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Diffstat (limited to 'sources/shiboken2/ext/sparsehash/google/sparsehash/densehashtable.h')
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diff --git a/sources/shiboken2/ext/sparsehash/google/sparsehash/densehashtable.h b/sources/shiboken2/ext/sparsehash/google/sparsehash/densehashtable.h deleted file mode 100644 index 33b191ec8..000000000 --- a/sources/shiboken2/ext/sparsehash/google/sparsehash/densehashtable.h +++ /dev/null @@ -1,1062 +0,0 @@ -// 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 -// -// A dense hashtable is a particular implementation of -// a hashtable: one that is meant to minimize memory allocation. -// It does this by using an array to store all the data. We -// steal a value from the key space to indicate "empty" array -// elements (ie indices where no item lives) and another to indicate -// "deleted" elements. -// -// (Note it is possible to change the value of the delete key -// on the fly; you can even remove it, though after that point -// the hashtable is insert_only until you set it again. The empty -// value however can't be changed.) -// -// To minimize allocation and pointer overhead, we use internal -// probing, in which the hashtable is a single table, and collisions -// are resolved by trying to insert again in another bucket. The -// most cache-efficient internal probing schemes are linear probing -// (which suffers, alas, from clumping) and quadratic probing, which -// is what we implement by default. -// -// Type requirements: value_type is required to be Copy Constructible -// and Default Constructible. It is not required to be (and commonly -// isn't) Assignable. -// -// You probably shouldn't use this code directly. Use -// <google/dense_hash_map> or <google/dense_hash_set> instead. - -// You can change the following below: -// HT_OCCUPANCY_FLT -- how full before we double size -// HT_EMPTY_FLT -- how empty before we halve size -// HT_MIN_BUCKETS -- default smallest bucket size -// -// You can also change enlarge_resize_percent (which defaults to -// HT_OCCUPANCY_FLT), and shrink_resize_percent (which defaults to -// HT_EMPTY_FLT) with set_resizing_parameters(). -// -// How to decide what values to use? -// shrink_resize_percent's default of .4 * OCCUPANCY_FLT, is probably good. -// HT_MIN_BUCKETS is probably unnecessary since you can specify -// (indirectly) the starting number of buckets at construct-time. -// For enlarge_resize_percent, you can use this chart to try to trade-off -// expected lookup time to the space taken up. By default, this -// code uses quadratic probing, though you can change it to linear -// via _JUMP below if you really want to. -// -// From http://www.augustana.ca/~mohrj/courses/1999.fall/csc210/lecture_notes/hashing.html -// NUMBER OF PROBES / LOOKUP Successful Unsuccessful -// Quadratic collision resolution 1 - ln(1-L) - L/2 1/(1-L) - L - ln(1-L) -// Linear collision resolution [1+1/(1-L)]/2 [1+1/(1-L)2]/2 -// -// -- enlarge_resize_percent -- 0.10 0.50 0.60 0.75 0.80 0.90 0.99 -// QUADRATIC COLLISION RES. -// probes/successful lookup 1.05 1.44 1.62 2.01 2.21 2.85 5.11 -// probes/unsuccessful lookup 1.11 2.19 2.82 4.64 5.81 11.4 103.6 -// LINEAR COLLISION RES. -// probes/successful lookup 1.06 1.5 1.75 2.5 3.0 5.5 50.5 -// probes/unsuccessful lookup 1.12 2.5 3.6 8.5 13.0 50.0 5000.0 - -#ifndef _DENSEHASHTABLE_H_ -#define _DENSEHASHTABLE_H_ - -// The probing method -// Linear probing -// #define JUMP_(key, num_probes) ( 1 ) -// Quadratic-ish probing -#define JUMP_(key, num_probes) ( num_probes ) - - -#include "google/sparsehash/sparseconfig.h" -#include <assert.h> -#include <stdio.h> -#include <stdlib.h> // for abort() -#include <algorithm> // For swap(), eg -#include <iostream> // For cerr -#include <memory> // For uninitialized_fill, uninitialized_copy -#include <utility> // for pair<> -#include <iterator> // for facts about iterator tags -#include "google/type_traits.h" // for true_type, integral_constant, etc. - -_START_GOOGLE_NAMESPACE_ - -using STL_NAMESPACE::pair; - -// Hashtable class, used to implement the hashed associative containers -// hash_set and hash_map. - -// Value: what is stored in the table (each bucket is a Value). -// Key: something in a 1-to-1 correspondence to a Value, that can be used -// to search for a Value in the table (find() takes a Key). -// HashFcn: Takes a Key and returns an integer, the more unique the better. -// ExtractKey: given a Value, returns the unique Key associated with