HashTableIterator< Key, Val > Class Template Reference

Unsafe Iterators for hashtables. More...

#include <agrum/base/core/hashTable.h>

Inheritance diagram for HashTableIterator< Key, Val >:

Collaboration diagram for HashTableIterator< Key, Val >:

Public Types
using	iterator_category = std::forward_iterator_tag
	types for STL compliance
using	key_type = Key
	types for STL compliance
using	mapped_type = Val
	types for STL compliance
using	value_type = std::pair< const Key, Val >
	types for STL compliance
using	reference = value_type&
	types for STL compliance
using	const_reference = const value_type&
	types for STL compliance
using	pointer = value_type*
	types for STL compliance
using	const_pointer = const value_type*
	types for STL compliance
using	difference_type = std::ptrdiff_t
	types for STL compliance

Public Member Functions
mapped_type &	val ()
	Returns the mapped value pointed to by the iterator.
Constructors / Destructors
	HashTableIterator () noexcept
	Basic constructor: creates an iterator pointing to nothing.
	HashTableIterator (const HashTable< Key, Val > &tab) noexcept
	Constructor for an iterator pointing to the first element of a hashtable.
	HashTableIterator (const HashTable< Key, Val > &tab, Size ind_elt)
	Constructor for an iterator pointing to the nth element of a hashtable.
	HashTableIterator (const HashTableIterator< Key, Val > &from) noexcept
	Copy constructor.
	HashTableIterator (HashTableIterator< Key, Val > &&from) noexcept
	Move constructor.
	~HashTableIterator () noexcept
	Class destructor.
Operators
HashTableIterator< Key, Val > &	operator= (const HashTableIterator< Key, Val > &from) noexcept
	Copy operator.
HashTableIterator< Key, Val > &	operator= (HashTableIterator< Key, Val > &&from) noexcept
	Move operator.
HashTableIterator< Key, Val > &	operator++ () noexcept
	Makes the iterator point to the next element in the hash table.
HashTableIterator< Key, Val > &	operator+= (Size i) noexcept
	Makes the iterator point to i elements further in the hashtable.
HashTableIterator< Key, Val >	operator+ (Size i) const noexcept
	Returns a new iterator.
bool	operator== (const HashTableIterator< Key, Val > &from) const noexcept
	Checks whether two iterators are pointing toward equal elements.
value_type &	operator* ()
	Returns the value pointed to by the iterator.
const value_type &	operator* () const
	Returns the value pointed to by the iterator.
Accessors / Modifiers
const key_type &	key () const
	Returns the key corresponding to the element pointed to by the iterator.
const mapped_type &	val () const
	Returns the mapped value pointed to by the iterator.
void	clear () noexcept
	Makes the iterator point toward nothing (in particular, it is not related anymore to its current hash table).
Operators
bool	operator== (const HashTableConstIterator< Key, Val > &from) const noexcept
	Checks whether two iterators are pointing toward equal elements.

Protected Member Functions
HashTable< Key, Val >::Bucket *	_getBucket_ () const noexcept
	Returns the current iterator's bucket.
Size	_getIndex_ () const noexcept
	Returns the index in the hashtable's node vector pointed to by the iterator.

Protected Attributes
const HashTable< Key, Val > *	_table_ {nullptr}
	The hash table the iterator is pointing to.
Size	_index_ {Size(0)}
	The index of the chained list pointed by the iterator in the array of nodes of the hash table.
HashTable< Key, Val >::Bucket *	_bucket_ {nullptr}
	The bucket in the chained list pointed to by the iterator.

Detailed Description

template<typename Key, typename Val>
class HashTableIterator< Key, Val >

Unsafe Iterators for hashtables.

HashTableIterator provides a fast but unsafe way to parse HashTables. They should only be used when parsing hashtables in which no element is removed from the hashtable. Removing an element where the iterator points to will mess the iterator as it will most certainly point to an unallocated memory. So, this kind of iterator should only be used when parsing "(key) constant" hash tables, e.g., when we wish to display the content of a hash table or when we wish to update the mapped values of some elements of the hash table without ever modifying their keys.

Developers may consider using HashTable<x,y>::iterator instead of HashTableIterator<x,y>.

