mirror of https://github.com/PCSX2/pcsx2.git
987 lines
40 KiB
C++
987 lines
40 KiB
C++
// Copyright (c) 2005, Google Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// ---
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// Author: Craig Silverstein
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//
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// A dense hashtable is a particular implementation of
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// a hashtable: one that is meant to minimize memory allocation.
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// It does this by using an array to store all the data. We
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// steal a value from the key space to indicate "empty" array
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// elements (ie indices where no item lives) and another to indicate
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// "deleted" elements.
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//
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// (Note it is possible to change the value of the delete key
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// on the fly; you can even remove it, though after that point
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// the hashtable is insert_only until you set it again. The empty
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// value however can't be changed.)
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//
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// To minimize allocation and pointer overhead, we use internal
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// probing, in which the hashtable is a single table, and collisions
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// are resolved by trying to insert again in another bucket. The
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// most cache-efficient internal probing schemes are linear probing
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// (which suffers, alas, from clumping) and quadratic probing, which
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// is what we implement by default.
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//
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// Type requirements: value_type is required to be Copy Constructible
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// and Default Constructible. It is not required to be (and commonly
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// isn't) Assignable.
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//
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// You probably shouldn't use this code directly. Use
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// <google/dense_hash_map> or <google/dense_hash_set> instead.
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// You can change the following below:
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// HT_OCCUPANCY_FLT -- how full before we double size
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// HT_EMPTY_FLT -- how empty before we halve size
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// HT_MIN_BUCKETS -- default smallest bucket size
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//
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// You can also change enlarge_resize_percent (which defaults to
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// HT_OCCUPANCY_FLT), and shrink_resize_percent (which defaults to
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// HT_EMPTY_FLT) with set_resizing_parameters().
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//
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// How to decide what values to use?
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// shrink_resize_percent's default of .4 * OCCUPANCY_FLT, is probably good.
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// HT_MIN_BUCKETS is probably unnecessary since you can specify
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// (indirectly) the starting number of buckets at construct-time.
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// For enlarge_resize_percent, you can use this chart to try to trade-off
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// expected lookup time to the space taken up. By default, this
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// code uses quadratic probing, though you can change it to linear
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// via _JUMP below if you really want to.
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//
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// From http://www.augustana.ca/~mohrj/courses/1999.fall/csc210/lecture_notes/hashing.html
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// NUMBER OF PROBES / LOOKUP Successful Unsuccessful
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// Quadratic collision resolution 1 - ln(1-L) - L/2 1/(1-L) - L - ln(1-L)
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// Linear collision resolution [1+1/(1-L)]/2 [1+1/(1-L)2]/2
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//
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// -- enlarge_resize_percent -- 0.10 0.50 0.60 0.75 0.80 0.90 0.99
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// QUADRATIC COLLISION RES.
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// probes/successful lookup 1.05 1.44 1.62 2.01 2.21 2.85 5.11
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// probes/unsuccessful lookup 1.11 2.19 2.82 4.64 5.81 11.4 103.6
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// LINEAR COLLISION RES.
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// probes/successful lookup 1.06 1.5 1.75 2.5 3.0 5.5 50.5
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// probes/unsuccessful lookup 1.12 2.5 3.6 8.5 13.0 50.0 5000.0
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#ifndef _DENSEHASHTABLE_H_
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#define _DENSEHASHTABLE_H_
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// The probing method
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// Linear probing
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// #define JUMP_(key, num_probes) ( 1 )
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// Quadratic-ish probing
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#define JUMP_(key, num_probes) ( num_probes )
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// Hashtable class, used to implement the hashed associative containers
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// hash_set and hash_map.
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#include <google/sparsehash/sparseconfig.h>
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h> // for abort()
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#include <algorithm> // For swap(), eg
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#include <iostream> // For cerr
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#include <memory> // For uninitialized_fill, uninitialized_copy
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#include <utility> // for pair<>
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#include <iterator> // for facts about iterator tags
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#include <google/type_traits.h> // for true_type, integral_constant, etc.
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_START_GOOGLE_NAMESPACE_
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using STL_NAMESPACE::pair;
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template <class Value, class Key, class HashFcn,
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class ExtractKey, class EqualKey, class Alloc>
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class dense_hashtable;
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template <class V, class K, class HF, class ExK, class EqK, class A>
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struct dense_hashtable_iterator;
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template <class V, class K, class HF, class ExK, class EqK, class A>
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struct dense_hashtable_const_iterator;
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// We're just an array, but we need to skip over empty and deleted elements
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template <class V, class K, class HF, class ExK, class EqK, class A>
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struct dense_hashtable_iterator {
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public:
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typedef dense_hashtable_iterator<V,K,HF,ExK,EqK,A> iterator;
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typedef dense_hashtable_const_iterator<V,K,HF,ExK,EqK,A> const_iterator;
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typedef STL_NAMESPACE::forward_iterator_tag iterator_category;
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typedef V value_type;
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typedef ptrdiff_t difference_type;
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typedef size_t size_type;
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typedef V& reference; // Value
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typedef V* pointer;
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// "Real" constructor and default constructor
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dense_hashtable_iterator(const dense_hashtable<V,K,HF,ExK,EqK,A> *h,
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pointer it, pointer it_end, bool advance)
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: ht(h), pos(it), end(it_end) {
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if (advance) advance_past_empty_and_deleted();
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}
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dense_hashtable_iterator() { }
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// The default destructor is fine; we don't define one
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// The default operator= is fine; we don't define one
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// Happy dereferencer
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reference operator*() const { return *pos; }
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pointer operator->() const { return &(operator*()); }
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// Arithmetic. The only hard part is making sure that
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// we're not on an empty or marked-deleted array element
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void advance_past_empty_and_deleted() {
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while ( pos != end && (ht->test_empty(*this) || ht->test_deleted(*this)) )
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++pos;
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}
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iterator& operator++() {
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assert(pos != end); ++pos; advance_past_empty_and_deleted(); return *this;
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}
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iterator operator++(int) { iterator tmp(*this); ++*this; return tmp; }
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// Comparison.