it. -// SetKey: given a Value* and a Key, modifies the value such that -// ExtractKey(value) == key. We guarantee this is only called -// with key == deleted_key or key == empty_key. -// EqualKey: Given two Keys, says whether they are the same (that is, -// if they are both associated with the same Value). -// Alloc: STL allocator to use to allocate memory. Currently ignored. - -template <class Value, class Key, class HashFcn, - class ExtractKey, class SetKey, class EqualKey, class Alloc> -class dense_hashtable; - -template <class V, class K, class HF, class ExK, class SetK, class EqK, class A> -struct dense_hashtable_iterator; - -template <class V, class K, class HF, class ExK, class SetK, class EqK, class A> -struct dense_hashtable_const_iterator; - -// We're just an array, but we need to skip over empty and deleted elements -template <class V, class K, class HF, class ExK, class SetK, class EqK, class A> -struct dense_hashtable_iterator { - public: - typedef dense_hashtable_iterator<V,K,HF,ExK,SetK,EqK,A> iterator; - typedef dense_hashtable_const_iterator<V,K,HF,ExK,SetK,EqK,A> const_iterator; - - typedef STL_NAMESPACE::forward_iterator_tag iterator_category; - typedef V value_type; - typedef STL_NAMESPACE::ptrdiff_t difference_type; - typedef size_t size_type; - typedef V& reference; // Value - typedef V* pointer; - - // "Real" constructor and default constructor - dense_hashtable_iterator(const dense_hashtable<V,K,HF,ExK,SetK,EqK,A> *h, - pointer it, pointer it_end, bool advance) - : ht(h), pos(it), end(it_end) { - if (advance) advance_past_empty_and_deleted(); - } - dense_hashtable_iterator() { } - // The default destructor is fine; we don't define one - // The default operator= is fine; we don't define one - - // Happy dereferencer - reference operator*() const { return *pos; } - pointer operator->() const { return &(operator*()); } - - // Arithmetic. The only hard part is making sure that - // we're not on an empty or marked-deleted array element - void advance_past_empty_and_deleted() { - while ( pos != end && (ht->test_empty(*this) || ht->test_deleted(*this)) ) - ++pos; - } - iterator& operator++() { - assert(pos != end); ++pos; advance_past_empty_and_deleted(); return *this; - } - iterator operator++(int) { iterator tmp(*this); ++*this; return tmp; } - - // Comparison. - bool operator==(const iterator& it) const { return pos == it.pos; } - bool operator!=(const iterator& it) const { return pos != it.pos; } - - - // The actual data - const dense_hashtable<V,K,HF,ExK,SetK,EqK,A> *ht; - pointer pos, end; -}; - - -// Now do it all again, but with const-ness! -template <class V, class K, class HF, class ExK, class SetK, class EqK, class A> -struct dense_hashtable_const_iterator { - public: - typedef dense_hashtable_iterator<V,K,HF,ExK,SetK,EqK,A> iterator; - typedef dense_hashtable_const_iterator<V,K,HF,ExK,SetK,EqK,A> const_iterator; - - typedef STL_NAMESPACE::forward_iterator_tag iterator_category; - typedef V value_type; - typedef STL_NAMESPACE::ptrdiff_t difference_type; - typedef size_t size_type; - typedef const V& reference; // Value - typedef const V* pointer; - - // "Real" constructor and default constructor - dense_hashtable_const_iterator( - const dense_hashtable<V,K,HF,ExK,SetK,EqK,A> *h, - pointer it, pointer it_end, bool advance) - : ht(h), pos(it), end(it_end) { - if (advance) advance_past_empty_and_deleted(); - } - dense_hashtable_const_iterator() { } - // This lets us convert regular iterators to const iterators - dense_hashtable_const_iterator(const iterator &it) - : ht(it.ht), pos(it.pos), end(it.end) { } - // The default destructor is fine; we don't define one - // The default operator= is fine; we don't define one - - // Happy dereferencer - reference operator*() const { return *pos; } - pointer operator->() const { return &(operator*()); } - - // Arithmetic. The only hard part is making sure that - // we're not on an empty or marked-deleted array element - void advance_past_empty_and_deleted() { - while ( pos != end && (ht->test_empty(*this) || ht->test_deleted(*this)) ) - ++pos; - } - const_iterator& operator++() { - assert(pos != end); ++pos; advance_past_empty_and_deleted(); return *this; - } - const_iterator operator++(int) { const_iterator tmp(*this); ++*this; return tmp; } - - // Comparison. - bool operator==(const const_iterator& it) const { return pos == it.pos; } - bool operator!