path: root/libstdc++-v3/include/tr1/hashtable

// Internal header for TR1 unordered_set and unordered_map -*- C++ -*-

// Copyright (C) 2005, 2006 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

/** @file 
 *  This is a TR1 C++ Library header. 
 */

// This header file defines std::tr1::hashtable, which is used to
// implement std::tr1::unordered_set, std::tr1::unordered_map, 
// std::tr1::unordered_multiset, and std::tr1::unordered_multimap.
// hashtable has many template parameters, partly to accommodate
// the differences between those four classes and partly to 
// accommodate policy choices that go beyond what TR1 calls for.

// ??? Arguably this should be Internal::hashtable, not std::tr1::hashtable.

// Class template hashtable attempts to encapsulate all reasonable
// variation among hash tables that use chaining.  It does not handle
// open addressing.

// References: 
// M. Austern, "A Proposal to Add Hash Tables to the Standard
//    Library (revision 4)," WG21 Document N1456=03-0039, 2003.
// D. E. Knuth, The Art of Computer Programming, v. 3, Sorting and Searching.
// A. Tavori and V. Dreizin, "Generic Associative Containers", 2004.
//    ??? Full citation?

#ifndef GNU_LIBSTDCXX_TR1_HASHTABLE_
#define GNU_LIBSTDCXX_TR1_HASHTABLE_

#include <utility>		// For std::pair
#include <memory>
#include <iterator>
#include <cstddef>
#include <cstdlib>
#include <cmath>
#include <bits/functexcept.h>
#include <tr1/type_traits>	// For true_type and false_type

//----------------------------------------------------------------------
// General utilities

namespace Internal
{
  template<bool Flag, typename IfTrue, typename IfFalse>
    struct IF;

  template<typename IfTrue, typename IfFalse>
    struct IF<true, IfTrue, IfFalse>
    { typedef IfTrue type; };
 
  template <typename IfTrue, typename IfFalse>
    struct IF<false, IfTrue, IfFalse>
    { typedef IfFalse type; };

  // Helper function: return distance(first, last) for forward
  // iterators, or 0 for input iterators.
  template<class Iterator>
    inline typename std::iterator_traits<Iterator>::difference_type
    distance_fw(Iterator first, Iterator last, std::input_iterator_tag)
    { return 0; }

  template<class Iterator>
    inline typename std::iterator_traits<Iterator>::difference_type
    distance_fw(Iterator first, Iterator last, std::forward_iterator_tag)
    { return std::distance(first, last); }

  template<class Iterator>
    inline typename std::iterator_traits<Iterator>::difference_type
    distance_fw(Iterator first, Iterator last)
    {
      typedef typename std::iterator_traits<Iterator>::iterator_category tag;
      return distance_fw(first, last, tag());
    }
  
} // namespace Internal

//----------------------------------------------------------------------
// Auxiliary types used for all instantiations of hashtable: nodes
// and iterators.

// Nodes, used to wrap elements stored in the hash table.  A policy
// template parameter of class template hashtable controls whether
// nodes also store a hash code. In some cases (e.g. strings) this may
// be a performance win.

namespace Internal
{
  template<typename Value, bool cache_hash_code>
    struct hash_node;

  template<typename Value>
    struct hash_node<Value, true>
    {
      Value m_v;
      std::size_t hash_code;
      hash_node* m_next;
    };

  template<typename Value>
    struct hash_node<Value, false>
    {
      Value m_v;
      hash_node* m_next;
    };

  // Local iterators, used to iterate within a bucket but not between
  // buckets.

  template<typename Value, bool cache>
    struct node_iterator_base
    {
      node_iterator_base(hash_node<Value, cache>* p)
      : m_cur(p) { }
      
      void
      incr()
      { m_cur = m_cur->m_next; }

      hash_node<Value, cache>* m_cur;
    };

  template<typename Value, bool cache>
    inline bool
    operator==(const node_iterator_base<Value, cache>& x,
	       const node_iterator_base<Value, cache>& y)
    { return x.m_cur == y.m_cur; }

  template<typename Value, bool cache>
    inline bool
    operator!=(const node_iterator_base<Value, cache>& x,
	       const node_iterator_base<Value, cache>& y)
    { return x.m_cur != y.m_cur; }

  template<typename Value, bool constant_iterators, bool cache>
    struct node_iterator
    : public node_iterator_base<Value, cache>
    {
      typedef Value                                    value_type;
      typedef typename IF<constant_iterators, const Value*, Value*>::type
                                                       pointer;
      typedef typename IF<constant_iterators, const Value&, Value&>::type
                                                       reference;
      typedef std::ptrdiff_t                           difference_type;
      typedef std::forward_iterator_tag                iterator_category;

      explicit
      node_iterator(hash_node<Value, cache>* p = 0)
      : node_iterator_base<Value, cache>(p) { }

      reference
      operator*() const
      { return this->m_cur->m_v; }
  
      pointer
      operator->() const
      { return &this->m_cur->m_v; }

      node_iterator&
      operator++()
      { 
	this->incr(); 
	return *this; 
      }
  
      node_iterator
      operator++(int)
      { 
	node_iterator tmp(*this);
	this->incr();
	return tmp;
      }
    };

  template<typename Value, bool constant_iterators, bool cache>
    struct node_const_iterator
    : public node_iterator_base<Value, cache>
    {
      typedef Value                                    value_type;
      typedef const Value*                             pointer;
      typedef const Value&                             reference;
      typedef std::ptrdiff_t                           difference_type;
      typedef std::forward_iterator_tag                iterator_category;

      explicit
      node_const_iterator(hash_node<Value, cache>* p = 0)
      : node_iterator_base<Value, cache>(p) { }

      node_const_iterator(const node_iterator<Value, constant_iterators,
			  cache>& x)
      : node_iterator_base<Value, cache>(x.m_cur) { }

      reference
      operator*() const
      { return this->m_cur->m_v; }
  
      pointer
      operator->() const
      { return &this->m_cur->m_v; }

      node_const_iterator&
      operator++()
      { 
	this->incr(); 
	return *this; 
      }
  
      node_const_iterator
      operator++(int)
      { 
	node_const_iterator tmp(*this);
	this->incr();
	return tmp;
      }
    };

  template<typename Value, bool cache>
    struct hashtable_iterator_base
    {
      hashtable_iterator_base(hash_node<Value, cache>* node,
			      hash_node<Value, cache>** bucket)
      : m_cur_node(node), m_cur_bucket(bucket)
      { }

      void
      incr()
      {
	m_cur_node = m_cur_node->m_next;
	if (!m_cur_node)
	  m_incr_bucket();
      }

      void
      m_incr_bucket();

      hash_node<Value, cache>* m_cur_node;
      hash_node<Value, cache>** m_cur_bucket;
    };