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bool operator==(const iterator& it) const { return pos == it.pos; }
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bool operator!=(const iterator& it) const { return pos != it.pos; }
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// The actual data
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const dense_hashtable<V,K,HF,ExK,EqK,A> *ht;
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pointer pos, end;
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};
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// Now do it all again, but with const-ness!
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template <class V, class K, class HF, class ExK, class EqK, class A>
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struct dense_hashtable_const_iterator {
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public:
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typedef dense_hashtable_iterator<V,K,HF,ExK,EqK,A> iterator;
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typedef dense_hashtable_const_iterator<V,K,HF,ExK,EqK,A> const_iterator;
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typedef STL_NAMESPACE::forward_iterator_tag iterator_category;
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typedef V value_type;
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typedef ptrdiff_t difference_type;
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typedef size_t size_type;
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typedef const V& reference; // Value
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typedef const V* pointer;
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// "Real" constructor and default constructor
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dense_hashtable_const_iterator(const dense_hashtable<V,K,HF,ExK,EqK,A> *h,
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pointer it, pointer it_end, bool advance)
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: ht(h), pos(it), end(it_end) {
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if (advance) advance_past_empty_and_deleted();
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}
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dense_hashtable_const_iterator() { }
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// This lets us convert regular iterators to const iterators
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dense_hashtable_const_iterator(const iterator &it)
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: ht(it.ht), pos(it.pos), end(it.end) { }
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// The default destructor is fine; we don't define one
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// The default operator= is fine; we don't define one
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// Happy dereferencer
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reference operator*() const { return *pos; }
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pointer operator->() const { return &(operator*()); }
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// Arithmetic. The only hard part is making sure that
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// we're not on an empty or marked-deleted array element
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void advance_past_empty_and_deleted() {
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while ( pos != end && (ht->test_empty(*this) || ht->test_deleted(*this)) )
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++pos;
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}
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const_iterator& operator++() {
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assert(pos != end); ++pos; advance_past_empty_and_deleted(); return *this;
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}
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const_iterator operator++(int) { const_iterator tmp(*this); ++*this; return tmp; }
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// Comparison.
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bool operator==(const const_iterator& it) const { return pos == it.pos; }
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bool operator!=(const const_iterator& it) const { return pos != it.pos; }
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// The actual data
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const dense_hashtable<V,K,HF,ExK,EqK,A> *ht;
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pointer pos, end;
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};
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template <class Value, class Key, class HashFcn,
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class ExtractKey, class EqualKey, class Alloc>
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class dense_hashtable {
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public:
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typedef Key key_type;
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typedef Value value_type;
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typedef HashFcn hasher;
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typedef EqualKey key_equal;
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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typedef value_type* pointer;
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typedef const value_type* const_pointer;
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typedef value_type& reference;
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typedef const value_type& const_reference;
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typedef dense_hashtable_iterator<Value, Key, HashFcn,
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ExtractKey, EqualKey, Alloc>
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iterator;
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typedef dense_hashtable_const_iterator<Value, Key, HashFcn,
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ExtractKey, EqualKey, Alloc>
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const_iterator;
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// How full we let the table get before we resize. Knuth says .8 is
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// good -- higher causes us to probe too much, though saves memory
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static const float HT_OCCUPANCY_FLT; // = 0.8;
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// How empty we let the table get before we resize lower.
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// (0.0 means never resize lower.)
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// It should be less than OCCUPANCY_FLT / 2 or we thrash resizing
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static const float HT_EMPTY_FLT; // = 0.4 * HT_OCCUPANCY_FLT
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// Minimum size we're willing to let hashtables be.
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// Must be a power of two, and at least 4.
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// Note, however, that for a given hashtable, the initial size is a
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// function of the first constructor arg, and may be >HT_MIN_BUCKETS.
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static const size_t HT_MIN_BUCKETS = 4;
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// By default, if you don't specify a hashtable size at
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// construction-time, we use this size. Must be a power of two, and
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// at least HT_MIN_BUCKETS.
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static const size_t HT_DEFAULT_STARTING_BUCKETS = 32;
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// ITERATOR FUNCTIONS
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iterator begin() { return iterator(this, table,
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table + num_buckets, true); }
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iterator end() { return iterator(this, table + num_buckets,
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table + num_buckets, true); }
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const_iterator begin() const { return const_iterator(this, table,
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table+num_buckets,true);}
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const_iterator end() const { return const_iterator(this, table + num_buckets,
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table+num_buckets,true);}
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// ACCESSOR FUNCTIONS for the things we templatize on, basically
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hasher hash_funct() const { return hash; }
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key_equal key_eq() const { return equals; }
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// Annoyingly, we can't copy values around, because they might have
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// const components (they're probably pair<const X, Y>). We use
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// explicit destructor invocation and placement new to get around
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// this. Arg.
