XML::Filter::Reindent

XML::Filter::Reindent(User Contributed Perl DocumentatXML::Filter::Reindent(3)



NAME
       XML::Filter::Reindent - Reformats whitespace for pretty printing XML

SYNOPSIS
        use XML::Handler::Composer;
        use XML::Filter::Reindent;

        my $composer = new XML::Handler::Composer (%OPTIONS);
        my $indent = new XML::Filter::Reindent (Handler => $composer, %OPTIONS);

DESCRIPTION
       XML::Filter::Reindent is a sub class of XML::Filter::DetectWS.

       XML::Filter::Reindent can be used as a PerlSAX filter to reformat an
       XML document before sending it to a PerlSAX handler that prints it
       (like XML::Handler::Composer.)

       Like XML::Filter::DetectWS, it detects ignorable whitespace and blocks
       of whitespace characters in certain places. It uses this information
       and information supplied by the user to determine where whitespace may
       be modified, deleted or inserted.  Based on the indent settings, it
       then modifies, inserts and deletes characters and ignorable_whitespace
       events accordingly.

       This is just a first stab at the implementation.  It may be buggy and
       may change completely!

Constructor Options
       o Handler
           The PerlSAX handler (or filter) that will receive the PerlSAX
           events from this filter.

       o Tab (Default: one space)
           The number of spaces per indent level for elements etc. in document
           content.

       o Newline (Default: "\x0A")
           The newline to use when re-indenting.  The default is the internal
           newline used by XML::Parser, XML::DOM etc., and should be fine when
           used in combination with XML::Handler::Composer.

$self->indent_children ($start_element_event)
       This method determines whether children of a certain element may be
       reformatted.  The default implementation checks the PreserveWS parame-
       ter of the specified start_element event and returns 0 if it is set or
       MAYBE otherwise.  The value MAYBE (2) indicates that further investiga-
       tion is needed, e.g.  by examining the element contents. A value of 1
       means yes, indent the child nodes, no further investigation is needed.

       NOTE: the PreserveWS parameter is set by the parent class, XML::Fil-
       ter::DetectWS, when the element or one of its ancestors has the
       attribute xml:space="preserve".

       Override this method to tweak the behavior of this class.

$self->indent_element ($start_element_event, $parent_says_indent)
       This method determines whether a certain element may be re-indented.
       The default implementation returns the value of the $parent_says_indent
       parameter, which was set to the value returned by indent_children for
       the parent element. In other words, the element will be re-indented if
       the parent element allows it.

       Override this method to tweak the behavior of this class.  I'm not sure
       how useful this hook is. Please provide feedback!

Current Implementation
       The current implementation puts all incoming Perl SAX events in a queue
       for further processing. When determining which nodes should be
       re-indented, it sometimes needs information from previous events, hence
       the use of the queue.

       The parameter (Compress => 1) is added to matching start_element and
       end_element events with no events in between This indicates to an XML
       printer that a compressed notation can be used, e.g <foo/>.

       If an element allows reformatting of its contents (xml:space="preserve"
       was not active and indent_children returned MAYBE), the element con-
       tents will be reformatted unless it only has one child node and that
       child is a regular text node (characters event.)  In that case, the
       element will be printed as <foo>text contents</foo>.

       If you want element nodes with just one text child to be reindented as
       well, simply override indent_children to return 1 instead of MAYBE (2.)

       This behavior may be changed or extended in the future.

CAVEATS
       This code is highly experimental!  It has not been tested well and the
       API may change.

       The code that detects blocks of whitespace at potential indent posi-
       tions may need some work.

AUTHOR
       Send bug reports, hints, tips, suggestions to Enno Derksen at
       <enno@att.com>.



perl v5.8.0                       2000-02-16          XML::Filter::Reindent(3)