janwas
29ea79f5eb
* ScriptableComplex.h: big bang (several hundred ms) for little buck: made all CStrW params const CStrW& instead. this should *always* be done as a matter of principle, unless the string actually needs to be modified (in which case compiler will tell you) * adts: slight improvement to hash table perf: change expansion threshold to 50% full, and implement quadratic probing (as suggested by matei) This was SVN commit r4122.
649 lines
14 KiB
C++
649 lines
14 KiB
C++
/**
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* =========================================================================
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* File : adts.h
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* Project : 0 A.D.
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* Description : useful Abstract Data Types not provided by STL.
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*
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* @author Jan.Wassenberg@stud.uni-karlsruhe.de
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* =========================================================================
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*/
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/*
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* Copyright (c) 2005 Jan Wassenberg
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*
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* Redistribution and/or modification are also permitted under the
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* terms of the GNU General Public License as published by the
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* Free Software Foundation (version 2 or later, at your option).
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#ifndef ADTS_H__
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#define ADTS_H__
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//-----------------------------------------------------------------------------
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// dynamic (grow-able) hash table
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//-----------------------------------------------------------------------------
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template<typename Key, typename T> class DHT_Traits
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{
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public:
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static const size_t initial_entries = 16;
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size_t hash(Key key) const;
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bool equal(Key k1, Key k2) const;
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Key get_key(T t) const;
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};
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template<> class DHT_Traits<const char*, const char*>
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{
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public:
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static const size_t initial_entries = 512;
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size_t hash(const char* key) const
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{
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return (size_t)fnv_lc_hash(key);
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}
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bool equal(const char* k1, const char* k2) const
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{
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return !strcmp(k1, k2);
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}
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const char* get_key(const char* t) const
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{
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return t;
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}
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};
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// intended for pointer types
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template<typename Key, typename T, typename Traits=DHT_Traits<Key,T> >
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class DynHashTbl
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{
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T* tbl;
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u16 num_entries;
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u16 max_entries; // when initialized, = 2**n for faster modulo
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Traits tr;
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T& get_slot(Key key) const
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{
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size_t hash = tr.hash(key);
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debug_assert(max_entries != 0); // otherwise, mask will be incorrect
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const uint mask = max_entries-1;
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for(;;)
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{
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T& t = tbl[hash & mask];
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// empty slot encountered => not found
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if(!t)
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return t;
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// keys are actually equal => found it
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if(tr.equal(key, tr.get_key(t)))
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return t;
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// keep going (linear probing)
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hash++;
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}
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}
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void expand_tbl()
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{
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// alloc a new table (but don't assign it to <tbl> unless successful)
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T* old_tbl = tbl;
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tbl = (T*)calloc(max_entries*2, sizeof(T));
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if(!tbl)
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{
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tbl = old_tbl;
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throw std::bad_alloc();
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}
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max_entries += max_entries;
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// must be set before get_slot
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// newly initialized, nothing to copy - done
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if(!old_tbl)
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return;
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// re-hash from old table into the new one
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for(size_t i = 0; i < max_entries/2u; i++)
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{
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T t = old_tbl[i];
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if(t)
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get_slot(tr.get_key(t)) = t;
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}
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free(old_tbl);
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}
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public:
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DynHashTbl()
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{
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tbl = 0;
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num_entries = 0;
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max_entries = tr.initial_entries/2; // will be doubled in expand_tbl
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debug_assert(is_pow2(max_entries));
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expand_tbl();
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}
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~DynHashTbl()
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{
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clear();
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}
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void clear()
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{
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// note: users might call clear() right before the dtor runs,
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// so safely handling calling this twice.
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SAFE_FREE(tbl);
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num_entries = 0;
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// rationale: must not set to 0 because expand_tbl only doubles the size.
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// don't keep the previous size because it may have become huge and
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// there is no provision for shrinking.
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max_entries = tr.initial_entries/2; // will be doubled in expand_tbl
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}
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void insert(const Key key, const T t)
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{
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// more than 75% full - increase table size.
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// do so before determining slot; this will invalidate previous pnodes.
