--- /dev/null
+/** @file hash_map.h
+ *
+ * Replacement for map<> using hash tables. */
+
+/*
+ * GiNaC Copyright (C) 1999-2003 Johannes Gutenberg University Mainz, Germany
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef __GINAC_HASH_MAP_H__
+#define __GINAC_HASH_MAP_H__
+
+#include <list>
+#include <iterator>
+#include <algorithm>
+#include <functional>
+#include <utility>
+
+
+namespace GiNaC {
+
+/*
+ * "Hashmap Light" - buckets only contain one value, quadratic probing,
+ * grows automatically
+ */
+
+namespace internal {
+
+// List of prime numbers shamelessly stolen from GCC STL
+enum { num_primes = 29 };
+
+static const unsigned long prime_list[num_primes] =
+{
+ 31ul, 53ul, 97ul, 193ul, 389ul,
+ 769ul, 1543ul, 3079ul, 6151ul, 12289ul,
+ 24593ul, 49157ul, 98317ul, 196613ul, 393241ul,
+ 786433ul, 1572869ul, 3145739ul, 6291469ul, 12582917ul,
+ 25165843ul, 50331653ul, 100663319ul, 201326611ul, 402653189ul,
+ 805306457ul, 1610612741ul, 3221225473ul, 4294967291ul
+};
+
+inline unsigned long next_prime(unsigned long n)
+{
+ const unsigned long *first = prime_list;
+ const unsigned long *last = prime_list + num_primes;
+ const unsigned long *pos = std::lower_bound(first, last, n);
+ return pos == last ? *(last - 1) : *pos;
+}
+
+} // namespace internal
+
+
+// Define default arguments
+template <typename T, template <class> class A = std::allocator>
+class exhashmap;
+
+
+/** Pair Associative Container with 'ex' objects as keys, that is implemented
+ * with a hash table and can be used as a replacement for map<> in many cases.
+ *
+ * Differences to map<>:
+ * - no lower_bound()/upper_bound()
+ * - no "insert with a hint" insert(iterator, key_type)
+ * - no reverse iterators, no rbegin()/rend()
+ * - no operator<()
+ * - comparison functor is hardcoded to ex_is_less
+ * - bucket_count() returns the number of buckets allocated in the hash table
+ * - insert() and erase() invalidate all iterators
+ * - average complexity of find() is constant time, worst case is O(n) */
+template <typename T, template <class> class A>
+class exhashmap {
+public:
+ static const unsigned min_num_buckets = 5; // must be prime
+
+ // Standard types
+ typedef ex key_type;
+ typedef T mapped_type;
+ typedef std::pair<key_type, T> value_type;
+ typedef ex_is_less key_compare;
+ typedef ex_is_equal key_equal;
+ typedef value_type & reference;
+ typedef const value_type & const_reference;
+ typedef value_type * pointer;
+ typedef const value_type * const_pointer;
+
+protected:
+ // Private types
+ enum bucket_state {
+ EMPTY, ///< bucket empty (never used)
+ USED, ///< bucket in use
+ ERASED ///< bucket empty (element deleted), but may be part of a search chain
+ };
+ typedef std::pair<bucket_state, value_type> Bucket;
+
+public:
+ // More standard types
+ typedef A<Bucket> allocator_type;
+
+protected:
+ // More private types
+ typedef std::vector<Bucket, allocator_type> Table;
+
+ typedef typename Table::iterator table_iterator;
+ typedef typename Table::const_iterator table_const_iterator;
+
+public:
+ // Iterators
+ template <typename Pointer, typename Reference, class TableIterator>
+ class exhashmap_iterator : public std::iterator<std::forward_iterator_tag, value_type, typename Table::difference_type, Pointer, Reference> {
+ protected:
+ friend class exhashmap;
+
+ public:
+ exhashmap_iterator() {}
+ exhashmap_iterator(TableIterator t, TableIterator te)
+ : it(t), table_end(te) {}
+
+ // Allow iterator to const_iterator conversion
+ template <typename P, typename R, class TI>
+ exhashmap_iterator(const exhashmap_iterator<P, R, TI> &other)
+ : it(other.get_it_()), table_end(other.get_table_end_()) {}
+
+ typename exhashmap_iterator::reference operator*() const
+ {
+ return it->second;
+ }
+
+ typename exhashmap_iterator::pointer operator->() const
+ {
+ return &(it->second);
+ }
+
+ exhashmap_iterator &operator++()
+ {
+ increment();
+ return *this;
+ }
+
+ exhashmap_iterator operator++(int)
+ {
+ exhashmap_iterator tmp = *this;
+ increment();
+ return tmp;