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private:
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void set_value(value_type* dst, const value_type& src) {
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dst->~value_type();
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new(dst) value_type(src);
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}
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void destroy_buckets(size_type first, size_type last) {
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for ( ; first != last; ++first)
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table[first].~value_type();
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}
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// DELETE HELPER FUNCTIONS
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// This lets the user describe a key that will indicate deleted
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// table entries. This key should be an "impossible" entry --
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// if you try to insert it for real, you won't be able to retrieve it!
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// (NB: while you pass in an entire value, only the key part is looked
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// at. This is just because I don't know how to assign just a key.)
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private:
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void squash_deleted() { // gets rid of any deleted entries we have
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if ( num_deleted ) { // get rid of deleted before writing
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dense_hashtable tmp(*this); // copying will get rid of deleted
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swap(tmp); // now we are tmp
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}
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assert(num_deleted == 0);
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}
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public:
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void set_deleted_key(const value_type &val) {
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// the empty indicator (if specified) and the deleted indicator
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// must be different
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assert(!use_empty || !equals(get_key(val), get_key(emptyval)));
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// It's only safe to change what "deleted" means if we purge deleted guys
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squash_deleted();
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use_deleted = true;
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set_value(&delval, val);
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}
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void clear_deleted_key() {
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squash_deleted();
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use_deleted = false;
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}
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// These are public so the iterators can use them
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// True if the item at position bucknum is "deleted" marker
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bool test_deleted(size_type bucknum) const {
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// The num_deleted test is crucial for read(): after read(), the ht values
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// are garbage, and we don't want to think some of them are deleted.
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return (use_deleted && num_deleted > 0 &&
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equals(get_key(delval), get_key(table[bucknum])));
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}
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bool test_deleted(const iterator &it) const {
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return (use_deleted && num_deleted > 0 &&
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equals(get_key(delval), get_key(*it)));
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}
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bool test_deleted(const const_iterator &it) const {
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return (use_deleted && num_deleted > 0 &&
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equals(get_key(delval), get_key(*it)));
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}
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// Set it so test_deleted is true. true if object didn't used to be deleted
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// See below (at erase()) to explain why we allow const_iterators
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bool set_deleted(const_iterator &it) {
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assert(use_deleted); // bad if set_deleted_key() wasn't called
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bool retval = !test_deleted(it);
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// &* converts from iterator to value-type
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set_value(const_cast<value_type*>(&(*it)), delval);
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return retval;
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}
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// Set it so test_deleted is false. true if object used to be deleted
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bool clear_deleted(const_iterator &it) {
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assert(use_deleted); // bad if set_deleted_key() wasn't called
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// happens automatically when we assign something else in its place
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return test_deleted(it);
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}
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// EMPTY HELPER FUNCTIONS
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// This lets the user describe a key that will indicate empty (unused)
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// table entries. This key should be an "impossible" entry --
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// if you try to insert it for real, you won't be able to retrieve it!
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// (NB: while you pass in an entire value, only the key part is looked
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// at. This is just because I don't know how to assign just a key.)
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public:
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// These are public so the iterators can use them
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// True if the item at position bucknum is "empty" marker
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bool test_empty(size_type bucknum) const {
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assert(use_empty); // we always need to know what's empty!
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return equals(get_key(emptyval), get_key(table[bucknum]));
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}
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bool test_empty(const iterator &it) const {
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assert(use_empty); // we always need to know what's empty!
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return equals(get_key(emptyval), get_key(*it));
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}
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bool test_empty(const const_iterator &it) const {
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assert(use_empty); // we always need to know what's empty!
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return equals(get_key(emptyval), get_key(*it));
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}
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private:
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// You can either set a range empty or an individual element
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void set_empty(size_type bucknum) {
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assert(use_empty);
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set_value(&table[bucknum], emptyval);
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}
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void fill_range_with_empty(value_type* table_start, value_type* table_end) {
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// Like set_empty(range), but doesn't destroy previous contents
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STL_NAMESPACE::uninitialized_fill(table_start, table_end, emptyval);
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}
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void set_empty(size_type buckstart, size_type buckend) {
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assert(use_empty);
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destroy_buckets(buckstart, buckend);
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fill_range_with_empty(table + buckstart, table + buckend);
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}
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public:
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// TODO(csilvers): change all callers of this to pass in a key instead,
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// and take a const key_type instead of const value_type.
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void set_empty_key(const value_type &val) {
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// Once you set the empty key, you can't change it
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assert(!use_empty);
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// The deleted indicator (if specified) and the empty indicator
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// must be different.