  // Global iterators, used for arbitrary iteration within a hash
  // table.  Larger and more expensive than local iterators.
  template<typename Value, bool cache>
    void
    hashtable_iterator_base<Value, cache>::
    m_incr_bucket()
    {
      ++m_cur_bucket;

      // This loop requires the bucket array to have a non-null sentinel.
      while (!*m_cur_bucket)
	++m_cur_bucket;
      m_cur_node = *m_cur_bucket;
    }

  template<typename Value, bool cache>
    inline bool
    operator==(const hashtable_iterator_base<Value, cache>& x,
	       const hashtable_iterator_base<Value, cache>& y)
    { return x.m_cur_node == y.m_cur_node; }

  template<typename Value, bool cache>
    inline bool
    operator!=(const hashtable_iterator_base<Value, cache>& x,
	       const hashtable_iterator_base<Value, cache>& y)
    { return x.m_cur_node != y.m_cur_node; }

  template<typename Value, bool constant_iterators, bool cache>
    struct hashtable_iterator
    : public hashtable_iterator_base<Value, cache>
    {
      typedef Value                                    value_type;
      typedef typename IF<constant_iterators, const Value*, Value*>::type
                                                       pointer;
      typedef typename IF<constant_iterators, const Value&, Value&>::type
                                                       reference;
      typedef std::ptrdiff_t                           difference_type;
      typedef std::forward_iterator_tag                iterator_category;

      hashtable_iterator(hash_node<Value, cache>* p,
			 hash_node<Value, cache>** b)
      : hashtable_iterator_base<Value, cache>(p, b) { }

      explicit
      hashtable_iterator(hash_node<Value, cache>** b)
      : hashtable_iterator_base<Value, cache>(*b, b) { }
  
      reference
      operator*() const
      { return this->m_cur_node->m_v; }
  
      pointer
      operator->() const
      { return &this->m_cur_node->m_v; }

      hashtable_iterator&
      operator++()
      { 
	this->incr();
	return *this;
      }
  
      hashtable_iterator
      operator++(int)
      { 
	hashtable_iterator tmp(*this);
	this->incr();
	return tmp;
      }
    };

  template<typename Value, bool constant_iterators, bool cache>
    struct hashtable_const_iterator
    : public hashtable_iterator_base<Value, cache>
    {
      typedef Value                                    value_type;
      typedef const Value*                             pointer;
      typedef const Value&                             reference;
      typedef std::ptrdiff_t                           difference_type;
      typedef std::forward_iterator_tag                iterator_category;

      hashtable_const_iterator(hash_node<Value, cache>* p,
			       hash_node<Value, cache>** b)
      : hashtable_iterator_base<Value, cache>(p, b) { }

      explicit
      hashtable_const_iterator(hash_node<Value, cache>** b)
      : hashtable_iterator_base<Value, cache>(*b, b) { }
  
      hashtable_const_iterator(const hashtable_iterator<Value,
			       constant_iterators, cache>& x)
      : hashtable_iterator_base<Value, cache>(x.m_cur_node, x.m_cur_bucket) { }

      reference
      operator*() const
      { return this->m_cur_node->m_v; }
  
      pointer
      operator->() const
      { return &this->m_cur_node->m_v; }

      hashtable_const_iterator&
      operator++()
      { 
	this->incr();
	return *this;
      }
  
      hashtable_const_iterator
      operator++(int)
      { 
	hashtable_const_iterator tmp(*this);
	this->incr();
	return tmp;
      }
    };
} // namespace Internal

// ----------------------------------------------------------------------
// Many of class template hashtable's template parameters are policy
// classes.  These are defaults for the policies.

namespace Internal
{
  // The two key extraction policies used by the *set and *map variants.
  template<typename T>
    struct identity
    {
      T
      operator()(const T& t) const
      { return t; }
    };

  template<typename Pair>
    struct extract1st
    {
      typename Pair::first_type
      operator()(const Pair& p) const
      { return p.first; }
    };

  // Default range hashing function: use division to fold a large number
  // into the range [0, N).
  struct mod_range_hashing
  {
    typedef std::size_t first_argument_type;
    typedef std::size_t second_argument_type;
    typedef std::size_t result_type;

    result_type
    operator() (first_argument_type r, second_argument_type N) const
    { return r % N; }
  };

  // Default ranged hash function H.  In principle it should be a
  // function object composed from objects of type H1 and H2 such that
  // h(k, N) = h2(h1(k), N), but that would mean making extra copies of
  // h1 and h2.  So instead we'll just use a tag to tell class template
  // hashtable to do that composition.
  struct default_ranged_hash { };

  // Default value for rehash policy.  Bucket size is (usually) the
  // smallest prime that keeps the load factor small enough.
  struct prime_rehash_policy
  {
    prime_rehash_policy(float z = 1.0);
    
    float
    max_load_factor() const;

    // Return a bucket size no smaller than n.
    std::size_t
    next_bkt(std::size_t n) const;
    
    // Return a bucket count appropriate for n elements
    std::size_t
    bkt_for_elements(std::size_t n) const;
    
    // n_bkt is current bucket count, n_elt is current element count,
    // and n_ins is number of elements to be inserted.  Do we need to
    // increase bucket count?  If so, return make_pair(true, n), where n
    // is the new bucket count.  If not, return make_pair(false, 0).
    std::pair<bool, std::size_t>
    need_rehash(std::size_t n_bkt, std::size_t n_elt, std::size_t n_ins) const;
    
    float m_max_load_factor;
    float m_growth_factor;
    mutable std::size_t m_next_resize;
  };

  // XXX This is a hack.  prime_rehash_policy's member functions, and
  // certainly the list of primes, should be defined in a .cc file.
  // We're temporarily putting them in a header because we don't have a
  // place to put TR1 .cc files yet.  There's no good reason for any of
  // prime_rehash_policy's member functions to be inline, and there's
  // certainly no good reason for X<> to exist at all.
  
