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   lineno
30       Accessor for current line number.
31
32   class
33       The "class" method is provided as a convenience, and really does
34       nothing more than returning "ref($self)". However, some people have
35       found that they appreciate the laziness of "$Foo->class eq 'whatever'",
36       so I have caved to popular demand and included it.
37
38       Returns the class of the Element as a string
39
40   tokens
41       The "tokens" method returns a list of MDOM::Token objects for the
42       Element, essentially getting back that part of the document as if it
43       had not been lexed.
44
45       This also means there are no Statements and no Structures in the list,
46       just the Token classes.
47
48   content
49       For any "MDOM::Element", the "content" method will reconstitute the
50       base code for it as a single string. This method is also the method
51       used for overloading stringification. When an Element is used in a
52       double-quoted string for example, this is the method that is called.
53
54       WARNING:
55
56       You should be aware that because of the way that here-docs are handled,
57       any here-doc content is not included in "content", and as such you
58       should not eval or execute the result if it contains any
59       MDOM::Token::HereDoc.
60
61       The MDOM::Document method "serialize" should be used to stringify a
62       PDOM document into something that can be executed as expected.
63
64       Returns the basic code as a string (excluding here-doc content).
65
66   parent
67       Elements themselves are not intended to contain other Elements, that is
68       left to the MDOM::Node abstract class, a subclass of "MDOM::Element".
69       However, all Elements can be contained within a parent Node.
70
71       If an Element is within a parent Node, the "parent" method returns the
72       Node.
73
74   statement
75       For a "MDOM::Element" that is contained (at some depth) within a
76       MDOM::Statment, the "statement" method will return the first parent
77       Statement object lexically 'above' the Element.
78
79       Returns a MDOM::Statement object, which may be the same Element if the
80       Element is itself a MDOM::Statement object.
81
82       Returns false if the Element is not within a Statement and is not
83       itself a Statement.
84
85   top
86       For a "MDOM::Element" that is contained within a PDOM tree, the "top"
87       method will return the top-level Node in the tree. Most of the time
88       this should be a MDOM::Document object, however this will not always be
89       so. For example, if a subroutine has been removed from its Document, to
90       be moved to another Document.
91
92       Returns the top-most PDOM object, which may be the same Element, if it
93       is not within any parent PDOM object.
94
95   document
96       For an Element that is contained within a MDOM::Document object, the
97       "document" method will return the top-level Document for the Element.
98
99       Returns the MDOM::Document for this Element, or false if the Element is
100       not contained within a Document.
101
102   next_sibling
103       All MDOM::Node objects (specifically, our parent Node) contain a number
104       of "MDOM::Element" objects. The "next_sibling" method returns the
105       "MDOM::Element" immediately after the current one, or false if there is
106       no next sibling.
107
108   snext_sibling
109       As per the other 's' methods, the "snext_sibling" method returns the
110       next significant sibling of the "MDOM::Element" object.
111
112       Returns a "MDOM::Element" object, or false if there is no 'next'
113       significant sibling.
114
115   previous_sibling
116       All MDOM::Node objects (specifically, our parent Node) contain a number
117       of "MDOM::Element" objects. The "previous_sibling" method returns the
118       Element immediately before the current one, or false if there is no
119       'previous' "MDOM::Element" object.
120
121   sprevious_sibling
122       As per the other 's' methods, the "sprevious_sibling" method returns
123       the previous significant sibling of the "MDOM::Element" object.
124
125       Returns a "MDOM::Element" object, or false if there is no 'previous'
126       significant sibling.
127
128   first_token
129       As a support method for higher-order algorithms that deal specifically
130       with tokens and actual Perl content, the "first_token" method finds the
131       first MDOM::Token object within or equal to this one.
132
133       That is, if called on a MDOM::Node subclass, it will descend until it
134       finds a MDOM::Token. If called on a MDOM::Token object, it will return
135       the same object.
136
137       Returns a MDOM::Token object, or dies on error (which should be
138       extremely rare and only occur if an illegal empty MDOM::Statement
139       exists below the current Element somewhere.
140
141   last_token
142       As a support method for higher-order algorithms that deal specifically
143       with tokens and actual Perl content, the "last_token" method finds the
144       last MDOM::Token object within or equal to this one.
145
146       That is, if called on a MDOM::Node subclass, it will descend until it
147       finds a MDOM::Token. If called on a MDOM::Token object, it will return
148       the itself.
149
150       Returns a MDOM::Token object, or dies on error (which should be
151       extremely rare and only occur if an illegal empty MDOM::Statement
152       exists below the current Element somewhere.
153
154   next_token
155       As a support method for higher-order algorithms that deal specifically
156       with tokens and actual Perl content, the "next_token" method finds the
157       MDOM::Token object that is immediately after the current Element, even
158       if it is not within the same parent MDOM::Node as the one for which the
159       method is being called.
160
161       Note that this is not defined as a MDOM::Token-specific method, because
