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Index: facade-and-adaptor.rst
|
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===================================================================
|
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RCS file: /cvsroot/boost/boost/libs/iterator/doc/facade-and-adaptor.rst,v
|
||||
retrieving revision 1.9
|
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retrieving revision 1.14
|
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diff -b -d -u -r1.9 -r1.14
|
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--- facade-and-adaptor.rst 22 Sep 2003 19:55:00 -0000 1.9
|
||||
+++ facade-and-adaptor.rst 18 Jan 2004 15:51:06 -0000 1.14
|
||||
@@ -3,17 +3,25 @@ None
|
||||
+++++++++++++++++++++++++++++
|
||||
|
||||
:Author: David Abrahams, Jeremy Siek, Thomas Witt
|
||||
-:Contact: dave@boost-consulting.com, jsiek@osl.iu.edu, witt@acm.org
|
||||
+:Contact: dave@boost-consulting.com, jsiek@osl.iu.edu, witt@styleadvisor.com
|
||||
:organization: `Boost Consulting`_, Indiana University `Open Systems
|
||||
- Lab`_, University of Hanover `Institute for Transport
|
||||
- Railway Operation and Construction`_
|
||||
-:date: $Date: 2004/01/18 19:56:39 $
|
||||
-:Number: N1530=03-0113
|
||||
+ Lab`_, `Zephyr Associates, Inc.`_
|
||||
+:date: $Date: 2004/01/18 19:56:39 $
|
||||
+
|
||||
+:Number: This is a revised version of N1530_\ =03-0113, which was
|
||||
+ accepted for Technical Report 1 by the C++ standard
|
||||
+ committee's library working group.
|
||||
+
|
||||
+.. Version 1.9 of this ReStructuredText document corresponds to
|
||||
+ n1530_, the paper accepted by the LWG.
|
||||
+
|
||||
+.. _n1530: http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1530.html
|
||||
+
|
||||
:copyright: Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All rights reserved
|
||||
|
||||
.. _`Boost Consulting`: http://www.boost-consulting.com
|
||||
.. _`Open Systems Lab`: http://www.osl.iu.edu
|
||||
-.. _`Institute for Transport Railway Operation and Construction`: http://www.ive.uni-hannover.de
|
||||
+.. _`Zephyr Associates, Inc.`: http://www.styleadvisor.com
|
||||
|
||||
:abstract: We propose a set of class templates that help programmers
|
||||
build standard-conforming iterators, both from scratch and
|
||||
@@ -124,15 +132,15 @@ None
|
||||
=================
|
||||
|
||||
This proposal is formulated in terms of the new ``iterator concepts``
|
||||
-as proposed in `n1477`_, since user-defined and especially adapted
|
||||
+as proposed in n1550_, since user-defined and especially adapted
|
||||
iterators suffer from the well known categorization problems that are
|
||||
inherent to the current iterator categories.
|
||||
|
||||
-.. _`n1477`: http://anubis.dkuug.dk/JTC1/SC22/WG21/docs/papers/2003/n1477.html
|
||||
+.. _n1550: http://anubis.dkuug.dk/JTC1/SC22/WG21/docs/papers/2003/n1550.html
|
||||
|
||||
-This proposal does not strictly depend on proposal `n1477`_, as there
|
||||
+This proposal does not strictly depend on proposal n1550_, as there
|
||||
is a direct mapping between new and old categories. This proposal
|
||||
-could be reformulated using this mapping if `n1477`_ was not accepted.
|
||||
+could be reformulated using this mapping if n1550_ was not accepted.
|
||||
|
||||
Interoperability
|
||||
================
|
||||
@@ -141,24 +149,24 @@ None
|
||||
current standard. There are currently two defect reports that are
|
||||
concerned with interoperability issues.
|
||||
|
||||
-Issue `179`_ concerns the fact that mutable container iterator types
|
||||
+Issue 179_ concerns the fact that mutable container iterator types
|
||||
are only required to be convertible to the corresponding constant
|
||||
iterator types, but objects of these types are not required to
|
||||
interoperate in comparison or subtraction expressions. This situation
|
||||
is tedious in practice and out of line with the way built in types
|
||||
work. This proposal implements the proposed resolution to issue
|
||||
-`179`_, as most standard library implementations do nowadays. In other
|
||||
+179_, as most standard library implementations do nowadays. In other
|
||||
words, if an iterator type A has an implicit or user defined
|
||||
conversion to an iterator type B, the iterator types are interoperable
|
||||
and the usual set of operators are available.
|
||||
|
||||
-Issue `280`_ concerns the current lack of interoperability between
|
||||
+Issue 280_ concerns the current lack of interoperability between
|
||||
reverse iterator types. The proposed new reverse_iterator template
|
||||
fixes the issues raised in 280. It provides the desired
|
||||
interoperability without introducing unwanted overloads.
|
||||
|
||||
-.. _`179`: http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-defects.html#179
|
||||
-.. _`280`: http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-active.html#280
|
||||
+.. _179: http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-defects.html#179
|
||||
+.. _280: http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-active.html#280
|
||||
|
||||
|
||||
Iterator Facade
|
||||
@@ -195,7 +203,7 @@ None
|
||||
* ``filter_iterator``, which provides a view of an iterator range in
|
||||
which some elements of the underlying range are skipped.
|
||||
|
||||
-.. _counting_iterator:
|
||||
+.. _counting:
|
||||
|
||||
* ``counting_iterator``, which adapts any incrementable type
|
||||
(e.g. integers, iterators) so that incrementing/decrementing the
|
||||
@@ -226,15 +234,13 @@ Issue 9.1 et al
|
||||
::
|
||||
|
||||
struct use_default;
|
||||
- const unsigned use_default_access = -1;
|
||||
|
||||
struct iterator_core_access { /* implementation detail */ };
|
||||
|
||||
template <
|
||||
class Derived
|
||||
, class Value
|
||||
- , unsigned AccessCategory
|
||||
- , class TraversalCategory
|
||||
+ , class CategoryOrTraversal
|
||||
, class Reference = Value&
|
||||
, class Difference = ptrdiff_t
|
||||
>
|
||||
@@ -244,8 +250,7 @@ Issue 9.1 et al.
|
||||
class Derived
|
||||
, class Base
|
||||
, class Value = use_default
|
||||
- , unsigned Access = use_default_access
|
||||
- , class Traversal = use_default
|
||||
+ , class CategoryOrTraversal = use_default
|
||||
, class Reference = use_default
|
||||
, class Difference = use_default
|
||||
>
|
||||
@@ -254,10 +259,9 @@ Issue 9.1 et al.
|
||||
template <
|
||||
class Iterator
|
||||
, class Value = use_default
|
||||
- , unsigned Access = use_default_access
|
||||
- , class Traversal = use_default
|
||||
+ , class CategoryOrTraversal = use_default
|
||||
, class Reference = use_default
|
||||
, class Difference = use_default
|
||||
>
|
||||
class indirect_iterator;
|
||||
|
||||
Issue 9.44y
|
||||
|
||||
+ template <class Dereferenceable>
|
||||
+ struct pointee;
|
||||
+
|
||||
+ template <class Dereferenceable>
|
||||
+ struct indirect_reference;
|
||||
+
|
||||
template <class Iterator>
|
||||
class reverse_iterator;
|
||||
|
||||
@@ -277,8 +287,7 @@ Issue 9.1 et al.
|
||||
|
||||
template <
|
||||
class Incrementable
|
||||
- , unsigned Access = use_default_access
|
||||
- , class Traversal = use_default
|
||||
+ , class CategoryOrTraversal = use_default
|
||||
, class Difference = use_default
|
||||
>
|
||||
class counting_iterator
|
||||
@@ -312,17 +321,35 @@ Issue 9.8
|
||||
Specialized adaptors [lib.iterator.special.adaptors]
|
||||
====================================================
|
||||
|
||||
-.. The requirements for all of these need to be written *much* more
|
||||
- formally -DWA
|
||||
-
|
||||
|
||||
-[*Note:* The ``enable_if_convertible<X,Y>::type`` expression used in
|
||||
+The ``enable_if_convertible<X,Y>::type`` expression used in
|
||||
this section is for exposition purposes. The converting constructors
|
||||
for specialized adaptors should be only be in an overload set provided
|
||||
that an object of type ``X`` is implicitly convertible to an object of
|
||||
-type ``Y``. The ``enable_if_convertible`` approach uses SFINAE to
|
||||
+type ``Y``.
|
||||
+The signatures involving ``enable_if_convertible`` should behave
|
||||
+*as-if* ``enable_if_convertible`` were defined to be::
|
||||
+
|
||||
+ template <bool> enable_if_convertible_impl
|
||||
+ {};
|
||||
+
|
||||
+ template <> enable_if_convertible_impl<true>
|
||||
+ { struct type; };
|
||||
+
|
||||
+ template<typename From, typename To>
|
||||
+ struct enable_if_convertible
|
||||
+ : enable_if_convertible_impl<is_convertible<From,To>::value>
|
||||
+ {};
|
||||
+
|
||||
+If an expression other than the default argument is used to supply
|
||||
+the value of a function parameter whose type is written in terms
|
||||
+of ``enable_if_convertible``, the program is ill-formed, no
|
||||
+diagnostic required.
|
||||
+
|
||||
+[*Note:* The ``enable_if_convertible`` approach uses SFINAE to
|
||||
take the constructor out of the overload set when the types are not
|
||||
-implicitly convertible.]
|
||||
+implicitly convertible.
|
||||
+]
|
||||
|
||||
|
||||
Indirect iterator
|
||||
@@ -330,6 +357,16 @@ Issue 9.44y
|
||||
|
||||
.. include:: indirect_iterator_abstract.rst
|
||||
|
||||
+Class template ``pointee``
|
||||
+....................................
|
||||
+
|
||||
+.. include:: pointee_ref.rst
|
||||
+
|
||||
+Class template ``indirect_reference``
|
||||
+.....................................
|
||||
+
|
||||
+.. include:: indirect_reference_ref.rst
|
||||
+
|
||||
Class template ``indirect_iterator``
|
||||
....................................
|
||||
|
||||
@@ -393,8 +430,7 @@
|
||||
|
||||
|
||||
|
||||
-..