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assert(!use_deleted || !equals(get_key(val), get_key(delval)));
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use_empty = true;
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set_value(&emptyval, val);
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assert(!table); // must set before first use
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// num_buckets was set in constructor even though table was NULL
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table = (value_type *) malloc(num_buckets * sizeof(*table));
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assert(table);
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fill_range_with_empty(table, table + num_buckets);
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}
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// FUNCTIONS CONCERNING SIZE
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public:
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size_type size() const { return num_elements - num_deleted; }
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// Buckets are always a power of 2
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size_type max_size() const { return (size_type(-1) >> 1U) + 1; }
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bool empty() const { return size() == 0; }
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size_type bucket_count() const { return num_buckets; }
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size_type max_bucket_count() const { return max_size(); }
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size_type nonempty_bucket_count() const { return num_elements; }
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private:
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// Because of the above, size_type(-1) is never legal; use it for errors
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static const size_type ILLEGAL_BUCKET = size_type(-1);
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private:
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// This is the smallest size a hashtable can be without being too crowded
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// If you like, you can give a min #buckets as well as a min #elts
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size_type min_size(size_type num_elts, size_type min_buckets_wanted) {
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size_type sz = HT_MIN_BUCKETS; // min buckets allowed
|
|
while ( sz < min_buckets_wanted || num_elts >= sz * enlarge_resize_percent )
|
|
sz *= 2;
|
|
return sz;
|
|
}
|
|
|
|
// Used after a string of deletes
|
|
void maybe_shrink() {
|
|
assert(num_elements >= num_deleted);
|
|
assert((bucket_count() & (bucket_count()-1)) == 0); // is a power of two
|
|
assert(bucket_count() >= HT_MIN_BUCKETS);
|
|
|
|
// If you construct a hashtable with < HT_DEFAULT_STARTING_BUCKETS,
|
|
// we'll never shrink until you get relatively big, and we'll never
|
|
// shrink below HT_DEFAULT_STARTING_BUCKETS. Otherwise, something
|
|
// like "dense_hash_set<int> x; x.insert(4); x.erase(4);" will
|
|
// shrink us down to HT_MIN_BUCKETS buckets, which is too small.
|
|
if (shrink_threshold > 0 &&
|
|
(num_elements-num_deleted) < shrink_threshold &&
|
|
bucket_count() > HT_DEFAULT_STARTING_BUCKETS ) {
|
|
size_type sz = bucket_count() / 2; // find how much we should shrink
|
|
while ( sz > HT_DEFAULT_STARTING_BUCKETS &&
|
|
(num_elements - num_deleted) < sz * shrink_resize_percent )
|
|
sz /= 2; // stay a power of 2
|
|
dense_hashtable tmp(*this, sz); // Do the actual resizing
|
|
swap(tmp); // now we are tmp
|
|
}
|
|
consider_shrink = false; // because we just considered it
|
|
}
|
|
|
|
// We'll let you resize a hashtable -- though this makes us copy all!
|
|
// When you resize, you say, "make it big enough for this many more elements"
|
|
void resize_delta(size_type delta) {
|
|
if ( consider_shrink ) // see if lots of deletes happened
|
|
maybe_shrink();
|
|
if ( bucket_count() > HT_MIN_BUCKETS &&
|
|
(num_elements + delta) <= enlarge_threshold )
|
|
return; // we're ok as we are
|
|
|
|
// Sometimes, we need to resize just to get rid of all the
|
|
// "deleted" buckets that are clogging up the hashtable. So when
|
|
// deciding whether to resize, count the deleted buckets (which
|
|
// are currently taking up room). But later, when we decide what
|
|
// size to resize to, *don't* count deleted buckets, since they
|
|
// get discarded during the resize.
|
|
const size_type needed_size = min_size(num_elements + delta, 0);
|
|
if ( needed_size > bucket_count() ) { // we don't have enough buckets
|
|
const size_type resize_to = min_size(num_elements - num_deleted + delta,
|
|
0);
|
|
dense_hashtable tmp(*this, resize_to);
|
|
swap(tmp); // now we are tmp
|
|
}
|
|
}
|
|
|
|
// Increase number of buckets, assuming value_type has trivial copy
|
|
// constructor and destructor. (Really, we want it to have "trivial
|
|
// move", because that's what realloc does. But there's no way to
|
|
// capture that using type_traits, so we pretend that move(x, y) is
|
|
// equivalent to "x.~T(); new(x) T(y);" which is pretty much
|
|
// correct, if a bit conservative.)
|
|
void expand_array(size_t resize_to, true_type) {
|
|
table = (value_type *) realloc(table, resize_to * sizeof(value_type));
|
|
assert(table);
|
|
fill_range_with_empty(table + num_buckets, table + resize_to);
|
|
}
|
|
|
|
// Increase number of buckets, without special assumptions about value_type.
|
|
// TODO(austern): make this exception safe. Handle exceptions from
|
|
// value_type's copy constructor.
