khashl.hh

/* The MIT License
   Copyright (c) 2008, 2009, 2011 by Attractive Chaos <attractor@live.co.uk>
   Permission is hereby granted, free of charge, to any person obtaining
   a copy of this software and associated documentation files (the
   "Software"), to deal in the Software without restriction, including
   without limitation the rights to use, copy, modify, merge, publish,
   distribute, sublicense, and/or sell copies of the Software, and to
   permit persons to whom the Software is furnished to do so, subject to
   the following conditions:
   The above copyright notice and this permission notice shall be
   included in all copies or substantial portions of the Software.
   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   SOFTWARE.
*/

#ifndef __AC_KHASHL_HPP
#define __AC_KHASHL_HPP

#include <functional> // for std::equal_to
#include <cstdlib>    // for malloc() etc
#include <cstring>    // for memset()
#include <stdint.h>   // for uint32_t

namespace klib {

/***********
 * HashSet *
 ***********/

template<class T, class Hash, class Eq = std::equal_to<T>, typename khint_t = uint32_t>
class KHashSet {
protected:
	khint_t bits, count;
	uint32_t *used;
	T *keys;
	static inline uint32_t __kh_used(const uint32_t *flag, khint_t i) { return flag[i>>5] >> (i&0x1fU) & 1U; };
	static inline void __kh_set_used(uint32_t *flag, khint_t i) { flag[i>>5] |= 1U<<(i&0x1fU); };
	static inline void __kh_set_unused(uint32_t *flag, khint_t i) { flag[i>>5] &= ~(1U<<(i&0x1fU)); };
	static inline khint_t __kh_fsize(khint_t m) { return m<32? 1 : m>>5; }
	static inline khint_t __kh_h2b(uint32_t hash, khint_t bits) { return hash * 2654435769U >> (32 - bits); }
	static inline khint_t __kh_h2b(uint64_t hash, khint_t bits) { return hash * 11400714819323198485ULL >> (64 - bits); }
public:
	KHashSet() : bits(0), count(0), used(NULL), keys(NULL) {};
	~KHashSet() { std::free(used); std::free(keys); };
	inline khint_t n_buckets() const { return used? khint_t(1) << bits : 0; }
	inline khint_t end() const { return n_buckets(); }
	inline khint_t size() const { return count; }
	inline T &key(khint_t x) { return keys[x]; };
	inline bool _used(khint_t i) const { return (used[i>>5] >> (i&0x1fU) & 1U); }
	void clear(void) {
		if (!used) return;
		memset(used, 0, __kh_fsize(n_buckets()) * sizeof(uint32_t));
		count = 0;
	}
	khint_t get(const T &key) const {
		khint_t i, last, mask, nb;
		if (keys == 0) return 0;
		nb = n_buckets();
		mask = nb - khint_t(1);
		i = last = __kh_h2b(Hash()(key), bits);
		while (__kh_used(used, i) && !Eq()(keys[i], key)) {
			i = (i + khint_t(1)) & mask;
			if (i == last) return nb;
		}
		return !__kh_used(used, i)? nb : i;
	}
	int resize(khint_t new_nb) {
		uint32_t *new_used = 0;
		khint_t j = 0, x = new_nb, nb, new_bits, new_mask;
		while ((x >>= khint_t(1)) != 0) ++j;
		if (new_nb & (new_nb - 1)) ++j;
		new_bits = j > 2? j : 2;
		new_nb = khint_t(1) << new_bits;
		if (count > (new_nb>>1) + (new_nb>>2)) return 0; // requested size is too small
		new_used = (uint32_t*)std::malloc(__kh_fsize(new_nb) * sizeof(uint32_t));
		memset(new_used, 0, __kh_fsize(new_nb) * sizeof(uint32_t));
		if (!new_used) return -1; /* not enough memory */
		nb = n_buckets();
		if (nb < new_nb) { /* expand */
			T *new_keys = (T*)std::realloc(keys, new_nb * sizeof(T));
			if (!new_keys) { std::free(new_used); return -1; }
			keys = new_keys;
		} /* otherwise shrink */
		new_mask = new_nb - 1;
		for (j = 0; j != nb; ++j) {
			if (!__kh_used(used, j)) continue;
			T key = keys[j];
			__kh_set_unused(used, j);
			while (1) { /* kick-out process; sort of like in Cuckoo hashing */
				khint_t i;
				i = __kh_h2b(Hash()(key), new_bits);
				while (__kh_used(new_used, i)) i = (i + khint_t(1)) & new_mask;
				__kh_set_used(new_used, i);
				if (i < nb && __kh_used(used, i)) { /* kick out the existing element */
					{ T tmp = keys[i]; keys[i] = key; key = tmp; }
					__kh_set_unused(used, i); /* mark it as deleted in the old hash table */
				} else { /* write the element and jump out of the loop */
					keys[i] = key;
					break;
				}
			}
		}
		if (nb > new_nb) /* shrink the hash table */
			keys = (T*)std::realloc(keys, new_nb * sizeof(T));
		std::free(used); /* free the working space */
		used = new_used, bits = new_bits;
		return 0;
	}
	khint_t put(const T &key, int *absent_ = 0) {
		khint_t nb, i, last, mask;
		int absent = -1;
		nb = n_buckets();
		if (count >= (nb>>1) + (nb>>2)) { // rehashing
			if (resize(nb + khint_t(1)) < 0) {
				if (absent_) *absent_ = -1;
				return nb;
			}
			nb = n_buckets();
		} // TODO: to implement automatically shrinking; resize() already support shrinking
		mask = nb - 1;
		i = last = __kh_h2b(Hash()(key), bits);
		while (__kh_used(used, i) && !Eq()(keys[i], key)) {
			i = (i + 1U) & mask;
			if (i == last) break;
		}
		if (!__kh_used(used, i)) { // not present at all
			keys[i] = key;
			__kh_set_used(used, i);
			++count, absent = 1;
		} else absent = 0; /* Don't touch keys[i] if present */
		if (absent_) *absent_ = absent;
		return i;
	}
	int del(khint_t i) {
		khint_t j = i, k, mask, nb = n_buckets();
		if (keys == 0 || i >= nb) return 0;
		mask = nb - khint_t(1);
		while (1) {
			j = (j + khint_t(1)) & mask;
			if (j == i || !__kh_used(used, j)) break; // j==i only when the table is completely full
			k = __kh_h2b(Hash()(keys[j]), bits);
			if ((j > i && (k <= i || k > j)) || (j < i && (k <= i && k > j)))
				keys[i] = keys[j], i = j;
		}
		__kh_set_unused(used, i);
		--count;
		return 1;
	}
};