|
||||
- LocalWords: Abrahams Siek Witt istream ostream iter MTL strided interoperate
|
||||
+.. LocalWords: Abrahams Siek Witt istream ostream iter MTL strided interoperate
|
||||
LocalWords: CRTP metafunctions inlining lvalue JGS incrementable BGL LEDA cv
|
||||
LocalWords: GraphBase struct ptrdiff UnaryFunction const int typename bool pp
|
||||
LocalWords: lhs rhs SFINAE markup iff tmp OtherDerived OtherIterator DWA foo
|
||||
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Index: indirect_iterator_ref.rst
|
||||
===================================================================
|
||||
RCS file: /cvsroot/boost/boost/libs/iterator/doc/indirect_iterator_ref.rst,v
|
||||
retrieving revision 1.2
|
||||
retrieving revision 1.21
|
||||
diff -w -d -u -b -r1.2 -r1.21
|
||||
--- indirect_iterator_ref.rst 22 Sep 2003 19:55:00 -0000 1.2
|
||||
+++ indirect_iterator_ref.rst 15 Jan 2004 00:01:33 -0000 1.21
|
||||
|
||||
|
||||
|
||||
@@ -3,82 +3,139 @@
|
||||
template <
|
||||
class Iterator
|
||||
, class Value = use_default
|
||||
|
||||
Issue 9.15
|
||||
|
||||
- , unsigned Access = use_default_access
|
||||
- , class Traversal = use_default
|
||||
+ , class CategoryOrTraversal = use_default
|
||||
, class Reference = use_default
|
||||
, class Difference = use_default
|
||||
>
|
||||
class indirect_iterator
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
- : public iterator_adaptor</* see discussion */>
|
||||
{
|
||||
- friend class iterator_core_access;
|
||||
public:
|
||||
+ typedef /* see below */ value_type;
|
||||
+ typedef /* see below */ reference;
|
||||
+ typedef /* see below */ pointer;
|
||||
+ typedef /* see below */ difference_type;
|
||||
+ typedef /* see below */ iterator_category;
|
||||
+
|
||||
indirect_iterator();
|
||||
indirect_iterator(Iterator x);
|
||||
+
|
||||
|
||||
Issue 9.15
|
||||
|
||||
template <
|
||||
- class Iterator2, class Value2, unsigned Access2, class Traversal2
|
||||
+ class Iterator2, class Value2, class Category2
|
||||
, class Reference2, class Difference2
|
||||
>
|
||||
indirect_iterator(
|
||||
indirect_iterator<
|
||||
- Iterator2, Value2, Access2, Traversal2, Reference2, Difference2
|
||||
+ Iterator2, Value2, Category2, Reference2, Difference2
|
||||
> const& y
|
||||
, typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
|
||||
);
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
- private: // as-if specification
|
||||
- typename indirect_iterator::reference dereference() const
|
||||
- {
|
||||
- return **this->base();
|
||||
- }
|
||||
+
|
||||
+ Iterator const& base() const;
|
||||
+ reference operator*() const;
|
||||
+ indirect_iterator& operator++();
|
||||
+ indirect_iterator& operator--();
|
||||
+ private:
|
||||
+ Iterator m_iterator; // exposition
|
||||
};
|
||||
|
||||
+
|
||||
+The member types of ``indirect_iterator`` are defined according to
|
||||
+the following pseudo-code, where ``V`` is
|
||||
+``iterator_traits<Iterator>::value_type``
|
||||
+
|
||||
+.. parsed-literal::
|
||||
+
|
||||
+ if (Value is use_default) then
|
||||
+ typedef remove_const<pointee<V>::type>::type value_type;
|
||||
+ else
|
||||
+ typedef remove_const<Value>::type value_type;
|
||||
+
|
||||
+ if (Reference is use_default) then
|
||||
+ if (Value is use_default) then
|
||||
+ typedef indirect_reference<V>::type reference;
|
||||
+ else
|
||||
+ typedef Value& reference;
|
||||
+ else
|
||||
+ typedef Reference reference;
|
||||
+
|
||||
+ if (Value is use_default) then
|
||||
+ typedef pointee<V>::type\* pointer;
|
||||
+ else
|
||||
+ typedef Value\* pointer;
|
||||
+
|
||||
+ if (Difference is use_default)
|
||||
+ typedef iterator_traits<Iterator>::difference_type difference_type;
|
||||
+ else
|
||||
+ typedef Difference difference_type;
|
||||
+
|
||||
+ if (CategoryOrTraversal is use_default)
|
||||
+ typedef |iterator-category|_\ (
|
||||
+ iterator_traversal<Iterator>::type,``reference``,``value_type``
|
||||
+ ) iterator_category;
|
||||
+ else
|
||||
+ typedef |iterator-category|_\ (
|
||||
+ CategoryOrTraversal,``reference``,``value_type``
|
||||
+ ) iterator_category;
|
||||
+
|
||||
+
|
||||
|
||||
``indirect_iterator`` requirements
|
||||
..................................
|
||||
|
||||
Issue 9.40x
|
||||
|
||||
-The ``value_type`` of the ``Iterator`` template parameter should
|
||||
-itself be dereferenceable. The return type of the ``operator*`` for
|
||||
-the ``value_type`` must be the same type as the ``Reference`` template
|
||||
-parameter. The ``Value`` template parameter will be the ``value_type``
|
||||
-for the ``indirect_iterator``, unless ``Value`` is const. If ``Value``
|
||||
-is ``const X``, then ``value_type`` will be *non-* ``const X``. The
|
||||
-default for ``Value`` is
|
||||
+The expression ``*v``, where ``v`` is an object of
|
||||
+``iterator_traits<Iterator>::value_type``, shall be valid
|
||||
+expression and convertible to ``reference``. ``Iterator`` shall
|
||||
+model the traversal concept indicated by ``iterator_category``.
|
||||
+``Value``, ``Reference``, and ``Difference`` shall be chosen so
|
||||
+that ``value_type``, ``reference``, and ``difference_type`` meet
|
||||
+the requirements indicated by ``iterator_category``.
|
||||
|
||||
-::
|
||||
+[Note: there are further requirements on the
|
||||
+``iterator_traits<Iterator>::value_type`` if the ``Value``
|
||||
+parameter is not ``use_default``, as implied by the algorithm for
|
||||
+deducing the default for the ``value_type`` member.]
|
||||
|
||||
- iterator_traits< iterator_traits<Iterator>::value_type >::value_type
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
+``indirect_iterator`` models
|
||||
+............................
|
||||
|
||||
-If the default is used for ``Value``, then there must be a valid
|
||||
-specialization of ``iterator_traits`` for the value type of the base
|
||||
-iterator.
|
||||
+In addition to the concepts indicated by ``iterator_category``
|
||||
+and by ``iterator_traversal<indirect_iterator>::type``, a
|
||||
+specialization of ``indirect_iterator`` models the following
|
||||
+concepts, Where ``v`` is an object of
|
||||
+``iterator_traits<Iterator>::value_type``:
|
||||
|
||||
-The ``Reference`` parameter will be the ``reference`` type of the
|
||||
-``indirect_iterator``. The default is ``Value&``.
|
||||
+ * Readable Iterator if ``reference(*v)`` is convertible to
|
||||
+ ``value_type``.
|
||||
|
||||
-The ``Access`` and ``Traversal`` parameters are passed unchanged to
|
||||
-the corresponding parameters of the ``iterator_adaptor`` base
|
||||
-class, and the ``Iterator`` parameter is passed unchanged as the
|
||||
-``Base`` parameter to the ``iterator_adaptor`` base class.
|
||||
+ * Writable Iterator if ``reference(*v) = t`` is a valid
|
||||
+ expression (where ``t`` is an object of type
|
||||
+ ``indirect_iterator::value_type``)
|
||||
|
||||
-The indirect iterator will model the most refined standard traversal
|
||||
-concept that is modeled by the ``Iterator`` type. The indirect
|
||||
-iterator will model the most refined standard access concept that is
|
||||
-modeled by the value type of ``Iterator``.
|
||||
+ * Lvalue Iterator if ``reference`` is a reference type.
|
||||
+
|
||||
+``indirect_iterator<X,V1,C1,R1,D1>`` is interoperable with
|
||||
+``indirect_iterator<Y,V2,C2,R2,D2>`` if and only if ``X`` is
|
||||
+interoperable with ``Y``.
|
||||
|
||||
|
||||
``indirect_iterator`` operations
|
||||
................................
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
+In addition to the operations required by the concepts described
|
||||
+above, specializations of ``indirect_iterator`` provide the
|
||||
+following operations.
|
||||
+
|
||||
+
|
||||
|
||||
Issue 9.28 and 9.37x
|
||||
|
||||
``indirect_iterator();``
|
||||
|
||||
:Requires: ``Iterator`` must be Default Constructible.
|
||||
:Returns: An instance of ``indirect_iterator`` with
|
||||
- a default constructed base object.
|
||||
+ a default-constructed ``m_iterator``.
|
||||
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
``indirect_iterator(Iterator x);``
|
||||
|
||||
:Returns: An instance of ``indirect_iterator`` with
|
||||
- the ``iterator_adaptor`` subobject copy constructed from ``x``.
|
||||
+ ``m_iterator`` copy constructed from ``x``.
|
||||
|
||||
::
|
||||
|
||||
|
||||
Issue 9.29
|
||||
|
||||
@@ -94,5 +151,27 @@
|
||||
);
|
||||
|
||||
:Requires: ``Iterator2`` is implicitly convertible to ``Iterator``.
|
||||
-:Returns: An instance of ``indirect_iterator`` that is a copy of ``y``.
|
||||
+:Returns: An instance of ``indirect_iterator`` whose
|
||||
+ ``m_iterator`` subobject is constructed from ``y.base()``.
|
||||
+
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
+``Iterator const& base() const;``
|
||||
|
||||
+:Returns: ``m_iterator``
|
||||
+
|
||||
+
|
||||
+``reference operator*() const;``
|
||||
+
|
||||
+:Returns: ``**m_iterator``
|
||||
+
|
||||
+
|
||||
+``indirect_iterator& operator++();``
|
||||
+
|
||||
+:Effects: ``++m_iterator``
|
||||
+:Returns: ``*this``
|
||||
+
|
||||
+
|
||||
+``indirect_iterator& operator--();``
|
||||
+
|
||||
+:Effects: ``--m_iterator``
|
||||
+:Returns: ``*this``
|
||||
Executable
BIN
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+22
@@ -0,0 +1,22 @@
|
||||
Index: iterator_adaptor_abstract.rst
|
||||
===================================================================
|
||||
RCS file: /cvsroot/boost/boost/libs/iterator/doc/iterator_adaptor_abstract.rst,v
|
||||
retrieving revision 1.1
|
||||
retrieving revision 1.2
|
||||
diff -b -d -u -r1.1 -r1.2
|
||||
--- iterator_adaptor_abstract.rst 5 Aug 2003 18:19:55 -0000 1.1
|
||||
+++ iterator_adaptor_abstract.rst 24 Nov 2003 05:02:46 -0000 1.2
|
||||
@@ -1,5 +1,11 @@ Issue 9.21
|
||||
-The ``iterator_adaptor`` is a base class template derived from an
|
||||
-instantiation of ``iterator_facade``. The core interface functions
|
||||
+.. Version 1.1 of this ReStructuredText document corresponds to
|
||||
+ n1530_, the paper accepted by the LWG.
