An interface for reading data objects of a given type from an arbitrary data source. More...

#include <DataReader.hpp>

Inheritance diagram for CDPL::Base::DataReader< T >:

Public Types
typedef T	DataType
	The type of the read data objects. More...

typedef std::shared_ptr< DataReader >	SharedPointer
	A reference-counted smart pointer [SHPTR] for dynamically allocated `DataReader` instances. More...

Public Types inherited from CDPL::Base::DataIOBase
typedef std::function< void(const DataIOBase &, double)>	IOCallbackFunction
	A functor class used to wrap I/O callback target functions. More...

Public Types inherited from CDPL::Base::ControlParameterContainer
typedef ParameterMap::value_type	ParameterEntry
	A Base::LookupKey / Base::Any pair used to store the control-parameter values and associated keys. More...

typedef ParameterMap::const_iterator	ConstParameterIterator
	A constant iterator used to iterate over the control-parameter entries. More...

typedef std::function< void(const LookupKey &, const Any &)>	ParameterChangedCallbackFunction
	A functor class that wraps callback target functions which get invoked when the value of a control-parameter has changed. More...

typedef std::function< void(const LookupKey &)>	ParameterRemovedCallbackFunction
	A functor class that wraps callback target functions which get invoked when a control-parameter entry has been removed. More...

typedef std::function< void()>	ParentChangedCallbackFunction
	A functor class that wraps callback target functions which get invoked when the parent container has been changed or was detached. More...

Public Member Functions
virtual DataReader &	read (DataType &obj, bool overwrite=true)=0
	Reads the data record at the current record index and stores the read data in obj. More...

virtual DataReader &	read (std::size_t idx, DataType &obj, bool overwrite=true)=0
	Reads the data record at index idx and stores the read data in obj. More...

virtual DataReader &	skip ()=0
	Skips the data record at the current record index. More...

virtual bool	hasMoreData ()=0
	Tells if there are any data records left to read. More...

virtual std::size_t	getRecordIndex () const =0
	Returns the index of the current data record. More...

virtual void	setRecordIndex (std::size_t idx)=0
	Sets the index of the current data record to idx. More...

virtual std::size_t	getNumRecords ()=0
	Returns the total number of available data records. More...

virtual	operator const void * () const =0
	Returns a pointer whose value indicates the error state of the reader. More...

virtual bool	operator! () const =0
	Tells whether the reader is in a bad state. More...

virtual void	close ()
	Performs a reader specific shutdown operation (if required). More...

Public Member Functions inherited from CDPL::Base::DataIOBase
std::size_t	registerIOCallback (const IOCallbackFunction &func)
	Registers an I/O callback target function. More...

void	unregisterIOCallback (std::size_t id)
	Unregisters the I/O callback function specified by id. More...

void	invokeIOCallbacks (double progress) const
	Invokes all registered I/O callback functions with the argument `*this`. More...

void	clearIOCallbacks ()
	Clears all registered I/O callback functions. More...

Public Member Functions inherited from CDPL::Base::ControlParameterContainer
std::size_t	getNumParameters () const
	Returns the number of container entries. More...

template<typename T >
void	setParameter (const LookupKey &key, T &&val)
	Sets the value of the control-parameter specified by key to val. More...

const Any &	getParameter (const LookupKey &key, bool throw_=false, bool local=false) const
	Returns the value of the control-parameter specified by key. More...

template<typename T >
const T &	getParameter (const LookupKey &key, bool local=false) const
	Returns the value of the control-parameter specified by key as a `const` reference to an object of type T. More...

template<typename T >
const T &	getParameterOrDefault (const LookupKey &key, const T &def_val, bool local=false) const
	Returns the value of the control-parameter specified by key as a `const` reference to an object of type T, or the default value def_val if a stored value does not exist. More...

bool	removeParameter (const LookupKey &key)
	Removes the entry for the control-parameter specified by key. More...

void	clearParameters ()
	Erases all container entries. More...

bool	isParameterSet (const LookupKey &key, bool local=false) const
	Tells whether or not a value has been assigned to the control-parameter specified by key. More...

void	addParameters (const ControlParameterContainer &cntnr)
	Adds the control-parameter value entries in the `ControlParameterContainer` instance cntnr. More...

void	copyParameters (const ControlParameterContainer &cntnr)
	Replaces the current set of properties by a copy of the entries in cntnr. More...

ConstParameterIterator	getParametersBegin () const
	Returns a constant iterator pointing to the beginning of the entries. More...

ConstParameterIterator	getParametersEnd () const
	Returns a constant iterator pointing to the end of the entries. More...

ConstParameterIterator	begin () const
	Returns a constant iterator pointing to the beginning of the entries. More...