+ }
+
+ template <typename P, typename R, class TI>
+ bool operator==(const exhashmap_iterator<P, R, TI> &other) const
+ {
+ return it == other.get_it_();
+ }
+
+ template <typename P, typename R, class TI>
+ bool operator!=(const exhashmap_iterator<P, R, TI> &other) const
+ {
+ return it != other.get_it_();
+ }
+
+ // Private access function
+ TableIterator get_it_() const { return it; }
+ TableIterator get_table_end_() const { return table_end; }
+
+ protected:
+ TableIterator it; ///< Pointer to current bucket
+ TableIterator table_end; ///< Pointer to one-past-last bucket
+
+ void increment()
+ {
+ if (it != table_end)
+ ++it;
+
+ // Skip empty and erased buckets
+ while (it != table_end && it->first != USED)
+ ++it;
+ }
+ };
+
+ typedef exhashmap_iterator<value_type*, value_type&, table_iterator> iterator;
+ typedef exhashmap_iterator<const value_type*, const value_type&, table_const_iterator> const_iterator;
+
+ // More standard types
+ typedef typename Table::size_type size_type;
+ typedef typename Table::difference_type difference_type;
+
+ class value_compare : public std::binary_function<value_type, value_type, bool>, private key_compare {
+ friend class exhashmap;
+ public:
+ bool operator()(const value_type &lhs, const value_type &rhs) const
+ {
+ return key_compare::operator()(lhs.first, rhs.first);
+ }
+
+ bool operator()(const key_type &lhs, const value_type &rhs) const
+ {
+ return key_compare::operator()(lhs, rhs.first);
+ }
+
+ bool operator()(const value_type &lhs, const key_type &rhs) const
+ {
+ return key_compare::operator()(lhs.first, rhs);
+ }
+ };
+
+protected:
+ // Private data
+ Table hashtab; ///< Vector of buckets, each bucket is kept sorted
+ size_type num_buckets; ///< Number of buckets (= hashtab.size())
+ size_type num_entries; ///< Number of values stored in container (cached for faster operation of size())
+
+ /** Return index of key in hash table. */
+ static size_type hash_index(const key_type &x, size_type nbuckets)
+ {
+ return x.gethash() % nbuckets;
+ }
+
+ static table_iterator find_bucket(const key_type &x, table_iterator tab, size_type nbuckets);
+ static table_const_iterator find_bucket(const key_type &x, table_const_iterator tab, size_type nbuckets);
+ static table_iterator find_bucket_for_insertion(const key_type &x, table_iterator tab, size_type nbuckets);
+
+ /** Return pointer to bucket corresponding to key (or first empty bucket). */
+ table_iterator find_bucket(const key_type &x)
+ {
+ return find_bucket(x, hashtab.begin(), num_buckets);
+ }
+
+ /** Return pointer to bucket corresponding to key (or first empty bucket). */
+ table_const_iterator find_bucket(const key_type &x) const
+ {
+ return find_bucket(x, hashtab.begin(), num_buckets);
+ }
+
+ /** Return pointer to bucket corresponding to key (or first empty or erased bucket). */
+ table_iterator find_bucket_for_insertion(const key_type &x)
+ {
+ return find_bucket_for_insertion(x, hashtab.begin(), num_buckets);
+ }
+
+ /** Return number of entries above which the table will grow. */
+ size_type hwm() const
+ {
+ // Try to keep at least 25% of the buckets free
+ return num_buckets - (num_buckets >> 2);
+ }
+
+ /** Empty all buckets in the table. */
+ void empty_all_buckets()
+ {
+ for (table_iterator i = hashtab.begin(); i != hashtab.end(); ++i)
+ i->first = EMPTY;
+ }
+
+ void grow();
+
+public:
+ // 23.3.1.1 Construct/copy/destroy
+ exhashmap() : num_buckets(min_num_buckets), num_entries(0)
+ {
+ hashtab.resize(num_buckets);
+ empty_all_buckets();
+ }
+
+ explicit exhashmap(size_type nbuckets) : num_entries(0)
+ {
+ num_buckets = internal::next_prime(nbuckets);
+ hashtab.resize(num_buckets);
+ empty_all_buckets();
+ }
+
+ template <class InputIterator>
+ exhashmap(InputIterator first, InputIterator last) : num_buckets(min_num_buckets), num_entries(0)
+ {
+ hashtab.resize(num_buckets);
+ empty_all_buckets();
+ insert(first, last);
+ }
+
+ exhashmap &operator=(const exhashmap &other)
+ {
+ exhashmap(other).swap(*this);
+ return *this;
+ }