|
||||
+
|
||||
+.. Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All
|
||||
+ rights reserved
|
||||
+
|
||||
+Each specialization of the ``iterator_adaptor`` class template is derived from
|
||||
+a specialization of ``iterator_facade``. The core interface functions
|
||||
expected by ``iterator_facade`` are implemented in terms of the
|
||||
``iterator_adaptor``\ 's ``Base`` template parameter. A class derived
|
||||
from ``iterator_adaptor`` typically redefines some of the core
|
||||
Executable
+35
@@ -0,0 +1,35 @@
|
||||
Index: iterator_adaptor_body.rst
|
||||
===================================================================
|
||||
RCS file: /cvsroot/boost/boost/libs/iterator/doc/iterator_adaptor_body.rst,v
|
||||
retrieving revision 1.2
|
||||
retrieving revision 1.3
|
||||
diff -b -d -u -r1.2 -r1.3
|
||||
--- iterator_adaptor_body.rst 22 Sep 2003 19:55:00 -0000 1.2
|
||||
+++ iterator_adaptor_body.rst 24 Nov 2003 05:02:46 -0000 1.3
|
||||
@@ -1,3 +1,9 @@
|
||||
+.. Version 1.2 of this ReStructuredText document corresponds to
|
||||
+ n1530_, the paper accepted by the LWG for TR1.
|
||||
+
|
||||
+.. Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All
|
||||
+ rights reserved
|
||||
+
|
||||
The ``iterator_adaptor`` class template adapts some ``Base`` [#base]_
|
||||
type to create a new iterator. Instantiations of ``iterator_adaptor``
|
||||
are derived from a corresponding instantiation of ``iterator_facade``
|
||||
@@ -19,7 +25,7 @@ Issue 9.1 et al
|
||||
redefined in the user's derived class.
|
||||
|
||||
Several of the template parameters of ``iterator_adaptor`` default
|
||||
-to ``use_default`` (or ``use_default_access``). This allows the
|
||||
+to ``use_default``. This allows the
|
||||
user to make use of a default parameter even when she wants to
|
||||
specify a parameter later in the parameter list. Also, the
|
||||
defaults for the corresponding associated types are somewhat
|
||||
@@ -28,6 +34,6 @@ Issue 9.45y
|
||||
the identity of the ``use_default`` type is not left unspecified
|
||||
because specification helps to highlight that the ``Reference``
|
||||
template parameter may not always be identical to the iterator's
|
||||
-``reference`` type, and will keep users making mistakes based on
|
||||
+``reference`` type, and will keep users from making mistakes based on
|
||||
that assumption.
|
||||
|
||||
Executable
+216
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|
||||
<?xml version="1.0" encoding="utf-8" ?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||||
<meta name="generator" content="Docutils 0.3.1: http://docutils.sourceforge.net/" />
|
||||
<title>Iterator Archetype</title>
|
||||
<meta name="author" content="David Abrahams, Jeremy Siek, Thomas Witt" />
|
||||
<meta name="organization" content="Boost Consulting, Indiana University Open Systems Lab, Zephyr Associates, Inc." />
|
||||
<meta name="date" content="2004-01-16" />
|
||||
<meta name="copyright" content="Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2004. All rights reserved" />
|
||||
<link rel="stylesheet" href="default.css" type="text/css" />
|
||||
</head>
|
||||
<body>
|
||||
<div class="document" id="iterator-archetype">
|
||||
<h1 class="title">Iterator Archetype</h1>
|
||||
<table class="docinfo" frame="void" rules="none">
|
||||
<col class="docinfo-name" />
|
||||
<col class="docinfo-content" />
|
||||
<tbody valign="top">
|
||||
<tr><th class="docinfo-name">Author:</th>
|
||||
<td>David Abrahams, Jeremy Siek, Thomas Witt</td></tr>
|
||||
<tr><th class="docinfo-name">Contact:</th>
|
||||
<td><a class="first reference" href="mailto:dave@boost-consulting.com">dave@boost-consulting.com</a>, <a class="reference" href="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</a>, <a class="last reference" href="mailto:witt@styleadvisor.com">witt@styleadvisor.com</a></td></tr>
|
||||
<tr><th class="docinfo-name">Organization:</th>
|
||||
<td><a class="first reference" href="http://www.boost-consulting.com">Boost Consulting</a>, Indiana University <a class="reference" href="http://www.osl.iu.edu">Open Systems
|
||||
Lab</a>, <a class="last reference" href="http://www.styleadvisor.com">Zephyr Associates, Inc.</a></td></tr>
|
||||
<tr><th class="docinfo-name">Date:</th>
|
||||
<td>2004-01-16</td></tr>
|
||||
<tr><th class="docinfo-name">Copyright:</th>
|
||||
<td>Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2004. All rights reserved</td></tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">abstract:</th><td class="field-body">iterator archetypes provide a means to check the compile time requirements of a generic component on its iterator arguments.</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<div class="contents topic" id="table-of-contents">
|
||||
<p class="topic-title"><a name="table-of-contents">Table of Contents</a></p>
|
||||
<ul class="simple">
|
||||
<li><a class="reference" href="#reference" id="id1" name="id1">Reference</a><ul>
|
||||
<li><a class="reference" href="#iterator-archetype-synopsis" id="id2" name="id2"><tt class="literal"><span class="pre">iterator_archetype</span></tt> Synopsis</a></li>
|
||||
<li><a class="reference" href="#access-category-tags" id="id3" name="id3"><tt class="literal"><span class="pre">Access</span> <span class="pre">Category</span> <span class="pre">Tags</span></tt></a></li>
|
||||
<li><a class="reference" href="#iterator-archetype-requirements" id="id4" name="id4"><tt class="literal"><span class="pre">iterator_archetype</span></tt> Requirements</a></li>
|
||||
<li><a class="reference" href="#iterator-archetype-models" id="id5" name="id5"><tt class="literal"><span class="pre">iterator_archetype</span></tt> Models</a></li>
|
||||
<li><a class="reference" href="#traits" id="id6" name="id6"><tt class="literal"><span class="pre">Traits</span></tt></a></li>
|
||||
</ul>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="section" id="reference">
|
||||
<h1><a class="toc-backref" href="#id1" name="reference">Reference</a></h1>
|
||||
<div class="section" id="iterator-archetype-synopsis">
|
||||
<h2><a class="toc-backref" href="#id2" name="iterator-archetype-synopsis"><tt class="literal"><span class="pre">iterator_archetype</span></tt> Synopsis</a></h2>
|
||||
<pre class="literal-block">
|
||||
namespace iterator_archetypes
|
||||
{
|
||||
// Access categories
|
||||
|
||||
typedef /*implementation defined*/ readable_iterator_t;
|
||||
typedef /*implementation defined*/ writable_iterator_t;
|
||||
typedef /*implementation defined*/ readable_writable_iterator_t;
|
||||
typedef /*implementation defined*/ readable_lvalue_iterator_t;
|
||||
typedef /*implementation defined*/ writable_lvalue_iterator_t;
|
||||
|
||||
}
|
||||
|
||||
template <
|
||||
class Value
|
||||
, class AccessCategory
|
||||
, class TraversalCategory
|
||||
>
|
||||
class iterator_archetype
|
||||
{
|
||||
typedef /* see below */ value_type;
|
||||
typedef /* see below */ reference;
|
||||
typedef /* see below */ pointer;
|
||||
typedef /* see below */ difference_type;
|
||||
typedef /* see below */ iterator_category;
|
||||
};
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section" id="access-category-tags">
|
||||
<h2><a class="toc-backref" href="#id3" name="access-category-tags"><tt class="literal"><span class="pre">Access</span> <span class="pre">Category</span> <span class="pre">Tags</span></tt></a></h2>
|
||||
<p>The access category types provided correspond to the following
|
||||
standard iterator access concept combinations:</p>
|
||||
<pre class="literal-block">
|
||||
readable_iterator_t :=
|
||||
|
||||
Readable Iterator
|
||||
|
||||
writable_iterator_t :=
|
||||
|
||||
Writeable Iterator
|
||||
|
||||
readable_writable_iterator_t :=
|
||||
|
||||
Readable Iterator & Writeable Iterator & Swappable Iterator
|
||||
|
||||
readable_lvalue_iterator_t :=
|
||||
|
||||
Readable Iterator & Lvalue Iterator
|
||||
|
||||
writeable_lvalue_iterator_t :=
|
||||
|
||||
Readable Iterator & Writeable Iterator & Swappable Iterator & Lvalue Iterator
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section" id="iterator-archetype-requirements">
|
||||
<h2><a class="toc-backref" href="#id4" name="iterator-archetype-requirements"><tt class="literal"><span class="pre">iterator_archetype</span></tt> Requirements</a></h2>
|
||||
<p>The <tt class="literal"><span class="pre">AccessCategory</span></tt> argument must be one of the predefined access
|
||||
category tags. The <tt class="literal"><span class="pre">TraversalCategory</span></tt> must be one of the standard
|
||||
traversal tags. The <tt class="literal"><span class="pre">Value</span></tt> type must satisfy the requirements of
|
||||
the iterator concept specified by <tt class="literal"><span class="pre">AccessCategory</span></tt> and
|
||||
<tt class="literal"><span class="pre">TraversalCategory</span></tt> as implied by the nested traits types.</p>
|
||||
</div>
|
||||
<div class="section" id="iterator-archetype-models">
|
||||
<h2><a class="toc-backref" href="#id5" name="iterator-archetype-models"><tt class="literal"><span class="pre">iterator_archetype</span></tt> Models</a></h2>
|
||||
<p><tt class="literal"><span class="pre">iterator_archetype</span></tt> models the iterator concepts specified by the
|
||||
<tt class="literal"><span class="pre">AccessCategory</span></tt> and <tt class="literal"><span class="pre">TraversalCategory</span></tt>
|
||||
arguments. <tt class="literal"><span class="pre">iterator_archetype</span></tt> does not model any other access
|
||||
concepts or any more derived traversal concepts.</p>
|
||||
</div>
|
||||
<div class="section" id="traits">
|
||||
<h2><a class="toc-backref" href="#id6" name="traits"><tt class="literal"><span class="pre">Traits</span></tt></a></h2>
|
||||
<p>The nested trait types are defined as follows:</p>
|
||||
<pre class="literal-block">
|
||||
if (AccessCategory == readable_iterator_t)
|
||||
|
||||
value_type = Value
|
||||
reference = Value
|
||||
pointer = Value*
|
||||
|
||||
else if (AccessCategory == writable_iterator_t)
|
||||
|
||||
value_type = void
|
||||
reference = void
|
||||
pointer = void
|
||||
|
||||
else if (AccessCategory == readable_writable_iterator_t)
|
||||
|
||||
value_type = Value
|
||||
|
||||
reference :=
|
||||
|
||||
A type X that is convertible to Value for which the following
|
||||
expression is valid. Given an object x of type X and v of type
|
||||
Value.
