Boost.MultiIndex Sequenced indices reference

Hashed indices

Boost.MultiIndex reference

Random access indices

Contents

• Header "boost/multi_index/sequenced_index_fwd.hpp" synopsis
• Header "boost/multi_index/sequenced_index.hpp" synopsis
  • sequenced index specifier
  • Sequenced indices
    • Complexity signature
    • Instantiation types
    • Constructors, copy and assignment
    • Iterators
    • Capacity operations
    • Modifiers
    • List operations
    • Rearrange operations
    • Serialization

Header "boost/multi_index/sequenced_index_fwd.hpp" synopsis

namespace boost{

namespace multi_index{

// sequenced index specifier

template<typename TagList=tag<> > struct sequenced;

// indices

namespace detail{

template<implementation defined> class index class name implementation defined;

} // namespace boost::multi_index::detail

} // namespace boost::multi_index 

} // namespace boost

sequenced_index_fwd.hpp provides forward declarations for the sequenced index specifier and its associated sequenced index class.

Header "boost/multi_index/sequenced_index.hpp" synopsis

#include <initializer_list>

namespace boost{

namespace multi_index{

// sequenced index specifier

template<typename TagList=tag<> > struct sequenced;

// indices

namespace detail{

template<implementation defined> class index class name implementation defined;

// index comparison:

// OP is any of ==,<,!=,>,>=,<=

template<arg set 1,arg set 2>
bool operator OP(
  const index class name<arg set 1>& x,const index class name<arg set 2>& y);

// index specialized algorithms:

template<implementation defined>
void swap(index class name& x,index class name& y);

} // namespace boost::multi_index::detail

} // namespace boost::multi_index 

} // namespace boost

sequenced index specifier

This index specifier allows for insertion of a sequenced index.

template<typename TagList=tag<> > struct sequenced;

If provided, TagList must be an instantiation of tag.

Sequenced indices

Sequenced indices are modeled after the semantics of a bidirectional list like std::list. Elements in a sequenced index are by default sorted according to their order of insertion: this means that new elements inserted through a different index of the multi_index_container are appended to the end of the sequenced index. Additionally, the index allows for free reordering of elements in the same vein as std::list does. Validity of iterators and references to elements is preserved in all operations.

Except where noted or if the corresponding interface does not exist, sequenced indices verify the same container requirements as std::list: we only provide descriptions of those types and operations that are either not present in std::list or behave differently. Some of the most important differences are:

• The complexity of some operations, notably insertion and deletion, differ from those of std::list.
• Unlike as in std::list, insertions into a sequenced index may fail due to clashings with other indices. This alters the semantics of the operations provided with respect to their analogues in std::list.
• Elements in a sequenced index are not mutable, and can only be changed by means of replace and modify member functions.

namespace boost{

namespace multi_index{

namespace detail{

template<implementation defined: dependent on types Value, Allocator, TagList>
class name is implementation defined
{ 
public:
  // types:

  typedef Value                                      value_type;
  typedef boost::tuples::null_type                   ctor_args;
  typedef TagList                                    tag_list;
  typedef Allocator                                  allocator_type;
  typedef typename allocator_type::reference         reference;
  typedef typename allocator_type::const_reference   const_reference;
  typedef implementation defined                     iterator;
  typedef implementation defined                     const_iterator;
  typedef implementation defined                     size_type;      
  typedef implementation defined                     difference_type;
  typedef typename allocator_type::pointer           pointer;
  typedef typename allocator_type::const_pointer     const_pointer;
  typedef equivalent to
    std::reverse_iterator<iterator>                  reverse_iterator;
  typedef equivalent to
    std::reverse_iterator<const_iterator>            const_reverse_iterator;

  // construct/copy/destroy:

  index class name& operator=(const index class name& x);
  index class name& operator=(std::initializer_list<value_type> list);

  template <class InputIterator>
  void assign(InputIterator first,InputIterator last);
  void assign(std::initializer_list<value_type> list);
  void assign(size_type n,const value_type& value);
    
  allocator_type get_allocator()const noexcept;

  // iterators:

  iterator               begin()noexcept;
  const_iterator         begin()const noexcept;
  iterator               end()noexcept;
  const_iterator         end()const noexcept;
  reverse_iterator       rbegin()noexcept;
  const_reverse_iterator rbegin()const noexcept;
  reverse_iterator       rend()noexcept;
  const_reverse_iterator rend()const noexcept;
  const_iterator         cbegin()const noexcept;
  const_iterator         cend()const noexcept;
  const_reverse_iterator crbegin()const noexcept;
  const_reverse_iterator crend()const noexcept;

  iterator       iterator_to(const value_type& x);
  const_iterator iterator_to(const value_type& x)const;