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if(num_entries*4 >= max_entries*3)
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expand_tbl();
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T& slot = get_slot(key);
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debug_assert(slot == 0); // not already present
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slot = t;
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num_entries++;
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}
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T find(Key key) const
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{
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return get_slot(key);
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}
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size_t size() const
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{
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return num_entries;
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}
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class iterator
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{
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public:
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typedef std::forward_iterator_tag iterator_category;
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typedef T value_type;
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typedef ptrdiff_t difference_type;
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typedef const T* pointer;
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typedef const T& reference;
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iterator()
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{
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}
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iterator(T* pos_, T* end_) : pos(pos_), end(end_)
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{
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}
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T& operator*() const
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{
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return *pos;
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}
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iterator& operator++() // pre
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{
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do
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pos++;
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while(pos != end && *pos == 0);
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return (*this);
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}
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bool operator==(const iterator& rhs) const
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{
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return pos == rhs.pos;
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}
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bool operator<(const iterator& rhs) const
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{
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return (pos < rhs.pos);
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}
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// derived
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const T* operator->() const
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{
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return &**this;
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}
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bool operator!=(const iterator& rhs) const
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{
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return !(*this == rhs);
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}
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iterator operator++(int) // post
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{
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iterator tmp = *this; ++*this; return tmp;
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}
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protected:
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T* pos;
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T* end;
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// only used when incrementing (avoid going beyond end of table)
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};
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iterator begin() const
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{
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T* pos = tbl;
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while(pos != tbl+max_entries && *pos == 0)
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pos++;
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return iterator(pos, tbl+max_entries);
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}
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iterator end() const
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{
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return iterator(tbl+max_entries, 0);
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}
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};
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//-----------------------------------------------------------------------------
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// FIFO bit queue
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//-----------------------------------------------------------------------------
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struct BitBuf
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{
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ulong buf;
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ulong cur; // bit to be appended (toggled by add())
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ulong len; // |buf| [bits]
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void reset()
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{
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buf = 0;
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cur = 0;
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len = 0;
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}
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// toggle current bit if desired, and add to buffer (new bit is LSB)
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void add(ulong toggle)
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{
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cur ^= toggle;
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buf <<= 1;
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buf |= cur;
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len++;
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}
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// extract LS n bits
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uint extract(ulong n)
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{
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ulong i = buf & ((1ul << n) - 1);
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buf >>= n;
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return i;
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}
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};
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//-----------------------------------------------------------------------------
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// ring buffer - static array, accessible modulo n
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//-----------------------------------------------------------------------------
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template<class T, size_t n> class RingBuf
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{
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size_t size_; // # of entries in buffer
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size_t head; // index of oldest item
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size_t tail; // index of newest item
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T data[n];
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public:
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RingBuf() : data() { clear(); }
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void clear() { size_ = 0; head = 0; tail = n-1; }
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size_t size() { return size_; }
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bool empty() { return size_ == 0; }
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const T& operator[](int ofs) const
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{
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debug_assert(!empty());
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size_t idx = (size_t)(head + ofs);
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return data[idx % n];
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}
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T& operator[](int ofs)
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{
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debug_assert(!empty());
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size_t idx = (size_t)(head + ofs);
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return data[idx % n];
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}
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T& front()
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{
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debug_assert(!empty());
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return data[head];
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}
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const T& front() const
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{
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debug_assert(!empty());
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return data[head];
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}
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T& back()
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{
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debug_assert(!empty());
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return data[tail];
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}
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const T& back() const
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{
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debug_assert(!empty());
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return data[tail];
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}
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void push_back(const T& item)
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{
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if(size_ < n)
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size_++;
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// do not complain - overwriting old values is legit
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// (e.g. sliding window).
