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+// Copyright (c) 2005, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// ---
+// Author: Craig Silverstein
+//
+// This is just a very thin wrapper over densehashtable.h, just
+// like sgi stl's stl_hash_set is a very thin wrapper over
+// stl_hashtable. The major thing we define is operator[], because
+// we have a concept of a data_type which stl_hashtable doesn't
+// (it only has a key and a value).
+//
+// This is more different from dense_hash_map than you might think,
+// because all iterators for sets are const (you obviously can't
+// change the key, and for sets there is no value).
+//
+// NOTE: this is exactly like sparse_hash_set.h, with the word
+// "sparse" replaced by "dense", except for the addition of
+// set_empty_key().
+//
+// YOU MUST CALL SET_EMPTY_KEY() IMMEDIATELY AFTER CONSTRUCTION.
+//
+// Otherwise your program will die in mysterious ways.
+//
+// In other respects, we adhere mostly to the STL semantics for
+// hash-set. One important exception is that insert() invalidates
+// iterators entirely. On the plus side, though, erase() doesn't
+// invalidate iterators at all, or even change the ordering of elements.
+//
+// Here are a few "power user" tips:
+//
+// 1) set_deleted_key():
+// If you want to use erase() you must call set_deleted_key(),
+// in addition to set_empty_key(), after construction.
+// The deleted and empty keys must differ.
+//
+// 2) resize(0):
+// When an item is deleted, its memory isn't freed right
+// away. This allows you to iterate over a hashtable,
+// and call erase(), without invalidating the iterator.
+// To force the memory to be freed, call resize(0).
+// For tr1 compatibility, this can also be called as rehash(0).
+//
+// 3) min_load_factor(0.0)
+// Setting the minimum load factor to 0.0 guarantees that
+// the hash table will never shrink.
+//
+// Guide to what kind of hash_set to use:
+// (1) dense_hash_set: fastest, uses the most memory
+// (2) sparse_hash_set: slowest, uses the least memory
+// (3) hash_set (STL): in the middle
+// Typically I use sparse_hash_set when I care about space and/or when
+// I need to save the hashtable on disk. I use hash_set otherwise. I
+// don't personally use dense_hash_set ever; some people use it for
+// small sets with lots of lookups.
+//
+// - dense_hash_set has, typically, a factor of 2 memory overhead (if your
+// data takes up X bytes, the hash_set uses X more bytes in overhead).
+// - sparse_hash_set has about 2 bits overhead per entry.
+// - sparse_hash_map can be 3-7 times slower than the others for lookup and,
+// especially, inserts. See time_hash_map.cc for details.
+//
+// See /usr/(local/)?doc/sparsehash-*/dense_hash_set.html
+// for information about how to use this class.
+
+#ifndef _DENSE_HASH_SET_H_
+#define _DENSE_HASH_SET_H_
+
+#include <google/sparsehash/sparseconfig.h>
+#include <stdio.h> // for FILE * in read()/write()
+#include <algorithm> // for the default template args
+#include <functional> // for equal_to
+#include <memory> // for alloc<>
+#include <utility> // for pair<>
+#include HASH_FUN_H // defined in config.h
+#include <google/sparsehash/densehashtable.h>
+
+
+_START_GOOGLE_NAMESPACE_
+
+using STL_NAMESPACE::pair;
+
+template <class Value,
+ class HashFcn = SPARSEHASH_HASH<Value>, // defined in sparseconfig.h
+ class EqualKey = STL_NAMESPACE::equal_to<Value>,
+ class Alloc = STL_NAMESPACE::allocator<Value> >
+class dense_hash_set {
+ private:
+ // Apparently identity is not stl-standard, so we define our own
+ struct Identity {
+ Value& operator()(Value& v) const { return v; }
+ const Value& operator()(const Value& v) const { return v; }
+ };
+ struct SetKey {
+ void operator()(Value* value, const Value& new_key) const {
+ *value = new_key;
+ }
+ };
+
+ // The actual data
+ typedef dense_hashtable<Value, Value, HashFcn,
+ Identity, SetKey, EqualKey, Alloc> ht;
+ ht rep;
+
+ public:
+ typedef typename ht::key_type key_type;
+ typedef typename ht::value_type value_type;
+ typedef typename ht::hasher hasher;
+ typedef typename ht::key_equal key_equal;
+ typedef Alloc allocator_type;
+
+ typedef typename ht::size_type size_type;
+ typedef typename ht::difference_type difference_type;
+ typedef typename ht::const_pointer pointer;
+ typedef typename ht::const_pointer const_pointer;
+ typedef typename ht::const_reference reference;
+ typedef typename ht::const_reference const_reference;
+
+ typedef typename ht::const_iterator iterator;
+ typedef typename ht::const_iterator const_iterator;
+ typedef typename ht::const_local_iterator local_iterator;
+ typedef typename ht::const_local_iterator const_local_iterator;
+
+
+ // Iterator functions -- recall all iterators are const
+ iterator begin() const { return rep.begin(); }
+ iterator end() const { return rep.end(); }
+
+ // These come from tr1's unordered_set. For us, a bucket has 0 or 1 elements.