+
+ // Iterators
+ iterator begin()
+ {
+ // Find first used bucket
+ table_iterator bucket = hashtab.begin();
+ while (bucket != hashtab.end() && bucket->first != USED)
+ ++bucket;
+ return iterator(bucket, hashtab.end());
+ }
+
+ const_iterator begin() const
+ {
+ // Find first used bucket
+ table_const_iterator bucket = hashtab.begin();
+ while (bucket != hashtab.end() && bucket->first != USED)
+ ++bucket;
+ return const_iterator(bucket, hashtab.end());
+ }
+
+ iterator end()
+ {
+ return iterator(hashtab.end(), hashtab.end());
+ }
+
+ const_iterator end() const
+ {
+ return const_iterator(hashtab.end(), hashtab.end());
+ }
+
+ // Capacity
+ bool empty() const
+ {
+ return num_entries == 0;
+ }
+
+ size_type size() const
+ {
+ return num_entries;
+ }
+
+ size_type max_size() const
+ {
+ return hashtab.max_size();
+ }
+
+ size_type bucket_count() const
+ {
+ return num_buckets;
+ }
+
+ // 23.3.1.2 Element access
+ T &operator[](const key_type &x)
+ {
+ return insert(value_type(x, mapped_type())).first->second;
+ }
+
+ // Modifiers
+ std::pair<iterator, bool> insert(const value_type &x);
+
+ template <class InputIterator>
+ void insert(InputIterator first, InputIterator last)
+ {
+ for (; first != last; ++first)
+ insert(*first);
+ }
+
+ void erase(iterator position)
+ {
+ table_iterator bucket = position.get_it_();
+ bucket->first = ERASED;
+ bucket->second.first = 0;
+ --num_entries;
+ }
+
+ size_type erase(const key_type &x);
+
+ void swap(exhashmap &other)
+ {
+ hashtab.swap(other.hashtab);
+ std::swap(num_buckets, other.num_buckets);
+ std::swap(num_entries, other.num_entries);
+ }
+
+ void clear();
+
+ // Observers
+ key_compare key_comp() const
+ {
+ return key_compare();
+ }
+
+ value_compare value_comp() const
+ {
+ return value_compare();
+ }
+
+ // 23.3.1.3 Map operations
+ iterator find(const key_type &x);
+ const_iterator find(const key_type &x) const;
+
+ size_type count(const key_type &x) const
+ {
+ return find(x) == end() ? 0 : 1;
+ }
+
+ std::pair<iterator, iterator> equal_range(const key_type &x)
+ {
+ iterator i = find(x);
+ if (i == end())
+ return std::make_pair(i, i);
+ else {
+ iterator j = ++i;
+ return std::make_pair(i, j);
+ }
+ }
+
+ std::pair<const_iterator, const_iterator> equal_range(const key_type &x) const
+ {
+ const_iterator i = find(x);
+ if (i == end())
+ return std::make_pair(i, i);
+ else {
+ const_iterator j = ++i;
+ return std::make_pair(i, j);
+ }
+ }
+
+ friend bool operator==(const exhashmap &lhs, const exhashmap &rhs)
+ {
+ if (lhs.num_entries != rhs.num_entries || lhs.num_buckets != rhs.num_buckets)
+ return false;
+
+ // We can't compare the tables directly as the elements may be
+ // in different order due to the collision handling. We therefore
+ // look up each value from the lhs map in the rhs map separately.
+ for (const_iterator itl = lhs.begin(); itl != lhs.end(); ++itl) {
+ const_iterator itr = rhs.find(itl->first);
+ if (itr == rhs.end())
+ return false;
+ if (itl->second != itr->second)
+ return false;
+ }
+ return true;
+ }
+
+ friend bool operator!=(const exhashmap &lhs, const exhashmap &rhs)
+ {
+ return !(lhs == rhs);
+ }
+
+ void dump() const
+ {
+ std::clog << "num_entries = " << num_entries << std::endl;
+ std::clog << "num_buckets = " << num_buckets << std::endl;
+ size_type t = 0;
+ for (table_const_iterator it = hashtab.begin(); it != hashtab.end(); ++it, ++t) {
+ std::clog << " bucket " << t << ": ";
+ std::clog << (it->first == EMPTY ? "free" : (it->first == USED ? "used" : "erased")) << ", " << it->second.first << " -> " << it->second.second << std::endl;
+ }
+ }
+};
+
+/** Return pointer to bucket corresponding to key (or first empty bucket). */
+template <typename T, template <class> class A>
+inline typename exhashmap<T, A>::table_iterator exhashmap<T, A>::find_bucket(const key_type &x, table_iterator tab, size_type nbuckets)
+{
+ // Quadratic probing
+ size_type h = hash_index(x, nbuckets);
+ size_type d = 1;
+ table_iterator it = tab + h;
