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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 sparsehashtable.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 sparse_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).
//
// We adhere mostly to the STL semantics for hash-set. One important
// exception is that insert() invalidates iterators entirely. On the
// plus side, though, delete() doesn't invalidate iterators at all, or
// even change the ordering of elements.
//
// Here are a few "power user" tips:
//
// 1) set_deleted_key():
// Unlike STL's hash_map, if you want to use erase() you
// *must* call set_deleted_key() after construction.
//
// 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 /unordered_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-*/sparse_hash_set.html
// for information about how to use this class.
#ifndef _SPARSE_HASH_SET_H_
#define _SPARSE_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/sparsehashtable.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 sparse_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 sparse_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
// TODO(csilvers): implement Alloc get_allocator() const;
hasher hash_funct() const { return rep.hash_funct(); }
hasher hash_function() const { return hash_funct(); } // tr1 name
key_equal key_eq() const { return rep.key_eq(); }
// Constructors
explicit sparse_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>
sparse_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(); }
void swap(sparse_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 routines
// THESE ARE NON-STANDARD! I make you specify an "impossible" key
// value to identify deleted buckets. You can change the key as
// time goes on, or get rid of it entirely to be insert-only.
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 sparse_hash_set& hs) const { return rep == hs.rep; }
bool operator!=(const sparse_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(sparse_hash_set<Val, HashFcn, EqualKey, Alloc>& hs1,
sparse_hash_set<Val, HashFcn, EqualKey, Alloc>& hs2) {
hs1.swap(hs2);
}
_END_GOOGLE_NAMESPACE_
#endif /* _SPARSE_HASH_SET_H_ */
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