ConstParameterIterator	end () const
	Returns a constant iterator pointing to the end of the entries. More...

void	setParent (const ControlParameterContainer *cntnr)
	Sets or removes the parent control-parameter container used to resolve requests for missing entries. More...

const ControlParameterContainer *	getParent () const
	Returns a pointer to the parent control-parameter container. More...

std::size_t	registerParameterChangedCallback (const ParameterChangedCallbackFunction &func)
	Registers a callback target function that gets invoked when the value of a control-parameter has changed. More...

void	unregisterParameterChangedCallback (std::size_t id)
	Unregisters the callback specified by id. More...

std::size_t	registerParameterRemovedCallback (const ParameterRemovedCallbackFunction &func)
	Registers a callback target function that gets invoked when a control-parameter entry has been removed. More...

void	unregisterParameterRemovedCallback (std::size_t id)
	Unregisters the callback specified by id. More...

std::size_t	registerParentChangedCallback (const ParentChangedCallbackFunction &func)
	Registers a callback target function that gets invoked when the parent container has been changed or was detached. More...

void	unregisterParentChangedCallback (std::size_t id)
	Unregisters the callback specified by id. More...

const ControlParameterContainer &	getParameters () const
	Returns a `const` reference to itself. More...

Protected Member Functions
DataReader &	operator= (const DataReader &reader)
	Assignment operator. More...

Protected Member Functions inherited from CDPL::Base::DataIOBase
	DataIOBase ()
	Default constructor. More...

	DataIOBase (const DataIOBase &io_base)
	Copy constructor. More...

	~DataIOBase ()
	Destructor. More...

DataIOBase &	operator= (const DataIOBase &io_base)
	Assignment operator. More...

Protected Member Functions inherited from CDPL::Base::ControlParameterContainer
	ControlParameterContainer ()
	Constructs an empty `ControlParameterContainer` instance. More...

	ControlParameterContainer (const ControlParameterContainer &cntnr)
	Constructs a copy of the `ControlParameterContainer` instance cntnr. More...

virtual	~ControlParameterContainer ()
	Destructor. More...

ControlParameterContainer &	operator= (const ControlParameterContainer &cntnr)
	Assignment operator. More...

Detailed Description

template<typename T>
class CDPL::Base::DataReader< T >

An interface for reading data objects of a given type from an arbitrary data source.

DataReader is the common interface of classes which read objects of a given type (specified by the template parameter T) from some data source (e.g. a file) that provides the data encoded in a particular storage format.

From the DataReader interface point of view, the data source is organized as an array of logical data records. Each record is addressed by a zero-based sequential record index and contains the data for exactly one data object. The total number of available data records (which is equal to the maximum record index plus 1) can be queried by the method getNumRecords().

Similar to low-level file I/O, data records may either be read in a sequential or in a random access manner. For sequential access the method read(DataType& obj) is provided which will read the data record at the 'current' record index (similar to a file pointer). The current record index is accessible by the method getRecordIndex() and can be modified using the method setRecordIndex() (similar to a seek operation).

For reading data records in a random access manner, the method read(std::size_t idx, DataType& obj) is available. In contrast to the former read() method, this method expects the index of the record to read as the first argument.

If a read() (or skip()) operation was successful, the current record index is updated to point to the record immediately following the just read (or skipped) data record. If an operation fails, the reader instance is set into an error state that can be queried by the operators operator const void*() and bool operator!(). Additionally, a DataReader implementation may decide to throw an exception of type Base::IOError to report the error condition.

Template Parameters

T	The type of the read data objects.

Member Typedef Documentation

◆ DataType

template<typename T >

typedef T CDPL::Base::DataReader< T >::DataType

The type of the read data objects.

◆ SharedPointer

template<typename T >

typedef std::shared_ptr<DataReader> CDPL::Base::DataReader< T >::SharedPointer

A reference-counted smart pointer [SHPTR] for dynamically allocated DataReader instances.

Member Function Documentation

◆ read() [1/2]

template<typename T >

virtual DataReader& CDPL::Base::DataReader< T >::read	(	DataType &	obj,
		bool	overwrite = `true`
	)

pure virtual

Reads the data record at the current record index and stores the read data in obj.

If the read operation was successful, the record index is incremented by 1.

Parameters

obj	The object storing the read data.
overwrite	Specifies whether any existing data in obj shall be replaced by the newly read data or if the read data should be appended (if supported by the reader and data type).

Returns: A reference to itself.

Exceptions

Base::IOError if an I/O error occurred.