  // capacity:

  bool      empty()const noexcept;
  size_type size()const noexcept;
  size_type max_size()const noexcept;

  void resize(size_type n);
  void resize(size_type n,const value_type& x);

  // access:

  const_reference front()const;
  const_reference back()const;

  // modifiers:

  template<typename... Args>
  std::pair<iterator,bool> emplace_front(Args&&... args);
  std::pair<iterator,bool> push_front(const value_type& x);
  std::pair<iterator,bool> push_front(value_type&& x);
  void                     pop_front();

  template<typename... Args>
  std::pair<iterator,bool> emplace_back(Args&&... args);
  std::pair<iterator,bool> push_back(const value_type& x);
  std::pair<iterator,bool> push_back(value_type&& x);
  void                     pop_back();

  template<typename... Args>
  std::pair<iterator,bool> emplace(iterator position,Args&&... args);
  std::pair<iterator,bool> insert(iterator position,const value_type& x);
  std::pair<iterator,bool> insert(iterator position,value_type&& x);
  void insert(iterator position,size_type n,const value_type& x);
  template<typename InputIterator>
  void insert(iterator position,InputIterator first,InputIterator last);
  void insert(iterator position,std::initializer_list<value_type> list);

  iterator erase(iterator position);
  iterator erase(iterator first,iterator last);

  bool replace(iterator position,const value_type& x);
  bool replace(iterator position,value_type&& x);
  template<typename Modifier> bool modify(iterator position,Modifier mod);
  template<typename Modifier,typename Rollback>
  bool modify(iterator position,Modifier mod,Rollback back);

  void swap(index class name& x);

  void clear()noexcept;

  // list operations:

  void splice(iterator position,index class name& x);
  void splice(iterator position,index class name& x,iterator i);
  void splice(
    iterator position,index class name& x,iterator first,iterator last);

  void remove(const value_type& value);
  template<typename Predicate> void remove_if(Predicate pred);

  void unique();
  template <class BinaryPredicate>
  void unique(BinaryPredicate binary_pred);

  void merge(index class name& x);
  template <typename Compare> void merge(index class name& x,Compare comp);

  void sort();
  template <typename Compare> void sort(Compare comp);

  void reverse()noexcept;

  // rearrange operations:

  void relocate(iterator position,iterator i); 
  void relocate(iterator position,iterator first,iterator last);
  template<typename InputIterator> void rearrange(InputIterator first);
}

// index comparison:

template<arg set 1,arg set 2>
bool operator==(
  const index class name<arg set 1>& x,
  const index class name<arg set 2>& y)
{
  return x.size()==y.size()&&std::equal(x.begin(),x.end(),y.begin());
}

template<arg set 1,arg set 2>
bool operator<(
  const index class name<arg set 1>& x,
  const index class name<arg set 2>& y)
{
  return std::lexicographical_compare(x.begin(),x.end(),y.begin(),y.end());
}

template<arg set 1,arg set 2>
bool operator!=(
  const index class name<arg set 1>& x,
  const index class name<arg set 2>& y)
{
  return !(x==y);
}

template<arg set 1,arg set 2>
bool operator>(
  const index class name<arg set 1>& x
  ,const index class name<arg set 2>& y)
{
  return y<x;
}

template<arg set 1,arg set 2>
bool operator>=(
  const index class name<arg set 1>& x,
  const index class name<arg set 2>& y)
{
  return !(x<y);
}

template<arg set 1,arg set 2>
bool operator<=(
  const index class name<arg set 1>& x,
  const index class name<arg set 2>& y)
{
  return !(x>y);
}

// index specialized algorithms:

template<implementation defined>
void swap(index class name& x,index class name& y);

} // namespace boost::multi_index::detail

} // namespace boost::multi_index 

} // namespace boost

Complexity signature

Here and in the descriptions of operations of sequenced indices, we adopt the scheme outlined in the complexity signature section. The complexity signature of sequenced indices is:

• copying: c(n)=n*log(n),
• insertion: i(n)=1 (constant),
• hinted insertion: h(n)=1 (constant),
• deletion: d(n)=1 (constant),
• replacement: r(n)=1 (constant),
• modifying: m(n)=1 (constant).

Instantiation types

Sequenced indices are instantiated internally to multi_index_container and specified by means of indexed_by with the sequenced index specifier. Instantiations are dependent on the following types:

• Value from multi_index_container,
• Allocator from multi_index_container,
• TagList from the index specifier (if provided, otherwise tag<> is assumed).

