1MDOM::Element(3)      User Contributed Perl Documentation     MDOM::Element(3)
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NAME

6       MDOM::Element - The abstract Element class, a base for all source
7       objects
8

INHERITANCE

10         MDOM::Element is the root of the PDOM tree
11

DESCRIPTION

13       The abstract "MDOM::Element" serves as a base class for all source-
14       related objects, from a single whitespace token to an entire document.
15       It provides a basic set of methods to provide a common interface and
16       basic implementations.
17

METHODS

19   significant
20       Because we treat whitespace and other non-code items as Tokens (in
21       order to be able to "round trip" the MDOM::Document back to a file) the
22       "significant" method allows us to distinguish between tokens that form
23       a part of the code, and tokens that aren't significant, such as
24       whitespace, POD, or the portion of a file after (and including) the
25       "__END__" token.
26
27       Returns true if the Element is significant, or false it not.
28
29   class
30       The "class" method is provided as a convenience, and really does
31       nothing more than returning "ref($self)". However, some people have
32       found that they appreciate the laziness of "$Foo->class eq 'whatever'",
33       so I have caved to popular demand and included it.
34
35       Returns the class of the Element as a string
36
37   tokens
38       The "tokens" method returns a list of MDOM::Token objects for the
39       Element, essentially getting back that part of the document as if it
40       had not been lexed.
41
42       This also means there are no Statements and no Structures in the list,
43       just the Token classes.
44
45   content
46       For any "MDOM::Element", the "content" method will reconstitute the
47       base code for it as a single string. This method is also the method
48       used for overloading stringification. When an Element is used in a
49       double-quoted string for example, this is the method that is called.
50
51       WARNING:
52
53       You should be aware that because of the way that here-docs are handled,
54       any here-doc content is not included in "content", and as such you
55       should not eval or execute the result if it contains any
56       MDOM::Token::HereDoc.
57
58       The MDOM::Document method "serialize" should be used to stringify a
59       PDOM document into something that can be executed as expected.
60
61       Returns the basic code as a string (excluding here-doc content).
62
63   parent
64       Elements themselves are not intended to contain other Elements, that is
65       left to the MDOM::Node abstract class, a subclass of "MDOM::Element".
66       However, all Elements can be contained within a parent Node.
67
68       If an Element is within a parent Node, the "parent" method returns the
69       Node.
70
71   statement
72       For a "MDOM::Element" that is contained (at some depth) within a
73       MDOM::Statment, the "statement" method will return the first parent
74       Statement object lexically 'above' the Element.
75
76       Returns a MDOM::Statement object, which may be the same Element if the
77       Element is itself a MDOM::Statement object.
78
79       Returns false if the Element is not within a Statement and is not
80       itself a Statement.
81
82   top
83       For a "MDOM::Element" that is contained within a PDOM tree, the "top"
84       method will return the top-level Node in the tree. Most of the time
85       this should be a MDOM::Document object, however this will not always be
86       so. For example, if a subroutine has been removed from its Document, to
87       be moved to another Document.
88
89       Returns the top-most PDOM object, which may be the same Element, if it
90       is not within any parent PDOM object.
91
92       For an Element that is contained within a MDOM::Document object, the
93       "document" method will return the top-level Document for the Element.
94
95       Returns the MDOM::Document for this Element, or false if the Element is
96       not contained within a Document.
97
98   next_sibling
99       All MDOM::Node objects (specifically, our parent Node) contain a number
100       of "MDOM::Element" objects. The "next_sibling" method returns the
101       "MDOM::Element" immediately after the current one, or false if there is
102       no next sibling.
103
104   snext_sibling
105       As per the other 's' methods, the "snext_sibling" method returns the
106       next significant sibling of the "MDOM::Element" object.
107
108       Returns a "MDOM::Element" object, or false if there is no 'next'
109       significant sibling.
110
111   previous_sibling
112       All MDOM::Node objects (specifically, our parent Node) contain a number
113       of "MDOM::Element" objects. The "previous_sibling" method returns the
114       Element immediately before the current one, or false if there is no
115       'previous' "MDOM::Element" object.
116
117   sprevious_sibling
118       As per the other 's' methods, the "sprevious_sibling" method returns
119       the previous significant sibling of the "MDOM::Element" object.
120
121       Returns a "MDOM::Element" object, or false if there is no 'previous'
122       significant sibling.
123
124   first_token
125       As a support method for higher-order algorithms that deal specifically
126       with tokens and actual Perl content, the "first_token" method finds the
127       first MDOM::Token object within or equal to this one.
128
129       That is, if called on a MDOM::Node subclass, it will descend until it
130       finds a MDOM::Token. If called on a MDOM::Token object, it will return
131       the same object.
132
133       Returns a MDOM::Token object, or dies on error (which should be
134       extremely rare and only occur if an illegal empty MDOM::Statement
135       exists below the current Element somewhere.
136
137   last_token
138       As a support method for higher-order algorithms that deal specifically
139       with tokens and actual Perl content, the "last_token" method finds the
140       last MDOM::Token object within or equal to this one.
141
142       That is, if called on a MDOM::Node subclass, it will descend until it
143       finds a MDOM::Token. If called on a MDOM::Token object, it will return
144       the itself.
145
146       Returns a MDOM::Token object, or dies on error (which should be
147       extremely rare and only occur if an illegal empty MDOM::Statement
148       exists below the current Element somewhere.
