174 lines
3.9 KiB
C++
174 lines
3.9 KiB
C++
/* A type-safe hash set.
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Copyright (C) 2014 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef hash_set_h
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#define hash_set_h
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#include "hash-table.h"
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/* implement default behavior for traits when types allow it. */
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struct default_hashset_traits
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{
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/* Hashes the passed in key. */
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template<typename T>
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static hashval_t
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hash (T *p)
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{
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return uintptr_t(p) >> 3;
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}
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template<typename T> static hashval_t hash(const T &v) { return v; }
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/* Return true if the two keys passed as arguments are equal. */
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template<typename T>
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static bool
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equal (const T &a, const T &b)
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{
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return a == b;
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}
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/* Called to dispose of the key before marking the entry as deleted. */
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template<typename T> static void remove (T &v) { v.~T (); }
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/* Mark the passed in entry as being deleted. */
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template<typename T>
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static void
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mark_deleted (T *&e)
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{
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e = reinterpret_cast<void *> (1);
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}
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/* Mark the passed in entry as being empty. */
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template<typename T>
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static void
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mark_empty (T *&e)
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{
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e = NULL;
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}
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/* Return true if the passed in entry is marked as deleted. */
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template<typename T>
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static bool
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is_deleted (T *e)
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{
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return e == reinterpret_cast<void *> (1);
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}
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/* Return true if the passed in entry is marked as empty. */
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template<typename T> static bool is_empty (T *e) { return e == NULL; }
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};
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template<typename Key, typename Traits = default_hashset_traits>
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class hash_set
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{
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struct hash_entry
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{
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Key m_key;
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typedef hash_entry value_type;
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typedef Key compare_type;
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typedef int store_values_directly;
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static hashval_t hash (const hash_entry &e)
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{
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return Traits::hash (e.m_key);
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}
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static bool equal (const hash_entry &a, const Key &b)
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{
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return Traits::equal (a.m_key, b);
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}
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static void remove (hash_entry &e) { Traits::remove (e.m_key); }
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static void
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mark_deleted (hash_entry &e)
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{
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Traits::mark_deleted (e.m_key);
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}
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static bool is_deleted (const hash_entry &e)
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{
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return Traits::is_deleted (e.m_key);
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}
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static void
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mark_empty (hash_entry &e)
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{
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Traits::mark_empty (e.m_key);
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}
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static bool
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is_empty (const hash_entry &e)
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{
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return Traits::is_empty (e.m_key);
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}
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};
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public:
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explicit hash_set (size_t n = 13) : m_table (n) {}
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/* If key k isn't already in the map add it to the map, and
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return false. Otherwise return true. */
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bool add (const Key &k)
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{
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hash_entry *e = m_table.find_slot_with_hash (k, Traits::hash (k),
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INSERT);
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bool existed = !hash_entry::is_empty (*e);
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if (!existed)
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e->m_key = k;
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return existed;
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}
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/* if the passed in key is in the map return its value otherwise NULL. */
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bool contains (const Key &k)
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{
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hash_entry &e = m_table.find_with_hash (k, Traits::hash (k));
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return !Traits::is_empty (e.m_key);
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}
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/* Call the call back on each pair of key and value with the passed in
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arg. */
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template<typename Arg, bool (*f)(const Key &, Arg)>
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void traverse (Arg a) const
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{
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for (typename hash_table<hash_entry>::iterator iter = m_table.begin ();
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iter != m_table.end (); ++iter)
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f ((*iter).m_key, a);
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}
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private:
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hash_table<hash_entry> m_table;
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};
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#endif
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