Usage example:

// creation of a hash table with 10 elements
HashTable<int,string> table;
for (int i = 0; i< 10; ++i)
  table.insert (i,"xxx" + string (i,'x'));
 
// parse the hash table
for (HashTable<int,string>::iterator iter = table.begin ();
       iter != table.end (); ++iter) {
  // display the values
  cerr << "at " << iter.key() << " value = " << iter.val () << endl;
  HashTable<int,string>::value_type& elt = *iter;
  std::pair<const int, string>& xelt = *iter;
}
 
// check whether two iterators point toward the same element
HashTable<int,string>::iterator iter1 = table1.begin();
HashTable<int,string>::iterator iter2 = table1.end();
if (iter1 != iter) {
  cerr << "iter1 and iter2 point toward different elements";
}
 
// make iter1 point toward nothing
iter1.clear ();

Template Parameters

Key	The gum::HashTable key.
Val	The gum::HashTable Value.

Definition at line 2465 of file hashTable.h.

Member Typedef Documentation

const_pointer

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::const_pointer = const value_type*

types for STL compliance

Definition at line 2476 of file hashTable.h.

const_reference

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::const_reference = const value_type&

types for STL compliance

Definition at line 2474 of file hashTable.h.

difference_type

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::difference_type = std::ptrdiff_t

types for STL compliance

Definition at line 2477 of file hashTable.h.

iterator_category

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::iterator_category = std::forward_iterator_tag

types for STL compliance

Definition at line 2469 of file hashTable.h.

key_type

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::key_type = Key

types for STL compliance

Definition at line 2470 of file hashTable.h.

mapped_type

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::mapped_type = Val

types for STL compliance

Definition at line 2471 of file hashTable.h.

pointer

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::pointer = value_type*

types for STL compliance

Definition at line 2475 of file hashTable.h.

reference

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::reference = value_type&

types for STL compliance

Definition at line 2473 of file hashTable.h.

value_type

template<typename Key, typename Val>

using HashTableIterator< Key, Val >::value_type = std::pair< const Key, Val >

types for STL compliance

Definition at line 2472 of file hashTable.h.

Constructor & Destructor Documentation

HashTableIterator() [1/5]

template<typename Key, typename Val>

HashTableIterator< Key, Val >::HashTableIterator ( )

explicitnoexcept

Basic constructor: creates an iterator pointing to nothing.

Definition at line 1917 of file hashTable_tpl.h.

                                                            :
      HashTableConstIterator< Key, Val >() {
    GUM_CONSTRUCTOR(HashTableIterator);
  }

References HashTableConstIterator< Key, Val >::HashTableConstIterator(), and HashTableIterator().

Referenced by HashTableIterator(), HashTableIterator(), HashTableIterator(), HashTableIterator(), HashTableIterator(), ~HashTableIterator(), operator+(), operator++(), operator+=(), operator=(), operator=(), and operator==().

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HashTableIterator() [2/5]

template<typename Key, typename Val>

HashTableIterator< Key, Val >::HashTableIterator ( const HashTable< Key, Val > & tab )

explicitnoexcept

Constructor for an iterator pointing to the first element of a hashtable.

Parameters

tab	The gum::HashTable to iterate over.

Definition at line 1923 of file hashTable_tpl.h.

                                                                                            :
      HashTableConstIterator< Key, Val >(tab) {
    GUM_CONSTRUCTOR(HashTableIterator);
  }

References HashTableConstIterator< Key, Val >::HashTableConstIterator(), HashTableIterator(), and HashTableConstIterator< Key, Val >::HashTable< Key, Val >.

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HashTableIterator() [3/5]

template<typename Key, typename Val>

HashTableIterator< Key, Val >::HashTableIterator	(	const HashTable< Key, Val > &	tab,
		Size	ind_elt )

Constructor for an iterator pointing to the nth element of a hashtable.

The method runs in time linear to ind_elt.

Parameters

tab	The hash table to which the so-called element belongs.
ind_elt	The position of the element in the hash table (0 means the first element).

Exceptions

UndefinedIteratorValue

Raised if the element cannot be found.