  struct lt
  {
    template<typename X, typename Y>
      bool
      operator()(X x, Y y)
      { return x < y; }
  };

  template<int dummy>
    struct X
    {
      static const int n_primes = 256;
      static const unsigned long primes[n_primes + 1];
    };

  template<int dummy>
    const int X<dummy>::n_primes;

  template<int dummy>
    const unsigned long X<dummy>::primes[n_primes + 1] =
    {
      2ul, 3ul, 5ul, 7ul, 11ul, 13ul, 17ul, 19ul, 23ul, 29ul, 31ul,
      37ul, 41ul, 43ul, 47ul, 53ul, 59ul, 61ul, 67ul, 71ul, 73ul, 79ul,
      83ul, 89ul, 97ul, 103ul, 109ul, 113ul, 127ul, 137ul, 139ul, 149ul,
      157ul, 167ul, 179ul, 193ul, 199ul, 211ul, 227ul, 241ul, 257ul,
      277ul, 293ul, 313ul, 337ul, 359ul, 383ul, 409ul, 439ul, 467ul,
      503ul, 541ul, 577ul, 619ul, 661ul, 709ul, 761ul, 823ul, 887ul,
      953ul, 1031ul, 1109ul, 1193ul, 1289ul, 1381ul, 1493ul, 1613ul,
      1741ul, 1879ul, 2029ul, 2179ul, 2357ul, 2549ul, 2753ul, 2971ul,
      3209ul, 3469ul, 3739ul, 4027ul, 4349ul, 4703ul, 5087ul, 5503ul,
      5953ul, 6427ul, 6949ul, 7517ul, 8123ul, 8783ul, 9497ul, 10273ul,
      11113ul, 12011ul, 12983ul, 14033ul, 15173ul, 16411ul, 17749ul,
      19183ul, 20753ul, 22447ul, 24281ul, 26267ul, 28411ul, 30727ul,
      33223ul, 35933ul, 38873ul, 42043ul, 45481ul, 49201ul, 53201ul,
      57557ul, 62233ul, 67307ul, 72817ul, 78779ul, 85229ul, 92203ul,
      99733ul, 107897ul, 116731ul, 126271ul, 136607ul, 147793ul,
      159871ul, 172933ul, 187091ul, 202409ul, 218971ul, 236897ul,
      256279ul, 277261ul, 299951ul, 324503ul, 351061ul, 379787ul,
      410857ul, 444487ul, 480881ul, 520241ul, 562841ul, 608903ul,
      658753ul, 712697ul, 771049ul, 834181ul, 902483ul, 976369ul,
      1056323ul, 1142821ul, 1236397ul, 1337629ul, 1447153ul, 1565659ul,
      1693859ul, 1832561ul, 1982627ul, 2144977ul, 2320627ul, 2510653ul,
      2716249ul, 2938679ul, 3179303ul, 3439651ul, 3721303ul, 4026031ul,
      4355707ul, 4712381ul, 5098259ul, 5515729ul, 5967347ul, 6456007ul,
      6984629ul, 7556579ul, 8175383ul, 8844859ul, 9569143ul, 10352717ul,
      11200489ul, 12117689ul, 13109983ul, 14183539ul, 15345007ul,
      16601593ul, 17961079ul, 19431899ul, 21023161ul, 22744717ul,
      24607243ul, 26622317ul, 28802401ul, 31160981ul, 33712729ul,
      36473443ul, 39460231ul, 42691603ul, 46187573ul, 49969847ul,
      54061849ul, 58488943ul, 63278561ul, 68460391ul, 74066549ul,
      80131819ul, 86693767ul, 93793069ul, 101473717ul, 109783337ul,
      118773397ul, 128499677ul, 139022417ul, 150406843ul, 162723577ul,
      176048909ul, 190465427ul, 206062531ul, 222936881ul, 241193053ul,
      260944219ul, 282312799ul, 305431229ul, 330442829ul, 357502601ul,
      386778277ul, 418451333ul, 452718089ul, 489790921ul, 529899637ul,
      573292817ul, 620239453ul, 671030513ul, 725980837ul, 785430967ul,
      849749479ul, 919334987ul, 994618837ul, 1076067617ul, 1164186217ul,
      1259520799ul, 1362662261ul, 1474249943ul, 1594975441ul,
      1725587117ul, 1866894511ul, 2019773507ul, 2185171673ul,
      2364114217ul, 2557710269ul, 2767159799ul, 2993761039ul,
      3238918481ul, 3504151727ul, 3791104843ul, 4101556399ul,
      4294967291ul,
      4294967291ul // sentinel so we don't have to test result of lower_bound
    };

  inline
  prime_rehash_policy::
  prime_rehash_policy(float z)
  : m_max_load_factor(z), m_growth_factor(2.f), m_next_resize(0)
  { }

  inline float
  prime_rehash_policy::
  max_load_factor() const
  { return m_max_load_factor; }

  // Return a prime no smaller than n.
  inline std::size_t
  prime_rehash_policy::
  next_bkt(std::size_t n) const
  {
    const unsigned long* const last = X<0>::primes + X<0>::n_primes;
    const unsigned long* p = std::lower_bound (X<0>::primes, last, n);
    m_next_resize = static_cast<std::size_t>(std::ceil(*p * m_max_load_factor));
    return *p;
  }

  // Return the smallest prime p such that alpha p >= n, where alpha
  // is the load factor.
  inline std::size_t
  prime_rehash_policy::
  bkt_for_elements(std::size_t n) const
  {
    const unsigned long* const last = X<0>::primes + X<0>::n_primes;
    const float min_bkts = n / m_max_load_factor;
    const unsigned long* p = std::lower_bound (X<0>::primes, last,
					       min_bkts, lt());
    m_next_resize = static_cast<std::size_t>(std::ceil(*p * m_max_load_factor));
    return *p;
  }

  // Finds the smallest prime p such that alpha p > n_elt + n_ins.
  // If p > n_bkt, return make_pair(true, p); otherwise return
  // make_pair(false, 0).  In principle this isn't very different from 
  // bkt_for_elements.
  
  // The only tricky part is that we're caching the element count at
  // which we need to rehash, so we don't have to do a floating-point
  // multiply for every insertion.
  
  inline std::pair<bool, std::size_t>
  prime_rehash_policy::
  need_rehash(std::size_t n_bkt, std::size_t n_elt, std::size_t n_ins) const
  {
    if (n_elt + n_ins > m_next_resize)
      {
	float min_bkts = (float(n_ins) + float(n_elt)) / m_max_load_factor;
	if (min_bkts > n_bkt)
	  {
	    min_bkts = std::max (min_bkts, m_growth_factor * n_bkt);
	    const unsigned long* const last = X<0>::primes + X<0>::n_primes;
	    const unsigned long* p = std::lower_bound (X<0>::primes, last,
						       min_bkts, lt());
	    m_next_resize = 
	      static_cast<std::size_t>(std::ceil(*p * m_max_load_factor));
	    return std::make_pair(true, *p);
	  }
	else 
	  {
	    m_next_resize = 
	      static_cast<std::size_t>(std::ceil(n_bkt * m_max_load_factor));
	    return std::make_pair(false, 0);
	  }
      }
    else
      return std::make_pair(false, 0);
  }

} // namespace Internal

//----------------------------------------------------------------------
// Base classes for std::tr1::hashtable.  We define these base classes
// because in some cases we want to do different things depending on
// the value of a policy class.  In some cases the policy class affects
// which member functions and nested typedefs are defined; we handle that
// by specializing base class templates.  Several of the base class templates
// need to access other members of class template hashtable, so we use
// the "curiously recurring template pattern" for them.

