Qore Programming Language Reference Manual  0.9.4.5
Qore::HashKeyReverseIterator Class Reference

This class an iterator class for hashes. More...

Inheritance diagram for Qore::HashKeyReverseIterator:

Public Member Methods

 constructor (hash< auto > h)
 Creates the hash iterator object. More...
 
 constructor ()
 Creates an empty iterator object. More...
 
 copy ()
 Creates a copy of the HashKeyReverseIterator object, iterating the same object as the original and in the same position. More...
 
string getValue ()
 returns the current key value or throws an INVALID-ITERATOR exception if the iterator is invalid More...
 
- Public Member Methods inherited from Qore::HashReverseIterator
 constructor (hash< auto > h)
 Creates the hash iterator object. More...
 
 constructor ()
 Creates an empty iterator object. More...
 
 copy ()
 Creates a copy of the HashReverseIterator 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 hash More...
 
bool last ()
 returns True if on the first element of the hash More...
 
bool next ()
 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...
 
bool prev ()
 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...
 
- 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...
 
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...
 
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...
 
 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...
 

Detailed Description

This class an iterator class for hashes.

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

Example: HashKeyReverseIterator basic usage
hash<auto> data = {
"key1" : 1,
"key2" : 2,
"key3" : 3,
};
HashKeyReverseIterator it(data);
while (it.next()) {
printf("iter: %n\n", it.getValue());
}
iter: "key3"
iter: "key2"
iter: "key1"
Note
See also
HashKeyIterator

Member Function Documentation

◆ constructor() [1/2]

Qore::HashKeyReverseIterator::constructor ( hash< auto >  h)

Creates the hash iterator object.

Parameters
hthe hash to iterate
Example:
HashKeyReverseIterator hi(h);

◆ constructor() [2/2]

Qore::HashKeyReverseIterator::constructor ( )

Creates an empty iterator object.

Example:
*hash<auto> h = get_hash_or_nothing();
HashKeyReverseIterator hi(h);

◆ copy()

Qore::HashKeyReverseIterator::copy ( )

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

Example:
HashKeyReverseIterator ni = i.copy();

◆ getValue()

string Qore::HashKeyReverseIterator::getValue ( )
virtual

returns the current key value or throws an INVALID-ITERATOR exception if the iterator is invalid

Returns
the current key value or throws an INVALID-ITERATOR exception if the iterator is invalid
Code Flags:
RET_VALUE_ONLY
Example:
HashKeyReverseIterator hi(hash);
while (hi.next())
printf("key: %s\n", hi.getValue());
Exceptions
INVALID-ITERATORthe iterator is not pointing at a valid element
ITERATOR-THREAD-ERRORthis exception is thrown if this method is called from any thread other than the thread that created the object

Reimplemented from Qore::HashIterator.