Constructors, copy and assignment

As explained in the index concepts section, indices do not have public constructors or destructors. Assignment, on the other hand, is provided.

Effects:

a=b;

where a and b are the multi_index_container objects to which *this and x belong, respectively.
Returns: *this.

Effects:

a=list;

where a is the multi_index_container object to which *this belongs.
Returns: *this.

Effects:

clear();
insert(end(),first,last);

Effects:

assign(list.begin(),list.end());

Effects:

clear();
for(size_type i=0;i<n;++n)push_back(v);

Iterators

Requires: x is a reference to an element of the container.
Returns: An iterator to x.
Complexity: Constant.
Exception safety: nothrow.

Capacity operations

Requires (first version): value_type is DefaultInsertable into multi_index_container.
Requires (second version): value_type is CopyInsertable into multi_index_container.
Effects: If size()<n, tries to append n-size() default-inserted elements (first version) or copies of x (second version) at the end of the index. If n<size(), erases the last size()-n elements.
Note: If an expansion is requested, the size of the index is not guaranteed to be n after this operation (other indices may ban insertions.)

Modifiers

Effects:

emplace(begin(),std::forward<Args>(args)...);

Returns: The return value is a pair p. p.second is true if and only if insertion took place. On successful insertion, p.first points to the element inserted; otherwise, p.first points to an element that caused the insertion to be banned. Note that more than one element can be causing insertion not to be allowed.

Effects:

insert(begin(),x);            // lvalue ref version
insert(begin(),std::move(x)); // rvalue ref version

Returns: The return value is a pair p. p.second is true if and only if insertion took place. On successful insertion, p.first points to the element inserted; otherwise, p.first points to an element that caused the insertion to be banned. Note that more than one element can be causing insertion not to be allowed.

Effects:

emplace(end(),std::forward<Args>(args)...);

Returns: The return value is a pair p. p.second is true if and only if insertion took place. On successful insertion, p.first points to the element inserted; otherwise, p.first points to an element that caused the insertion to be banned. Note that more than one element can be causing insertion not to be allowed.

Effects:

insert(end(),x);            // lvalue ref version
insert(end(),std::move(x)); // rvalue ref version

Returns: The return value is a pair p. p.second is true if and only if insertion took place. On successful insertion, p.first points to the element inserted; otherwise, p.first points to an element that caused the insertion to be banned. Note that more than one element can be causing insertion not to be allowed.

Requires: value_type is EmplaceConstructible into multi_index_container from args.
Effects: Inserts a value_type object constructed with std::forward<Args>(args)... before position if insertion is allowed by all other indices of the multi_index_container.
Returns: The return value is a pair p. p.second is true if and only if insertion took place. On successful insertion, p.first points to the element inserted; otherwise, p.first points to an element that caused the insertion to be banned. Note that more than one element can be causing insertion not to be allowed.
Complexity: O(I(n)).
Exception safety: Strong.

Requires (first version): value_type is CopyInsertable into multi_index_container. position is a valid iterator of the index.
Requires (second version): value_type is MoveInsertable into multi_index_container. position is a valid iterator of the index.
Effects: Inserts x before position if insertion is allowed by all other indices of the multi_index_container.
Returns: The return value is a pair p. p.second is true if and only if insertion took place. On successful insertion, p.first points to the element inserted; otherwise, p.first points to an element that caused the insertion to be banned. Note that more than one element can be causing insertion not to be allowed.
Complexity: O(I(n)).
Exception safety: Strong.

Effects:

for(size_type i=0;i<n;++i)insert(position,x);

Requires: position is a valid iterator of the index. InputIterator is an input iterator. value_type is EmplaceConstructible into multi_index_container from *first. first and last are not iterators into any index of the multi_index_container to which this index belongs. last is reachable from first.
Effects: For each element of [first, last), in this order, inserts it before position if insertion is allowed by all other indices of the multi_index_container.
Complexity: O(m*I(n+m)), where m is the number of elements in [first,last).
Exception safety: Basic.

Effects:

insert(position,list.begin(),list.end());

Requires: position is a valid dereferenceable iterator of the index.
Effects: Deletes the element pointed to by position.
Returns: An iterator pointing to the element immediately following the one that was deleted, or end() if no such element exists.
Complexity: O(D(n)).
Exception safety: nothrow.

Requires: [first,last) is a valid range of the index.
Effects: Deletes the elements in [first,last).
Returns: last.
Complexity: O(m*D(n)), where m is the number of elements in [first,last).
Exception safety: nothrow.

