data/TWiki/TWikiLineIteratorDotPm.txt
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     1 ---+ Package =TWiki::LineIterator=
       
     2 
       
     3 Iterator over the lines in a file
       
     4 
       
     5 
       
     6 %TOC%
       
     7 
       
     8 ---++ new( $file )
       
     9 
       
    10 Create a new iterator over the given file. if the file cannot be opened, then
       
    11 there will be no elements in the iterator.
       
    12 
       
    13 
       
    14 ---++ hasNext() -> $boolean
       
    15 
       
    16 Returns false when the iterator is exhausted.
       
    17 
       
    18 <verbatim>
       
    19 my $it = new TWiki::ListIterator(\@list);
       
    20 while ($it->hasNext()) {
       
    21    ...
       
    22 </verbatim>
       
    23 
       
    24 
       
    25 ---++ next() -> $data
       
    26 
       
    27 Return the next line in the file.
       
    28 
       
    29 The iterator object can be customised to pre- and post-process entries from
       
    30 the list before returning them. This is done by setting two fields in the
       
    31 iterator object:
       
    32 
       
    33    * ={filter}= can be defined to be a sub that filters each entry. The entry
       
    34      will be ignored (next() will not return it) if the filter returns false.
       
    35    * ={process}= can be defined to be a sub to process each entry before it
       
    36      is returned by next. The value returned from next is the value returned
       
    37      by the process function.
       
    38 
       
    39 For example,
       
    40 <verbatim>
       
    41 my $it = new TWiki::LineIterator("/etc/passwd");
       
    42 $it->{filter} = sub { $_[0] =~ /^.*?:/; return $1; };
       
    43 $it->{process} = sub { return "User $_[0]"; };
       
    44 while ($it->hasNext()) {
       
    45     my $x = $it->next();
       
    46     print "$x\n";
       
    47 }
       
    48 </verbatim>
       
    49