Qore::ObjectPairReverseIterator Class Reference

This class an iterator class for objects. More...

#include <QC_ObjectPairReverseIterator.dox.h>

Inheritance diagram for Qore::ObjectPairReverseIterator:

Public Member Methods
	constructor (object o)
	Creates the object iterator object. More...
	constructor ()
	Creates an empty iterator object. More...
	copy ()
	Creates a copy of the ObjectPairReverseIterator object, iterating the same object as the original and in the same position. More...
hash< auto >	getValue ()
	returns a hash with the current key and value (a hash with 2 keys: "key" and "value") or throws an INVALID-ITERATOR exception if the iterator is invalid More...
Public Member Methods inherited from Qore::ObjectReverseIterator
	constructor (object o)
	Creates the object iterator object. More...
	constructor ()
	Creates an empty iterator object. More...
	copy ()
	Creates a copy of the ObjectReverseIterator object, iterating the same object as the original and in the same position. More...
bool	first ()
	returns True if on the last element of the object More...
bool	last ()
	returns True if on the first element of the object More...
bool	next ()
	Moves the current position to the previous element in the object; returns False if there are no more elements; if the iterator is not pointing at a valid element before this call, the iterator will be positioned on the last element in the object if the object is not empty. More...
bool	prev ()
	Moves the current position to the next element in the object; returns False if there are no more elements; if the iterator is not pointing at a valid element before this call, the iterator will be positioned on the first element in the object if the object is not empty. More...
Public Member Methods inherited from Qore::ObjectIterator
	constructor (object o)
	Creates the object iterator object. More...
	constructor ()
	Creates an empty object iterator object. More...
	copy ()
	Creates a copy of the ObjectIterator object, iterating the same object as the original and in the same position. More...
Public Member Methods inherited from Qore::HashIterator
	constructor (hash< auto > h)
	Creates the hash iterator object. More...
	constructor ()
	Creates an empty hash iterator object. More...
	copy ()
	Creates a copy of the HashIterator object, iterating the same object as the original and in the same position. More...
bool	empty ()
	returns True if the hash is empty; False if not More...
bool	first ()
	returns True if on the first element of the hash More...
string	getKey ()
	returns the current key value or throws an INVALID-ITERATOR exception if the iterator is invalid More...
auto	getKeyValue ()
	returns the current value of the current hash key being iterated or throws an INVALID-ITERATOR exception if the iterator is invalid More...
auto	getValue ()
	returns the current key value or throws an INVALID-ITERATOR exception if the iterator is invalid More...
hash< auto >	getValuePair ()
	returns a hash with the current key and value (a hash with 2 keys: "key" and "value") or throws an INVALID-ITERATOR exception if the iterator is invalid More...
bool	last ()
	returns True if on the last element of the hash More...
bool	next ()
	Moves the current position to the next element in the hash; returns False if there are no more elements; if the iterator is not pointing at a valid element before this call, the iterator will be positioned on the first element in the hash if the hash is not empty. More...
bool	prev ()
	Moves the current position to the previous element in the hash; returns False if there are no more elements; if the iterator is not pointing at a valid element before this call, the iterator will be positioned on the last element in the hash if the hash is not empty. More...
	reset ()
	Reset the iterator instance to its initial state. More...
bool	valid ()
	returns True if the iterator is currently pointing at a valid element, False if not More...
abstract bool	prev ()
	Moves the current position to the previous element; returns False if there are no more elements. More...
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...
abstract bool	empty ()
	returns True if the object to iterate is empty; False if not More...
abstract bool	first ()
	returns True if on the first element More...
abstract bool	last ()
	returns True if on the last element More...

Detailed Description

This class an iterator class for objects.

Call ObjectPairReverseIterator::next() to iterate through the object in reverse order; do not use the iterator if ObjectPairReverseIterator::next() returns False. A object can be iterated in reverse order by calling ObjectPairReverseIterator::prev() instead of ObjectPairReverseIterator::next()

Example: ObjectPairReverseIterator basic usage

class Class1 {
   public {
      int attr1;
      date attr2;
   }
   constructor() {
      attr1 = 1;
      attr2 = now();
   }
}
Class1 o();
 
ObjectPairReverseIterator it(o);
while (it.next()) {
    printf("iter: %n\n", it.getValue());
}
 
iter: hash: (key : "attr2", value : 2013-04-17 16:38:31 Wed +02:00 (CEST))
iter: hash: (key : "attr1", value : 1)

Note

• In general, the ObjectPairReverseIterator class is not designed to be accessed from multiple threads; it was created without locking for fast and efficient use when used from a single thread. For methods that would be unsafe to use in another thread, any use of such methods in threads other than the thread where the constructor was called will cause an ITERATOR-THREAD-ERROR to be thrown.
• ObjectPairReverseIterator is functionally equivalent to ObjectPairIterator, but the effect of ObjectPairReverseIterator::next() and ObjectPairReverseIterator::prev() are the opposite of ObjectPairIterator::next() and ObjectPairIterator::prev(); that is ObjectPairReverseIterator::next() will iterate through the object in reverse order, while ObjectPairReverseIterator::prev() iterates in forward order. Additionally the meanings of the return values for ObjectPairReverseIterator::first() and ObjectPairReverseIterator::last() are swapped in respect to ObjectPairIterator::first() and ObjectPairIterator::last().

See also

ObjectPairIterator

Member Function Documentation

constructor() [1/2]

Qore::ObjectPairReverseIterator::constructor

(

)

Creates an empty iterator object.

Example:

*object obj = get_object_or_nothing();
ObjectPairReverseIterator i(obj);

constructor() [2/2]

Qore::ObjectPairReverseIterator::constructor

(

object

o

)

Creates the object iterator object.

Parameters

o	the object to iterate

Example:

ObjectPairReverseIterator i(obj);

copy()

Qore::ObjectPairReverseIterator::copy

(

)

Creates a copy of the ObjectPairReverseIterator object, iterating the same object as the original and in the same position.

Example:

ObjectPairReverseIterator ni = i.copy();

getValue()

hash< auto > Qore::ObjectPairReverseIterator::getValue ( )

virtual

returns a hash with the current key and value (a hash with 2 keys: "key" and "value") or throws an INVALID-ITERATOR exception if the iterator is invalid

Returns

a hash with the current key and value (a hash with 2 keys: "key" and "value") or throws an INVALID-ITERATOR exception if the iterator is invalid

Code Flags:

RET_VALUE_ONLY

Example:

foreach hash<auto> h in (new ObjectPairReverseIterator(obj))
    printf("%s: %y\n", h.key, h.value);

Exceptions

INVALID-ITERATOR	the iterator is not pointing at a valid element
ITERATOR-THREAD-ERROR	this exception is thrown if this method is called from any thread other than the thread that created the object

Since

Qore 0.8.6.2

Reimplemented from Qore::HashIterator.