namespace Internal
{
  // class template map_base.  If the hashtable has a value type of the
  // form pair<T1, T2> and a key extraction policy that returns the
  // first part of the pair, the hashtable gets a mapped_type typedef.
  // If it satisfies those criteria and also has unique keys, then it
  // also gets an operator[].
  
  template<typename K, typename V, typename Ex, bool unique, typename Hashtable>
    struct map_base { };
	  
  template<typename K, typename Pair, typename Hashtable>
    struct map_base<K, Pair, extract1st<Pair>, false, Hashtable>
    {
      typedef typename Pair::second_type mapped_type;
    };

  template<typename K, typename Pair, typename Hashtable>
    struct map_base<K, Pair, extract1st<Pair>, true, Hashtable>
    {
      typedef typename Pair::second_type mapped_type;
      
      mapped_type&
      operator[](const K& k)
      {
	Hashtable* h = static_cast<Hashtable*>(this);
	typename Hashtable::iterator it = 
	  h->insert(std::make_pair(k, mapped_type())).first;
	return it->second;
      }
    };

  // class template rehash_base.  Give hashtable the max_load_factor
  // functions iff the rehash policy is prime_rehash_policy.
  template<typename RehashPolicy, typename Hashtable>
    struct rehash_base { };

  template<typename Hashtable>
    struct rehash_base<prime_rehash_policy, Hashtable>
    {
      float
      max_load_factor() const
      {
	const Hashtable* This = static_cast<const Hashtable*>(this);
	return This->rehash_policy()->max_load_factor();
      }

      void
      max_load_factor(float z)
      {
	Hashtable* This = static_cast<Hashtable*>(this);
	This->rehash_policy(prime_rehash_policy(z));    
      }
    };

  // Class template hash_code_base.  Encapsulates two policy issues that
  // aren't quite orthogonal.
  //   (1) the difference between using a ranged hash function and using
  //       the combination of a hash function and a range-hashing function.
  //       In the former case we don't have such things as hash codes, so
  //       we have a dummy type as placeholder.
  //   (2) Whether or not we cache hash codes.  Caching hash codes is
  //       meaningless if we have a ranged hash function.
  // We also put the key extraction and equality comparison function 
  // objects here, for convenience.
  
  // Primary template: unused except as a hook for specializations.
  
  template<typename Key, typename Value,
	   typename ExtractKey, typename Equal,
	   typename H1, typename H2, typename H,
	   bool cache_hash_code>
    struct hash_code_base;

  // Specialization: ranged hash function, no caching hash codes.  H1
  // and H2 are provided but ignored.  We define a dummy hash code type.
  template<typename Key, typename Value,
	   typename ExtractKey, typename Equal,
	   typename H1, typename H2, typename H>
    struct hash_code_base<Key, Value, ExtractKey, Equal, H1, H2, H, false>
    {
    protected:
      hash_code_base(const ExtractKey& ex, const Equal& eq,
		     const H1&, const H2&, const H& h)
      : m_extract(ex), m_eq(eq), m_ranged_hash(h) { }

      typedef void* hash_code_t;
  
      hash_code_t
      m_hash_code(const Key& k) const
      { return 0; }
  
      std::size_t
      bucket_index(const Key& k, hash_code_t, std::size_t N) const
      { return m_ranged_hash (k, N); }

      std::size_t
      bucket_index(const hash_node<Value, false>* p, std::size_t N) const
      { return m_ranged_hash (m_extract (p->m_v), N); }
  
      bool
      compare(const Key& k, hash_code_t, hash_node<Value, false>* n) const
      { return m_eq (k, m_extract(n->m_v)); }

      void
      store_code(hash_node<Value, false>*, hash_code_t) const
      { }

      void
      copy_code(hash_node<Value, false>*, const hash_node<Value, false>*) const
      { }
      
      void
      m_swap(hash_code_base& x)
      {
	std::swap(m_extract, x.m_extract);
	std::swap(m_eq, x.m_eq);
	std::swap(m_ranged_hash, x.m_ranged_hash);
      }

    protected:
      ExtractKey m_extract;
      Equal m_eq;
      H m_ranged_hash;
    };


  // No specialization for ranged hash function while caching hash codes.
  // That combination is meaningless, and trying to do it is an error.
  
  
  // Specialization: ranged hash function, cache hash codes.  This
  // combination is meaningless, so we provide only a declaration
  // and no definition.
  
  template<typename Key, typename Value,
	    typename ExtractKey, typename Equal,
	    typename H1, typename H2, typename H>
    struct hash_code_base<Key, Value, ExtractKey, Equal, H1, H2, H, true>;


  // Specialization: hash function and range-hashing function, no
  // caching of hash codes.  H is provided but ignored.  Provides
  // typedef and accessor required by TR1.
  
  template<typename Key, typename Value,
	   typename ExtractKey, typename Equal,
	   typename H1, typename H2>
    struct hash_code_base<Key, Value, ExtractKey, Equal, H1, H2,
			  default_ranged_hash, false>
    {
      typedef H1 hasher;
      
      hasher
      hash_function() const
      { return m_h1; }

    protected:
      hash_code_base(const ExtractKey& ex, const Equal& eq,
		     const H1& h1, const H2& h2, const default_ranged_hash&)
      : m_extract(ex), m_eq(eq), m_h1(h1), m_h2(h2) { }

      typedef std::size_t hash_code_t;
      
      hash_code_t
      m_hash_code(const Key& k) const
      { return m_h1(k); }
      
      std::size_t
      bucket_index(const Key&, hash_code_t c, std::size_t N) const
      { return m_h2 (c, N); }

      std::size_t
      bucket_index(const hash_node<Value, false>* p, std::size_t N) const
      { return m_h2 (m_h1 (m_extract (p->m_v)), N); }

      bool
      compare(const Key& k, hash_code_t, hash_node<Value, false>* n) const
      { return m_eq (k, m_extract(n->m_v)); }

      void
      store_code(hash_node<Value, false>*, hash_code_t) const
      { }

      void
      copy_code(hash_node<Value, false>*, const hash_node<Value, false>*) const
      { }

      void
      m_swap(hash_code_base& x)
      {
	std::swap(m_extract, x.m_extract);
	std::swap(m_eq, x.m_eq);
	std::swap(m_h1, x.m_h1);
	std::swap(m_h2, x.m_h2);
      }

    protected:
      ExtractKey m_extract;
      Equal m_eq;
      H1 m_h1;
      H2 m_h2;
    };

