NAME

SYNOPSIS

   ## As a normal perl object:
   $writer = XML::ValidWriter->new(
      DOCTYPE => $xml_doc_type,
      OUTPUT => \*FH
   ) ;
   $writer->startTag( 'b1' ) ;
   $writer->startTag( 'c2' ) ;
   $writer->end ;

   ## Writing to a scalar:
   $writer = XML::ValidWriter->new(
      DOCTYPE => $xml_doc_type,
      OUTPUT => \$buf
   ) ;

   ## Or, in scripting mode:
   use XML::Doctype         NAME => a, SYSTEM_ID => 'a.dtd' ;
   use XML::ValidWriter qw( :all :dtd_tags ) ;
   b1 ;                # Emits <a><b1>
   c2( attr=>"val" ) ; # Emits </b1><b2><c2 attr="val">
   endAllTags ;        # Emits </c2></b2></a>

   ## If you've got an XML::Doctype object handy:
   use XML::ValidWriter qw( :dtd_tags ), DOCTYPE => $doctype ;

   ## If you've saved a preparsed DTD as a perl module
   use FooML::Doctype::v1_0001 ;
   use XML::ValidWriter qw( :dtd_tags ) ;

   #
   # This all assumes that the DTD contains:
   #
   #   <!ELEMENT a ( b1, b2?, b3* ) >
   #      <!ATTLIST   a aa1 CDATA       #REQUIRED >
   #   <!ELEMENT b1 ( c1 ) >
   #   <!ELEMENT b2 ( c2 ) >
   #

STATUS

Many methods supplied by XML::Writer are not yet supplied here.

DESCRIPTION

   $writer->TABLE( $content, ...attrs... ) ;
   $writer->start_TABLE( ...attrs... ) ;
   $writer->end_TABLE() ;
   $writer->empty_TABLE( ...attrs... ) ;

. These are created for undeclared elements--those elements not explicitly declared with an <!ELEMENT ..> declaration--as well. If an element type name conflicts with a method, it will not override the internal method.

When an XML::Doctype is parsed, the name of the doctype defines the root node of the document. This name can be changed, though, see XML::Doctype for details.

In addition to the object-oriented API, a function API is also provided. This allows you to import most of the methods of XML::ValidWriter as functions using standard import specifications:

   use XML::ValidWriter qw( :all ) ; ## Could list function names instead

":all" does not import the functions named after elements mentioned in the DTD, you need to import those tags using ":dtd_tags":

   use XML::Doctype NAME => 'foo', SYSTEM_ID => 'fooml.dtd' ;
   use XML::ValidWriter qw( :all :dtd_tags ) ;

or

   BEGIN {
      $doctype = XML::Doctype->new( ... ) ;
   }

   use XML::ValidWriter DOCTYPE => $doctype, qw( :all :dtd_tags ) ;

OUTPUT OPTIMIZATION

"<a...></a>" becomes '<a... />'

Spurious emissions of "]]><![CDATA[" are supressed.

XML::ValidWriter chooses whether or not to use a <![CDATA[...]]> section or simply escape '<' and '&'. If you are emitting content for an element in multiple calls to "characters", the first call decides whether or not to use CDATA, so it's to your advantage to emit as much in the first call as possible. You can do

   characters( @lots_of_segments ) ;

if it helps.

METHODS AND FUNCTIONS

To call these routines as functions use either the DOCTYPE or :dtd_tags options in the parameters to the use statement:

   use XML::ValidWriter DOCTYPE => XML::Doctype->new( ... ) ;
   use XML::ValidWriter qw( :dtd_tags ) ;

This associates an XML::ValidWriter and an XML::Doctype with the package. These are used by the routines when called as functions.

new

   $writer = XML::ValidWriter->new( DTD => $dtd, OUTPUT => \*FH ) ;
    

Creates an XML::ValidWriter.

