NAME

       MDOM::Element - The abstract Element class, a base for all source objects

INHERITANCE

         MDOM::Element is the root of the PDOM tree

DESCRIPTION

       The abstract "MDOM::Element" serves as a base class for all source-related objects, from a single
       whitespace token to an entire document. It provides a basic set of methods to provide a common interface
       and basic implementations.

METHODS

   significant
       Because we treat whitespace and other non-code items as Tokens (in order to be able to "round trip" the
       MDOM::Document back to a file) the "significant" method allows us to distinguish between tokens that form
       a part of the code, and tokens that aren't significant, such as whitespace, POD, or the portion of a file
       after (and including) the "__END__" token.

       Returns true if the Element is significant, or false it not.

   lineno
       Accessor for current line number.

   class
       The "class" method is provided as a convenience, and really does nothing more than returning
       "ref($self)". However, some people have found that they appreciate the laziness of "$Foo->class eq
       'whatever'", so I have caved to popular demand and included it.

       Returns the class of the Element as a string

   tokens
       The "tokens" method returns a list of MDOM::Token objects for the Element, essentially getting back that
       part of the document as if it had not been lexed.

       This also means there are no Statements and no Structures in the list, just the Token classes.

   content
       For any "MDOM::Element", the "content" method will reconstitute the base code for it as a single string.
       This method is also the method used for overloading stringification. When an Element is used in a double-
       quoted string for example, this is the method that is called.

       WARNING:

       You should be aware that because of the way that here-docs are handled, any here-doc content is not
       included in "content", and as such you should not eval or execute the result if it contains any
       MDOM::Token::HereDoc.

       The MDOM::Document method "serialize" should be used to stringify a PDOM document into something that can
       be executed as expected.

       Returns the basic code as a string (excluding here-doc content).

   parent
       Elements themselves are not intended to contain other Elements, that is left to the MDOM::Node abstract
       class, a subclass of "MDOM::Element".  However, all Elements can be contained within a parent Node.

       If an Element is within a parent Node, the "parent" method returns the Node.

   statement
       For a "MDOM::Element" that is contained (at some depth) within a MDOM::Statment, the "statement" method
       will return the first parent Statement object lexically 'above' the Element.

       Returns a MDOM::Statement object, which may be the same Element if the Element is itself a
       MDOM::Statement object.

       Returns false if the Element is not within a Statement and is not itself a Statement.

   top
       For a "MDOM::Element" that is contained within a PDOM tree, the "top" method will return the top-level
       Node in the tree. Most of the time this should be a MDOM::Document object, however this will not always
       be so. For example, if a subroutine has been removed from its Document, to be moved to another Document.

       Returns the top-most PDOM object, which may be the same Element, if it is not within any parent PDOM
       object.

   document
       For an Element that is contained within a MDOM::Document object, the "document" method will return the
       top-level Document for the Element.

       Returns the MDOM::Document for this Element, or false if the Element is not contained within a Document.

   next_sibling
       All MDOM::Node objects (specifically, our parent Node) contain a number of "MDOM::Element" objects. The
       "next_sibling" method returns the "MDOM::Element" immediately after the current one, or false if there is
       no next sibling.

   snext_sibling
       As per the other 's' methods, the "snext_sibling" method returns the next significant sibling of the
       "MDOM::Element" object.

       Returns a "MDOM::Element" object, or false if there is no 'next' significant sibling.

   previous_sibling
       All MDOM::Node objects (specifically, our parent Node) contain a number of "MDOM::Element" objects. The
       "previous_sibling" method returns the Element immediately before the current one, or false if there is no
       'previous' "MDOM::Element" object.

   sprevious_sibling
       As per the other 's' methods, the "sprevious_sibling" method returns the previous significant sibling of
       the "MDOM::Element" object.

       Returns a "MDOM::Element" object, or false if there is no 'previous' significant sibling.

   first_token
       As a support method for higher-order algorithms that deal specifically with tokens and actual Perl
       content, the "first_token" method finds the first MDOM::Token object within or equal to this one.

       That is, if called on a MDOM::Node subclass, it will descend until it finds a MDOM::Token. If called on a
       MDOM::Token object, it will return the same object.

       Returns a MDOM::Token object, or dies on error (which should be extremely rare and only occur if an
       illegal empty MDOM::Statement exists below the current Element somewhere.

   last_token
       As a support method for higher-order algorithms that deal specifically with tokens and actual Perl
       content, the "last_token" method finds the last MDOM::Token object within or equal to this one.

       That is, if called on a MDOM::Node subclass, it will descend until it finds a MDOM::Token. If called on a
       MDOM::Token object, it will return the itself.