  // Specialization: hash function and range-hashing function, 
  // caching hash codes.  H is provided but ignored.  Provides
  // typedef and accessor required by TR1.
  template<typename Key, typename Value,
	   typename ExtractKey, typename Equal,
	   typename H1, typename H2>
    struct hash_code_base<Key, Value, ExtractKey, Equal, H1, H2,
			  default_ranged_hash, true>
    {
      typedef H1 hasher;
      
      hasher
      hash_function() const
      { return m_h1; }

    protected:
      hash_code_base(const ExtractKey& ex, const Equal& eq,
		     const H1& h1, const H2& h2, const default_ranged_hash&)
      : m_extract(ex), m_eq(eq), m_h1(h1), m_h2(h2) { }

      typedef std::size_t hash_code_t;
  
      hash_code_t
      m_hash_code (const Key& k) const
      { return m_h1(k); }
  
      std::size_t
      bucket_index(const Key&, hash_code_t c, std::size_t N) const
      { return m_h2 (c, N); }

      std::size_t
      bucket_index(const hash_node<Value, true>* p, std::size_t N) const
      { return m_h2 (p->hash_code, N); }

      bool
      compare(const Key& k, hash_code_t c, hash_node<Value, true>* n) const
      { return c == n->hash_code && m_eq(k, m_extract(n->m_v)); }

      void
      store_code(hash_node<Value, true>* n, hash_code_t c) const
      { n->hash_code = c; }

      void
      copy_code(hash_node<Value, true>* to,
		const hash_node<Value, true>* from) const
      { to->hash_code = from->hash_code; }

      void
      m_swap(hash_code_base& x)
      {
	std::swap(m_extract, x.m_extract);
	std::swap(m_eq, x.m_eq);
	std::swap(m_h1, x.m_h1);
	std::swap(m_h2, x.m_h2);
      }
      
    protected:
      ExtractKey m_extract;
      Equal m_eq;
      H1 m_h1;
      H2 m_h2;
    };

} // namespace internal

namespace std
{ 
_GLIBCXX_BEGIN_NAMESPACE(tr1)

  //----------------------------------------------------------------------
  // Class template hashtable, class definition.
  
  // Meaning of class template hashtable's template parameters
  
  // Key and Value: arbitrary CopyConstructible types.
  
  // Allocator: an allocator type ([lib.allocator.requirements]) whose
  // value type is Value.
  
  // ExtractKey: function object that takes a object of type Value
  // and returns a value of type Key.
  
  // Equal: function object that takes two objects of type k and returns
  // a bool-like value that is true if the two objects are considered equal.
  
  // H1: the hash function.  A unary function object with argument type
  // Key and result type size_t.  Return values should be distributed
  // over the entire range [0, numeric_limits<size_t>:::max()].
  
  // H2: the range-hashing function (in the terminology of Tavori and
  // Dreizin).  A binary function object whose argument types and result
  // type are all size_t.  Given arguments r and N, the return value is
  // in the range [0, N).
  
  // H: the ranged hash function (Tavori and Dreizin). A binary function
  // whose argument types are Key and size_t and whose result type is
  // size_t.  Given arguments k and N, the return value is in the range
  // [0, N).  Default: h(k, N) = h2(h1(k), N).  If H is anything other
  // than the default, H1 and H2 are ignored.
  
  // RehashPolicy: Policy class with three members, all of which govern
  // the bucket count. n_bkt(n) returns a bucket count no smaller
  // than n.  bkt_for_elements(n) returns a bucket count appropriate
  // for an element count of n.  need_rehash(n_bkt, n_elt, n_ins)
  // determines whether, if the current bucket count is n_bkt and the
  // current element count is n_elt, we need to increase the bucket
  // count.  If so, returns make_pair(true, n), where n is the new
  // bucket count.  If not, returns make_pair(false, <anything>).
  
  // ??? Right now it is hard-wired that the number of buckets never
  // shrinks.  Should we allow RehashPolicy to change that?
  
  // cache_hash_code: bool.  true if we store the value of the hash
  // function along with the value.  This is a time-space tradeoff.
  // Storing it may improve lookup speed by reducing the number of times
  // we need to call the Equal function.
  
  // constant_iterators: bool.  true if iterator and const_iterator are
  // both constant iterator types.  This is true for unordered_set and
  // unordered_multiset, false for unordered_map and unordered_multimap.
  
  // unique_keys: bool.  true if the return value of hashtable::count(k)
  // is always at most one, false if it may be an arbitrary number.  This
  // true for unordered_set and unordered_map, false for unordered_multiset
  // and unordered_multimap.
  
  template<typename Key, typename Value, 
	   typename Allocator,
	   typename ExtractKey, typename Equal,
	   typename H1, typename H2,
	   typename H, typename RehashPolicy,
	   bool cache_hash_code,
	   bool constant_iterators,
	   bool unique_keys>
    class hashtable
    : public Internal::rehash_base<RehashPolicy,
				   hashtable<Key, Value, Allocator, ExtractKey,
					     Equal, H1, H2, H, RehashPolicy,
					     cache_hash_code, constant_iterators,
					     unique_keys> >,
      public Internal::hash_code_base<Key, Value, ExtractKey, Equal, H1, H2, H,
				      cache_hash_code>,
      public Internal::map_base<Key, Value, ExtractKey, unique_keys,
				hashtable<Key, Value, Allocator, ExtractKey,
					  Equal, H1, H2, H, RehashPolicy,
					  cache_hash_code, constant_iterators,
					  unique_keys> >
    {
    public:
      typedef Allocator                                      allocator_type;
      typedef Value                                          value_type;
      typedef Key                                            key_type;
      typedef Equal                                          key_equal;
      // mapped_type, if present, comes from map_base.
      // hasher, if present, comes from hash_code_base.
      typedef typename Allocator::difference_type            difference_type;
      typedef typename Allocator::size_type                  size_type;
      typedef typename Allocator::reference                  reference;
      typedef typename Allocator::const_reference            const_reference;
      
      typedef Internal::node_iterator<value_type, constant_iterators,
				      cache_hash_code>
        local_iterator;
      typedef Internal::node_const_iterator<value_type, constant_iterators,
					    cache_hash_code>
        const_local_iterator;

      typedef Internal::hashtable_iterator<value_type, constant_iterators,
					   cache_hash_code>
        iterator;
      typedef Internal::hashtable_const_iterator<value_type, constant_iterators,
						 cache_hash_code>
        const_iterator;

    private:
      typedef Internal::hash_node<Value, cache_hash_code>    node;
      typedef typename Allocator::template rebind<node>::other
        node_allocator_t;
      typedef typename Allocator::template rebind<node*>::other
        bucket_allocator_t;

    private:
      node_allocator_t m_node_allocator;
      node** m_buckets;
      size_type m_bucket_count;
      size_type m_element_count;
      RehashPolicy m_rehash_policy;
      
      node*
      m_allocate_node(const value_type& v);
  
      void
      m_deallocate_node(node* n);
  
      void
      m_deallocate_nodes(node**, size_type);

      node**
      m_allocate_buckets(size_type n);
  
      void
      m_deallocate_buckets(node**, size_type n);

    public:			    // Constructor, destructor, assignment, swap
      hashtable(size_type bucket_hint,
		const H1&, const H2&, const H&,
		const Equal&, const ExtractKey&,
		const allocator_type&);
  
      template<typename InIter>
        hashtable(InIter first, InIter last,
		  size_type bucket_hint,
		  const H1&, const H2&, const H&,
		  const Equal&, const ExtractKey&,
		  const allocator_type&);
  
      hashtable(const hashtable&);
      
      hashtable&
      operator=(const hashtable&);
  
