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

  PPI::Element is the root of the PDOM tree

The abstract PPI::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.

Because we treat whitespace and other non-code items as Tokens (in order to be able to round trip the PPI::Document back to a file) the CWsignificant method allows us to distinguish between tokens that form a part of the code, and tokens that arn'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.

The CWtokens method returns a list of PPI::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.

For any PPI::Element, the CWcontent 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 CWcontent, and as such you should NOT eval or execute the result if it contains any PPI::Token::HereDoc.

The PPI::Document method CWserialize 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).

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

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

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

Returns a PPI::Statement object, which may be the same Element if the Element is itself a PPI::Statement object. Returns false if the Element is not within a Statement and is not itself a Statement.

For a PPI::Element that is contained within a PDOM tree, the CWtop method will return the top-level Node in the tree. Most of the time this should be a PPI::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.

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

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

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

As per the other 's' methods, the CWsnext_sibling method returns the next significant sibling of the PPI::Element object.

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

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

As per the other 's' methods, the CWsprevious_sibling method returns the previous significant sibling of the PPI::Element object.

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

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

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

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

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

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

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

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

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

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

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

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

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

As per the Clone module, the CWclone 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.

NOTE: This has temporarily been moved to Storable::dclone until a critical but in Clone can be fixed. The CWinsert_before method allows you to insert lexical perl content, in the form of PPI::Element objects, before the calling Element. You need to be very careful when modifying perl code, as it's easy to break things.

This method is not yet implemented, mainly due to the difficulty in making it Do What You Mean. The CWinsert_after method allows you to insert lexical perl content, in the form of PPI::Element objects, after the calling Element. You need to be very careful when modifying perl code, as it's easy to break things.

This method is not yet implemented, mainly due to the difficulty in making it Do What You Mean.

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

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

For a given Element, the CWremove 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 CWundef if an error occurs while trying to remove the Element. Although some higher level class support more exotic forms of replace, at the basic level the CWreplace 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 exactly the same class as the one being replaced.

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

Returns the location as a reference to a two-element array in the form CW[ $line, $col ]. The values are in a human format, with the first character of the file located at CW[ 1, 1 ]. Returns CWundef on error, or if the PPI::Document object has not been indexed.

It would be nice if CWlocation 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.

See the support section in the main module

Adam Kennedy (Maintainer), <http://ali.as/>, cpan@ali.as

Copyright (c) 2004 - 2005 Adam Kennedy. All rights reserved.

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.