The value passed for OUTPUT may be:

import

Can't think of why you'd call this method directly, it gets called when you use this module:

   use XML::ValidWriter qw( :all ) ;
    

In addition to the normal functionality of exporting functions like startTag() and endTag(), XML::ValidWriter's import() can create functions corresponding to all elements in a DTD. This is done using the special ":dtd_tags" export symbol. For example,

   use XML::Doctype     NAME => 'FooML', SYSTEM_ID => 'fooml.dtd' ;
   use XML::ValidWriter qw( :dtd_tags ) ;
    

where fooml.dtd referse to a tag type of 'blurb' causes these functions to be imported:

   blurb()         # calls defaultWriter->startTag( 'blurb', @_ ) ;
   blurb_element() # calls defaultWriter->dataElement( 'blurb', @_ ) ;
   empty_blurb()   # calls defaultWriter->emptyTag( 'blurb', @_ ) ;
   end_blurb()     # calls defaultWriter->endTag( 'blurb' ) ;
    

The range of characters for element types is much larger than the range of characters for bareword perl subroutine names, which are limited to [a-zA-Z0-9_]. In this case, XML::ValidWriter will export an oddly named function that you can use a symbolic reference to call (you will need "no strict 'refs' ;" if you are doing a "use strict ;"):

   &{"space-1999:moonbase"}( ...attributes ... ) ;
    

. XML::ValidWriter will also try to fold the name in to bareword space by converting /\W/ symbols to '_'. If the resulting function name,

   space_1999_moonbase( ...attributes... ) ;
    

has not been generated and is not the name of an element type, then it will also be exported.

If you are using a DTD that might introduce function names that conflict with existing ones, simple export them in to their own namespace:

   package ML ;

   use XML::Doctype     NAME => 'foo', SYSTEM_ID => 'fooml.dtd' ;
   use XML::ValidWriter qw( :dtd_tags ) ;

   package main ;

   use XML::ValidWriter qw( :all ) ;

   ML::foo ;
   ML::c2 ;
   ML::c1 ;
   ML::end_a ;
    

I gave serious thought to converting ':' in element names to '::' in function declarations, which might work well in the functions-in-their-own- namespace case, but not in the default case, since Perl does not (yet) have relative namespaces. Another alternative is to allow a mapping of XML namespaces to Perl namespaces to be done.

characters

   characters( "escaped text", "& more" ) ;
   $writer->characters( "escaped text", "& more" ) ;
    

Emits character data. Character data will be escaped before output, by either transforming '<' and '&' to &lt; and &amp;, or by enclosing in a '"<![CDATA[...]]>"' bracket, depending on which will be more human-readable, according to the module.

dataElement

   $writer->dataElement( $tag ) ;
   $writer->dataElement( $tag, $content ) ;
   $writer->dataElement( $tag, $content, attr1 => $val1, ... ) ;
   dataElement( $tag ) ;
   dataElement( $tag, $content ) ;
   dataElement( $tag, $content, attr1 => $val1, ... ) ;
    

Does the equivalent to

   ## Split the optional args in to attributes and elements arrays.
   $writer->startTag( $tag, @attributes ) ;
   $writer->characters( $content ) ;
   $writer->endTag( $tag ) ;
    

This function is exportable as dataElement(), and is also exported for each element 'foo' found in the DTD as foo().

defaultWriter

   $writer = defaultWriter ;       ## Not a method!
   $writer = defaultWriter( 'Foo::Bar' ) ;
    

Returns the default XML::ValidWriter for the given package, or the current package if none is specified. This is useful for getting at methods like "reset" that are not also functions.

Croaks if no default writer has been defined (see "import").

doctype

   # Using the writer's associated DTD:
   doctype ;

   # Ignoring the writer's associated DTD:
   doctype( $type ) ;
   doctype( $type, undef, $system ) ;
   doctype( $type, $public, $system ) ;

   $writer->doctype ;
   ...etc
    

See "internalDoctype" to emit the entire DTD in the document.

This checks to make sure that no doctype or elements have been emitted.

A warning is emitted if standalone="yes" was specified in the <?xml..?> declaration and a system id is specified. This is extremely likely to be an error. If you need to silence the warning, write me (see below).

Passing '' or '0' (zero) as a $public_id or as a $system_id also generates a warning, as these are extremely likely to be errors.

emptyTag

   emptyTag( $tag[, attr1 => $val1... ] ) ;
   $writer->emptyTag( $tag[, attr1 => $val1... ] ) ;
    

Emits an empty tag like '<foo />'. The extra space is for compatibility with XHTML.

endTag

   endTag ;
   endTag( 'a' ) ;
   $writer->endTag ;
   $writer->endTag( 'a' ) ;
    

Prints one or more end tags. The tag name is optional and defaults to the most recently emitted start tag if not present.

This will emit as many close tags as necessary to close the supplied tag name, or will emit an error if the tag name specified is not open in the output document.

end

   $writer->end ;      # Not a function!!
    