|
||||
|
||||
x = v
|
||||
|
||||
pointer = Value*
|
||||
|
||||
else if (AccessCategory == readable_lvalue_iterator_t)
|
||||
|
||||
value_type = Value
|
||||
reference = Value const&
|
||||
pointer = Value const*
|
||||
|
||||
else if (AccessCategory == writable_lvalue_iterator_t)
|
||||
|
||||
value_type = Value
|
||||
reference = Value&
|
||||
pointer = Value*
|
||||
|
||||
if ( TraversalCategory is convertible to forward_traversal_tag )
|
||||
|
||||
difference_type := ptrdiff_t
|
||||
|
||||
else
|
||||
|
||||
difference_type := unspecified type
|
||||
|
||||
|
||||
iterator_category :=
|
||||
|
||||
A type X satisfying the following two constraints:
|
||||
|
||||
1. X is convertible to X1, and not to any more-derived
|
||||
type, where X1 is defined by:
|
||||
|
||||
if (reference is a reference type
|
||||
&& TraversalCategory is convertible to forward_traversal_tag)
|
||||
{
|
||||
if (TraversalCategory is convertible to random_access_traversal_tag)
|
||||
X1 = random_access_iterator_tag
|
||||
else if (TraversalCategory is convertible to bidirectional_traversal_tag)
|
||||
X1 = bidirectional_iterator_tag
|
||||
else
|
||||
X1 = forward_iterator_tag
|
||||
}
|
||||
else
|
||||
{
|
||||
if (TraversalCategory is convertible to single_pass_traversal_tag
|
||||
&& reference != void)
|
||||
X1 = input_iterator_tag
|
||||
else
|
||||
X1 = output_iterator_tag
|
||||
}
|
||||
|
||||
2. X is convertible to TraversalCategory
|
||||
</pre>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<hr class="footer" />
|
||||
<div class="footer">
|
||||
<a class="reference" href="iterator_archetypes.rst">View document source</a>.
|
||||
Generated by <a class="reference" href="http://docutils.sourceforge.net/">Docutils</a> from <a class="reference" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> source.
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
Executable
BIN
Binary file not shown.
Executable
+181
@@ -0,0 +1,181 @@
|
||||
++++++++++++++++++++
|
||||
Iterator Archetype
|
||||
++++++++++++++++++++
|
||||
|
||||
:Author: David Abrahams, Jeremy Siek, Thomas Witt
|
||||
:Contact: dave@boost-consulting.com, jsiek@osl.iu.edu, witt@styleadvisor.com
|
||||
:organization: `Boost Consulting`_, Indiana University `Open Systems
|
||||
Lab`_, `Zephyr Associates, Inc.`_
|
||||
:date: $Date$
|
||||
:copyright: Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2004. All rights reserved
|
||||
|
||||
.. _`Boost Consulting`: http://www.boost-consulting.com
|
||||
.. _`Open Systems Lab`: http://www.osl.iu.edu
|
||||
.. _`Zephyr Associates, Inc.`: http://www.styleadvisor.com
|
||||
|
||||
:abstract: iterator archetypes provide a means to check the compile time requirements of a generic component on its iterator arguments.
|
||||
|
||||
.. contents:: Table of Contents
|
||||
|
||||
Reference
|
||||
=========
|
||||
|
||||
``iterator_archetype`` Synopsis
|
||||
...............................
|
||||
|
||||
::
|
||||
|
||||
namespace iterator_archetypes
|
||||
{
|
||||
// Access categories
|
||||
|
||||
typedef /*implementation defined*/ readable_iterator_t;
|
||||
typedef /*implementation defined*/ writable_iterator_t;
|
||||
typedef /*implementation defined*/ readable_writable_iterator_t;
|
||||
typedef /*implementation defined*/ readable_lvalue_iterator_t;
|
||||
typedef /*implementation defined*/ writable_lvalue_iterator_t;
|
||||
|
||||
}
|
||||
|
||||
template <
|
||||
class Value
|
||||
, class AccessCategory
|
||||
, class TraversalCategory
|
||||
>
|
||||
class iterator_archetype
|
||||
{
|
||||
typedef /* see below */ value_type;
|
||||
typedef /* see below */ reference;
|
||||
typedef /* see below */ pointer;
|
||||
typedef /* see below */ difference_type;
|
||||
typedef /* see below */ iterator_category;
|
||||
};
|
||||
|
||||
``Access Category Tags``
|
||||
........................
|
||||
|
||||
The access category types provided correspond to the following
|
||||
standard iterator access concept combinations:
|
||||
|
||||
::
|
||||
|
||||
readable_iterator_t :=
|
||||
|
||||
Readable Iterator
|
||||
|
||||
writable_iterator_t :=
|
||||
|
||||
Writeable Iterator
|
||||
|
||||
readable_writable_iterator_t :=
|
||||
|
||||
Readable Iterator & Writeable Iterator & Swappable Iterator
|
||||
|
||||
readable_lvalue_iterator_t :=
|
||||
|
||||
Readable Iterator & Lvalue Iterator
|
||||
|
||||
writeable_lvalue_iterator_t :=
|
||||
|
||||
Readable Iterator & Writeable Iterator & Swappable Iterator & Lvalue Iterator
|
||||
|
||||
``iterator_archetype`` Requirements
|
||||
...................................
|
||||
|
||||
The ``AccessCategory`` argument must be one of the predefined access
|
||||
category tags. The ``TraversalCategory`` must be one of the standard
|
||||
traversal tags. The ``Value`` type must satisfy the requirements of
|
||||
the iterator concept specified by ``AccessCategory`` and
|
||||
``TraversalCategory`` as implied by the nested traits types.
|
||||
|
||||
``iterator_archetype`` Models
|
||||
.............................
|
||||
|
||||
``iterator_archetype`` models the iterator concepts specified by the
|
||||
``AccessCategory`` and ``TraversalCategory``
|
||||
arguments. ``iterator_archetype`` does not model any other access
|
||||
concepts or any more derived traversal concepts.
|
||||
|
||||
``Traits``
|
||||
..........
|
||||
|
||||
The nested trait types are defined as follows:
|
||||
|
||||
::
|
||||
|
||||
if (AccessCategory == readable_iterator_t)
|
||||
|
||||
value_type = Value
|
||||
reference = Value
|
||||
pointer = Value*
|
||||
|
||||
else if (AccessCategory == writable_iterator_t)
|
||||
|
||||
value_type = void
|
||||
reference = void
|
||||
pointer = void
|
||||
|
||||
else if (AccessCategory == readable_writable_iterator_t)
|
||||
|
||||
value_type = Value
|
||||
|
||||
reference :=
|
||||
|
||||
A type X that is convertible to Value for which the following
|
||||
expression is valid. Given an object x of type X and v of type
|
||||
Value.
|
||||
|
||||
x = v
|
||||
|
||||
pointer = Value*
|
||||
|
||||
else if (AccessCategory == readable_lvalue_iterator_t)
|
||||
|
||||
value_type = Value
|
||||
reference = Value const&
|
||||
pointer = Value const*
|
||||
|
||||
else if (AccessCategory == writable_lvalue_iterator_t)
|
||||
|
||||
value_type = Value
|
||||
reference = Value&
|
||||
pointer = Value*
|
||||
|
||||
if ( TraversalCategory is convertible to forward_traversal_tag )
|
||||
|
||||
difference_type := ptrdiff_t
|
||||
|
||||
else
|
||||
|
||||
difference_type := unspecified type
|
||||
|
||||
|
||||
iterator_category :=
|
||||
|
||||
A type X satisfying the following two constraints:
|
||||
|
||||
1. X is convertible to X1, and not to any more-derived
|
||||
type, where X1 is defined by:
|
||||
|
||||
if (reference is a reference type
|
||||
&& TraversalCategory is convertible to forward_traversal_tag)
|
||||
{
|
||||
if (TraversalCategory is convertible to random_access_traversal_tag)
|
||||
X1 = random_access_iterator_tag
|
||||
else if (TraversalCategory is convertible to bidirectional_traversal_tag)
|
||||
X1 = bidirectional_iterator_tag
|
||||
else
|
||||
X1 = forward_iterator_tag
|
||||
}
|
||||
else
|
||||
{
|
||||
if (TraversalCategory is convertible to single_pass_traversal_tag
|
||||
&& reference != void)
|
||||
X1 = input_iterator_tag
|
||||
else
|
||||
X1 = output_iterator_tag
|
||||
}
|
||||
|
||||
2. X is convertible to TraversalCategory
|
||||
|
||||
|
||||
Executable
+3153
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Executable
+8
@@ -0,0 +1,8 @@
|
||||
::
|
||||
|
||||
template<typename IteratorTuple>
|
||||
zip_iterator<IteratorTuple>
|
||||
make_zip_iterator(IteratorTuple t);
|
||||
|
||||
:Returns: An instance of ``zip_iterator<IteratorTuple>`` with ``m_iterator_tuple``
|
||||
initialized to ``t``.
|
||||
Executable
+2761
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Load Diff
Executable
BIN
Binary file not shown.