+ while (it->first != EMPTY && !(it->first == USED && key_equal()(it->second.first, x))) {
+ h = (h + d) % nbuckets;
+ d += 2;
+ it = tab + h;
+ }
+ return it;
+}
+
+/** Return pointer to bucket corresponding to key (or first empty bucket). */
+template <typename T, template <class> class A>
+inline typename exhashmap<T, A>::table_const_iterator exhashmap<T, A>::find_bucket(const key_type &x, table_const_iterator tab, size_type nbuckets)
+{
+ // Quadratic probing
+ size_type h = hash_index(x, nbuckets);
+ size_type d = 1;
+ table_const_iterator it = tab + h;
+ while (it->first != EMPTY && !(it->first == USED && key_equal()(it->second.first, x))) {
+ h = (h + d) % nbuckets;
+ d += 2;
+ it = tab + h;
+ }
+ return it;
+}
+
+/** Return pointer to bucket corresponding to key (or first empty or erased bucket). */
+template <typename T, template <class> class A>
+inline typename exhashmap<T, A>::table_iterator exhashmap<T, A>::find_bucket_for_insertion(const key_type &x, table_iterator tab, size_type nbuckets)
+{
+ // Quadratic probing
+ size_type h = hash_index(x, nbuckets);
+ size_type d = 1;
+ table_iterator it = tab + h;
+ while (it->first != EMPTY && !key_equal()(it->second.first, x)) {
+ h = (h + d) % nbuckets;
+ d += 2;
+ it = tab + h;
+ }
+ return it;
+}
+
+/** Grow hash table */
+template <typename T, template <class> class A>
+void exhashmap<T, A>::grow()
+{
+ // Allocate new empty hash table
+ size_type new_num_buckets = internal::next_prime(num_buckets + 1);
+ Table new_hashtab;
+ new_hashtab.resize(new_num_buckets);
+ for (table_iterator it = new_hashtab.begin(); it != new_hashtab.end(); ++it)
+ it->first = EMPTY;
+
+ // Re-insert all elements into new table
+ for (table_const_iterator it = hashtab.begin(); it != hashtab.end(); ++it) {
+ if (it->first == USED) {
+ table_iterator bucket = find_bucket(it->second.first, new_hashtab.begin(), new_num_buckets);
+ *bucket = *it;
+ }
+ }
+
+ // Swap with the old table
+ hashtab.swap(new_hashtab);
+ num_buckets = new_num_buckets;
+}
+
+template <typename T, template <class> class A>
+std::pair<typename exhashmap<T, A>::iterator, bool> exhashmap<T, A>::insert(const value_type &x)
+{
+ table_iterator bucket = find_bucket_for_insertion(x.first);
+ if (bucket->first == USED) {
+ // Value already in map
+ return std::make_pair(iterator(bucket, hashtab.end()), false);
+ } else {
+ // Insert new value
+ bucket->first = USED;
+ bucket->second = x;
+ ++num_entries;
+ if (num_entries >= hwm()) {
+ grow();
+ bucket = find_bucket(x.first);
+ }
+ return std::make_pair(iterator(bucket, hashtab.end()), true);
+ }
+}
+
+template <typename T, template <class> class A>
+typename exhashmap<T, A>::size_type exhashmap<T, A>::erase(const key_type &x)
+{
+ iterator i = find(x);
+ if (i != end()) {
+ erase(i);
+ return 1;
+ } else
+ return 0;
+}
+
+template <typename T, template <class> class A>
+typename exhashmap<T, A>::iterator exhashmap<T, A>::find(const key_type &x)
+{
+ table_iterator bucket = find_bucket(x);
+ if (bucket->first == USED)
+ return iterator(bucket, hashtab.end());
+ else
+ return end();
+}
+
+template <typename T, template <class> class A>
+typename exhashmap<T, A>::const_iterator exhashmap<T, A>::find(const key_type &x) const
+{
+ table_const_iterator bucket = find_bucket(x);
+ if (bucket->first == USED)
+ return const_iterator(bucket, hashtab.end());
+ else
+ return end();
+}
+
+template <typename T, template <class> class A>
+void exhashmap<T, A>::clear()
+{
+ for (table_iterator i = hashtab.begin(); i != hashtab.end(); ++i) {
+ i->first = EMPTY;
+ i->second.first = 0;
+ i->second.second = T();
+ }
+ num_entries = 0;
+}
+
+} // namespace GiNaC
+
+
+// Specializations of Standard Library algorithms
+namespace std {
+
+/** Specialization of std::swap() for exhashmap. */
+template <typename T, template <class> class A>
+inline void swap(GiNaC::exhashmap<T, A> &lhs, GiNaC::exhashmap<T, A> &rhs)
+{
+ lhs.swap(rhs);
+}
+
+} // namespace std
+
+#endif // ndef __GINAC_HASH_MAP_H__
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