      ~hashtable();

      void swap(hashtable&);

    public:				// Basic container operations
      iterator
      begin()
      {
	iterator i(m_buckets);
	if (!i.m_cur_node)
	  i.m_incr_bucket();
	return i;
      }

      const_iterator
      begin() const
      {
	const_iterator i(m_buckets);
	if (!i.m_cur_node)
	  i.m_incr_bucket();
	return i;
      }

      iterator
      end()
      { return iterator(m_buckets + m_bucket_count); }

      const_iterator
      end() const
      { return const_iterator(m_buckets + m_bucket_count); }

      size_type
      size() const
      { return m_element_count; }
  
      bool
      empty() const
      { return size() == 0; }

      allocator_type
      get_allocator() const
      { return m_node_allocator; }
  
      size_type
      max_size() const
      { return m_node_allocator.max_size(); }

    public:				// Bucket operations
      size_type
      bucket_count() const
      { return m_bucket_count; }
  
      size_type
      max_bucket_count() const
      { return max_size(); }
  
      size_type
      bucket_size(size_type n) const
      { return std::distance(begin(n), end(n)); }
  
      size_type bucket(const key_type& k) const
      { 
	return this->bucket_index(k, this->m_hash_code, this->m_bucket_count);
      }

      local_iterator
      begin(size_type n)
      { return local_iterator(m_buckets[n]); }
  
      local_iterator
      end(size_type)
      { return local_iterator(0); }
  
      const_local_iterator
      begin(size_type n) const
      { return const_local_iterator(m_buckets[n]); }
  
      const_local_iterator
      end(size_type) const
      { return const_local_iterator(0); }

      float
      load_factor() const
      { 
	return static_cast<float>(size()) / static_cast<float>(bucket_count());
      }
      // max_load_factor, if present, comes from rehash_base.

      // Generalization of max_load_factor.  Extension, not found in TR1.  Only
      // useful if RehashPolicy is something other than the default.
      const RehashPolicy&
      rehash_policy() const
      { return m_rehash_policy; }
      
      void 
      rehash_policy(const RehashPolicy&);

    public:				// lookup
      iterator
      find(const key_type&);

      const_iterator
      find(const key_type& k) const;

      size_type
      count(const key_type& k) const;

      std::pair<iterator, iterator>
      equal_range(const key_type& k);

      std::pair<const_iterator, const_iterator>
      equal_range(const key_type& k) const;

    private:			// Insert and erase helper functions
      // ??? This dispatching is a workaround for the fact that we don't
      // have partial specialization of member templates; it would be
      // better to just specialize insert on unique_keys.  There may be a
      // cleaner workaround.
      typedef typename Internal::IF<unique_keys,
				    std::pair<iterator, bool>, iterator>::type
        Insert_Return_Type;

      typedef typename Internal::IF<unique_keys,
				    Internal::extract1st<Insert_Return_Type>,
				    Internal::identity<Insert_Return_Type>
                                   >::type
        Insert_Conv_Type;

      node*
      find_node(node* p, const key_type& k,
		typename hashtable::hash_code_t c) const;

      std::pair<iterator, bool>
      insert(const value_type&, std::tr1::true_type);
  
      iterator
      insert(const value_type&, std::tr1::false_type);

      void
      erase_node(node*, node**);

    public:				// Insert and erase
      Insert_Return_Type
      insert(const value_type& v) 
      { 
	return this->insert(v, std::tr1::integral_constant<bool,
			    unique_keys>());
      }

      iterator
      insert(iterator, const value_type& v)
      { return iterator(Insert_Conv_Type()(this->insert(v))); }
      
      const_iterator
      insert(const_iterator, const value_type& v)
      { return const_iterator(Insert_Conv_Type()(this->insert(v))); }

      template<typename InIter>
        void
        insert(InIter first, InIter last);

      iterator
      erase(iterator);

      const_iterator
      erase(const_iterator);

      size_type
      erase(const key_type&);

      iterator
      erase(iterator, iterator);

      const_iterator
      erase(const_iterator, const_iterator);

      void
      clear();

    public:
      // Set number of buckets to be apropriate for container of n element.
      void rehash(size_type n);
      
    private:
      // Unconditionally change size of bucket array to n.
      void m_rehash(size_type n);
    };

  //----------------------------------------------------------------------
  // Definitions of class template hashtable's out-of-line member functions.
  
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::node*
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    m_allocate_node(const value_type& v)
    {
      node* n = m_node_allocator.allocate(1);
      try
	{
	  get_allocator().construct(&n->m_v, v);
	  n->m_next = 0;
	  return n;
	}
      catch(...)
	{
	  m_node_allocator.deallocate(n, 1);
	  __throw_exception_again;
	}
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    void
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    m_deallocate_node(node* n)
    {
      get_allocator().destroy(&n->m_v);
      m_node_allocator.deallocate(n, 1);
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    void
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    m_deallocate_nodes(node** array, size_type n)
    {
      for (size_type i = 0; i < n; ++i)
	{
	  node* p = array[i];
	  while (p)
	    {
	      node* tmp = p;
	      p = p->m_next;
	      m_deallocate_node (tmp);
	    }
	  array[i] = 0;
	}
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::node**
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    m_allocate_buckets(size_type n)
    {
      bucket_allocator_t alloc(m_node_allocator);