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BIN
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BIN
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BIN
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@@ -0,0 +1,202 @@
|
||||
Index: transform_iterator_ref.rst
|
||||
===================================================================
|
||||
RCS file: /cvsroot/boost/boost/libs/iterator/doc/transform_iterator_ref.rst,v
|
||||
retrieving revision 1.3
|
||||
retrieving revision 1.15
|
||||
diff -w -d -u -b -r1.3 -r1.15
|
||||
--- transform_iterator_ref.rst 21 Sep 2003 11:13:46 -0000 1.3
|
||||
+++ transform_iterator_ref.rst 15 Jan 2004 00:06:57 -0000 1.15
|
||||
@@ -1,3 +1,5 @@
|
||||
+.. Version 1.3 of this document was accepted for TR1
|
||||
+
|
||||
::
|
||||
|
||||
template <class UnaryFunction,
|
||||
@@ -5,26 +7,55 @@
|
||||
class Reference = use_default,
|
||||
class Value = use_default>
|
||||
class transform_iterator
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
- : public iterator_adaptor</* see discussion */>
|
||||
{
|
||||
- friend class iterator_core_access;
|
||||
public:
|
||||
+ typedef /* see below */ value_type;
|
||||
+ typedef /* see below */ reference;
|
||||
+ typedef /* see below */ pointer;
|
||||
+ typedef iterator_traits<Iterator>::difference_type difference_type;
|
||||
+ typedef /* see below */ iterator_category;
|
||||
+
|
||||
transform_iterator();
|
||||
transform_iterator(Iterator const& x, UnaryFunction f);
|
||||
|
||||
|
||||
Issue 9.43x
|
||||
|
||||
- template<class OtherIterator, class R2, class V2>
|
||||
+ template<class F2, class I2, class R2, class V2>
|
||||
transform_iterator(
|
||||
- transform_iterator<UnaryFunction, OtherIterator, R2, V2> const& t
|
||||
- , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0 // exposition
|
||||
+ transform_iterator<F2, I2, R2, V2> const& t
|
||||
+ , typename enable_if_convertible<I2, Iterator>::type* = 0 // exposition only
|
||||
+ , typename enable_if_convertible<F2, UnaryFunction>::type* = 0 // exposition only
|
||||
);
|
||||
-
|
||||
|
||||
Issues 9.37x and 9.12
|
||||
|
||||
+ Iterator const& base() const;
|
||||
+ reference operator*() const;
|
||||
+ transform_iterator& operator++();
|
||||
+ transform_iterator& operator--();
|
||||
private:
|
||||
- typename transform_iterator::value_type dereference() const;
|
||||
- UnaryFunction m_f;
|
||||
+ Iterator m_iterator; // exposition only
|
||||
+ UnaryFunction m_f; // exposition only
|
||||
};
|
||||
|
||||
|
||||
Issue 9.41x
|
||||
|
||||
+If ``Reference`` is ``use_default`` then the ``reference`` member of
|
||||
+``transform_iterator`` is
|
||||
+``result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type``.
|
||||
+Otherwise, ``reference`` is ``Reference``.
|
||||
+
|
||||
+If ``Value`` is ``use_default`` then the ``value_type`` member is
|
||||
+``remove_cv<remove_reference<reference> >::type``. Otherwise,
|
||||
+``value_type`` is ``Value``.
|
||||
+
|
||||
+
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
+If ``Iterator`` models Readable Lvalue Iterator and if ``Iterator``
|
||||
+models Random Access Traversal Iterator, then ``iterator_category`` is
|
||||
+convertible to ``random_access_iterator_tag``. Otherwise, if
|
||||
+``Iterator`` models Bidirectional Traversal Iterator, then
|
||||
+``iterator_category`` is convertible to
|
||||
+``bidirectional_iterator_tag``. Otherwise ``iterator_category`` is
|
||||
+convertible to ``forward_iterator_tag``. If ``Iterator`` does not
|
||||
+model Readable Lvalue Iterator then ``iterator_category`` is
|
||||
+convertible to ``input_iterator_tag``.
|
||||
+
|
||||
+
|
||||
``transform_iterator`` requirements
|
||||
...................................
|
||||
|
||||
@@ -34,27 +65,55 @@
|
||||
where the type of ``f(*i)`` must be
|
||||
``result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type``.
|
||||
|
||||
|
||||
Issue 9.37x
|
||||
|
||||
-The type ``Iterator`` must at least model Readable Iterator. The
|
||||
-resulting ``transform_iterator`` models the most refined of the
|
||||
+The argument ``Iterator`` shall model Readable Iterator.
|
||||
+
|
||||
+
|
||||
+``transform_iterator`` models
|
||||
+.............................
|
||||
+
|
||||
+The resulting ``transform_iterator`` models the most refined of the
|
||||
following options that is also modeled by ``Iterator``.
|
||||
|
||||
- * Writable Lvalue Iterator if ``result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type`` is a non-const reference.
|
||||
+ * Writable Lvalue Iterator if ``transform_iterator::reference`` is a non-const reference.
|
||||
|
||||
- * Readable Lvalue Iterator if ``result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type`` is a const
|
||||
- reference.
|
||||
+ * Readable Lvalue Iterator if ``transform_iterator::reference`` is a const reference.
|
||||
|
||||
* Readable Iterator otherwise.
|
||||
|
||||
-
|
||||
The ``transform_iterator`` models the most refined standard traversal
|
||||
-concept that is modeled by ``Iterator``.
|
||||
+concept that is modeled by the ``Iterator`` argument.
|
||||
|
||||
Issue 9.41x
|
||||
|
||||
-The ``reference`` type of ``transform_iterator`` is
|
||||
-``result_of<UnaryFunction(iterator_traits<Iterator>::reference)>::type``.
|
||||
-The ``value_type`` is ``remove_cv<remove_reference<reference> >::type``.
|
||||
|
||||
Issue 9.37x.
|
||||
|
||||
+If ``transform_iterator`` is a model of Readable Lvalue Iterator then
|
||||
+it models the following original iterator concepts depending on what
|
||||
+the ``Iterator`` argument models.
|
||||
|
||||
-``transform_iterator`` public operations
|
||||
-........................................
|
||||
++-----------------------------------+---------------------------------+
|
||||
+| If ``Iterator`` models | then ``filter_iterator`` models |
|
||||
++===================================+=================================+
|
||||
+| Single Pass Iterator | Input Iterator |
|
||||
++-----------------------------------+---------------------------------+
|
||||
+| Forward Traversal Iterator | Forward Iterator |
|
||||
++-----------------------------------+---------------------------------+
|
||||
+| Bidirectional Traversal Iterator | Bidirectional Iterator |
|
||||
++-----------------------------------+---------------------------------+
|
||||
+| Random Access Traversal Iterator | Random Access Iterator |
|
||||
++-----------------------------------+---------------------------------+
|
||||
+
|
||||
+If ``transform_iterator`` models Writable Lvalue Iterator then it is a
|
||||
+mutable iterator (as defined in the old iterator requirements).
|
||||
+
|
||||
+``transform_iterator<F1, X, R1, V1>`` is interoperable with
|
||||
+``transform_iterator<F2, Y, R2, V2>`` if and only if ``X`` is
|
||||
+interoperable with ``Y``.
|
||||
+
|
||||
+
|
||||
+
|
||||
+``transform_iterator`` operations
|
||||
+.................................
|
||||
+
|
||||
+In addition to the operations required by the concepts modeled by
|
||||
+``transform_iterator``, ``transform_iterator`` provides the following
|
||||
+operations.
|
||||
|
||||
|
||||
``transform_iterator();``
|
||||
@@ -80,14 +139,30 @@
|
||||
:Returns: An instance of ``transform_iterator`` that is a copy of ``t``.
|
||||
:Requires: ``OtherIterator`` is implicitly convertible to ``Iterator``.
|
||||
|
||||
+
|
||||
+``Iterator const& base() const;``
|
||||
+
|
||||
+:Returns: ``m_iterator``
|
||||
+
|
||||
+
|
||||
``UnaryFunction functor() const;``
|
||||
|
||||
:Returns: ``m_f``
|
||||
|
||||
-``transform_iterator`` private operations
|
||||
-.........................................
|
||||
|
||||
-``typename transform_iterator::value_type dereference() const;``
|
||||
+``reference operator*() const;``
|
||||
|
||||
-:Returns: ``m_f(transform_iterator::dereference());``
|
||||
+:Returns: ``m_f(*m_iterator)``
|
||||
+
|
||||
+
|
||||
+``transform_iterator& operator++();``
|
||||
+
|
||||
+:Effects: ``++m_iterator``
|
||||
+:Returns: ``*this``
|
||||
+
|
||||
+
|
||||
+``transform_iterator& operator--();``
|
||||
+
|
||||
+:Effects: ``--m_iterator``
|
||||
+:Returns: ``*this``
|
||||
|
||||
Executable
+352
@@ -0,0 +1,352 @@
|
||||
<?xml version="1.0" encoding="utf-8" ?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||||
<meta name="generator" content="Docutils 0.3.1: http://docutils.sourceforge.net/" />
|
||||
<title>Zip Iterator</title>
|
||||
<meta name="author" content="David Abrahams, Thomas Becker" />
|
||||
<meta name="organization" content="Boost Consulting, Zephyr Associates, Inc." />
|
||||
<meta name="date" content="2004-01-19" />
|
||||
<meta name="copyright" content="Copyright David Abrahams and Thomas Becker 2003. All rights reserved" />
|
||||
<link rel="stylesheet" href="default.css" type="text/css" />
|
||||
</head>
|
||||
<body>
|
||||
<div class="document" id="zip-iterator">
|
||||
<h1 class="title">Zip Iterator</h1>
|
||||
<table class="docinfo" frame="void" rules="none">
|
||||
<col class="docinfo-name" />
|
||||
<col class="docinfo-content" />
|
||||
<tbody valign="top">
|
||||
<tr><th class="docinfo-name">Author:</th>
|
||||
<td>David Abrahams, Thomas Becker</td></tr>
|
||||
<tr><th class="docinfo-name">Contact:</th>
|
||||
<td><a class="first reference" href="mailto:dave@boost-consulting.com">dave@boost-consulting.com</a>, <a class="last reference" href="mailto:thomas@styleadvisor.com">thomas@styleadvisor.com</a></td></tr>
|
||||
<tr><th class="docinfo-name">Organization:</th>
|
||||
<td><a class="first reference" href="http://www.boost-consulting.com">Boost Consulting</a>, <a class="last reference" href="http://www.styleadvisor.com">Zephyr Associates, Inc.</a></td></tr>
|
||||
<tr><th class="docinfo-name">Date:</th>
|
||||
<td>2004-01-19</td></tr>
|
||||
<tr><th class="docinfo-name">Copyright:</th>
|
||||
<td>Copyright David Abrahams and Thomas Becker 2003. All rights reserved</td></tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">abstract:</th><td class="field-body">The zip iterator provides the ability to parallel-iterate
|
||||
over several controlled sequences simultaneously. A zip
|
||||
iterator is constructed from a tuple of iterators. Moving
|
||||
the zip iterator moves all the iterators in parallel.