+ local_iterator begin(size_type i) const { return rep.begin(i); }
+ local_iterator end(size_type i) const { return rep.end(i); }
+
+
+ // Accessor functions
+ hasher hash_funct() const { return rep.hash_funct(); }
+ key_equal key_eq() const { return rep.key_eq(); }
+
+
+ // Constructors
+ explicit dense_hash_set(size_type expected_max_items_in_table = 0,
+ const hasher& hf = hasher(),
+ const key_equal& eql = key_equal())
+ : rep(expected_max_items_in_table, hf, eql) { }
+
+ template <class InputIterator>
+ dense_hash_set(InputIterator f, InputIterator l,
+ size_type expected_max_items_in_table = 0,
+ const hasher& hf = hasher(),
+ const key_equal& eql = key_equal())
+ : rep(expected_max_items_in_table, hf, eql) {
+ rep.insert(f, l);
+ }
+ // We use the default copy constructor
+ // We use the default operator=()
+ // We use the default destructor
+
+ void clear() { rep.clear(); }
+ // This clears the hash set without resizing it down to the minimum
+ // bucket count, but rather keeps the number of buckets constant
+ void clear_no_resize() { rep.clear_no_resize(); }
+ void swap(dense_hash_set& hs) { rep.swap(hs.rep); }
+
+
+ // Functions concerning size
+ size_type size() const { return rep.size(); }
+ size_type max_size() const { return rep.max_size(); }
+ bool empty() const { return rep.empty(); }
+ size_type bucket_count() const { return rep.bucket_count(); }
+ size_type max_bucket_count() const { return rep.max_bucket_count(); }
+
+ // These are tr1 methods. bucket() is the bucket the key is or would be in.
+ size_type bucket_size(size_type i) const { return rep.bucket_size(i); }
+ size_type bucket(const key_type& key) const { return rep.bucket(key); }
+ float load_factor() const {
+ return size() * 1.0f / bucket_count();
+ }
+ float max_load_factor() const {
+ float shrink, grow;
+ rep.get_resizing_parameters(&shrink, &grow);
+ return grow;
+ }
+ void max_load_factor(float new_grow) {
+ float shrink, grow;
+ rep.get_resizing_parameters(&shrink, &grow);
+ rep.set_resizing_parameters(shrink, new_grow);
+ }
+ // These aren't tr1 methods but perhaps ought to be.
+ float min_load_factor() const {
+ float shrink, grow;
+ rep.get_resizing_parameters(&shrink, &grow);
+ return shrink;
+ }
+ void min_load_factor(float new_shrink) {
+ float shrink, grow;
+ rep.get_resizing_parameters(&shrink, &grow);
+ rep.set_resizing_parameters(new_shrink, grow);
+ }
+ // Deprecated; use min_load_factor() or max_load_factor() instead.
+ void set_resizing_parameters(float shrink, float grow) {
+ return rep.set_resizing_parameters(shrink, grow);
+ }
+
+ void resize(size_type hint) { rep.resize(hint); }
+ void rehash(size_type hint) { resize(hint); } // the tr1 name
+
+ // Lookup routines
+ iterator find(const key_type& key) const { return rep.find(key); }
+
+ size_type count(const key_type& key) const { return rep.count(key); }
+
+ pair<iterator, iterator> equal_range(const key_type& key) const {
+ return rep.equal_range(key);
+ }
+
+ // Insertion routines
+ pair<iterator, bool> insert(const value_type& obj) {
+ pair<typename ht::iterator, bool> p = rep.insert(obj);
+ return pair<iterator, bool>(p.first, p.second); // const to non-const
+ }
+ template <class InputIterator>
+ void insert(InputIterator f, InputIterator l) { rep.insert(f, l); }
+ void insert(const_iterator f, const_iterator l) { rep.insert(f, l); }
+ // required for std::insert_iterator; the passed-in iterator is ignored
+ iterator insert(iterator, const value_type& obj) { return insert(obj).first; }
+
+
+ // Deletion and empty routines
+ // THESE ARE NON-STANDARD! I make you specify an "impossible" key
+ // value to identify deleted and empty buckets. You can change the
+ // deleted key as time goes on, or get rid of it entirely to be insert-only.
+ void set_empty_key(const key_type& key) { rep.set_empty_key(key); }
+ void set_deleted_key(const key_type& key) { rep.set_deleted_key(key); }
+ void clear_deleted_key() { rep.clear_deleted_key(); }
+
+ // These are standard
+ size_type erase(const key_type& key) { return rep.erase(key); }
+ void erase(iterator it) { rep.erase(it); }
+ void erase(iterator f, iterator l) { rep.erase(f, l); }
+
+
+ // Comparison
+ bool operator==(const dense_hash_set& hs) const { return rep == hs.rep; }
+ bool operator!=(const dense_hash_set& hs) const { return rep != hs.rep; }
+
+
+ // I/O -- this is an add-on for writing metainformation to disk
+ bool write_metadata(FILE *fp) { return rep.write_metadata(fp); }
+ bool read_metadata(FILE *fp) { return rep.read_metadata(fp); }
+ bool write_nopointer_data(FILE *fp) { return rep.write_nopointer_data(fp); }
+ bool read_nopointer_data(FILE *fp) { return rep.read_nopointer_data(fp); }
+};
+
+template <class Val, class HashFcn, class EqualKey, class Alloc>
+inline void swap(dense_hash_set<Val, HashFcn, EqualKey, Alloc>& hs1,
+ dense_hash_set<Val, HashFcn, EqualKey, Alloc>& hs2) {
+ hs1.swap(hs2);
+}
+
+_END_GOOGLE_NAMESPACE_
+
+#endif /* _DENSE_HASH_SET_H_ */