|
|
void expand_array(size_t resize_to, false_type) {
|
|
value_type* new_table =
|
|
(value_type *) malloc(resize_to * sizeof(value_type));
|
|
assert(new_table);
|
|
STL_NAMESPACE::uninitialized_copy(table, table + num_buckets, new_table);
|
|
fill_range_with_empty(new_table + num_buckets, new_table + resize_to);
|
|
destroy_buckets(0, num_buckets);
|
|
free(table);
|
|
table = new_table;
|
|
}
|
|
|
|
// Used to actually do the rehashing when we grow/shrink a hashtable
|
|
void copy_from(const dense_hashtable &ht, size_type min_buckets_wanted) {
|
|
clear(); // clear table, set num_deleted to 0
|
|
|
|
// If we need to change the size of our table, do it now
|
|
const size_type resize_to = min_size(ht.size(), min_buckets_wanted);
|
|
if ( resize_to > bucket_count() ) { // we don't have enough buckets
|
|
typedef integral_constant<bool,
|
|
(has_trivial_copy<value_type>::value &&
|
|
has_trivial_destructor<value_type>::value)>
|
|
realloc_ok; // we pretend mv(x,y) == "x.~T(); new(x) T(y)"
|
|
expand_array(resize_to, realloc_ok());
|
|
num_buckets = resize_to;
|
|
reset_thresholds();
|
|
}
|
|
|
|
// We use a normal iterator to get non-deleted bcks from ht
|
|
// We could use insert() here, but since we know there are
|
|
// no duplicates and no deleted items, we can be more efficient
|
|
assert((bucket_count() & (bucket_count()-1)) == 0); // a power of two
|
|
for ( const_iterator it = ht.begin(); it != ht.end(); ++it ) {
|
|
size_type num_probes = 0; // how many times we've probed
|
|
size_type bucknum;
|
|
const size_type bucket_count_minus_one = bucket_count() - 1;
|
|
for (bucknum = hash(get_key(*it)) & bucket_count_minus_one;
|
|
!test_empty(bucknum); // not empty
|
|
bucknum = (bucknum + JUMP_(key, num_probes)) & bucket_count_minus_one) {
|
|
++num_probes;
|
|
assert(num_probes < bucket_count()); // or else the hashtable is full
|
|
}
|
|
set_value(&table[bucknum], *it); // copies the value to here
|
|
num_elements++;
|
|
}
|
|
}
|
|
|
|
// Required by the spec for hashed associative container
|
|
public:
|
|
// Though the docs say this should be num_buckets, I think it's much
|
|
// more useful as req_elements. As a special feature, calling with
|
|
// req_elements==0 will cause us to shrink if we can, saving space.
|
|
void resize(size_type req_elements) { // resize to this or larger
|
|
if ( consider_shrink || req_elements == 0 )
|
|
maybe_shrink();
|
|
if ( req_elements > num_elements )
|
|
return resize_delta(req_elements - num_elements);
|
|
}
|
|
|
|
// Change the value of shrink_resize_percent and
|
|
// enlarge_resize_percent. The description at the beginning of this
|
|
// file explains how to choose the values. Setting the shrink
|
|
// parameter to 0.0 ensures that the table never shrinks.
|
|
void set_resizing_parameters(float shrink, float grow) {
|
|
assert(shrink >= 0.0);
|
|
assert(grow <= 1.0);
|
|
assert(shrink <= grow/2.0);
|
|
shrink_resize_percent = shrink;
|
|
enlarge_resize_percent = grow;
|
|
reset_thresholds();
|
|
}
|
|
|
|
// CONSTRUCTORS -- as required by the specs, we take a size,
|
|
// but also let you specify a hashfunction, key comparator,
|
|
// and key extractor. We also define a copy constructor and =.
|
|
// DESTRUCTOR -- needs to free the table
|
|
explicit dense_hashtable(size_type expected_max_items_in_table = 0,
|
|
const HashFcn& hf = HashFcn(),
|
|
const EqualKey& eql = EqualKey(),
|
|
const ExtractKey& ext = ExtractKey())
|
|
: hash(hf), equals(eql), get_key(ext), num_deleted(0),
|
|
use_deleted(false), use_empty(false),
|
|
delval(), emptyval(), enlarge_resize_percent(HT_OCCUPANCY_FLT),
|
|
shrink_resize_percent(HT_EMPTY_FLT), table(NULL),
|
|
num_buckets(expected_max_items_in_table == 0
|
|
? HT_DEFAULT_STARTING_BUCKETS
|
|
: min_size(expected_max_items_in_table, 0)),
|
|
num_elements(0) {
|
|
// table is NULL until emptyval is set. However, we set num_buckets
|
|
// here so we know how much space to allocate once emptyval is set
|
|
reset_thresholds();
|
|
}
|
|
|
|
// As a convenience for resize(), we allow an optional second argument
|
|
// which lets you make this new hashtable a different size than ht
|
|
dense_hashtable(const dense_hashtable& ht,
|
|
size_type min_buckets_wanted = HT_DEFAULT_STARTING_BUCKETS)
|
|
: hash(ht.hash), equals(ht.equals), get_key(ht.get_key), num_deleted(0),
|
|
use_deleted(ht.use_deleted), use_empty(ht.use_empty),
|
|
delval(ht.delval), emptyval(ht.emptyval),
|
|
enlarge_resize_percent(ht.enlarge_resize_percent),
|
|
shrink_resize_percent(ht.shrink_resize_percent), table(NULL),
|
|
num_buckets(0), num_elements(0) {
|
|
reset_thresholds();
|
|
copy_from(ht, min_buckets_wanted); // copy_from() ignores deleted entries
|
|
}
|
|
|
|
dense_hashtable& operator= (const dense_hashtable& ht) {
