JLANG::JObjectSampler< T, JSampler_t > Class Template Reference

Auxiliary class to sample objects from a JRewindableObjectIterator. More...

#include <JObjectSampler.hh>

Inheritance diagram for JLANG::JObjectSampler< T, JSampler_t >:

Public Types
typedef JObjectIterator< T > ::pointer_type	pointer_type

Public Member Functions
	JObjectSampler (JRewindableObjectIterator< T > &input)
	Constructor. More...
	JObjectSampler (JRewindableObjectIterator< T > &input, const JSampler_t< T > &sampler)
	Constructor. More...
virtual bool	hasNext () override
	Check availability of next element. More...
virtual const pointer_type &	next () override
	Get next element. More...
const JSampler_t< T > &	getSampler () const
	Get sampler. More...
JSampler_t< T > &	getSampler ()
	Get sampler. More...
virtual skip_type	skip (const skip_type ns)
	Skip items. More...

Protected Attributes
JRewindableObjectIterator< T > &	in
JSampler_t< T >	sampler
JPointer< T >	ps
bool	has_next

Detailed Description

template<class T, template< class > class JSampler_t = JSampler>
class JLANG::JObjectSampler< T, JSampler_t >

Auxiliary class to sample objects from a JRewindableObjectIterator.

This class can be used for iterations that are different than strict sequential. The first template parameter corresponds to the data type of the iteration and the second to the sampler.
The sampling is defined by the number of objects to be skipped. The number of objects to be skipped is returned by the function object operator of the sampler which takes the actual object as input.
The default JSampler corresponds to zero elements to be skipped, which in turn corresponds to the iteration of all objects in sequential order.

The JObjectSampler class implements the JObjectIterator using a reference to a JRewindableObjectIterator object so that the sampling of objects can continue ad infinitum.

Method JObjectSampler::hasNext normally returns true, unless

• there are no available objects; or
• given sampler rejects every object.

Note that the internal sampler is a copy of the specified sampler and not a reference thereof.

Definition at line 40 of file JObjectSampler.hh.

Member Typedef Documentation

template<class T, template< class > class JSampler_t = JSampler>

typedef JObjectIterator<T>::pointer_type JLANG::JObjectSampler< T, JSampler_t >::pointer_type

Definition at line 45 of file JObjectSampler.hh.

Constructor & Destructor Documentation

template<class T, template< class > class JSampler_t = JSampler>

JLANG::JObjectSampler< T, JSampler_t >::JObjectSampler ( JRewindableObjectIterator< T > &  input )

inline

Constructor.

Parameters

input

input

Definition at line 52 of file JObjectSampler.hh.

                                                        :
      in      (input),
      has_next(false)
    {}

template<class T, template< class > class JSampler_t = JSampler>

JLANG::JObjectSampler< T, JSampler_t >::JObjectSampler ( JRewindableObjectIterator< T > &  input, const JSampler_t< T > &  sampler  )

inline

Constructor.

Parameters

input	input
sampler	sampler

Definition at line 64 of file JObjectSampler.hh.

                                                          :
      in      (input),
      has_next(false)
    {
      this->sampler = sampler;
    }

Member Function Documentation

template<class T, template< class > class JSampler_t = JSampler>

virtual bool JLANG::JObjectSampler< T, JSampler_t >::hasNext ( )

inlineoverridevirtual

Check availability of next element.

Returns

true if the iteration has more elements; else false

Implements JLANG::JObjectIterator< T >.

Definition at line 78 of file JObjectSampler.hh.

    {
      while (!has_next) {

        if (!in.hasNext()) {
          in.rewind();
        }

        if (in.hasNext()) {

          ps.set(in.next());
          
          skip_type ns = sampler(*ps);

          if (ns == 0) {

            has_next = true;

          } else {

            while ((ns -= in.skip(ns)) != 0) {
              in.rewind();
            }
          }

        } else {

          // nothing to sample
          
          break;
        }
      }

      return has_next;
    }

template<class T, template< class > class JSampler_t = JSampler>

virtual const pointer_type& JLANG::JObjectSampler< T, JSampler_t >::next ( )

inlineoverridevirtual

Get next element.

Returns

pointer to element

Implements JLANG::JObjectIterator< T >.

Definition at line 120 of file JObjectSampler.hh.

    {
      if (!has_next) {
        ps.reset(NULL);
      }

      has_next = false;
      
      return ps;
    }

template<class T, template< class > class JSampler_t = JSampler>

const JSampler_t<T>& JLANG::JObjectSampler< T, JSampler_t >::getSampler ( ) const

inline

Get sampler.

Returns

sampler

Definition at line 137 of file JObjectSampler.hh.

    {
      return sampler;
    }

template<class T, template< class > class JSampler_t = JSampler>

JSampler_t<T>& JLANG::JObjectSampler< T, JSampler_t >::getSampler ( )

inline

Get sampler.

Returns

sampler

Definition at line 148 of file JObjectSampler.hh.

    {
      return sampler;
    }

template<class T>

virtual skip_type JLANG::JObjectIterator< T >::skip ( const skip_type  ns )

inlinevirtualinherited

Skip items.

Parameters

ns	number of items to skip

Returns

number of items skipped

Reimplemented in JLANG::JPipe< T >, JLANG::JPipe< JTail_t >, JLANG::JPipe< JHead_t >, JLANG::JSTDObjectIterator< T >, JLANG::JAbstractObjectReader< T >, JLANG::JAbstractObjectReader< const event_type >, JLANG::JAbstractObjectReader< JNullType >, JLANG::JAbstractObjectReader< const T >, JLANG::JAbstractObjectReader< JTail_t >, JLANG::JAbstractObjectReader< JHead_t >, JLANG::JAbstractObjectReader< KM3NETDAQ::KM3NETDAQ::JDAQEvent >, and JLANG::JAbstractObjectReader< JDAQSummaryslice >.

Definition at line 90 of file JObjectIterator.hh.

    {
      skip_type i = 0;

      for ( ; i != ns && hasNext(); ++i) {
        next();
      }

      return i;
    }

Member Data Documentation

template<class T, template< class > class JSampler_t = JSampler>

JRewindableObjectIterator<T>& JLANG::JObjectSampler< T, JSampler_t >::in

protected

Definition at line 154 of file JObjectSampler.hh.

template<class T, template< class > class JSampler_t = JSampler>

JSampler_t<T> JLANG::JObjectSampler< T, JSampler_t >::sampler

protected

Definition at line 155 of file JObjectSampler.hh.

template<class T, template< class > class JSampler_t = JSampler>

JPointer<T> JLANG::JObjectSampler< T, JSampler_t >::ps

protected

Definition at line 156 of file JObjectSampler.hh.

template<class T, template< class > class JSampler_t = JSampler>

bool JLANG::JObjectSampler< T, JSampler_t >::has_next

protected

Definition at line 157 of file JObjectSampler.hh.

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

• JObjectSampler.hh