       Returns a MDOM::Token object, or dies on error (which should be extremely rare and only occur if an
       illegal empty MDOM::Statement exists below the current Element somewhere.

   next_token
       As a support method for higher-order algorithms that deal specifically with tokens and actual Perl
       content, the "next_token" method finds the MDOM::Token object that is immediately after the current
       Element, even if it is not within the same parent MDOM::Node as the one for which the method is being
       called.

       Note that this is not defined as a MDOM::Token-specific method, because it can be useful to find the next
       token that is after, say, a MDOM::Statement, although obviously it would be useless to want the next
       token after a MDOM::Document.

       Returns a MDOM::Token object, or false if there are no more tokens after the Element.

   previous_token
       As a support method for higher-order algorithms that deal specifically with tokens and actual Perl
       content, the "previous_token" method finds the MDOM::Token object that is immediately before the current
       Element, even if it is not within the same parent MDOM::Node as this one.

       Note that this is not defined as a MDOM::Token-only method, because it can be useful to find the token is
       before, say, a MDOM::Statement, although obviously it would be useless to want the next token before a
       MDOM::Document.

       Returns a MDOM::Token object, or false if there are no more tokens before the "Element".

   clone
       As per the Clone module, the "clone" method makes a perfect copy of an Element object. In the generic
       case, the implementation is done using the Clone module's mechanism itself. In higher-order cases, such
       as for Nodes, there is more work involved to keep the parent-child links intact.

   insert_before @Elements
       The "insert_before" method allows you to insert lexical perl content, in the form of "MDOM::Element"
       objects, before the calling "Element". You need to be very careful when modifying perl code, as it's easy
       to break things.

       In its initial incarnation, this method allows you to insert a single Element, and will perform some
       basic checking to prevent you inserting something that would be structurally wrong (in PDOM terms).

       In future, this method may be enhanced to allow the insertion of multiple Elements, inline-parsed code
       strings or MDOM::Document::Fragment objects.

       Returns true if the Element was inserted, false if it can not be inserted, or "undef" if you do not
       provide a MDOM::Element object as a parameter.

   insert_after @Elements
       The "insert_after" method allows you to insert lexical perl content, in the form of "MDOM::Element"
       objects, after the calling "Element". You need to be very careful when modifying perl code, as it's easy
       to break things.

       In its initial incarnation, this method allows you to insert a single Element, and will perform some
       basic checking to prevent you inserting something that would be structurally wrong (in PDOM terms).

       In future, this method may be enhanced to allow the insertion of multiple Elements, inline-parsed code
       strings or MDOM::Document::Fragment objects.

       Returns true if the Element was inserted, false if it can not be inserted, or "undef" if you do not
       provide a MDOM::Element object as a parameter.

   remove
       For a given "MDOM::Element", the "remove" method will remove it from its parent intact, along with all of
       its children.

       Returns the "Element" itself as a convenience, or "undef" if an error occurs while trying to remove the
       "Element".

   delete
       For a given "MDOM::Element", the "remove" method will remove it from its parent, immediately deleting the
       "Element" and all of its children (if it has any).

       Returns true if the "Element" was successfully deleted, or "undef" if an error occurs while trying to
       remove the "Element".

   replace $Element
       Although some higher level class support more exotic forms of replace, at the basic level the "replace"
       method takes a single "Element" as an argument and replaces the current "Element" with it.

       To prevent accidental damage to code, in this initial implementation the replacement element must be of
       the same class (or a subclass) as the one being replaced.

   location
       If the Element exists within a MDOM::Document that has indexed the Element locations using
       "MDOM::Document::index_locations", the "location" method will return the location of the first character
       of the Element within the Document.

       Returns the location as a reference to a three-element array in the form "[ $line, $rowchar, $col ]". The
       values are in a human format, with the first character of the file located at "[ 1, 1, 1 ]".

       The second and third numbers are similar, except that the second is the literal horizontal character, and
       the third is the visual column, taking into account tabbing.

       Returns "undef" on error, or if the MDOM::Document object has not been indexed.

TO DO

       It would be nice if "location" could be used in an ad-hoc manner. That is, if called on an Element within
       a Document that has not been indexed, it will do a one-off calculation to find the location. It might be
       very painful if someone started using it a lot, without remembering to index the document, but it would
       be handy for things that are only likely to use it once, such as error handlers.

SUPPORT

       See the support section in the main module.

AUTHOR

       Adam Kennedy <adamk@cpan.org>

COPYRIGHT

       Copyright 2001 - 2006 Adam Kennedy.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl
       itself.

       The full text of the license can be found in the LICENSE file included with this module.