=(const const_iterator& it) const { return pos != it.pos; } - - - // The actual data - const dense_hashtable<V,K,HF,ExK,SetK,EqK,A> *ht; - pointer pos, end; -}; - -template <class Value, class Key, class HashFcn, - class ExtractKey, class SetKey, class EqualKey, class Alloc> -class dense_hashtable { - public: - typedef Key key_type; - typedef Value value_type; - typedef HashFcn hasher; - typedef EqualKey key_equal; - - typedef size_t size_type; - typedef STL_NAMESPACE::ptrdiff_t difference_type; - typedef value_type* pointer; - typedef const value_type* const_pointer; - typedef value_type& reference; - typedef const value_type& const_reference; - typedef dense_hashtable_iterator<Value, Key, HashFcn, - ExtractKey, SetKey, EqualKey, Alloc> - iterator; - - typedef dense_hashtable_const_iterator<Value, Key, HashFcn, - ExtractKey, SetKey, EqualKey, Alloc> - const_iterator; - - // These come from tr1. For us they're the same as regular iterators. - typedef iterator local_iterator; - typedef const_iterator const_local_iterator; - - // How full we let the table get before we resize, by default. - // Knuth says .8 is good -- higher causes us to probe too much, - // though it saves memory. - static const float HT_OCCUPANCY_FLT; // = 0.5; - - // How empty we let the table get before we resize lower, by default. - // (0.0 means never resize lower.) - // It should be less than OCCUPANCY_FLT / 2 or we thrash resizing - static const float HT_EMPTY_FLT; // = 0.4 * HT_OCCUPANCY_FLT - - // Minimum size we're willing to let hashtables be. - // Must be a power of two, and at least 4. - // Note, however, that for a given hashtable, the initial size is a - // function of the first constructor arg, and may be >HT_MIN_BUCKETS. - static const size_t HT_MIN_BUCKETS = 4; - - // By default, if you don't specify a hashtable size at - // construction-time, we use this size. Must be a power of two, and - // at least HT_MIN_BUCKETS. - static const size_t HT_DEFAULT_STARTING_BUCKETS = 32; - - - // ITERATOR FUNCTIONS - iterator begin() { return iterator(this, table, - table + num_buckets, true); } - iterator end() { return iterator(this, table + num_buckets, - table + num_buckets, true); } - const_iterator begin() const { return const_iterator(this, table, - table+num_buckets,true);} - const_iterator end() const { return const_iterator(this, table + num_buckets, - table+num_buckets,true);} - - // These come from tr1 unordered_map. They iterate over 'bucket' n. - // For sparsehashtable, we could consider each 'group' to be a bucket, - // I guess, but I don't really see the point. We'll just consider - // bucket n to be the n-th element of the sparsetable, if it's occupied, - // or some empty element, otherwise. - local_iterator begin(size_type i) { - return local_iterator(this, table + i, table + i+1, false); - } - local_iterator end(size_type i) { - local_iterator it = begin(i); - if (!test_empty(i) && !test_deleted(i)) - ++it; - return it; - } - const_local_iterator begin(size_type i) const { - return const_local_iterator(this, table + i, table + i+1, false); - } - const_local_iterator end(size_type i) const { - const_local_iterator it = begin(i); - if (!test_empty(i) && !test_deleted(i)) - ++it; - return it; - } - - // ACCESSOR FUNCTIONS for the things we templatize on, basically - hasher hash_funct() const { return hash; } - key_equal key_eq() const { return equals; } - - private: - // Annoyingly, we can't copy values around, because they might have - // const components (they're probably pair<const X, Y>). We use - // explicit destructor invocation and placement new to get around - // this. Arg. - void set_value(value_type* dst, const value_type& src) { - dst->~value_type(); - new(dst) value_type(src); - } - - void destroy_buckets(size_type first, size_type last) { - for ( ; first != last; ++first) - table[first].~value_type(); - } - - // DELETE HELPER FUNCTIONS - // This lets the user describe a key that will indicate deleted - // table entries. This key should be an "impossible" entry -- - // if you try to insert it for real, you won't be able to retrieve it! - // (NB: while you pass in an entire value, only the key part is looked - // at. This is just because I don't know how to assign just a key.) - private: - void squash_deleted() { // gets rid of any deleted entries we have - if ( num_deleted ) { // get rid of deleted before writing - dense_hashtable tmp(*this); // copying will get rid of deleted - swap(tmp); // now we are tmp - } - assert(num_deleted == 0); - } - - public: - void set_deleted_key(const key_type &key) { - // the empty indicator (if specified) and the deleted indicator - // must be different - assert(!use_empty || !equals(key, get_key(emptyval))); - // It's only safe to change what "deleted" means if we purge deleted guys - squash_deleted(); - use_deleted = true; - delkey = key; - } - void clear_deleted_key() { - squash_deleted(); - use_deleted = false; - } - - // These are public so the iterators can use them - // True if the item at position bucknum is "deleted" marker - bool test_deleted(size_type bucknum) const { - // The num_deleted test is crucial for read(): after read(), the ht values - // are garbage, and we don't want to think some of them are deleted. - return (use_deleted && num_deleted > 0 && - equals(delkey, get_key(table[bucknum]))); - } - bool test_deleted(const iterator &it) const { - return (use_deleted && num_deleted > 0 && - equals(delkey, get_key(*it))); - } - bool test_deleted(const const_iterator &it) const { - return (use_deleted && num_deleted > 0 && - equals(delkey, get_key(*it))); - } - // Set it so test_deleted is true. true if object didn't used to be deleted - // See below (at erase()) to explain why we allow const_iterators - bool set_deleted(const_iterator &it) { - assert(use_deleted); // bad if set_deleted_key() wasn't called - bool retval = !test_deleted(it); - // &* converts from iterator to value-type - set_key(const_cast<value_type*>(&(*it)), delkey); - return retval; - } - // Set it so test_deleted is false. true if object used to be deleted - bool clear_deleted(const_iterator &it) { - assert(use_deleted); // bad if set_deleted_key() wasn't called - // happens automatically when we assign something else in its place - return test_deleted(it); - } - - // EMPTY HELPER FUNCTIONS - // This lets the user describe a key that will indicate empty (unused) - // table entries. This key should be an "impossible" entry -- - // if you try to insert it for real, you won't be able to retrieve it! - // (NB: while you pass in an entire value, only the key part is looked - // at. This is just because I don't know how to assign just a key.) - public: - // These are public so the iterators can use them - // True if the item at position bucknum is "empty" marker - bool test_empty(size_type bucknum) const { - assert(use_empty); // we always need to know what's empty! - return equals(get_key(emptyval), get_key(table[bucknum])); - } - bool test_empty(const iterator &it) const { - assert(use_empty); // we always need to know what's empty! - return equals(get_key(emptyval), get_key(*it)); - } - bool test_empty(const const_iterator &it) const { - assert(use_empty); // we always need to know what's empty! - return equals(get_key(emptyval), get_key(*it)); - } - - private: - // You can either set a range empty or an individual element - void set_empty(size_type bucknum) { - assert(use_empty); - set_value(&table[bucknum], emptyval); - } - void fill_range_with_empty(value_type* table_start, value_type* table_end) { - // Like set_empty(range), but doesn't destroy previous contents - STL_NAMESPACE::uninitialized_fill(table_start, table_end, emptyval); - } - void set_empty(size_type buckstart, size_type buckend) { - assert(use_empty); - destroy_buckets(buckstart, buckend); - fill_range_with_empty(table + buckstart, table + buckend); - } - - public: - // TODO(csilvers): change all callers of this to pass in a key instead, - // and take a const key_type instead of const value_type. - void set_empty_key(const value_type &val) { - // Once you set the empty key, you can't change it - assert(!use_empty); - // The deleted indicator (if specified) and the empty indicator - // must be different. - assert(!use_deleted || !equals(get_key(val), delkey)); - use_empty = true; - set_value(&emptyval, val); - - assert(!table); // must set before first use - // num_buckets was set in constructor even though table was NULL - table = (value_type *) malloc(num_buckets * sizeof(*table)); - assert(table); - fill_range_with_empty(table, table + num_buckets); - } - - // FUNCTIONS CONCERNING SIZE - public: - size_type size() const { return num_elements - num_deleted; } - // Buckets are always a power of 2 - size_type max_size() const { return (size_type(-1) >> 1U) + 1; } - bool empty() const { return size() == 0; } - size_type bucket_count() const { return num_buckets; } - size_type max_bucket_count() const { return max_size(); } - size_type nonempty_bucket_count() const { return num_elements; } - // These are tr1 methods. Their idea of 'bucket' doesn't map well to - // what we do. We just say every bucket has 0 or 1 items in it. - size_type bucket_size(size_type i) const { - return begin(i) == end(i) ? 