 #define kroundup32(x) (--(x), (x)|=(x)>>1, (x)|=(x)>>2, (x)|=(x)>>4, (x)|=(x)>>8, (x)|=(x)>>16, ++(x))
  15 #endif
  16
  17 #define __ac_isempty(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&2)
  18 #define __ac_isdel(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&1)
  19 #define __ac_isempty(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&2)
  20 #define __ac_isdel(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&1)
  21 #define __ac_iseither(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&3)
  22 #define __ac_set_isdel_false(flag, i) (flag[i>>4]&=~(1ul<<((i&0xfU)<<1)))
  23 #define __ac_set_isempty_false(flag, i) (flag[i>>4]&=~(2ul<<((i&0xfU)<<1)))
  24 #define __ac_set_isboth_false(flag, i) (flag[i>>4]&=~(3ul<<((i&0xfU)<<1)))
  25 #define __ac_set_isdel_true(flag, i) (flag[i>>4]|=1ul<<((i&0xfU)<<1))
  26
  27 #define __ac_fsize(m) ((m) < 16? 1 : (m)>>4)
  28
  29 template<class T, class Hash, class Eq = std::equal_to<T>, typename khint_t = uint32_t>
  30 class KHash {
  31         khint_t n_buckets, count, n_occupied, upper_bound;
  32         uint32_t *flags;
  33         T *keys;
  34 public:
  35         KHash() : n_buckets(0), count(0), n_occupied(0), upper_bound(0), flags(NULL), keys(NULL) {};
  36         ~KHash() { std::free(flags); std::free(keys); };
  37         khint_t capacity(void) const { return n_buckets; };
  38         khint_t size(void) const { return count; };
  39         khint_t begin(void) const { return 0; };
  40         khint_t end(void) const { return n_buckets; };
  41
  42         void exist(khint_t x) const { return !__ac_iseither(flags, x); };
  43         T &at(khint_t x) { return keys[x]; };
  44
  45         khint_t get(const T &key) const {
  46                 if (n_buckets) {
  47                         khint_t k, i, last, mask, step = 0;
  48                         mask = n_buckets - 1;
  49                         k = Hash()(key); i = k & mask;
  50                         last = i;
  51                         while (!__ac_isempty(flags, i) && (__ac_isdel(flags, i) || !Eq()(keys[i], key))) {
  52                                 i = (i + (++step)) & mask;
  53                                 if (i == last) return n_buckets;
  54                         }
  55                         return __ac_iseither(flags, i)? n_buckets : i;
  56                 } else return 0;
  57         };
  58
  59         int resize(khint_t new_n_buckets) {
  60                 uint32_t *new_flags = 0;
  61                 khint_t j = 1;
  62                 {
  63                         kroundup32(new_n_buckets);
  64                         if (new_n_buckets < 4) new_n_buckets = 4;
  65                         if (count >= (new_n_buckets>>1) + (new_n_buckets>>2)) j = 0;    /* requested count is too small */
  66                         else { /* hash table count to be changed (shrink or expand); rehash */
  67                                 new_flags = (uint32_t*)std::malloc(__ac_fsize(new_n_buckets) * sizeof(uint32_t));
  68                                 if (!new_flags) return -1;
  69                                 ::memset(new_flags, 0xaa, __ac_fsize(new_n_buckets) * sizeof(uint32_t));
  70                                 if (n_buckets < new_n_buckets) {        /* expand */
  71                                         T *new_keys = (T*)std::realloc((void *)keys, new_n_buckets * sizeof(T));
  72                                         if (!new_keys) { std::free(new_flags); return -1; }
  73                                         keys = new_keys;
  74                                 } /* otherwise shrink */
  75                         }
  76                 }
  77                 if (j) { /* rehashing is needed */
  78                         for (j = 0; j != n_buckets; ++j) {
  79                                 if (__ac_iseither(flags, j) == 0) {
  80                                         T key = keys[j];
  81                                         khint_t new_mask;
  82                                         new_mask = new_n_buckets - 1;
  83                                         __ac_set_isdel_true(flags, j);
  84                                         while (1) { /* kick-out process; sort of like in Cuckoo hashing */
  85                                                 khint_t k, i, step = 0;
  86                                                 k = Hash()(key);
  87                                                 i = k & new_mask;
  88                                                 while (!__ac_isempty(new_flags, i)) i = (i + (++step)) & new_mask;
  89                                                 __ac_set_isempty_false(new_flags, i);
  90                                                 if (i < n_buckets && __ac_iseither(flags, i) == 0) { /* kick out the existing element */
  91                                                         { T tmp = keys[i]; keys[i] = key; key = tmp; }
  92                                                         __ac_set_isdel_true(flags, i); /* mark it as deleted in the old hash table */
  93                                                 } else { /* write the element and jump out of the loop */
  94                                                         keys[i] = key;
  95                                                         break;
  96                                                 }
  97                                         }
  98                                 }
  99                         }
 100                         if (n_buckets > new_n_buckets) /* shrink the hash table */
 101                                 keys = (T*)std::realloc((void *)keys, new_n_buckets * sizeof(T));
 102                         std::free(flags); /* free the working space */
 103                         flags = new_flags;
 104                         n_buckets = new_n_buckets;
 105                         n_occupied = count;
 106                         upper_bound = (n_buckets>>1) + (n_buckets>>2);
 107                 }
 108                 return 0;
 109         };
 110
 111         khint_t put(const T &key, int *ret) {
 112                 khint_t x;
 113                 if (n_occupied >= upper_bound) { /* update the hash table */
 114                         if (n_buckets > (count<<1)) {
 115                                 if (resize(n_buckets - 1) < 0) { /* clear "deleted" elements */
 116                                         *ret = -1; return n_buckets;
 117                                 }
 118                         } else if (resize(n_buckets + 1) < 0) { /* expand the hash table */
 119                                 *ret = -1; return n_buckets;
 120                         }
 121                 } /* TODO: to implement automatically shrinking; resize() already support shrinking */
 122                 {
 123                         khint_t k, i, site, last, mask = n_buckets - 1, step = 0;
 124                         x = site = n_buckets; k = Hash()(key); i = k & mask;
 125                         if (__ac_isempty(flags, i)) x = i; /* for speed up */
 126                         else {
 127                                 last = i;
 128                                 while (!__ac_isempty(flags, i) && (__ac_isdel(flags, i) || !Eq()(keys[i], key))) {
 129                                         if (__ac_isdel(flags, i)) site = i;
 130                                         i = (i + (++step)) & mask;
 131                                         if (i == last) { x = site; break; }
 132                                 }
 133                                 if (x == n_buckets) {
 134                                         if (__ac_isempty(flags, i) && site != n_buckets) x = site;
 135                                         else x = i;
 136                                 }
 137                         }
 138                 }
 139                 if (__ac_isempty(flags, x)) { /* not present at all */
 140                         keys[x] = key;
 141                         __ac_set_isboth_false(flags, x);
 142                         ++count; ++n_occupied;
 143                         *ret = 1;
 144                 } else if (__ac_isdel(flags, x)) { /* deleted */
 145                         keys[x] = key;
 146                         __ac_set_isboth_false(flags, x);
 147                         ++count;
 148                         *ret = 2;
 149                 } else *ret = 0; /* Don't touch keys[x] if present and not deleted */
 150                 return x;
 151         };
 152
 153         void del(khint_t x) {
 154                 if (x != n_buckets && !__ac_iseither(flags, x)) {
 155                         __ac_set_isdel_true(flags, x);
 156                         --count;
 157                 }
 158         };
 159 };
 160
 161 } // end of namespace klib
 162
 163 #endif