162       it can be useful to find the next token that is after, say, a
163       MDOM::Statement, although obviously it would be useless to want the
164       next token after a MDOM::Document.
165
166       Returns a MDOM::Token object, or false if there are no more tokens
167       after the Element.
168
169   previous_token
170       As a support method for higher-order algorithms that deal specifically
171       with tokens and actual Perl content, the "previous_token" method finds
172       the MDOM::Token object that is immediately before the current Element,
173       even if it is not within the same parent MDOM::Node as this one.
174
175       Note that this is not defined as a MDOM::Token-only method, because it
176       can be useful to find the token is before, say, a MDOM::Statement,
177       although obviously it would be useless to want the next token before a
178       MDOM::Document.
179
180       Returns a MDOM::Token object, or false if there are no more tokens
181       before the "Element".
182
183   clone
184       As per the Clone module, the "clone" method makes a perfect copy of an
185       Element object. In the generic case, the implementation is done using
186       the Clone module's mechanism itself. In higher-order cases, such as for
187       Nodes, there is more work involved to keep the parent-child links
188       intact.
189
190   insert_before @Elements
191       The "insert_before" method allows you to insert lexical perl content,
192       in the form of "MDOM::Element" objects, before the calling "Element".
193       You need to be very careful when modifying perl code, as it's easy to
194       break things.
195
196       In its initial incarnation, this method allows you to insert a single
197       Element, and will perform some basic checking to prevent you inserting
198       something that would be structurally wrong (in PDOM terms).
199
200       In future, this method may be enhanced to allow the insertion of
201       multiple Elements, inline-parsed code strings or
202       MDOM::Document::Fragment objects.
203
204       Returns true if the Element was inserted, false if it can not be
205       inserted, or "undef" if you do not provide a MDOM::Element object as a
206       parameter.
207
208   insert_after @Elements
209       The "insert_after" method allows you to insert lexical perl content, in
210       the form of "MDOM::Element" objects, after the calling "Element". You
211       need to be very careful when modifying perl code, as it's easy to break
212       things.
213
214       In its initial incarnation, this method allows you to insert a single
215       Element, and will perform some basic checking to prevent you inserting
216       something that would be structurally wrong (in PDOM terms).
217
218       In future, this method may be enhanced to allow the insertion of
219       multiple Elements, inline-parsed code strings or
220       MDOM::Document::Fragment objects.
221
222       Returns true if the Element was inserted, false if it can not be
223       inserted, or "undef" if you do not provide a MDOM::Element object as a
224       parameter.
225
226   remove
227       For a given "MDOM::Element", the "remove" method will remove it from
228       its parent intact, along with all of its children.
229
230       Returns the "Element" itself as a convenience, or "undef" if an error
231       occurs while trying to remove the "Element".
232
233   delete
234       For a given "MDOM::Element", the "remove" method will remove it from
235       its parent, immediately deleting the "Element" and all of its children
236       (if it has any).
237
238       Returns true if the "Element" was successfully deleted, or "undef" if
239       an error occurs while trying to remove the "Element".
240
241   replace $Element
242       Although some higher level class support more exotic forms of replace,
243       at the basic level the "replace" method takes a single "Element" as an
244       argument and replaces the current "Element" with it.
245
246       To prevent accidental damage to code, in this initial implementation
247       the replacement element must be of the same class (or a subclass) as
248       the one being replaced.
249
250   location
251       If the Element exists within a MDOM::Document that has indexed the
252       Element locations using "MDOM::Document::index_locations", the
253       "location" method will return the location of the first character of
254       the Element within the Document.
255
256       Returns the location as a reference to a three-element array in the
257       form "[ $line, $rowchar, $col ]". The values are in a human format,
258       with the first character of the file located at "[ 1, 1, 1 ]".
259
260       The second and third numbers are similar, except that the second is the
261       literal horizontal character, and the third is the visual column,
262       taking into account tabbing.
263
264       Returns "undef" on error, or if the MDOM::Document object has not been
265       indexed.
266

TO DO

268       It would be nice if "location" could be used in an ad-hoc manner. That
269       is, if called on an Element within a Document that has not been
270       indexed, it will do a one-off calculation to find the location. It
271       might be very painful if someone started using it a lot, without
272       remembering to index the document, but it would be handy for things
273       that are only likely to use it once, such as error handlers.
274

SUPPORT

276       See the support section in the main module.
277

AUTHOR

279       Adam Kennedy <adamk@cpan.org>
280
282       Copyright 2001 - 2006 Adam Kennedy.
283
284       This program is free software; you can redistribute it and/or modify it
285       under the same terms as Perl itself.
286
287       The full text of the license can be found in the LICENSE file included
288       with this module.
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292perl v5.34.0                      2022-01-21                  MDOM::Element(3)
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