Definition at line 1929 of file hashTable_tpl.h.

                                                                                                 :
      HashTableConstIterator< Key, Val >(tab, ind_elt) {
    GUM_CONSTRUCTOR(HashTableIterator);
  }

References HashTableConstIterator< Key, Val >::HashTableConstIterator(), HashTableIterator(), and HashTableConstIterator< Key, Val >::HashTable< Key, Val >.

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HashTableIterator() [4/5]

template<typename Key, typename Val>

HashTableIterator< Key, Val >::HashTableIterator ( const HashTableIterator< Key, Val > & from )

noexcept

Copy constructor.

Parameters

from	The gum::HashTableIterator to copy.

Definition at line 1935 of file hashTable_tpl.h.

                                                          :
      HashTableConstIterator< Key, Val >(from) {
    GUM_CONS_CPY(HashTableIterator);
  }

References HashTableConstIterator< Key, Val >::HashTableConstIterator(), and HashTableIterator().

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HashTableIterator() [5/5]

template<typename Key, typename Val>

HashTableIterator< Key, Val >::HashTableIterator ( HashTableIterator< Key, Val > && from )

noexcept

Move constructor.

Parameters

from	The gum::HashTableIterator to move.

Definition at line 1942 of file hashTable_tpl.h.

                                                                                                :
      HashTableConstIterator< Key, Val >(std::move(from)) {
    GUM_CONS_MOV(HashTableIterator);
  }

References HashTableConstIterator< Key, Val >::HashTableConstIterator(), and HashTableIterator().

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~HashTableIterator()

template<typename Key, typename Val>

HashTableIterator< Key, Val >::~HashTableIterator ( )

noexcept

Class destructor.

Definition at line 1948 of file hashTable_tpl.h.

                                                             {
    GUM_DESTRUCTOR(HashTableIterator);
  }

References HashTableIterator().

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Member Function Documentation

_getBucket_()

template<typename Key, typename Val>

HashTable< Key, Val >::Bucket * HashTableConstIterator< Key, Val >::_getBucket_ ( ) const

nodiscardprotectednoexceptinherited

Returns the current iterator's bucket.

Returns

Returns the current iterator's bucket.

Definition at line 1903 of file hashTable_tpl.h.

                                                                     {
    return _bucket_;
  }

References _bucket_.

_getIndex_()

template<typename Key, typename Val>

Size HashTableConstIterator< Key, Val >::_getIndex_ ( ) const

nodiscardprotectednoexceptinherited

Returns the index in the hashtable's node vector pointed to by the iterator.

Returns

Returns the index in the hashtable's node vector pointed to by the iterator.

Definition at line 1908 of file hashTable_tpl.h.

                                                                     {
    return _index_;
  }

References _index_.

clear()

template<typename Key, typename Val>

void HashTableConstIterator< Key, Val >::clear ( )

noexceptinherited

Makes the iterator point toward nothing (in particular, it is not related anymore to its current hash table).

Definition at line 1799 of file hashTable_tpl.h.

                                                          {
    _table_  = nullptr;
    _bucket_ = nullptr;
    _index_  = 0;
  }

References _bucket_, _index_, and _table_.

key()

template<typename Key, typename Val>

const HashTableConstIterator< Key, Val >::key_type & HashTableConstIterator< Key, Val >::key ( ) const

nodiscardinherited

Returns the key corresponding to the element pointed to by the iterator.

Warning

Using this method on an iterator that points to an element that has been deleted will most certainly result in a segfault. If unsure, use a safe iterator instead of an unsafe one.

Returns

Returns the key corresponding to the element pointed to by the iterator.

Definition at line 1786 of file hashTable_tpl.h.

                                                    {
    if (_bucket_) return _bucket_->pair.first;
    else { GUM_ERROR(UndefinedIteratorValue, "Accessing a nullptr object") }
  }

References _bucket_, and GUM_ERROR.

operator*() [1/2]

template<typename Key, typename Val>

HashTableIterator< Key, Val >::value_type & HashTableIterator< Key, Val >::operator*

(

)

Returns the value pointed to by the iterator.