      // We allocate one extra bucket to hold a sentinel, an arbitrary
      // non-null pointer.  Iterator increment relies on this.
      node** p = alloc.allocate(n+1);
      std::fill(p, p+n, (node*) 0);
      p[n] = reinterpret_cast<node*>(0x1000);
      return p;
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    void
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    m_deallocate_buckets(node** p, size_type n)
    {
      bucket_allocator_t alloc(m_node_allocator);
      alloc.deallocate(p, n+1);
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    hashtable(size_type bucket_hint,
	      const H1& h1, const H2& h2, const H& h,
	      const Eq& eq, const Ex& exk,
	      const allocator_type& a)
    : Internal::rehash_base<RP,hashtable>(),
      Internal::hash_code_base<K, V, Ex, Eq, H1, H2, H, c>(exk, eq, h1, h2, h),
      Internal::map_base<K, V, Ex, u, hashtable>(),
      m_node_allocator(a),
      m_bucket_count(0),
      m_element_count(0),
      m_rehash_policy()
    {
      m_bucket_count = m_rehash_policy.next_bkt(bucket_hint);
      m_buckets = m_allocate_buckets(m_bucket_count);
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    template<typename InIter>
      hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
      hashtable(InIter f, InIter l,
		size_type bucket_hint,
		const H1& h1, const H2& h2, const H& h,
		const Eq& eq, const Ex& exk,
		const allocator_type& a)
      : Internal::rehash_base<RP,hashtable>(),
	Internal::hash_code_base<K, V, Ex, Eq, H1, H2, H, c> (exk, eq,
							      h1, h2, h),
	Internal::map_base<K,V,Ex,u,hashtable>(),
	m_node_allocator(a),
	m_bucket_count (0),
	m_element_count(0),
	m_rehash_policy()
      {
	m_bucket_count = std::max(m_rehash_policy.next_bkt(bucket_hint),
				  m_rehash_policy.
				  bkt_for_elements(Internal::
						   distance_fw(f, l)));
	m_buckets = m_allocate_buckets(m_bucket_count);
	try
	  {
	    for (; f != l; ++f)
	      this->insert(*f);
	  }
	catch(...)
	  {
	    clear();
	    m_deallocate_buckets(m_buckets, m_bucket_count);
	    __throw_exception_again;
	  }
      }
  
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    hashtable(const hashtable& ht)
    : Internal::rehash_base<RP, hashtable>(ht),
      Internal::hash_code_base<K, V, Ex, Eq, H1, H2, H, c>(ht),
      Internal::map_base<K, V, Ex, u, hashtable>(ht),
      m_node_allocator(ht.get_allocator()),
      m_bucket_count(ht.m_bucket_count),
      m_element_count(ht.m_element_count),
      m_rehash_policy(ht.m_rehash_policy)
    {
      m_buckets = m_allocate_buckets (m_bucket_count);
      try
	{
	  for (size_t i = 0; i < ht.m_bucket_count; ++i)
	    {
	      node* n = ht.m_buckets[i];
	      node** tail = m_buckets + i;
	      while (n)
		{
		  *tail = m_allocate_node(n->m_v);
		  this->copy_code(*tail, n);
		  tail = &((*tail)->m_next);
		  n = n->m_next;
		}
	    }
	}
      catch (...)
	{
	  clear();
	  m_deallocate_buckets (m_buckets, m_bucket_count);
	  __throw_exception_again;
	}
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>&
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    operator=(const hashtable& ht)
    {
      hashtable tmp(ht);
      this->swap(tmp);
      return *this;
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    ~hashtable()
    {
      clear();
      m_deallocate_buckets(m_buckets, m_bucket_count);
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    void
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    swap(hashtable& x)
    {
      // The only base class with member variables is hash_code_base.  We
      // define hash_code_base::m_swap because different specializations
      // have different members.
      Internal::hash_code_base<K, V, Ex, Eq, H1, H2, H, c>::m_swap(x);

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 431. Swapping containers with unequal allocators.
      std::__alloc_swap<node_allocator_t>::_S_do_it(m_node_allocator,
						    x.m_node_allocator);

      std::swap(m_rehash_policy, x.m_rehash_policy);
      std::swap(m_buckets, x.m_buckets);
      std::swap(m_bucket_count, x.m_bucket_count);
      std::swap(m_element_count, x.m_element_count);
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    void
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    rehash_policy(const RP& pol)
    {
      m_rehash_policy = pol;
      size_type n_bkt = pol.bkt_for_elements(m_element_count);
      if (n_bkt > m_bucket_count)
	m_rehash (n_bkt);
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::iterator
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    find(const key_type& k)
    {
      typename hashtable::hash_code_t code = this->m_hash_code (k);
      std::size_t n = this->bucket_index(k, code, this->bucket_count());
      node* p = find_node (m_buckets[n], k, code);
      return p ? iterator(p, m_buckets + n) : this->end();
    }
  
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::const_iterator
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    find(const key_type& k) const
    {
      typename hashtable::hash_code_t code = this->m_hash_code (k);
      std::size_t n = this->bucket_index(k, code, this->bucket_count());
      node* p = find_node (m_buckets[n], k, code);
      return p ? const_iterator(p, m_buckets + n) : this->end();
    }
  
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::size_type
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    count(const key_type& k) const
    {
      typename hashtable::hash_code_t code = this->m_hash_code (k);
      std::size_t n = this->bucket_index (k, code, this->bucket_count());
      size_t result = 0;
      for (node* p = m_buckets[n]; p ; p = p->m_next)
	if (this->compare (k, code, p))
	  ++result;
      return result;
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    std::pair<typename hashtable<K, V, A, Ex, Eq, H1,
				 H2, H, RP, c, ci, u>::iterator,
	      typename hashtable<K, V, A, Ex, Eq, H1,
				 H2, H, RP, c, ci, u>::iterator>
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    equal_range(const key_type& k)
    {
      typename hashtable::hash_code_t code = this->m_hash_code (k);
      std::size_t n = this->bucket_index(k, code, this->bucket_count());
      node** head = m_buckets + n;
      node* p = find_node (*head, k, code);
      
      if (p)
	{
	  node* p1 = p->m_next;
	  for (; p1 ; p1 = p1->m_next)
	    if (!this->compare (k, code, p1))
	      break;

	  iterator first(p, head);
	  iterator last(p1, head);
	  if (!p1)
	    last.m_incr_bucket();
	  return std::make_pair(first, last);
	}
      else
	return std::make_pair(this->end(), this->end());
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    std::pair<typename hashtable<K, V, A, Ex, Eq, H1,
				 H2, H, RP, c, ci, u>::const_iterator,
	      typename hashtable<K, V, A, Ex, Eq, H1,
				 H2, H, RP, c, ci, u>::const_iterator>
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    equal_range(const key_type& k) const
    {
      typename hashtable::hash_code_t code = this->m_hash_code (k);
      std::size_t n = this->bucket_index(k, code, this->bucket_count());
      node** head = m_buckets + n;
      node* p = find_node (*head, k, code);

      if (p)
	{
	  node* p1 = p->m_next;
	  for (; p1 ; p1 = p1->m_next)
	    if (!this->compare (k, code, p1))
	      break;

	  const_iterator first(p, head);
	  const_iterator last(p1, head);
	  if (!p1)
	    last.m_incr_bucket();
	  return std::make_pair(first, last);
	}
      else
	return std::make_pair(this->end(), this->end());
    }