|
||||
Dereferencing the zip iterator returns a tuple that contains
|
||||
the results of dereferencing the individual iterators.</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<div class="contents topic" id="table-of-contents">
|
||||
<p class="topic-title"><a name="table-of-contents">Table of Contents</a></p>
|
||||
<ul class="simple">
|
||||
<li><a class="reference" href="#zip-iterator-synopsis" id="id2" name="id2"><tt class="literal"><span class="pre">zip_iterator</span></tt> synopsis</a></li>
|
||||
<li><a class="reference" href="#zip-iterator-requirements" id="id3" name="id3"><tt class="literal"><span class="pre">zip_iterator</span></tt> requirements</a></li>
|
||||
<li><a class="reference" href="#zip-iterator-models" id="id4" name="id4"><tt class="literal"><span class="pre">zip_iterator</span></tt> models</a></li>
|
||||
<li><a class="reference" href="#zip-iterator-operations" id="id5" name="id5"><tt class="literal"><span class="pre">zip_iterator</span></tt> operations</a></li>
|
||||
<li><a class="reference" href="#examples" id="id6" name="id6">Examples</a></li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="section" id="zip-iterator-synopsis">
|
||||
<h1><a class="toc-backref" href="#id2" name="zip-iterator-synopsis"><tt class="literal"><span class="pre">zip_iterator</span></tt> synopsis</a></h1>
|
||||
<pre class="literal-block">
|
||||
template<typename IteratorTuple>
|
||||
class zip_iterator
|
||||
{
|
||||
|
||||
public:
|
||||
typedef /* see below */ reference;
|
||||
typedef reference value_type;
|
||||
typedef value_type* pointer;
|
||||
typedef /* see below */ difference_type;
|
||||
typedef /* see below */ iterator_category;
|
||||
|
||||
zip_iterator();
|
||||
zip_iterator(IteratorTuple iterator_tuple);
|
||||
|
||||
template<typename OtherIteratorTuple>
|
||||
zip_iterator(
|
||||
const zip_iterator<OtherIteratorTuple>& other
|
||||
, typename enable_if_convertible<
|
||||
OtherIteratorTuple
|
||||
, IteratorTuple>::type* = 0 // exposition only
|
||||
);
|
||||
|
||||
const IteratorTuple& get_iterator_tuple() const;
|
||||
|
||||
private:
|
||||
IteratorTuple m_iterator_tuple; // exposition only
|
||||
};
|
||||
|
||||
template<typename IteratorTuple>
|
||||
zip_iterator<IteratorTuple>
|
||||
make_zip_iterator(IteratorTuple t);
|
||||
</pre>
|
||||
<p>The <tt class="literal"><span class="pre">reference</span></tt> member of <tt class="literal"><span class="pre">zip_iterator</span></tt> is the type of the tuple
|
||||
made of the reference types of the iterator types in the <tt class="literal"><span class="pre">IteratorTuple</span></tt>
|
||||
argument.</p>
|
||||
<p>The <tt class="literal"><span class="pre">difference_type</span></tt> member of <tt class="literal"><span class="pre">zip_iterator</span></tt> is the <tt class="literal"><span class="pre">difference_type</span></tt>
|
||||
of the first of the iterator types in the <tt class="literal"><span class="pre">IteratorTuple</span></tt> argument.</p>
|
||||
<p>The <tt class="literal"><span class="pre">iterator_category</span></tt> member of <tt class="literal"><span class="pre">zip_iterator</span></tt> is convertible to the
|
||||
minimum of the traversal categories of the iterator types in the <tt class="literal"><span class="pre">IteratorTuple</span></tt>
|
||||
argument. For example, if the <tt class="literal"><span class="pre">zip_iterator</span></tt> holds only vector
|
||||
iterators, then <tt class="literal"><span class="pre">iterator_category</span></tt> is convertible to
|
||||
<tt class="literal"><span class="pre">boost::random_access_traversal_tag</span></tt>. If you add a list iterator, then
|
||||
<tt class="literal"><span class="pre">iterator_category</span></tt> will be convertible to <tt class="literal"><span class="pre">boost::bidirectional_traversal_tag</span></tt>,
|
||||
but no longer to <tt class="literal"><span class="pre">boost::random_access_traversal_tag</span></tt>.</p>
|
||||
</div>
|
||||
<div class="section" id="zip-iterator-requirements">
|
||||
<h1><a class="toc-backref" href="#id3" name="zip-iterator-requirements"><tt class="literal"><span class="pre">zip_iterator</span></tt> requirements</a></h1>
|
||||
<p>All iterator types in the argument <tt class="literal"><span class="pre">IteratorTuple</span></tt> shall model Readable Iterator.</p>
|
||||
</div>
|
||||
<div class="section" id="zip-iterator-models">
|
||||
<h1><a class="toc-backref" href="#id4" name="zip-iterator-models"><tt class="literal"><span class="pre">zip_iterator</span></tt> models</a></h1>
|
||||
<p>The resulting <tt class="literal"><span class="pre">zip_iterator</span></tt> models Readable Iterator.</p>
|
||||
<p>The fact that the <tt class="literal"><span class="pre">zip_iterator</span></tt> models only Readable Iterator does not
|
||||
prevent you from modifying the values that the individual iterators point
|
||||
to. The tuple returned by the <tt class="literal"><span class="pre">zip_iterator</span></tt>'s <tt class="literal"><span class="pre">operator*</span></tt> is a tuple
|
||||
constructed from the reference types of the individual iterators, not
|
||||
their value types. For example, if <tt class="literal"><span class="pre">zip_it</span></tt> is a <tt class="literal"><span class="pre">zip_iterator</span></tt> whose
|
||||
first member iterator is an <tt class="literal"><span class="pre">std::vector<double>::iterator</span></tt>, then the
|
||||
following line will modify the value which the first member iterator of
|
||||
<tt class="literal"><span class="pre">zip_it</span></tt> currently points to:</p>
|
||||
<pre class="literal-block">
|
||||
zip_it->get<0>() = 42.0;
|
||||
</pre>
|
||||
<p>Consider the set of standard traversal concepts obtained by taking
|
||||
the most refined standard traversal concept modeled by each individual
|
||||
iterator type in the <tt class="literal"><span class="pre">IteratorTuple</span></tt> argument.The <tt class="literal"><span class="pre">zip_iterator</span></tt>
|
||||
models the least refined standard traversal concept in this set.</p>
|
||||
<p><tt class="literal"><span class="pre">zip_iterator<IteratorTuple1></span></tt> is interoperable with
|
||||
<tt class="literal"><span class="pre">zip_iterator<IteratorTuple2></span></tt> if and only if <tt class="literal"><span class="pre">IteratorTuple1</span></tt>
|
||||
is interoperable with <tt class="literal"><span class="pre">IteratorTuple2</span></tt>.</p>
|
||||
</div>
|
||||
<div class="section" id="zip-iterator-operations">
|
||||
<h1><a class="toc-backref" href="#id5" name="zip-iterator-operations"><tt class="literal"><span class="pre">zip_iterator</span></tt> operations</a></h1>
|
||||
<p>In addition to the operations required by the concepts modeled by
|
||||
<tt class="literal"><span class="pre">zip_iterator</span></tt>, <tt class="literal"><span class="pre">zip_iterator</span></tt> provides the following
|
||||
operations.</p>
|
||||
<p><tt class="literal"><span class="pre">zip_iterator();</span></tt></p>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">zip_iterator</span></tt> with <tt class="literal"><span class="pre">m_iterator_tuple</span></tt>
|
||||
default constructed.</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<p><tt class="literal"><span class="pre">zip_iterator(IteratorTuple</span> <span class="pre">iterator_tuple);</span></tt></p>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">zip_iterator</span></tt> with <tt class="literal"><span class="pre">m_iterator_tuple</span></tt>
|
||||
initialized to <tt class="literal"><span class="pre">iterator_tuple</span></tt>.</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<pre class="literal-block">
|
||||
template<typename OtherIteratorTuple>
|
||||
zip_iterator(
|
||||
const zip_iterator<OtherIteratorTuple>& other
|
||||
, typename enable_if_convertible<
|
||||
OtherIteratorTuple
|
||||
, IteratorTuple>::type* = 0 // exposition only
|
||||
);
|
||||
</pre>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">zip_iterator</span></tt> that is a copy of <tt class="literal"><span class="pre">other</span></tt>.</td>
|
||||
</tr>
|
||||
<tr class="field"><th class="field-name">Requires:</th><td class="field-body"><tt class="literal"><span class="pre">OtherIteratorTuple</span></tt> is implicitly convertible to <tt class="literal"><span class="pre">IteratorTuple</span></tt>.</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<p><tt class="literal"><span class="pre">const</span> <span class="pre">IteratorTuple&</span> <span class="pre">get_iterator_tuple()</span> <span class="pre">const;</span></tt></p>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="literal"><span class="pre">m_iterator_tuple</span></tt></td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<p><tt class="literal"><span class="pre">reference</span> <span class="pre">operator*()</span> <span class="pre">const;</span></tt></p>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">A tuple consisting of the results of dereferencing all iterators in
|
||||
<tt class="literal"><span class="pre">m_iterator_tuple</span></tt>.</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<p><tt class="literal"><span class="pre">zip_iterator&</span> <span class="pre">operator++();</span></tt></p>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Effects:</th><td class="field-body">Increments each iterator in <tt class="literal"><span class="pre">m_iterator_tuple</span></tt>.</td>
|
||||
</tr>
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="literal"><span class="pre">*this</span></tt></td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<p><tt class="literal"><span class="pre">zip_iterator&</span> <span class="pre">operator--();</span></tt></p>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Effects:</th><td class="field-body">Decrements each iterator in <tt class="literal"><span class="pre">m_iterator_tuple</span></tt>.</td>
|
||||
</tr>
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="literal"><span class="pre">*this</span></tt></td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<pre class="literal-block">