|
|
if (&ht == this) return *this; // don't copy onto ourselves
|
|
clear();
|
|
hash = ht.hash;
|
|
equals = ht.equals;
|
|
get_key = ht.get_key;
|
|
use_deleted = ht.use_deleted;
|
|
use_empty = ht.use_empty;
|
|
set_value(&delval, ht.delval);
|
|
set_value(&emptyval, ht.emptyval);
|
|
enlarge_resize_percent = ht.enlarge_resize_percent;
|
|
shrink_resize_percent = ht.shrink_resize_percent;
|
|
copy_from(ht, HT_MIN_BUCKETS); // sets num_deleted to 0 too
|
|
return *this;
|
|
}
|
|
|
|
~dense_hashtable() {
|
|
if (table) {
|
|
destroy_buckets(0, num_buckets);
|
|
free(table);
|
|
}
|
|
}
|
|
|
|
// Many STL algorithms use swap instead of copy constructors
|
|
void swap(dense_hashtable& ht) {
|
|
STL_NAMESPACE::swap(hash, ht.hash);
|
|
STL_NAMESPACE::swap(equals, ht.equals);
|
|
STL_NAMESPACE::swap(get_key, ht.get_key);
|
|
STL_NAMESPACE::swap(num_deleted, ht.num_deleted);
|
|
STL_NAMESPACE::swap(use_deleted, ht.use_deleted);
|
|
STL_NAMESPACE::swap(use_empty, ht.use_empty);
|
|
STL_NAMESPACE::swap(enlarge_resize_percent, ht.enlarge_resize_percent);
|
|
STL_NAMESPACE::swap(shrink_resize_percent, ht.shrink_resize_percent);
|
|
{ value_type tmp; // for annoying reasons, swap() doesn't work
|
|
set_value(&tmp, delval);
|
|
set_value(&delval, ht.delval);
|
|
set_value(&ht.delval, tmp);
|
|
}
|
|
{ value_type tmp; // for annoying reasons, swap() doesn't work
|
|
set_value(&tmp, emptyval);
|
|
set_value(&emptyval, ht.emptyval);
|
|
set_value(&ht.emptyval, tmp);
|
|
}
|
|
STL_NAMESPACE::swap(table, ht.table);
|
|
STL_NAMESPACE::swap(num_buckets, ht.num_buckets);
|
|
STL_NAMESPACE::swap(num_elements, ht.num_elements);
|
|
reset_thresholds();
|
|
ht.reset_thresholds();
|
|
}
|
|
|
|
// It's always nice to be able to clear a table without deallocating it
|
|
void clear() {
|
|
if (table)
|
|
destroy_buckets(0, num_buckets);
|
|
num_buckets = min_size(0,0); // our new size
|
|
reset_thresholds();
|
|
table = (value_type *) realloc(table, num_buckets * sizeof(*table));
|
|
assert(table);
|
|
fill_range_with_empty(table, table + num_buckets);
|
|
num_elements = 0;
|
|
num_deleted = 0;
|
|
}
|
|
|
|
// Clear the table without resizing it.
|
|
// Mimicks the stl_hashtable's behaviour when clear()-ing in that it
|
|
// does not modify the bucket count
|
|
void clear_no_resize() {
|
|
if (table) {
|
|
set_empty(0, num_buckets);
|
|
}
|
|
// don't consider to shrink before another erase()
|
|
reset_thresholds();
|
|
num_elements = 0;
|
|
num_deleted = 0;
|
|
}
|
|
|
|
// LOOKUP ROUTINES
|
|
private:
|
|
// Returns a pair of positions: 1st where the object is, 2nd where
|
|
// it would go if you wanted to insert it. 1st is ILLEGAL_BUCKET
|
|
// if object is not found; 2nd is ILLEGAL_BUCKET if it is.
|
|
// Note: because of deletions where-to-insert is not trivial: it's the
|
|
// first deleted bucket we see, as long as we don't find the key later
|
|
pair<size_type, size_type> find_position(const key_type &key) const {
|
|
size_type num_probes = 0; // how many times we've probed
|
|
const size_type bucket_count_minus_one = bucket_count() - 1;
|
|
size_type bucknum = hash(key) & bucket_count_minus_one;
|
|
size_type insert_pos = ILLEGAL_BUCKET; // where we would insert
|
|
while ( 1 ) { // probe until something happens
|
|
if ( test_empty(bucknum) ) { // bucket is empty
|
|
if ( insert_pos == ILLEGAL_BUCKET ) // found no prior place to insert
|
|
return pair<size_type,size_type>(ILLEGAL_BUCKET, bucknum);
|
|
else
|
|
return pair<size_type,size_type>(ILLEGAL_BUCKET, insert_pos);
|
|
|
|
} else if ( test_deleted(bucknum) ) {// keep searching, but mark to insert
|
|
if ( insert_pos == ILLEGAL_BUCKET )
|
|
insert_pos = bucknum;
|
|
|
|
} else if ( equals(key, get_key(table[bucknum])) ) {
|
|
return pair<size_type,size_type>(bucknum, ILLEGAL_BUCKET);
|
|
}
|
|
++num_probes; // we're doing another probe
|
|
bucknum = (bucknum + JUMP_(key, num_probes)) & bucket_count_minus_one;
|
|
assert(num_probes < bucket_count()); // don't probe too many times!
|
|
}
|
|
}
|
|
|
|
public:
|
|
iterator find(const key_type& key) {
|
|
if ( size() == 0 ) return end();
|
|
pair<size_type, size_type> pos = find_position(key);
|
|
if ( pos.first == ILLEGAL_BUCKET ) // alas, not there
|
|
return end();
|
|
else
|
|
return iterator(this, table + pos.first, table + num_buckets, false);
|
|
}
|
|
|
|
const_iterator find(const key_type& key) const {
|
|
if ( size() == 0 ) return end();
|
|
pair<size_type, size_type> pos = find_position(key);
|
|
if ( pos.first == ILLEGAL_BUCKET ) // alas, not there
|
|
return end();
|
|
else
|
|
return const_iterator(this, table + pos.first, table+num_buckets, false);
|
|
}
|
|
|
|
// Counts how many elements have key key. For maps, it's either 0 or 1.