Emits all necessary end tags to close the document. Available as a method only, since 'end' is a little to generic to be exported as a function name, IMHO. See 'endAllTags' for the plain function equivalent function.

endAllTags

   endAllTags ;
   $writer->endAllTags ;
    

A plain function that emits all necessart end tags to close the document. Corresponds to the method "end", but is exportable as a function/

exportDTDTags

   $writer->exportDTDTags() ;
   $writer->exportDTDTags( $to_pkg ) ;
    

Exports the tags found in the DTD to the caller's namespace.

getDataMode

   $m = getDataMode ;
   $m = $writer->getDataMode ;
    

Returns TRUE if the writer is in DATA_MODE.

getDoctype

   $dtd = getDoctype ;
   $dtd = $writer->getDoctype ;
    

This is used to get the writer's XML::Doctype object.

getOutput

   $fh = getOutput ;
   $fh = $writer->getOutput ;
    

Gets the filehandle an XML::ValidWriter sends output to.

rawCharacters

   rawCharacters( "<unescaped text>", "& more text" ) ;
   $writer->rawCharacters( "<unescaped text>", "& more text" ) ;
    

This allows you to emit raw text without any escape processing. The text is not examined for tags, so you can invalidate your document and even corrupt it's well-formedness.

reset

   $writer->reset ;        # Not a function!
    

Resets a writer to be initialized, but not have emitted anything.

This is useful if you need to abort output, but want to reuse the XML::ValidWriter.

setDataMode

   setDataMode( 1 ) ;
   $writer->setDataMode( 1 ) ;
    

Enable or disable data mode.

setDoctype

   setDoctype $doctype ;
   $writer->setDoctype( $doctype ) ;
    

This is used to set the doctype object.

select_xml

   select_xml OUTHANDLE ;  # Nnot a method!!
    

Selects a filehandle to send the XML output to when not using the object oriented interface. This is similar to perl's builtin select, but only affects startTag and endTag functions, (not methods).

This is only needed if you want to interleave output to the selected output files (usually STDOUT, see "select" in perlfunc and to an XML file on another filehandle.

If you want to redirect all output (yours and XML::Writer's) to the same file, just use Perl's built-in select(), since startTag and endTag emit to the currently selected filehandle by default.

Like select, this returns the old value.

setOutput

   setOutput( \*FH ) ;
   $writer->setOutput( \*FH ) ;
    

Sets the filehandle an XML::ValidWriter sends output to.

startTag

   startTag( 'a', attr => val ) ;  # use default XML::ValidWriter for
                                   # current package.
   $writer->startTag( 'a', attr => val ) ;
    

Emits a named start tag with optional attributes. If the named tag cannot be a child of the most recently started tag, then any tags that need to be opened between that one and the named tag are opened.

If the named tag cannot be enclosed within the most recently opened tag, no matter how deep, then startTag() tries to end as few started tags as necessary to allow the named tag to be emitted within a tag already on the stack.

This warns (once) if no <?xml?> declaration has been emitted. It does not check to see if a <!DOCTYPE...> has been emitted. It dies if an attempt is made to emit a second root element.

xmlDecl([[$encoding][, $standalone])

   xmlDecl ;
   xmlDecl( "UTF-8" ) ;
   xmlDecl( "UTF-8", "yes" ) ;
   $writer->xmlDecl( ... ) ;
    

Emits an XML declaration. Must be called before any of the other output routines.

If $encoding is not defined, it is not output. This is slightly different than XML::Writer, which outputs 'UTF-8' if you pass in undef, 0, or ''.

If $encoding is '' or 0, then it is output as "" or "0" and a warning is generated.

If $standalone is defined and is not 'no', 0, or '', it is output as 'yes'. If it is 'no', then it is output as 'no'. If it's 0 or '' it is not output.

AUTOLOAD

This function is called whenever a function or method is not found in XML::ValidWriter.

If it was a method being called, and the desired method name is a start or end tag found in the DTD, then a method is cooked up on the fly.

These methods are slower than normal methods, but they are cached so that they don't need to be recompiled. The speed penalty is probably not significant since they do I/O and are thus usually orders of magnitude slower than normal Perl methods.

DESTROY

DESTROY is called when an XML::ValidWriter is cleaned up. This is used to automatically close all tags that remain open. This will not work if you have closed the output filehandle that the ValidWriter was using.

This method will also warn if anything was emitted bit no root node was emitted. This warning can be silenced by calling

   $writer->reset() ;
    

when you abandon output.

AUTHOR

COPYRIGHT

This module is licensed under your choice of the Artistic, BSD or General Public License.