0 : 1; - } - - - - private: - // Because of the above, size_type(-1) is never legal; use it for errors - static const size_type ILLEGAL_BUCKET = size_type(-1); - - private: - // This is the smallest size a hashtable can be without being too crowded - // If you like, you can give a min #buckets as well as a min #elts - size_type min_size(size_type num_elts, size_type min_buckets_wanted) { - 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); - } - - // Get and 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 get_resizing_parameters(float* shrink, float* grow) const { - *shrink = shrink_resize_percent; - *grow = enlarge_resize_percent; - } - void set_resizing_parameters(float shrink, float grow) { - assert(shrink >= 0.0); - assert(grow <= 1.0); - if (shrink > grow/2.0f) - shrink = grow / 2.0f; // otherwise we thrash hashtable size - 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(), - const SetKey& set = SetKey()) - : hash(hf), equals(eql), get_key(ext), set_key(set), num_deleted(0), - use_deleted(false), use_empty(false), - delkey(), 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), set_key(ht.set_key), num_deleted(0), - use_deleted(ht.use_deleted), use_empty(ht.use_empty), - delkey(ht.delkey), 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; - set_key = ht.set_key; - use_deleted = ht.use_deleted; - use_empty = ht.use_empty; - delkey = ht.delkey; - 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(set_key, ht.set_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); - STL_NAMESPACE::swap(delkey, ht.delkey); - { 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); - } - - // This is a tr1 method: the bucket a given key is in, or what bucket - // it would be put in, if it were to be inserted. Shrug. - size_type bucket(const key_type& key) const { - pair<size_type, size_type> pos = find_position(key); - return pos.first == ILLEGAL_BUCKET ? pos.second : pos.first; - } - - // 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) { - iterator pos = find(key); // either an iterator or end - if (pos == end()) { - return pair<iterator,iterator>(pos, pos); - } else { - const iterator startpos = pos++; - return pair<iterator,iterator>(startpos, pos); - } - } - pair<const_iterator,const_iterator> equal_range(const key_type& key) const { - const_iterator pos = find(key); // either an iterator or end - if (pos == end()) { - return pair<const_iterator,const_iterator>(pos, pos); - } else { - const const_iterator startpos = pos++; - return pair<const_iterator,const_iterator>(startpos, 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 delkey or emptyval - assert(!use_empty || !equals(get_key(obj), get_key(emptyval))); - assert(!use_deleted || !equals(get_key(obj), delkey)); - 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 delkey or emptyval - assert(!use_empty || !equals(key, get_key(emptyval))); - assert(!use_deleted || !equals(key, delkey)); - 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 { - return !(*this == ht); - } - - - // 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 delkey - 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; - SetKey set_key; - size_type num_deleted; // how many occupied buckets are marked deleted - bool use_deleted; // false until delkey has been set - bool use_empty; // you must do this before you start - // TODO(csilvers): make a pointer, and get rid of use_deleted (benchmark!) - key_type delkey; // 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 SetK, class EqK, class A> -inline void swap(dense_hashtable<V,K,HF,ExK,SetK,EqK,A> &x, - dense_hashtable<V,K,HF,ExK,SetK,EqK,A> &y) { - x.swap(y); -} - -#undef JUMP_ - -template <class V, class K, class HF, class ExK, class SetK, class EqK, class A> -const typename dense_hashtable<V,K,HF,ExK,SetK,EqK,A>::size_type -dense_hashtable<V,K,HF,ExK,SetK,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. -// However, we go with .5, getting better performance at the cost of -// more space (a trade-off densehashtable explicitly chooses to make). -// Feel free to play around with different values, though. -template <class V, class K, class HF, class ExK, class SetK, class EqK, class A> -const float dense_hashtable<V,K,HF,ExK,SetK,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 SetK, class EqK, class A> -const float dense_hashtable<V,K,HF,ExK,SetK,EqK,A>::HT_EMPTY_FLT - = 0.4f * dense_hashtable<V,K,HF,ExK,SetK,EqK,A>::HT_OCCUPANCY_FLT; - -_END_GOOGLE_NAMESPACE_ - -#endif /* _DENSEHASHTABLE_H_ */ |