|
|
size_type count(const key_type &key) const {
|
|
pair<size_type, size_type> pos = find_position(key);
|
|
return pos.first == ILLEGAL_BUCKET ? 0 : 1;
|
|
}
|
|
|
|
// Likewise, equal_range doesn't really make sense for us. Oh well.
|
|
pair<iterator,iterator> equal_range(const key_type& key) {
|
|
const iterator pos = find(key); // either an iterator or end
|
|
return pair<iterator,iterator>(pos, pos);
|
|
}
|
|
pair<const_iterator,const_iterator> equal_range(const key_type& key) const {
|
|
const const_iterator pos = find(key); // either an iterator or end
|
|
return pair<iterator,iterator>(pos, pos);
|
|
}
|
|
|
|
|
|
// INSERTION ROUTINES
|
|
private:
|
|
// If you know *this is big enough to hold obj, use this routine
|
|
pair<iterator, bool> insert_noresize(const value_type& obj) {
|
|
// First, double-check we're not inserting delval or emptyval
|
|
assert(!use_empty || !equals(get_key(obj), get_key(emptyval)));
|
|
assert(!use_deleted || !equals(get_key(obj), get_key(delval)));
|
|
const pair<size_type,size_type> pos = find_position(get_key(obj));
|
|
if ( pos.first != ILLEGAL_BUCKET) { // object was already there
|
|
return pair<iterator,bool>(iterator(this, table + pos.first,
|
|
table + num_buckets, false),
|
|
false); // false: we didn't insert
|
|
} else { // pos.second says where to put it
|
|
if ( test_deleted(pos.second) ) { // just replace if it's been del.
|
|
const_iterator delpos(this, table + pos.second, // shrug:
|
|
table + num_buckets, false);// shouldn't need const
|
|
clear_deleted(delpos);
|
|
assert( num_deleted > 0);
|
|
--num_deleted; // used to be, now it isn't
|
|
} else {
|
|
++num_elements; // replacing an empty bucket
|
|
}
|
|
set_value(&table[pos.second], obj);
|
|
return pair<iterator,bool>(iterator(this, table + pos.second,
|
|
table + num_buckets, false),
|
|
true); // true: we did insert
|
|
}
|
|
}
|
|
|
|
public:
|
|
// This is the normal insert routine, used by the outside world
|
|
pair<iterator, bool> insert(const value_type& obj) {
|
|
resize_delta(1); // adding an object, grow if need be
|
|
return insert_noresize(obj);
|
|
}
|
|
|
|
// When inserting a lot at a time, we specialize on the type of iterator
|
|
template <class InputIterator>
|
|
void insert(InputIterator f, InputIterator l) {
|
|
// specializes on iterator type
|
|
insert(f, l, typename STL_NAMESPACE::iterator_traits<InputIterator>::iterator_category());
|
|
}
|
|
|
|
// Iterator supports operator-, resize before inserting
|
|
template <class ForwardIterator>
|
|
void insert(ForwardIterator f, ForwardIterator l,
|
|
STL_NAMESPACE::forward_iterator_tag) {
|
|
size_type n = STL_NAMESPACE::distance(f, l); // TODO(csilvers): standard?
|
|
resize_delta(n);
|
|
for ( ; n > 0; --n, ++f)
|
|
insert_noresize(*f);
|
|
}
|
|
|
|
// Arbitrary iterator, can't tell how much to resize
|
|
template <class InputIterator>
|
|
void insert(InputIterator f, InputIterator l,
|
|
STL_NAMESPACE::input_iterator_tag) {
|
|
for ( ; f != l; ++f)
|
|
insert(*f);
|
|
}
|
|
|
|
|
|
// DELETION ROUTINES
|
|
size_type erase(const key_type& key) {
|
|
// First, double-check we're not trying to erase delval or emptyval
|
|
assert(!use_empty || !equals(key, get_key(emptyval)));
|
|
assert(!use_deleted || !equals(key, get_key(delval)));
|
|
const_iterator pos = find(key); // shrug: shouldn't need to be const
|
|
if ( pos != end() ) {
|
|
assert(!test_deleted(pos)); // or find() shouldn't have returned it
|
|
set_deleted(pos);
|
|
++num_deleted;
|
|
consider_shrink = true; // will think about shrink after next insert
|
|
return 1; // because we deleted one thing
|
|
} else {
|
|
return 0; // because we deleted nothing
|
|
}
|
|
}
|
|
|
|
// This is really evil: really it should be iterator, not const_iterator.
|
|
// But...the only reason keys are const is to allow lookup.
|
|
// Since that's a moot issue for deleted keys, we allow const_iterators
|
|
void erase(const_iterator pos) {
|
|
if ( pos == end() ) return; // sanity check
|
|
if ( set_deleted(pos) ) { // true if object has been newly deleted
|
|
++num_deleted;
|
|
consider_shrink = true; // will think about shrink after next insert
|
|
}
|
|
}
|
|
|
|
void erase(const_iterator f, const_iterator l) {
|
|
for ( ; f != l; ++f) {
|
|
if ( set_deleted(f) ) // should always be true
|
|
++num_deleted;
|
|
}
|
|
consider_shrink = true; // will think about shrink after next insert
|
|
}
|
|
|
|
|
|
// COMPARISON
|
|
bool operator==(const dense_hashtable& ht) const {
|
|
if (size() != ht.size()) {
|
|
return false;
|
|
} else if (this == &ht) {
|
|
return true;
|
|
} else {
|
|
// Iterate through the elements in "this" and see if the
|
|
// corresponding element is in ht
|
|
for ( const_iterator it = begin(); it != end(); ++it ) {
|
|
const_iterator it2 = ht.find(get_key(*it));
|
|
if ((it2 == ht.end()) || (*it != *it2)) {
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
}
|
|
bool operator!=(const dense_hashtable& ht) const {
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|
return !(*this == ht);
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|
}
|
|
|
|
|
|
// I/O
|
|
// We support reading and writing hashtables to disk. Alas, since
|
|
// I don't know how to write a hasher or key_equal, you have to make
|
|
// sure everything but the table is the same. We compact before writing
|
|
//
|
|
// NOTE: These functions are currently TODO. They've not been implemented.
