Qore::AbstractIterator Class Reference

This class defines an abstract interface for iterators. More...

#include <QC_AbstractIterator.dox.h>

Inheritance diagram for Qore::AbstractIterator:

Public Member Methods
abstract auto	getValue ()
	returns the current value More...
abstract bool	next ()
	Moves the current position to the next element; returns False if there are no more elements. More...
abstract bool	valid ()
	returns True if the iterator is currently pointing at a valid element, False if not More...

Detailed Description

This class defines an abstract interface for iterators.

Classes inheriting this class can be used to iterate abstract or complex objects with while Statements (using AbstractIterator::next()) or directly in the following language constructs:

• Map Operator (map)
• Fold Right Operator (foldr) and Fold Left Operator (foldl)
• Select From List Operator (select)
• foreach Statements

Member Function Documentation

getValue()

abstract auto Qore::AbstractIterator::getValue ( )

pure virtual

returns the current value

Returns

the current value

Example:

while (i.next()) {
    printf("+ %y\n", i.getValue());
}

Exceptions

INVALID-ITERATOR

the iterator is not pointing at a valid element

See also

AbstractIterator::valid()

Implemented in Qore::AbstractLineIterator, Qore::SQL::AbstractSQLStatement, Qore::DataLineIterator, Qore::FileLineIterator, Qore::HashIterator, Qore::HashKeyIterator, Qore::HashKeyReverseIterator, Qore::HashListIterator, Qore::HashPairIterator, Qore::HashPairReverseIterator, Qore::InputStreamLineIterator, Qore::ListHashIterator, Qore::ListIterator, Qore::ObjectKeyIterator, Qore::ObjectKeyReverseIterator, Qore::ObjectPairIterator, Qore::ObjectPairReverseIterator, Qore::RangeIterator, Qore::SingleValueIterator, and Qore::SQL::SQLStatement.

next()

abstract bool Qore::AbstractIterator::next ( )

pure virtual

Moves the current position to the next element; returns False if there are no more elements.

This method will return True again after it returns False once if the object being iterated is not empty, otherwise it will always return False. The iterator object should not be used after this method returns False

Returns

False if there are no more elements (in which case the iterator object is invalid and should not be used); True if successful (meaning that the iterator object is valid)

Example:

while (i.next()) {
    printf(" + %y\n", i.getValue());
}

Implemented in Qore::AbstractLineIterator, Qore::SQL::AbstractSQLStatement, Qore::DataLineIterator, Qore::FileLineIterator, Qore::HashIterator, Qore::HashListIterator, Qore::HashListReverseIterator, Qore::HashReverseIterator, Qore::InputStreamLineIterator, Qore::ListHashIterator, Qore::ListHashReverseIterator, Qore::ListIterator, Qore::ListReverseIterator, Qore::ObjectReverseIterator, Qore::RangeIterator, Qore::SingleValueIterator, and Qore::SQL::SQLStatement.

valid()

abstract bool Qore::AbstractIterator::valid ( )

pure virtual

returns True if the iterator is currently pointing at a valid element, False if not

Returns

True if the iterator is currently pointing at a valid element, False if not

Example:

if (i.valid())
    printf("current value: %y\n", i.getValue());

Implemented in Qore::AbstractLineIterator, Qore::SQL::AbstractSQLStatement, Qore::DataLineIterator, Qore::FileLineIterator, Qore::HashIterator, Qore::HashListIterator, Qore::InputStreamLineIterator, Qore::ListHashIterator, Qore::ListIterator, Qore::RangeIterator, Qore::SingleValueIterator, and Qore::SQL::SQLStatement.