Warning

using this method on an iterator that points to an element that has been deleted will most certainly result in a segfault. If unsure, use a safe iterator instead of an unsafe one.

Returns

Returns the value pointed to by the iterator.

Definition at line 1998 of file hashTable_tpl.h.

                                                                                             {
    return const_cast< value_type& >(HashTableConstIterator< Key, Val >::operator*());
  }

References HashTableConstIterator< Key, Val >::operator*().

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operator*() [2/2]

template<typename Key, typename Val>

const HashTableIterator< Key, Val >::value_type & HashTableIterator< Key, Val >::operator*

(

)

const

Returns the value pointed to by the iterator.

Warning

using this method on an iterator that points to an element that has been deleted will most certainly result in a segfault. If unsure, use a safe iterator instead of an unsafe one.

Returns

Returns the value pointed to by the iterator.

Definition at line 2004 of file hashTable_tpl.h.

                                                     {
    return HashTableConstIterator< Key, Val >::operator*();
  }

References HashTableConstIterator< Key, Val >::operator*().

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operator+()

template<typename Key, typename Val>

HashTableIterator< Key, Val > HashTableIterator< Key, Val >::operator+ ( Size i ) const

noexcept

Returns a new iterator.

Parameters

i	The number of increments.

Returns

Returns this gum::HashTableIterator.

Definition at line 1985 of file hashTable_tpl.h.

                                                                                               {
    HashTableIterator< Key, Val > iter{*this};
    iter += nb;
    return iter;
  }

References HashTableIterator().

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operator++()

template<typename Key, typename Val>

HashTableIterator< Key, Val > & HashTableIterator< Key, Val >::operator++ ( )

noexcept

Makes the iterator point to the next element in the hash table.

for (iter = begin(); iter != end(); ++iter) { }

The above loop is guaranteed to parse the whole hash table as long as no element is added to or deleted from the hash table while being in the loop.

Warning

performing a ++ on an iterator that points to an element that has been deleted will most certainly result in a segfault.

Returns

Returns this gum::HashTableIterator.

Definition at line 1973 of file hashTable_tpl.h.

                                                                                    {
    HashTableConstIterator< Key, Val >::operator++();
    return *this;
  }

References HashTableIterator(), and HashTableConstIterator< Key, Val >::operator++().

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operator+=()

template<typename Key, typename Val>

HashTableIterator< Key, Val > & HashTableIterator< Key, Val >::operator+= ( Size i )

noexcept

Makes the iterator point to i elements further in the hashtable.

Parameters

i	The number of increments.

Returns

Returns this gum::HashTableIterator.

Definition at line 1979 of file hashTable_tpl.h.

                                                                                         {
    HashTableConstIterator< Key, Val >::operator+=(nb);
    return *this;
  }

References HashTableIterator(), and HashTableConstIterator< Key, Val >::operator+=().

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operator=() [1/2]

template<typename Key, typename Val>

HashTableIterator< Key, Val > & HashTableIterator< Key, Val >::operator= ( const HashTableIterator< Key, Val > & from )

noexcept

Copy operator.

Parameters

from	The gum::HashTableIterator to copy.

Returns

Returns this gum::HashTableIterator.

Definition at line 1960 of file hashTable_tpl.h.

                                                                                               {
    HashTableConstIterator< Key, Val >::operator=(from);
    return *this;
  }

References HashTableIterator(), and HashTableConstIterator< Key, Val >::operator=().

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operator=() [2/2]

template<typename Key, typename Val>

HashTableIterator< Key, Val > & HashTableIterator< Key, Val >::operator= ( HashTableIterator< Key, Val > && from )

noexcept

Move operator.

Parameters

from	The gum::HashTableIterator to move.

Returns

Returns this gum::HashTableIterator.

Definition at line 1967 of file hashTable_tpl.h.

                                                                                          {
    HashTableConstIterator< Key, Val >::operator=(std::move(from));
    return *this;
  }

References HashTableIterator(), and HashTableConstIterator< Key, Val >::operator=().

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operator==() [1/2]

template<typename Key, typename Val>

bool HashTableConstIterator< Key, Val >::operator== ( const HashTableConstIterator< Key, Val > & from ) const

noexceptinherited

Checks whether two iterators are pointing toward equal elements.