|
|
bool write_metadata(FILE *fp) {
|
|
squash_deleted(); // so we don't have to worry about delval
|
|
return false; // TODO
|
|
}
|
|
|
|
bool read_metadata(FILE *fp) {
|
|
num_deleted = 0; // since we got rid before writing
|
|
assert(use_empty); // have to set this before calling us
|
|
if (table) free(table); // we'll make our own
|
|
// TODO: read magic number
|
|
// TODO: read num_buckets
|
|
reset_thresholds();
|
|
table = (value_type *) malloc(num_buckets * sizeof(*table));
|
|
assert(table);
|
|
fill_range_with_empty(table, table + num_buckets);
|
|
// TODO: read num_elements
|
|
for ( size_type i = 0; i < num_elements; ++i ) {
|
|
// TODO: read bucket_num
|
|
// TODO: set with non-empty, non-deleted value
|
|
}
|
|
return false; // TODO
|
|
}
|
|
|
|
// If your keys and values are simple enough, we can write them to
|
|
// disk for you. "simple enough" means value_type is a POD type
|
|
// that contains no pointers. However, we don't try to normalize
|
|
// endianness
|
|
bool write_nopointer_data(FILE *fp) const {
|
|
for ( const_iterator it = begin(); it != end(); ++it ) {
|
|
// TODO: skip empty/deleted values
|
|
if ( !fwrite(&*it, sizeof(*it), 1, fp) ) return false;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// When reading, we have to override the potential const-ness of *it
|
|
bool read_nopointer_data(FILE *fp) {
|
|
for ( iterator it = begin(); it != end(); ++it ) {
|
|
// TODO: skip empty/deleted values
|
|
if ( !fread(reinterpret_cast<void*>(&(*it)), sizeof(*it), 1, fp) )
|
|
return false;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
private:
|
|
// The actual data
|
|
hasher hash; // required by hashed_associative_container
|
|
key_equal equals;
|
|
ExtractKey get_key;
|
|
size_type num_deleted; // how many occupied buckets are marked deleted
|
|
bool use_deleted; // false until delval has been set
|
|
bool use_empty; // you must do this before you start
|
|
value_type delval; // which key marks deleted entries
|
|
value_type emptyval; // which key marks unused entries
|
|
float enlarge_resize_percent; // how full before resize
|
|
float shrink_resize_percent; // how empty before resize
|
|
size_type shrink_threshold; // num_buckets * shrink_resize_percent
|
|
size_type enlarge_threshold; // num_buckets * enlarge_resize_percent
|
|
value_type *table;
|
|
size_type num_buckets;
|
|
size_type num_elements;
|
|
bool consider_shrink; // true if we should try to shrink before next insert
|
|
|
|
void reset_thresholds() {
|
|
enlarge_threshold = static_cast<size_type>(num_buckets
|
|
* enlarge_resize_percent);
|
|
shrink_threshold = static_cast<size_type>(num_buckets
|
|
* shrink_resize_percent);
|
|
consider_shrink = false; // whatever caused us to reset already considered
|
|
}
|
|
};
|
|
|
|
// We need a global swap as well
|
|
template <class V, class K, class HF, class ExK, class EqK, class A>
|
|
inline void swap(dense_hashtable<V,K,HF,ExK,EqK,A> &x,
|
|
dense_hashtable<V,K,HF,ExK,EqK,A> &y) {
|
|
x.swap(y);
|
|
}
|
|
|
|
#undef JUMP_
|
|
|
|
template <class V, class K, class HF, class ExK, class EqK, class A>
|
|
const typename dense_hashtable<V,K,HF,ExK,EqK,A>::size_type
|
|
dense_hashtable<V,K,HF,ExK,EqK,A>::ILLEGAL_BUCKET;
|
|
|
|
// How full we let the table get before we resize. Knuth says .8 is
|
|
// good -- higher causes us to probe too much, though saves memory
|
|
template <class V, class K, class HF, class ExK, class EqK, class A>
|
|
const float dense_hashtable<V,K,HF,ExK,EqK,A>::HT_OCCUPANCY_FLT = 0.5f;
|
|
|
|
// How empty we let the table get before we resize lower.
|
|
// It should be less than OCCUPANCY_FLT / 2 or we thrash resizing
|
|
template <class V, class K, class HF, class ExK, class EqK, class A>
|
|
const float dense_hashtable<V,K,HF,ExK,EqK,A>::HT_EMPTY_FLT = 0.4f *
|
|
dense_hashtable<V,K,HF,ExK,EqK,A>::HT_OCCUPANCY_FLT;
|
|
|
|
_END_GOOGLE_NAMESPACE_
|
|
|
|
#endif /* _DENSEHASHTABLE_H_ */
|