149
150   next_token
151       As a support method for higher-order algorithms that deal specifically
152       with tokens and actual Perl content, the "next_token" method finds the
153       MDOM::Token object that is immediately after the current Element, even
154       if it is not within the same parent MDOM::Node as the one for which the
155       method is being called.
156
157       Note that this is not defined as a MDOM::Token-specific method, because
158       it can be useful to find the next token that is after, say, a
159       MDOM::Statement, although obviously it would be useless to want the
160       next token after a MDOM::Document.
161
162       Returns a MDOM::Token object, or false if there are no more tokens
163       after the Element.
164
165   previous_token
166       As a support method for higher-order algorithms that deal specifically
167       with tokens and actual Perl content, the "previous_token" method finds
168       the MDOM::Token object that is immediately before the current Element,
169       even if it is not within the same parent MDOM::Node as this one.
170
171       Note that this is not defined as a MDOM::Token-only method, because it
172       can be useful to find the token is before, say, a MDOM::Statement,
173       although obviously it would be useless to want the next token before a
174       MDOM::Document.
175
176       Returns a MDOM::Token object, or false if there are no more tokens
177       before the "Element".
178
179   clone
180       As per the Clone module, the "clone" method makes a perfect copy of an
181       Element object. In the generic case, the implementation is done using
182       the Clone module's mechanism itself. In higher-order cases, such as for
183       Nodes, there is more work involved to keep the parent-child links
184       intact.
185
186   insert_before @Elements
187       The "insert_before" method allows you to insert lexical perl content,
188       in the form of "MDOM::Element" objects, before the calling "Element".
189       You need to be very careful when modifying perl code, as it's easy to
190       break things.
191
192       In its initial incarnation, this method allows you to insert a single
193       Element, and will perform some basic checking to prevent you inserting
194       something that would be structurally wrong (in PDOM terms).
195
196       In future, this method may be enhanced to allow the insertion of
197       multiple Elements, inline-parsed code strings or
198       MDOM::Document::Fragment objects.
199
200       Returns true if the Element was inserted, false if it can not be
201       inserted, or "undef" if you do not provide a MDOM::Element object as a
202       parameter.
203
204   insert_after @Elements
205       The "insert_after" method allows you to insert lexical perl content, in
206       the form of "MDOM::Element" objects, after the calling "Element". You
207       need to be very careful when modifying perl code, as it's easy to break
208       things.
209
210       In its initial incarnation, this method allows you to insert a single
211       Element, and will perform some basic checking to prevent you inserting
212       something that would be structurally wrong (in PDOM terms).
213
214       In future, this method may be enhanced to allow the insertion of
215       multiple Elements, inline-parsed code strings or
216       MDOM::Document::Fragment objects.
217
218       Returns true if the Element was inserted, false if it can not be
219       inserted, or "undef" if you do not provide a MDOM::Element object as a
220       parameter.
221
222   remove
223       For a given "MDOM::Element", the "remove" method will remove it from
224       its parent intact, along with all of its children.
225
226       Returns the "Element" itself as a convenience, or "undef" if an error
227       occurs while trying to remove the "Element".
228
229   delete
230       For a given "MDOM::Element", the "remove" method will remove it from
231       its parent, immediately deleting the "Element" and all of its children
232       (if it has any).
233
234       Returns true if the "Element" was successfully deleted, or "undef" if
235       an error occurs while trying to remove the "Element".
236
237   replace $Element
238       Although some higher level class support more exotic forms of replace,
239       at the basic level the "replace" method takes a single "Element" as an
240       argument and replaces the current "Element" with it.
241
242       To prevent accidental damage to code, in this initial implementation
243       the replacement element must be of the same class (or a subclass) as
244       the one being replaced.
245
246   location
247       If the Element exists within a MDOM::Document that has indexed the
248       Element locations using "MDOM::Document::index_locations", the
249       "location" method will return the location of the first character of
250       the Element within the Document.
251
252       Returns the location as a reference to a three-element array in the
253       form "[ $line, $rowchar, $col ]". The values are in a human format,
254       with the first character of the file located at "[ 1, 1, 1 ]".
255
256       The second and third numbers are similar, except that the second is the
257       literal horizontal character, and the third is the visual column,
258       taking into account tabbing.
259
260       Returns "undef" on error, or if the MDOM::Document object has not been
261       indexed.
262

TO DO

264       It would be nice if "location" could be used in an ad-hoc manner. That
265       is, if called on an Element within a Document that has not been
266       indexed, it will do a one-off calculation to find the location. It
267       might be very painful if someone started using it a lot, without
268       remembering to index the document, but it would be handy for things
269       that are only likely to use it once, such as error handlers.
270

SUPPORT

272       See the support section in the main module.
273

AUTHOR

275       Adam Kennedy <adamk@cpan.org>
276
278       Copyright 2001 - 2006 Adam Kennedy.
279
280       This program is free software; you can redistribute it and/or modify it
281       under the same terms as Perl itself.
282
283       The full text of the license can be found in the LICENSE file included
284       with this module.
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288perl v5.12.0                      2008-03-10                  MDOM::Element(3)
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