Requires (first version): value_type is CopyAssignable. position is a valid dereferenceable iterator of the index.
Requires (second version): value_type is MoveAssignable. position is a valid dereferenceable iterator of the index.
Effects: Assigns the value x to the element pointed to by position into the multi_index_container to which the index belongs if replacing is allowed by all other indices of the multi_index_container.
Postconditions: Validity of position is preserved in all cases.
Returns: true if the replacement took place, false otherwise.
Complexity: O(R(n)).
Exception safety: Strong. If an exception is thrown by some user-provided operation the multi_index_container to which the index belongs remains in its original state.

Requires: mod is a unary function object accepting arguments of type value_type&. position is a valid dereferenceable iterator of the index. The execution of mod(e), where e is the element pointed to by position, does not invoke any operation of the multi_index_container after e is directly modified or, before modification, if the operation would invalidate position.
Effects: Calls mod(e) where e is the element pointed to by position and rearranges *position into all the indices of the multi_index_container. Rearrangement on sequenced indices does not change the position of the element with respect to the index; rearrangement on other indices may or might not succeed. If the rearrangement fails, the element is erased.
Postconditions: Validity of position is preserved if the operation succeeds.
Returns: true if the operation succeeded, false otherwise.
Complexity: O(M(n)).
Exception safety: Basic. If an exception is thrown by some user-provided operation (including mod), then the element pointed to by position is erased.

Requires: mod and back are unary function objects accepting arguments of type value_type&. position is a valid dereferenceable iterator of the index. The execution of mod(e), where e is the element pointed to by position, does not invoke any operation of the multi_index_container after e is directly modified or, before modification, if the operation would invalidate position. back(e) does not invoke any operation of the multi_index_container.
Effects: Calls mod(e) where e is the element pointed to by position and tries to rearrange *position into all the indices of the multi_index_container. Rearrangement on sequenced indices does not change the position of the element with respect to the index; rearrangement on other indices may or might not succeed. If the rearrangement fails, back(e) is invoked: if the resulting value of e is consistent with its original position and constraints in all indices, the element is kept, otherwise it is erased.
Postconditions: Validity of position is preserved except if the element is erased under the conditions described below.
Returns: true if the operation succeeded, false otherwise.
Complexity: O(M(n)).
Exception safety: Strong, except if mod or back throw an exception or back(e) fails to properly restore the element or there is a throwing user-provided operation after invoking back(e), in which cases the modified element is erased. If back throws inside the handling code executing after some other user-provided operation has thrown, it is the exception generated by back that is rethrown.

List operations

Sequenced indices provide the full set of list operations found in std::list; the semantics of these member functions, however, differ from that of std::list in some cases as insertions might not succeed due to banning by other indices. Similarly, the complexity of the operations may depend on the other indices belonging to the same multi_index_container.

Requires: position is a valid iterator of the index. &x!=this.
Effects: Inserts the contents of x before position, in the same order as they were in x. Those elements successfully inserted are erased from x.
Complexity: O(x.size()*I(n+x.size()) + x.size()*D(x.size())).
Exception safety: Basic.

Requires: position is a valid iterator of the index. i is a valid dereferenceable iterator x.
Effects: Inserts the element pointed to by i before position: if insertion is successful, the element is erased from x. In the special case &x==this, no copy or deletion is performed, and the operation is always successful. If position==i, no operation is performed.
Postconditions: If &x==this, no iterator or reference is invalidated.
Complexity: If &x==this, constant; otherwise O(I(n) + D(n)).
Exception safety: If &x==this, nothrow; otherwise, strong.

Requires: position is a valid iterator of the index. first and last are valid iterators of x. last is reachable from first. position is not in the range [first,last).
Effects: For each element in the range [first,last), insertion is tried before position; if the operation is successful, the element is erased from x. In the special case &x==this, no copy or deletion is performed, and insertions are always successful.
Postconditions: If &x==this, no iterator or reference is invalidated.
Complexity: If &x==this, constant; otherwise O(m*I(n+m) + m*D(x.size())) where m is the number of elements in [first,last).
Exception safety: If &x==this, nothrow; otherwise, basic.

Effects: Erases all elements of the index which compare equal to value.
Complexity: O(n + m*D(n)), where m is the number of elements erased.
Exception safety: Basic.

Effects: Erases all elements x of the index for which pred(x) holds.
Complexity: O(n + m*D(n)), where m is the number of elements erased.
Exception safety: Basic.