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else
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head = (head + 1) % n;
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tail = (tail + 1) % n;
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data[tail] = item;
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}
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void pop_front()
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{
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if(size_ != 0)
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{
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size_--;
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head = (head + 1) % n;
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}
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else
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debug_warn("underflow");
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}
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class iterator
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{
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public:
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typedef std::random_access_iterator_tag iterator_category;
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typedef T value_type;
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typedef ptrdiff_t difference_type;
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typedef T* pointer;
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typedef T& reference;
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iterator() : data(0), pos(0)
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{}
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iterator(T* data_, size_t pos_) : data(data_), pos(pos_)
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{}
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T& operator[](int idx) const
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{ return data[(pos+idx) % n]; }
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T& operator*() const
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{ return data[pos % n]; }
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T* operator->() const
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{ return &**this; }
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iterator& operator++() // pre
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{ ++pos; return (*this); }
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iterator operator++(int) // post
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{ iterator tmp = *this; ++*this; return tmp; }
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bool operator==(const iterator& rhs) const
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{ return data == rhs.data && pos == rhs.pos; }
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bool operator!=(const iterator& rhs) const
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{ return !(*this == rhs); }
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bool operator<(const iterator& rhs) const
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{ return (pos < rhs.pos); }
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iterator& operator+=(difference_type ofs)
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{ pos += ofs; return *this; }
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iterator& operator-=(difference_type ofs)
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{ return (*this += -ofs); }
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iterator operator+(difference_type ofs) const
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{ iterator tmp = *this; return (tmp += ofs); }
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iterator operator-(difference_type ofs) const
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{ iterator tmp = *this; return (tmp -= ofs); }
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difference_type operator-(const iterator right) const
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{ return (difference_type)(pos - right.pos); }
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protected:
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T* data;
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size_t pos;
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// not mod-N so that begin != end when buffer is full.
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};
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class const_iterator
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{
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public:
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typedef std::random_access_iterator_tag iterator_category;
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typedef T value_type;
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typedef ptrdiff_t difference_type;
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typedef const T* pointer;
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typedef const T& reference;
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const_iterator() : data(0), pos(0)
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{}
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const_iterator(const T* data_, size_t pos_) : data(data_), pos(pos_)
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{}
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const T& operator[](int idx) const
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{ return data[(pos+idx) % n]; }
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const T& operator*() const
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{ return data[pos % n]; }
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const T* operator->() const
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{ return &**this; }
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const_iterator& operator++() // pre
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{ ++pos; return (*this); }
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const_iterator operator++(int) // post
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{ const_iterator tmp = *this; ++*this; return tmp; }
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bool operator==(const const_iterator& rhs) const
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{ return data == rhs.data && pos == rhs.pos; }
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bool operator!=(const const_iterator& rhs) const
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{ return !(*this == rhs); }
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bool operator<(const const_iterator& rhs) const
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{ return (pos < rhs.pos); }
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iterator& operator+=(difference_type ofs)
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{ pos += ofs; return *this; }
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iterator& operator-=(difference_type ofs)
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{ return (*this += -ofs); }
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iterator operator+(difference_type ofs) const
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{ iterator tmp = *this; return (tmp += ofs); }
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iterator operator-(difference_type ofs) const
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{ iterator tmp = *this; return (tmp -= ofs); }
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difference_type operator-(const iterator right) const
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{ return (difference_type)(pos - right.pos); }
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protected:
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const T* data;
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size_t pos;
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// not mod-N so that begin != end when buffer is full.