|
||||
template<typename IteratorTuple>
|
||||
zip_iterator<IteratorTuple>
|
||||
make_zip_iterator(IteratorTuple t);
|
||||
</pre>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">zip_iterator<IteratorTuple></span></tt> with <tt class="literal"><span class="pre">m_iterator_tuple</span></tt>
|
||||
initialized to <tt class="literal"><span class="pre">t</span></tt>.</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<pre class="literal-block">
|
||||
template<typename IteratorTuple>
|
||||
zip_iterator<IteratorTuple>
|
||||
make_zip_iterator(IteratorTuple t);
|
||||
</pre>
|
||||
<table class="field-list" frame="void" rules="none">
|
||||
<col class="field-name" />
|
||||
<col class="field-body" />
|
||||
<tbody valign="top">
|
||||
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">zip_iterator<IteratorTuple></span></tt> with <tt class="literal"><span class="pre">m_iterator_tuple</span></tt>
|
||||
initialized to <tt class="literal"><span class="pre">t</span></tt>.</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
</div>
|
||||
<div class="section" id="examples">
|
||||
<h1><a class="toc-backref" href="#id6" name="examples">Examples</a></h1>
|
||||
<p>There are two main types of applications of the <tt class="literal"><span class="pre">zip_iterator</span></tt>. The first
|
||||
one concerns runtime efficiency: If one has several controlled sequences
|
||||
of the same length that must be somehow processed, e.g., with the
|
||||
<tt class="literal"><span class="pre">for_each</span></tt> algorithm, then it is more efficient to perform just
|
||||
one parallel-iteration rather than several individual iterations. For an
|
||||
example, assume that <tt class="literal"><span class="pre">vect_of_doubles</span></tt> and <tt class="literal"><span class="pre">vect_of_ints</span></tt>
|
||||
are two vectors of equal length containing doubles and ints, respectively,
|
||||
and consider the following two iterations:</p>
|
||||
<pre class="literal-block">
|
||||
std::vector<double>::const_iterator beg1 = vect_of_doubles.begin();
|
||||
std::vector<double>::const_iterator end1 = vect_of_doubles.end();
|
||||
std::vector<int>::const_iterator beg2 = vect_of_ints.begin();
|
||||
std::vector<int>::const_iterator end2 = vect_of_ints.end();
|
||||
|
||||
std::for_each(beg1, end1, func_0());
|
||||
std::for_each(beg2, end2, func_1());
|
||||
</pre>
|
||||
<p>These two iterations can now be replaced with a single one as follows:</p>
|
||||
<pre class="literal-block">
|
||||
std::for_each(
|
||||
boost::make_zip_iterator(
|
||||
boost::make_tuple(beg1, beg2)
|
||||
),
|
||||
boost::make_zip_iterator(
|
||||
boost::make_tuple(end1, end2)
|
||||
),
|
||||
zip_func()
|
||||
);
|
||||
</pre>
|
||||
<p>A non-generic implementation of <tt class="literal"><span class="pre">zip_func</span></tt> could look as follows:</p>
|
||||
<pre class="literal-block">
|
||||
struct zip_func :
|
||||
public std::unary_function<const boost::tuple<const double&, const int&>&, void>
|
||||
{
|
||||
void operator()(const boost::tuple<const double&, const int&>& t) const
|
||||
{
|
||||
m_f0(t.get<0>());
|
||||
m_f1(t.get<1>());
|
||||
}
|
||||
|
||||
private:
|
||||
func_0 m_f0;
|
||||
func_1 m_f1;
|
||||
};
|
||||
</pre>
|
||||
<p>The second important application of the <tt class="literal"><span class="pre">zip_iterator</span></tt> is as a building block
|
||||
to make combining iterators. A combining iterator is an iterator
|
||||
that parallel-iterates over several controlled sequences and, upon
|
||||
dereferencing, returns the result of applying a functor to the values of the
|
||||
sequences at the respective positions. This can now be achieved by using the
|
||||
<tt class="literal"><span class="pre">zip_iterator</span></tt> in conjunction with the <tt class="literal"><span class="pre">transform_iterator</span></tt>.</p>
|
||||
<p>Suppose, for example, that you have two vectors of doubles, say
|
||||
<tt class="literal"><span class="pre">vect_1</span></tt> and <tt class="literal"><span class="pre">vect_2</span></tt>, and you need to expose to a client
|
||||
a controlled sequence containing the products of the elements of
|
||||
<tt class="literal"><span class="pre">vect_1</span></tt> and <tt class="literal"><span class="pre">vect_2</span></tt>. Rather than placing these products
|
||||
in a third vector, you can use a combining iterator that calculates the
|
||||
products on the fly. Let us assume that <tt class="literal"><span class="pre">tuple_multiplies</span></tt> is a
|
||||
functor that works like <tt class="literal"><span class="pre">std::multiplies</span></tt>, except that it takes
|
||||
its two arguments packaged in a tuple. Then the two iterators
|
||||
<tt class="literal"><span class="pre">it_begin</span></tt> and <tt class="literal"><span class="pre">it_end</span></tt> defined below delimit a controlled
|
||||
sequence containing the products of the elements of <tt class="literal"><span class="pre">vect_1</span></tt> and
|
||||
<tt class="literal"><span class="pre">vect_2</span></tt>:</p>
|
||||
<pre class="literal-block">
|
||||
typedef boost::tuple<
|
||||
std::vector<double>::const_iterator,
|
||||
std::vector<double>::const_iterator
|
||||
> the_iterator_tuple;
|
||||
|
||||
typedef boost::zip_iterator<
|
||||
the_iterator_tuple
|
||||
> the_zip_iterator;
|
||||
|
||||
typedef boost::transform_iterator<
|
||||
tuple_multiplies<double>,
|
||||
the_zip_iterator
|
||||
> the_transform_iterator;
|
||||
|
||||
the_transform_iterator it_begin(
|
||||
the_zip_iterator(
|
||||
the_iterator_tuple(
|
||||
vect_1.begin(),
|
||||
vect_2.begin()
|
||||
)
|
||||
),
|
||||
tuple_multiplies<double>()
|
||||
);
|
||||
|
||||
the_transform_iterator it_end(
|
||||
the_zip_iterator(
|
||||
the_iterator_tuple(
|
||||
vect_1.end(),
|
||||
vect_2.end()
|
||||
)
|
||||
),
|
||||
tuple_multiplies<double>()
|
||||
);
|
||||
</pre>
|
||||
<p>The source code for these examples can be found <a class="reference" href="../example/zip_iterator_examples.cpp">here</a>.</p>
|
||||
</div>
|
||||
</div>
|
||||
<hr class="footer" />
|
||||
<div class="footer">
|
||||
<a class="reference" href="zip_iterator.rst">View document source</a>.
|
||||
Generated by <a class="reference" href="http://docutils.sourceforge.net/">Docutils</a> from <a class="reference" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> source.
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
Executable
BIN
Binary file not shown.
Executable
+25
@@ -0,0 +1,25 @@
|
||||
+++++++++++++
|
||||
Zip Iterator
|
||||
+++++++++++++
|
||||
|
||||
:Author: David Abrahams, Thomas Becker
|
||||
:Contact: dave@boost-consulting.com, thomas@styleadvisor.com
|
||||
:organization: `Boost Consulting`_, `Zephyr Associates, Inc.`_
|
||||
:date: $Date$
|
||||
:copyright: Copyright David Abrahams and Thomas Becker 2003. All rights reserved
|
||||
|
||||
.. _`Boost Consulting`: http://www.boost-consulting.com
|
||||
.. _`Zephyr Associates, Inc.`: http://www.styleadvisor.com
|
||||
|
||||
:abstract:
|
||||
|
||||
.. include:: zip_iterator_abstract.rst
|
||||
|
||||
.. contents:: Table of Contents
|
||||
|
||||
``zip_iterator`` synopsis
|
||||
...............................
|
||||
|
||||
.. include:: zip_iterator_ref.rst
|
||||
.. include:: make_zip_iterator.rst
|
||||
.. include:: zip_iterator_eg.rst
|
||||
Executable
+6
@@ -0,0 +1,6 @@
|
||||
The zip iterator provides the ability to parallel-iterate
|
||||
over several controlled sequences simultaneously. A zip
|
||||
iterator is constructed from a tuple of iterators. Moving
|
||||
the zip iterator moves all the iterators in parallel.
|
||||
Dereferencing the zip iterator returns a tuple that contains
|
||||
the results of dereferencing the individual iterators.
|
||||
Executable
+117
@@ -0,0 +1,117 @@
|
||||
Examples
|
||||
........
|
||||
|
||||
There are two main types of applications of the ``zip_iterator``. The first
|
||||
one concerns runtime efficiency: If one has several controlled sequences
|
||||
of the same length that must be somehow processed, e.g., with the
|
||||
``for_each`` algorithm, then it is more efficient to perform just
|
||||
one parallel-iteration rather than several individual iterations. For an
|
||||
example, assume that ``vect_of_doubles`` and ``vect_of_ints``
|
||||
are two vectors of equal length containing doubles and ints, respectively,
|
||||
and consider the following two iterations:
|
||||
|
||||
::
|
||||
|
||||
|
||||
std::vector<double>::const_iterator beg1 = vect_of_doubles.begin();
|
||||
std::vector<double>::const_iterator end1 = vect_of_doubles.end();
|
||||
std::vector<int>::const_iterator beg2 = vect_of_ints.begin();
|
||||
std::vector<int>::const_iterator end2 = vect_of_ints.end();
|
||||
|
||||
std::for_each(beg1, end1, func_0());
|
||||
std::for_each(beg2, end2, func_1());
|
||||
|
||||
These two iterations can now be replaced with a single one as follows:
|
||||
|
||||
::
|
||||
|
||||
|
||||
std::for_each(
|
||||
boost::make_zip_iterator(
|
||||
boost::make_tuple(beg1, beg2)
|
||||
),
|
||||
boost::make_zip_iterator(
|
||||
boost::make_tuple(end1, end2)
|
||||
),
|
||||
zip_func()
|
||||
);
|
||||
|
||||
A non-generic implementation of ``zip_func`` could look as follows:
|
||||
|
||||
::
|
||||
|
||||
|
||||
struct zip_func :
|
||||
public std::unary_function<const boost::tuple<const double&, const int&>&, void>
|
||||
{
|
||||
void operator()(const boost::tuple<const double&, const int&>& t) const
|
||||
{
|
||||
m_f0(t.get<0>());
|
||||
m_f1(t.get<1>());
|
||||
}
|
||||
|
||||
private:
|
||||
func_0 m_f0;
|
||||
func_1 m_f1;
|
||||
};
|
||||
|
||||
The second important application of the ``zip_iterator`` is as a building block
|
||||
to make combining iterators. A combining iterator is an iterator
|
||||
that parallel-iterates over several controlled sequences and, upon
|
||||
dereferencing, returns the result of applying a functor to the values of the
|
||||
sequences at the respective positions. This can now be achieved by using the
|
||||
``zip_iterator`` in conjunction with the ``transform_iterator``.
