public package Foswiki::Iterator

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public package Foswiki::Iterator

This class cannot be instantiated on its own - it is an interface specification for iterators. See for more information on the iterator pattern.

The interface only supports forward iteration. Subclasses should use this as their base class (so that $it->isa("Foswiki::Iterator") returns true), and must implement hasNext and next per the specification below.

See Foswiki::ListIterator for an example implementation.

hasNext() -> $boolean

Returns true if the iterator has more items, or false when the iterator is exhausted.

next() -> $data

Return the next data in the iteration.

The data may be any type.

The iterator object can be customised to pre- and post-process entries from the list before returning them. This is done by setting two fields in the iterator object:

  • {filter} can be defined to be a sub that filters each entry. The entry will be ignored (next() will not return it) if the filter returns false.
  • {process} can be defined to be a sub to process each entry before it is returned by next. The value returned from next is the value returned by the process function.

reset() -> $boolean

resets the iterator to the begining - returns false if it can't

ObjectMethod all() → @list

Exhaust the iterator. Return all remaining elements in the iteration as a list. The returned list should be considered to be immutable.

The default implementation simply runs the iterator to its end.

Topic revision: r1 - 19 Apr 2011, ProjectContributor

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