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};
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iterator begin()
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{
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return iterator(data, (size_ < n)? 0 : head);
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}
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const_iterator begin() const
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{
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return const_iterator(data, (size_ < n)? 0 : head);
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}
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iterator end()
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{
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return iterator(data, (size_ < n)? size_ : head+n);
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}
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const_iterator end() const
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{
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return const_iterator(data, (size_ < n)? size_ : head+n);
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}
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};
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// Matei's slightly friendlier hashtable for value-type keys
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template<typename K, typename T, typename HashCompare >
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class MateiHashTbl
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{
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static const size_t initial_entries = 16;
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struct Entry {
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bool valid;
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K key;
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T value;
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Entry() : valid(false) {}
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Entry(const K& k, T v) { key=k; value=v; }
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Entry& operator=(const Entry& other) {
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valid = other.valid;
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key = other.key;
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value = other.value;
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return *this;
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}
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};
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Entry* tbl;
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u16 num_entries;
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u16 max_entries; // when initialized, = 2**n for faster modulo
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HashCompare hashFunc;
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Entry& get_slot(K key) const
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{
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size_t hash = hashFunc(key);
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//debug_assert(max_entries != 0); // otherwise, mask will be incorrect
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const uint mask = max_entries-1;
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int stride = 1; // for quadratic probing
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for(;;)
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{
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Entry& e = tbl[hash & mask];
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// empty slot encountered => not found
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if(!e.valid)
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return e;
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// keys are actually equal => found it
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if(e.key == key)
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return e;
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// keep going (quadratic probing)
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hash += stride;
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stride++;
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}
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}
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void expand_tbl()
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{
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// alloc a new table (but don't assign it to <tbl> unless successful)
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Entry* old_tbl = tbl;
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tbl = new Entry[max_entries*2];
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if(!tbl)
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{
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tbl = old_tbl;
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throw std::bad_alloc();
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}
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max_entries += max_entries;
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// must be set before get_slot
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// newly initialized, nothing to copy - done
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if(!old_tbl)
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return;
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// re-hash from old table into the new one
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for(size_t i = 0; i < max_entries/2u; i++)
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{
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Entry& e = old_tbl[i];
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if(e.valid)
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get_slot(e.key) = e;
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}
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delete[] old_tbl;
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}
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void delete_contents()
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{
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if(tbl)
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{
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delete[] tbl;
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tbl = 0;
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}
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}
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public:
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MateiHashTbl()
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{
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tbl = 0;
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num_entries = 0;
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max_entries = initial_entries/2; // will be doubled in expand_tbl
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//debug_assert(is_pow2(max_entries));
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expand_tbl();
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}
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~MateiHashTbl()
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{
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delete_contents();
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}
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void clear()
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{
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delete_contents();
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num_entries = 0;
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// rationale: must not set to 0 because expand_tbl only doubles the size.
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// don't keep the previous size because it may have become huge and
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// there is no provision for shrinking.
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max_entries = initial_entries/2; // will be doubled in expand_tbl
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expand_tbl();
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}
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bool contains(const K& key) const
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{
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return get_slot(key).valid;
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}
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T& operator[](const K& key)
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{
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Entry* slot = &get_slot(key);
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if(slot->valid)
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{
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return slot->value;
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}
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// no element exists for this key - insert it into the table
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// (this is slightly different from STL::hash_map in that we insert a new element
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// on a get for a nonexistent key, but hopefully that's not a problem)
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// if more than 75% full, increase table size and find slot again
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if(num_entries*4 >= max_entries*2)
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{
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expand_tbl();
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slot = &get_slot(key); // find slot again since we expanded
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}
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slot->valid = true;
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slot->key = key;
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num_entries++;
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|
return slot->value;
|
|
}
|
|
|
|
size_t size() const
|
|
{
|
|
return num_entries;
|
|
}
|
|
|
|
// Not an STL iterator, more like a Java one
|
|
// Usage: for(HashTable::Iterator it(table); it.valid(); it.advance()) { do stuff to it.key() and it.value() }
|
|
class Iterator
|
|
{
|
|
private:
|
|
Entry* pos;
|
|
Entry* end;
|
|
|
|
public:
|
|
Iterator(const MateiHashTbl& ht)
|
|
{
|
|
pos = ht.tbl;
|
|
end = ht.tbl + ht.max_entries;
|
|
while(pos < end && !pos->valid)
|
|
pos++;
|
|
};
|
|
|
|
bool valid() const
|
|
{
|
|
return pos < end;
|
|
}
|
|
|
|
void advance()
|
|
{
|
|
do {
|
|
pos++;
|
|
}
|
|
while(pos < end && !pos->valid);
|
|
}
|
|
|
|
const K& key()
|
|
{
|
|
return pos->key;
|
|
}
|
|
|
|
T& value()
|
|
{
|
|
return pos->value;
|
|
}
|
|
};
|
|
};
|
|
|
|
|
|
#endif // #ifndef ADTS_H__
|