|
||||
|
||||
Suppose, for example, that you have two vectors of doubles, say
|
||||
``vect_1`` and ``vect_2``, and you need to expose to a client
|
||||
a controlled sequence containing the products of the elements of
|
||||
``vect_1`` and ``vect_2``. Rather than placing these products
|
||||
in a third vector, you can use a combining iterator that calculates the
|
||||
products on the fly. Let us assume that ``tuple_multiplies`` is a
|
||||
functor that works like ``std::multiplies``, except that it takes
|
||||
its two arguments packaged in a tuple. Then the two iterators
|
||||
``it_begin`` and ``it_end`` defined below delimit a controlled
|
||||
sequence containing the products of the elements of ``vect_1`` and
|
||||
``vect_2``:
|
||||
|
||||
::
|
||||
|
||||
|
||||
typedef boost::tuple<
|
||||
std::vector<double>::const_iterator,
|
||||
std::vector<double>::const_iterator
|
||||
> the_iterator_tuple;
|
||||
|
||||
typedef boost::zip_iterator<
|
||||
the_iterator_tuple
|
||||
> the_zip_iterator;
|
||||
|
||||
typedef boost::transform_iterator<
|
||||
tuple_multiplies<double>,
|
||||
the_zip_iterator
|
||||
> the_transform_iterator;
|
||||
|
||||
the_transform_iterator it_begin(
|
||||
the_zip_iterator(
|
||||
the_iterator_tuple(
|
||||
vect_1.begin(),
|
||||
vect_2.begin()
|
||||
)
|
||||
),
|
||||
tuple_multiplies<double>()
|
||||
);
|
||||
|
||||
the_transform_iterator it_end(
|
||||
the_zip_iterator(
|
||||
the_iterator_tuple(
|
||||
vect_1.end(),
|
||||
vect_2.end()
|
||||
)
|
||||
),
|
||||
tuple_multiplies<double>()
|
||||
);
|
||||
|
||||
|
||||
The source code for these examples can be found `here`__.
|
||||
|
||||
__ ../example/zip_iterator_examples.cpp
|
||||
Executable
+152
@@ -0,0 +1,152 @@
|
||||
|
||||
::
|
||||
|
||||
template<typename IteratorTuple>
|
||||
class zip_iterator
|
||||
{
|
||||
|
||||
public:
|
||||
typedef /* see below */ reference;
|
||||
typedef reference value_type;
|
||||
typedef value_type* pointer;
|
||||
typedef /* see below */ difference_type;
|
||||
typedef /* see below */ iterator_category;
|
||||
|
||||
zip_iterator();
|
||||
zip_iterator(IteratorTuple iterator_tuple);
|
||||
|
||||
template<typename OtherIteratorTuple>
|
||||
zip_iterator(
|
||||
const zip_iterator<OtherIteratorTuple>& other
|
||||
, typename enable_if_convertible<
|
||||
OtherIteratorTuple
|
||||
, IteratorTuple>::type* = 0 // exposition only
|
||||
);
|
||||
|
||||
const IteratorTuple& get_iterator_tuple() const;
|
||||
|
||||
private:
|
||||
IteratorTuple m_iterator_tuple; // exposition only
|
||||
};
|
||||
|
||||
template<typename IteratorTuple>
|
||||
zip_iterator<IteratorTuple>
|
||||
make_zip_iterator(IteratorTuple t);
|
||||
|
||||
|
||||
The ``reference`` member of ``zip_iterator`` is the type of the tuple
|
||||
made of the reference types of the iterator types in the ``IteratorTuple``
|
||||
argument.
|
||||
|
||||
The ``difference_type`` member of ``zip_iterator`` is the ``difference_type``
|
||||
of the first of the iterator types in the ``IteratorTuple`` argument.
|
||||
|
||||
The ``iterator_category`` member of ``zip_iterator`` is convertible to the
|
||||
minimum of the traversal categories of the iterator types in the ``IteratorTuple``
|
||||
argument. For example, if the ``zip_iterator`` holds only vector
|
||||
iterators, then ``iterator_category`` is convertible to
|
||||
``boost::random_access_traversal_tag``. If you add a list iterator, then
|
||||
``iterator_category`` will be convertible to ``boost::bidirectional_traversal_tag``,
|
||||
but no longer to ``boost::random_access_traversal_tag``.
|
||||
|
||||
|
||||
``zip_iterator`` requirements
|
||||
...................................
|
||||
|
||||
All iterator types in the argument ``IteratorTuple`` shall model Readable Iterator.
|
||||
|
||||
|
||||
``zip_iterator`` models
|
||||
.............................
|
||||
|
||||
The resulting ``zip_iterator`` models Readable Iterator.
|
||||
|
||||
The fact that the ``zip_iterator`` models only Readable Iterator does not
|
||||
prevent you from modifying the values that the individual iterators point
|
||||
to. The tuple returned by the ``zip_iterator``'s ``operator*`` is a tuple
|
||||
constructed from the reference types of the individual iterators, not
|
||||
their value types. For example, if ``zip_it`` is a ``zip_iterator`` whose
|
||||
first member iterator is an ``std::vector<double>::iterator``, then the
|
||||
following line will modify the value which the first member iterator of
|
||||
``zip_it`` currently points to:
|
||||
|
||||
::
|
||||
|
||||
zip_it->get<0>() = 42.0;
|
||||
|
||||
|
||||
Consider the set of standard traversal concepts obtained by taking
|
||||
the most refined standard traversal concept modeled by each individual
|
||||
iterator type in the ``IteratorTuple`` argument.The ``zip_iterator``
|
||||
models the least refined standard traversal concept in this set.
|
||||
|
||||
``zip_iterator<IteratorTuple1>`` is interoperable with
|
||||
``zip_iterator<IteratorTuple2>`` if and only if ``IteratorTuple1``
|
||||
is interoperable with ``IteratorTuple2``.
|
||||
|
||||
|
||||
|
||||
``zip_iterator`` operations
|
||||
.................................
|
||||
|
||||
In addition to the operations required by the concepts modeled by
|
||||
``zip_iterator``, ``zip_iterator`` provides the following
|
||||
operations.
|
||||
|
||||
|
||||
``zip_iterator();``
|
||||
|
||||
:Returns: An instance of ``zip_iterator`` with ``m_iterator_tuple``
|
||||
default constructed.
|
||||
|
||||
|
||||
``zip_iterator(IteratorTuple iterator_tuple);``
|
||||
|
||||
:Returns: An instance of ``zip_iterator`` with ``m_iterator_tuple``
|
||||
initialized to ``iterator_tuple``.
|
||||
|
||||
|
||||
::
|
||||
|
||||
template<typename OtherIteratorTuple>
|
||||
zip_iterator(
|
||||
const zip_iterator<OtherIteratorTuple>& other
|
||||
, typename enable_if_convertible<
|
||||
OtherIteratorTuple
|
||||
, IteratorTuple>::type* = 0 // exposition only
|
||||
);
|
||||
|
||||
:Returns: An instance of ``zip_iterator`` that is a copy of ``other``.
|
||||
:Requires: ``OtherIteratorTuple`` is implicitly convertible to ``IteratorTuple``.
|
||||
|
||||
|
||||
``const IteratorTuple& get_iterator_tuple() const;``
|
||||
|
||||
:Returns: ``m_iterator_tuple``
|
||||
|
||||
|
||||
``reference operator*() const;``
|
||||
|
||||
:Returns: A tuple consisting of the results of dereferencing all iterators in
|
||||
``m_iterator_tuple``.
|
||||
|
||||
|
||||
``zip_iterator& operator++();``
|
||||
|
||||
:Effects: Increments each iterator in ``m_iterator_tuple``.
|
||||
:Returns: ``*this``
|
||||
|
||||
|
||||
``zip_iterator& operator--();``
|
||||
|
||||
:Effects: Decrements each iterator in ``m_iterator_tuple``.
|
||||
:Returns: ``*this``
|
||||
|
||||
::
|
||||
|
||||
template<typename IteratorTuple>
|
||||
zip_iterator<IteratorTuple>
|
||||
make_zip_iterator(IteratorTuple t);
|
||||
|
||||
:Returns: An instance of ``zip_iterator<IteratorTuple>`` with ``m_iterator_tuple``
|
||||
initialized to ``t``.
|
||||
Executable
+59
@@ -0,0 +1,59 @@
|
||||
// Copyright David Abrahams 2004. Use, modification and distribution is
|
||||
// subject to 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)
|
||||
|
||||
#include <boost/iterator/iterator_adaptor.hpp>
|
||||
#include <boost/pending/iterator_tests.hpp>
|
||||
#include <cassert>
|
||||
|
||||
struct mutable_it : boost::iterator_adaptor<mutable_it,int*>
|
||||
{
|
||||
typedef boost::iterator_adaptor<mutable_it,int*> super_t;
|
||||
|
||||
mutable_it();
|
||||
explicit mutable_it(int* p) : super_t(p) {}
|
||||
|
||||
bool equal(mutable_it const& rhs) const
|
||||
{
|
||||
return this->base() == rhs.base();
|
||||
}
|
||||
};
|
||||
|
||||
struct constant_it : boost::iterator_adaptor<constant_it,int const*>
|
||||
{
|
||||
typedef boost::iterator_adaptor<constant_it,int const*> super_t;
|
||||
|
||||
constant_it();
|
||||
explicit constant_it(int* p) : super_t(p) {}
|
||||
constant_it(mutable_it const& x) : super_t(x.base()) {}
|
||||
|
||||
bool equal(constant_it const& rhs) const
|
||||
{
|
||||
return this->base() == rhs.base();
|
||||
}
|
||||
};
|
||||
|
||||
int main()
|
||||
{
|
||||
int data[] = { 49, 77 };
|
||||
|
||||
mutable_it i(data);
|
||||
constant_it j(data + 1);
|
||||
assert(i < j);
|
||||
assert(j > i);
|
||||
assert(i <= j);
|
||||
assert(j >= i);
|
||||
assert(j - i == 1);
|
||||
assert(i - j == -1);
|
||||
|
||||
constant_it k = i;
|
||||
|
||||
assert(!(i < k));
|
||||
assert(!(k > i));
|
||||
assert(i <= k);
|
||||
assert(k >= i);
|
||||
assert(k - i == 0);
|
||||
assert(i - k == 0);
|
||||
|
||||
return 0;
|
||||
}
|
||||
Reference in New Issue
Block a user