  // Find the node whose key compares equal to k, beginning the search
  // at p (usually the head of a bucket).  Return nil if no node is found.
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::node* 
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    find_node(node* p, const key_type& k,
	      typename hashtable::hash_code_t code) const
    {
      for ( ; p ; p = p->m_next)
	if (this->compare (k, code, p))
	  return p;
      return false;
    }

  // Insert v if no element with its key is already present.
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    std::pair<typename hashtable<K, V, A, Ex, Eq, H1,
				 H2, H, RP, c, ci, u>::iterator, bool>
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    insert(const value_type& v, std::tr1::true_type)
    {
      const key_type& k = this->m_extract(v);
      typename hashtable::hash_code_t code = this->m_hash_code (k);
      size_type n = this->bucket_index(k, code, m_bucket_count);
      
      if (node* p = find_node(m_buckets[n], k, code))
	return std::make_pair(iterator(p, m_buckets + n), false);

      std::pair<bool, size_t> do_rehash
	= m_rehash_policy.need_rehash(m_bucket_count, m_element_count, 1);

      // Allocate the new node before doing the rehash so that we don't
      // do a rehash if the allocation throws.
      node* new_node = m_allocate_node (v);
      
      try
	{
	  if (do_rehash.first)
	    {
	      n = this->bucket_index(k, code, do_rehash.second);
	      m_rehash(do_rehash.second);
	    }

	  new_node->m_next = m_buckets[n];
	  this->store_code(new_node, code);
	  m_buckets[n] = new_node;
	  ++m_element_count;
	  return std::make_pair(iterator(new_node, m_buckets + n), true);
	}
      catch (...)
	{
	  m_deallocate_node (new_node);
	  __throw_exception_again;
	}
    }
  
  // Insert v unconditionally.
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::iterator
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    insert(const value_type& v, std::tr1::false_type)
    {
      std::pair<bool, std::size_t> do_rehash
	= m_rehash_policy.need_rehash(m_bucket_count, m_element_count, 1);
      if (do_rehash.first)
	m_rehash(do_rehash.second);

      const key_type& k = this->m_extract(v);
      typename hashtable::hash_code_t code = this->m_hash_code (k);
      size_type n = this->bucket_index(k, code, m_bucket_count);
      
      node* new_node = m_allocate_node (v);
      node* prev = find_node(m_buckets[n], k, code);
      if (prev)
	{
	  new_node->m_next = prev->m_next;
	  prev->m_next = new_node;
	}
      else
	{
	  new_node->m_next = m_buckets[n];
	  m_buckets[n] = new_node;
	}
      this->store_code(new_node, code);

      ++m_element_count;
      return iterator(new_node, m_buckets + n);
    }

  // For erase(iterator) and erase(const_iterator).
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    void
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    erase_node(node* p, node** b)
    {
      node* cur = *b;
      if (cur == p)
	*b = cur->m_next;
      else
	{
	  node* next = cur->m_next;
	  while (next != p)
	    {
	      cur = next;
	      next = cur->m_next;
	    }
	  cur->m_next = next->m_next;
	}

      m_deallocate_node (p);
      --m_element_count;
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    template<typename InIter>
      void 
      hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
      insert(InIter first, InIter last)
      {
	size_type n_elt = Internal::distance_fw (first, last);
	std::pair<bool, std::size_t> do_rehash
	  = m_rehash_policy.need_rehash(m_bucket_count, m_element_count, n_elt);
	if (do_rehash.first)
	  m_rehash(do_rehash.second);

	for (; first != last; ++first)
	  this->insert (*first);
      }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::iterator
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    erase(iterator i)
    {
      iterator result = i;
      ++result;
      erase_node(i.m_cur_node, i.m_cur_bucket);
      return result;
    }
  
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::const_iterator
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    erase(const_iterator i)
    {
      const_iterator result = i;
      ++result;
      erase_node(i.m_cur_node, i.m_cur_bucket);
      return result;
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::size_type
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    erase(const key_type& k)
    {
      typename hashtable::hash_code_t code = this->m_hash_code (k);
      size_type n = this->bucket_index(k, code, m_bucket_count);
      size_type result = 0;
      
      node** slot = m_buckets + n;
      while (*slot && ! this->compare (k, code, *slot))
	slot = &((*slot)->m_next);

      while (*slot && this->compare (k, code, *slot))
	{
	  node* n = *slot;
	  *slot = n->m_next;
	  m_deallocate_node (n);
	  --m_element_count;
	  ++result;
	}

      return result;
    }

  // ??? This could be optimized by taking advantage of the bucket
  // structure, but it's not clear that it's worth doing.  It probably
  // wouldn't even be an optimization unless the load factor is large.
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::iterator
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    erase(iterator first, iterator last)
    {
      while (first != last)
	first = this->erase(first);
      return last;
    }
  
  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    typename hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::const_iterator
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    erase(const_iterator first, const_iterator last)
    {
      while (first != last)
	first = this->erase(first);
      return last;
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    void
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    clear()
    {
      m_deallocate_nodes(m_buckets, m_bucket_count);
      m_element_count = 0;
    }

  template<typename K, typename V, 
	   typename A, typename Ex, typename Eq,
	   typename H1, typename H2, typename H, typename RP,
	   bool c, bool ci, bool u>
    void
    hashtable<K, V, A, Ex, Eq, H1, H2, H, RP, c, ci, u>::
    m_rehash(size_type N)
    {
      node** new_array = m_allocate_buckets (N);
      try
	{
	  for (size_type i = 0; i < m_bucket_count; ++i)
	    while (node* p = m_buckets[i])
	      {
		size_type new_index = this->bucket_index (p, N);
		m_buckets[i] = p->m_next;
		p->m_next = new_array[new_index];
		new_array[new_index] = p;
	      }
	  m_deallocate_buckets(m_buckets, m_bucket_count);
	  m_bucket_count = N;
	  m_buckets = new_array;
	}
      catch (...)
	{
	  // A failure here means that a hash function threw an exception.
	  // We can't restore the previous state without calling the hash
	  // function again, so the only sensible recovery is to delete
	  // everything.
	  m_deallocate_nodes(new_array, N);
	  m_deallocate_buckets(new_array, N);
	  m_deallocate_nodes(m_buckets, m_bucket_count);
	  m_element_count = 0;
	  __throw_exception_again;
	}
    }

_GLIBCXX_END_NAMESPACE
}				// Namespace std::tr1

#endif /* GNU_LIBSTDCXX_TR1_HASHTABLE_ */