/***********
 * HashMap *
 ***********/

template<class KType, class VType>
struct KHashMapBucket { KType key; VType val; };

template<class T, class Hash, typename khint_t>
struct KHashMapHash { khint_t operator() (const T &a) const { return Hash()(a.key); } };

template<class T, class Eq>
struct KHashMapEq { bool operator() (const T &a, const T &b) const { return Eq()(a.key, b.key); } };

template<class KType, class VType, class Hash, class Eq=std::equal_to<KType>, typename khint_t=uint32_t>
class KHashMap : public KHashSet<KHashMapBucket<KType, VType>,
		KHashMapHash<KHashMapBucket<KType, VType>, Hash, khint_t>,
		KHashMapEq<KHashMapBucket<KType, VType>, Eq>, khint_t>
{
protected:
	typedef KHashMapBucket<KType, VType> bucket_t;
	typedef KHashSet<bucket_t, KHashMapHash<bucket_t, Hash, khint_t>, KHashMapEq<bucket_t, Eq>, khint_t> hashset_t;
public:
	khint_t get(const KType &key) const {
		bucket_t t = { key, VType() };
		return hashset_t::get(t);
	}
	khint_t put(const KType &key, int *absent) {
		bucket_t t = { key, VType() };
		return hashset_t::put(t, absent);
	}
	inline KType &key(khint_t i) { return hashset_t::key(i).key; }
	inline VType &value(khint_t i) { return hashset_t::key(i).val; }
	inline VType &operator[] (const KType &key) {
		bucket_t t = { key, VType() };
		return value(hashset_t::put(t));
	}
};

/****************************
 * HashSet with cached hash *
 ****************************/

template<class KType, typename khint_t>
struct KHashSetCachedBucket { KType key; khint_t hash; };

template<class T, typename khint_t>
struct KHashCachedHash { khint_t operator() (const T &a) const { return a.hash; } };

template<class T, class Eq>
struct KHashCachedEq { bool operator() (const T &a, const T &b) const { return a.hash == b.hash && Eq()(a.key, b.key); } };

template<class KType, class Hash, class Eq = std::equal_to<KType>, typename khint_t = uint32_t>
class KHashSetCached : public KHashSet<KHashSetCachedBucket<KType, khint_t>,
		KHashCachedHash<KHashSetCachedBucket<KType, khint_t>, khint_t>,
		KHashCachedEq<KHashSetCachedBucket<KType, khint_t>, Eq>, khint_t>
{
	typedef KHashSetCachedBucket<KType, khint_t> bucket_t;
	typedef KHashSet<bucket_t, KHashCachedHash<bucket_t, khint_t>, KHashCachedEq<bucket_t, Eq>, khint_t> hashset_t;
public:
	khint_t get(const KType &key) const {
		bucket_t t = { key, Hash()(key) };
		return hashset_t::get(t);
	}
	khint_t put(const KType &key, int *absent) {
		bucket_t t = { key, Hash()(key) };
		return hashset_t::put(t, absent);
	}
	inline KType &key(khint_t i) { return hashset_t::key(i).key; }
};

/****************************
 * HashMap with cached hash *
 ****************************/

template<class KType, class VType, typename khint_t>
struct KHashMapCachedBucket { KType key; VType val; khint_t hash; };

template<class KType, class VType, class Hash, class Eq = std::equal_to<KType>, typename khint_t = uint32_t>
class KHashMapCached : public KHashSet<KHashMapCachedBucket<KType, VType, khint_t>,
		KHashCachedHash<KHashMapCachedBucket<KType, VType, khint_t>, khint_t>,
		KHashCachedEq<KHashMapCachedBucket<KType, VType, khint_t>, Eq>, khint_t>
{
protected:
	typedef KHashMapCachedBucket<KType, VType, khint_t> bucket_t;
	typedef KHashSet<bucket_t, KHashCachedHash<bucket_t, khint_t>, KHashCachedEq<bucket_t, Eq>, khint_t> hashset_t;
public:
	khint_t get(const KType &key) const {
		bucket_t t = { key, VType(), Hash()(key) };
		return hashset_t::get(t);
	}
	khint_t put(const KType &key, int *absent) {
		bucket_t t = { key, VType(), Hash()(key) };
		return hashset_t::put(t, absent);
	}
	inline KType &key(khint_t i) { return hashset_t::key(i).key; }
	inline VType &value(khint_t i) { return hashset_t::key(i).val; }
	inline VType &operator[] (const KType &key) {
		bucket_t t = { key, VType(), Hash()(key) };
		return value(hashset_t::put(t));
	}
};

}

#endif /* __AC_KHASHL_HPP */