Parameters

from	The gum::HashTableConstIterator to test for equality.

Returns

Returns true if this and from are equal.

Definition at line 1889 of file hashTable_tpl.h.

                                                                     {
    return (_bucket_ == from._bucket_);
  }

Referenced by HashTableIterator< Key, Val >::operator==().

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operator==() [2/2]

template<typename Key, typename Val>

bool HashTableIterator< Key, Val >::operator== ( const HashTableIterator< Key, Val > & from ) const

noexcept

Checks whether two iterators are pointing toward equal elements.

Parameters

from	The gum::HashTableIterator to test for equality.

Returns

Returns true if this and from are equal.

Definition at line 1992 of file hashTable_tpl.h.

                                                                {
    return HashTableConstIterator< Key, Val >::operator==(from);
  }

References HashTableIterator(), and HashTableConstIterator< Key, Val >::operator==().

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val() [1/2]

template<typename Key, typename Val>

const HashTableConstIterator< Key, Val >::mapped_type & HashTableConstIterator< Key, Val >::val ( ) const

nodiscardinherited

Returns the mapped value pointed to by the iterator.

Warning

Using this method on an iterator that points to an element that has been deleted will most certainly result in a segfault. If unsure, use a safe iterator instead of an unsafe one.

Returns

Returns the mapped value pointed to by the iterator.

Definition at line 1793 of file hashTable_tpl.h.

                                                    {
    if (_bucket_) return _bucket_->val();
    else { GUM_ERROR(UndefinedIteratorValue, "Accessing a nullptr object") }
  }

References _bucket_, and GUM_ERROR.

val() [2/2]

template<typename Key, typename Val>

HashTableIterator< Key, Val >::mapped_type & HashTableIterator< Key, Val >::val

(

)

Returns the mapped value pointed to by the iterator.

Warning

using this method on an iterator that points to an element that has been deleted will most certainly result in a segfault. If unsure, use a safe iterator instead of an unsafe one.

Returns

Returns the mapped value pointed to by the iterator.

Definition at line 1953 of file hashTable_tpl.h.

                                                                                        {
    if (this->_bucket_) return this->_bucket_->val();
    else { GUM_ERROR(UndefinedIteratorValue, "Accessing a nullptr object") }
  }

References HashTableConstIterator< Key, Val >::_bucket_, and GUM_ERROR.

Member Data Documentation

_bucket_

template<typename Key, typename Val>

HashTable<Key,Val>::Bucket* HashTableConstIterator< Key, Val >::_bucket_ {nullptr}

protectedinherited

The bucket in the chained list pointed to by the iterator.

Definition at line 2396 of file hashTable.h.

{nullptr};

Referenced by _getBucket_(), gum::HashTableConstIteratorSafe< const gum::DiscreteVariable *, Idx >::_getIndex_(), clear(), key(), operator*(), operator++(), operator+=(), operator=(), val(), and HashTableIterator< Key, Val >::val().

_index_

template<typename Key, typename Val>

Size HashTableConstIterator< Key, Val >::_index_ {Size(0)}

protectedinherited

The index of the chained list pointed by the iterator in the array of nodes of the hash table.

Definition at line 2393 of file hashTable.h.

{Size(0)};

Referenced by _getIndex_(), clear(), operator+=(), and operator=().

_table_

template<typename Key, typename Val>

const HashTable< Key, Val >* HashTableConstIterator< Key, Val >::_table_ {nullptr}

protectedinherited

The hash table the iterator is pointing to.

Definition at line 2387 of file hashTable.h.

{nullptr};

Referenced by HashTableConstIterator(), HashTableConstIterator(), HashTableConstIterator(), clear(), gum::HashTable< const gum::DiscreteVariable *, Idx >::eraseByVal(), gum::HashTable< const gum::DiscreteVariable *, Idx >::key(), gum::HashTableConstIteratorSafe< const gum::DiscreteVariable *, Idx >::key(), operator+=(), and operator=().

---

The documentation for this class was generated from the following files:

• agrum/base/core/hashTable.h
• agrum/base/core/hashTable_tpl.h