public package
Foswiki::ListIterator
public package
Foswiki::ListIterator is a
Foswiki::Iterator
implements Foswiki::Iterator
Iterator over a perl list
WARNING: this Iterator will skip any elements that are == undef.
SMELL: hasNext should not 'return 1 if defined($this→{next}), but rather use a boolean - to allow array elements to be undef too.
new(\@list)
Create a new iterator over the given list. Designed primarily for operations
over fully defined lists of object references. The list is not damaged in
any way.
hasNext() → $boolean
Returns false when the iterator is exhausted.
my $it = new Foswiki::ListIterator(\@list);
while ($it->hasNext()) {
...
skip(count) → $countremaining
skip X elements (returns 0 if successful, or number of elements remaining to skip if there are not enough elements to skip)
skip must set up next as though hasNext was called.
next() → $data
Return the next entry in the list.
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.
For example,
my @list = ( 1, 2, 3 );
my $it = new Foswiki::ListIterator(\@list);
$it->{filter} = sub { return $_[0] != 2 };
$it->{process} = sub { return $_[0] + 1 };
while ($it->hasNext()) {
my $x = $it->next();
print "$x, ";
}
will print
2, 4
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.
This method is cheap if it is called when the cursor is at the first
element in the iteration, and expensive otherwise, as it requires a list
copy to be made.
reset() → $boolean
Start at the begining of the list
$it->reset();
while ($it->hasNext()) {
...