Implemented in CDPL::Util::StreamDataReader< DataType, ReaderImpl >, CDPL::Util::MultiFormatDataReader< DataType >, CDPL::Util::CompoundDataReader< DataType >, and CDPL::Pharm::PSDMoleculeReader.

◆ read() [2/2]

template<typename T >

virtual DataReader& CDPL::Base::DataReader< T >::read	(	std::size_t	idx,
		DataType &	obj,
		bool	overwrite = `true`
	)

pure virtual

Reads the data record at index idx and stores the read data in obj.

If the read operation was successful, the record index is set to idx + 1.

Parameters

idx	The zero-based index of the data record to read.
obj	The object storing the read data.
overwrite	Specifies whether any existing data in obj shall be replaced by the newly read data or if the read data should be appended (if supported by the reader and data type).

Returns: A reference to itself.

Exceptions

Base::IndexError if idx is greater or equal to the number of records. Base::IOError if an I/O error occurred.

Implemented in CDPL::Util::StreamDataReader< DataType, ReaderImpl >, CDPL::Util::MultiFormatDataReader< DataType >, CDPL::Util::CompoundDataReader< DataType >, and CDPL::Pharm::PSDMoleculeReader.

◆ skip()

template<typename T >

virtual DataReader& CDPL::Base::DataReader< T >::skip ( )

pure virtual

Skips the data record at the current record index.

If the operation was successful, the record index is incremented by 1.

Returns: A reference to itself.

Exceptions

Base::IOError if an I/O error occurred.

◆ hasMoreData()

template<typename T >

virtual bool CDPL::Base::DataReader< T >::hasMoreData ( )

pure virtual

Tells if there are any data records left to read.

Returns: true if there are data records left to read, and false otherwise.

Exceptions

Base::IOError if an I/O error occurred.

◆ getRecordIndex()

template<typename T >

virtual std::size_t CDPL::Base::DataReader< T >::getRecordIndex ( ) const

pure virtual

Returns the index of the current data record.

Returns: The zero-based index of the current data record.

◆ setRecordIndex()

template<typename T >

virtual void CDPL::Base::DataReader< T >::setRecordIndex ( std::size_t idx )

pure virtual

Sets the index of the current data record to idx.

Parameters

idx	The zero-based index of the data record.

Exceptions

Base::IndexError if idx is greater or equal to the number of available data records. Base::IOError if an I/O error occurred.

◆ getNumRecords()

template<typename T >

virtual std::size_t CDPL::Base::DataReader< T >::getNumRecords ( )

pure virtual

Returns the total number of available data records.

Returns: The total number of available data records.

Exceptions

Base::IOError if an I/O error occurred.

◆ operator const void *()

template<typename T >

virtual CDPL::Base::DataReader< T >::operator const void * ( ) const

pure virtual

Returns a pointer whose value indicates the error state of the reader.

The operator allows to write expressions like:

if (reader) { ...

if (reader.skip()) { ...

Returns: A non-null pointer if the reader is in a good state, a null pointer otherwise.

Note: The returned pointer is not meant to be dereferenced, it is just a state indicator.

See also: operator!()

◆ operator!()

template<typename T >

virtual bool CDPL::Base::DataReader< T >::operator! ( ) const

pure virtual

Tells whether the reader is in a bad state.

The operator allows to write expressions like:

if (!reader) { ...

if (!reader.skip()) { ...

Returns: false if the reader is in a good state, and true otherwise.

See also: operator const void*()

◆ close()

template<typename T >

virtual void CDPL::Base::DataReader< T >::close ( )

inlinevirtual

Performs a reader specific shutdown operation (if required).

Exceptions

Base::IOError if an I/O error occurred.

Reimplemented in CDPL::Util::MultiFormatDataReader< DataType >, CDPL::Util::FileDataReader< ReaderImpl, DataType >, and CDPL::Util::CompressedDataReader< ReaderImpl, DecompStream, DataType >.

◆ operator=()

template<typename T >

CDPL::Base::DataReader< T > & CDPL::Base::DataReader< T >::operator= ( const DataReader< T > & reader )

protected

Assignment operator.

Parameters

reader The DataReader instance to copy.

Returns: A reference to itself.

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

DataReader.hpp

Public Types

Public Member Functions

Protected Member Functions

Detailed Description

template<typename T> class CDPL::Base::DataReader< T >

Member Typedef Documentation

◆ DataType

◆ SharedPointer

Member Function Documentation

◆ read() [1/2]

◆ read() [2/2]

◆ skip()

◆ hasMoreData()

◆ getRecordIndex()

◆ setRecordIndex()

◆ getNumRecords()

◆ operator const void *()

◆ operator!()

◆ close()

◆ operator=()

template<typename T>
class CDPL::Base::DataReader< T >