Effects: Eliminates all but the first element from every consecutive group of equal elements referred to by the iterator i in the range [first+1,last) for which *i==*(i-1).
Complexity: O(n + m*D(n)), where m is the number of elements erased.
Exception safety: Basic.

Effects: Eliminates all but the first element from every consecutive group of elements referred to by the iterator i in the range [first+1,last) for which binary_pred(*i,*(i-1)) holds.
Complexity: O(n + m*D(n)), where m is the number of elements erased.
Exception safety: Basic.

Requires: std::less<value_type> induces a strict weak ordering over value_type. Both the index and x are sorted according to std::less<value_type>.
Effects: Attempts to insert every element of x into the corresponding position of the index (according to the order). Elements successfully inserted are erased from x. The resulting sequence is stable, i.e. equivalent elements of either container preserve their relative position. In the special case &x==this, no operation is performed.
Postconditions: Elements in the index and remaining elements in x are sorted. Validity of iterators to the index and of non-erased elements of x references is preserved.
Complexity: If &x==this, constant; otherwise O(n + x.size()*I(n+x.size()) + x.size()*D(x.size())).
Exception safety: If &x==this, nothrow; otherwise, basic.

Requires: Compare induces a strict weak ordering over value_type. Both the index and x are sorted according to comp.
Effects: Attempts to insert every element of x into the corresponding position of the index (according to comp). Elements successfully inserted are erased from x. The resulting sequence is stable, i.e. equivalent elements of either container preserve their relative position. In the special case &x==this, no operation is performed.
Postconditions: Elements in the index and remaining elements in x are sorted according to comp. Validity of iterators to the index and of non-erased elements of x references is preserved.
Complexity: If &x==this, constant; otherwise O(n + x.size()*I(n+x.size()) + x.size()*D(x.size())).
Exception safety: If &x==this, nothrow; otherwise, basic.

Requires: std::less<value_type> induces a strict weark ordering over value_type.
Effects: Sorts the index according to std::less<value_type>. The sorting is stable, i.e. equivalent elements preserve their relative position.
Postconditions: Validity of iterators and references is preserved.
Complexity: O(n*log(n)).
Exception safety: nothrow if std::less<value_type> does not throw; otherwise, basic.

Requires: Compare induces a strict weak ordering over value_type.
Effects: Sorts the index according to comp. The sorting is stable, i.e. equivalent elements preserve their relative position.
Postconditions: Validity of iterators and references is preserved.
Complexity: O(n*log(n)).
Exception safety: nothrow if comp does not throw; otherwise, basic.

Effects: Reverses the order of the elements in the index.
Postconditions: Validity of iterators and references is preserved.
Complexity: O(n).

Rearrange operations

These operations, without counterpart in std::list (although splice provides partially overlapping functionality), perform individual and global repositioning of elements inside the index.

Requires: position is a valid iterator of the index. i is a valid dereferenceable iterator of the index.
Effects: Inserts the element pointed to by i before position. If position==i, no operation is performed.
Postconditions: No iterator or reference is invalidated.
Complexity: Constant.
Exception safety: nothrow.

Requires: position is a valid iterator of the index. first and last are valid iterators of the index. last is reachable from first. position is not in the range [first,last).
Effects: The range of elements [first,last) is repositioned just before position.
Postconditions: No iterator or reference is invalidated.
Complexity: Constant.
Exception safety: nothrow.

Requires: The range [first, std::advance(first,n)), where n is the size of the index, is a free view of the index.
Effects: The elements are rearranged so as to match the order of the previously described view.
Postconditions: No iterator or reference is invalidated.
Complexity: O(n).
Exception safety: Basic.

Serialization

Indices cannot be serialized on their own, but only as part of the multi_index_container into which they are embedded. In describing the additional preconditions and guarantees associated to sequenced indices with respect to serialization of their embedding containers, we use the concepts defined in the multi_index_container serialization section.

Requires: No additional requirements to those imposed by the container.

Requires: No additional requirements to those imposed by the container.
Postconditions: On successful loading, each of the elements of [begin(), end()) is a restored copy of the corresponding element in [m.get<i>().begin(), m.get<i>().end()), where i is the position of the sequenced index in the container.

Requires: it is a valid iterator of the index. The associated multi_index_container has been previously saved.

Postconditions: On successful loading, if it was dereferenceable then *it' is the restored copy of *it, otherwise it'==end().
Note: It is allowed that it be a const_iterator and the restored it' an iterator, or viceversa.

Hashed indices

Boost.MultiIndex reference

Random access indices

Revised December 29th 2018

© Copyright 2003-2018 Joaquín M López Muñoz. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)