CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType > Class Template Reference

A STL compatible random access iterator for container elements accessible by index. More...

#include <IndexedElementIterator.hpp>

Inheritance diagram for CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType >:

Public Member Functions
template<typename ValueType2 , typename AccessFunc2 , typename IndexType2 >
	IndexedElementIterator (const IndexedElementIterator< ValueType2, AccessFunc2, IndexType2 > &it)
	Constructs and initializes the iterator with another iterator object. More...
	IndexedElementIterator (const AccessFunc &access_func, IndexType start_idx)
	Constructs and initializes the iterator with the access function access_func and the start element index start_idx. More...
const AccessFunc &	getAccessFunc () const
IndexType	getIndex () const
template<typename ValueType2 , typename AccessFunc2 , typename IndexType2 >
CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType >::DifferenceType	distance_to (const IndexedElementIterator< ValueType2, AccessFunc2, IndexType2 > &it) const

Detailed Description

template<typename ValueType, typename AccessFunc, typename IndexType = std::size_t>
class CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType >

A STL compatible random access iterator for container elements accessible by index.

The rationale for IndexedElementIterator is to allow STL-style iteration over the elements of container classes which do not provide suitable iterators on their own, but allow element access by some sort of consecutive index. IndexedElementIterator is a random access iterator and therefore provides both increment and decrement operations and constant-time methods for moving forward and backward in arbitrary-sized steps. Random access iterators essentially provide all of the operations of ordinary C/C++ pointer arithmetic (see [STLRAI] for details).

As an example consider the class StringContainer which provides access to stored C++ strings via a method getString(std::size_t idx):

class StringContainer
{
 
public:
 
   .....
 
   std::string getString(std::size_t idx); // retrieves a reference to a stored string by its index
   std::size_t getNumStrings() const;      // returns the total number of stored strings
 
   .....
 
};

To implement an iterator for string traversal using IndexedElementIterator, one first has to define a StringContainer access functor that returns a reference to the string stored at a particular index.

A possible implementation of this functor may look like this:

class StringAccessFunc
{
   
public:
   StringAccessFunc(StringContainer* cntnr): container(ctnr) {}
 
   std::string& operator()(std::size_t idx) const {
      return container->getString(idx);
   }
 
   bool operator==(const StringAccessFunc& func) const {
      return (func.container == container);
   }
 
private:
   StringContainer* cntnr;
};

With StringAccessFunc in hands, the type of the string traversal iterator for StringContainer is defined as:

typedef IndexedElementIterator<std::string, StringAccessFunc> StringIterator;

StringIterator can then easily be used with STL-algorithms, e.g. to find a particular string in a StringContainer instance:

StringContainer str_molGraph;
 
   ..... // do something with 'str_container'
 
// does 'str_container' contain the string "foobar"?
 
bool contains_foobar = (std::find(StringIterator(&str_container, 0),        
                                  StringIterator(&str_container, str_container.getNumStrings()),
                                  std::string("foobar")) 
                        != StringIterator(&str_container, str_container.getNumStrings())); 

Template Parameters

ValueType	The type of the elements accessed by the iterator.
AccessFunc	The type of the functor object used to access the elements by index.
IndexType	The type of the indices used to access the elements.

Constructor & Destructor Documentation

IndexedElementIterator() [1/2]

template<typename ValueType , typename AccessFunc , typename IndexType = std::size_t>

template<typename ValueType2 , typename AccessFunc2 , typename IndexType2 >

CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType >::IndexedElementIterator ( const IndexedElementIterator< ValueType2, AccessFunc2, IndexType2 > &  it )

inline

Constructs and initializes the iterator with another iterator object.

Parameters

it	The other iterator.

IndexedElementIterator() [2/2]

template<typename ValueType , typename AccessFunc , typename IndexType = std::size_t>

CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType >::IndexedElementIterator ( const AccessFunc &  access_func, IndexType  start_idx  )

inline

Constructs and initializes the iterator with the access function access_func and the start element index start_idx.

Parameters

access_func	The element access function to use.
start_idx	The index of the first element the iterator will point to.

Member Function Documentation

getAccessFunc()

template<typename ValueType , typename AccessFunc , typename IndexType >

const AccessFunc & CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType >::getAccessFunc

getIndex()

template<typename ValueType , typename AccessFunc , typename IndexType >

IndexType CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType >::getIndex

distance_to()

template<typename ValueType , typename AccessFunc , typename IndexType = std::size_t>

template<typename ValueType2 , typename AccessFunc2 , typename IndexType2 >

CDPL::Util::IndexedElementIterator<ValueType, AccessFunc, IndexType>::DifferenceType CDPL::Util::IndexedElementIterator< ValueType, AccessFunc, IndexType >::distance_to

(

const IndexedElementIterator< ValueType2, AccessFunc2, IndexType2 > &

it

)

const

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

• IndexedElementIterator.hpp