1PPI::Element(3) User Contributed Perl Documentation PPI::Element(3)
2
6 PPI::Element - The abstract Element class, a base for all source
7 objects
8
10 PPI::Element is the root of the PDOM tree
11
13 The abstract "PPI::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
19 significant
20 Because we treat whitespace and other non-code items as Tokens (in
22 order to be able to "round trip" the PPI::Document back to a file) the
23 "significant" method allows us to distinguish between tokens that form
24 a part of the code, and tokens that aren't significant, such as white‐
25 space, POD, or the portion of a file after (and including) the
26 "__END__" token.
27 Returns true if the Element is significant, or false it not.
29 class
31 The "class" method is provided as a convenience, and really does noth‐
33 ing more than returning "ref($self)". However, some people have found
34 that they appreciate the laziness of "$Foo->class eq 'whatever'", so I
35 have caved to popular demand and included it.
36 Returns the class of the Element as a string
38 tokens
40 The "tokens" method returns a list of PPI::Token objects for the Ele‐
42 ment, essentially getting back that part of the document as if it had
43 not been lexed.
44 This also means there are no Statements and no Structures in the list,
46 just the Token classes.
47 content
49 For any "PPI::Element", the "content" method will reconstitute the base
51 code for it as a single string. This method is also the method used for
52 overloading stringification. When an Element is used in a double-quoted
53 string for example, this is the method that is called.
54 WARNING:
56 You should be aware that because of the way that here-docs are handled,
58 any here-doc content is not included in "content", and as such you
59 should not eval or execute the result if it contains any
60 PPI::Token::HereDoc.
61 The PPI::Document method "serialize" should be used to stringify a PDOM
63 document into something that can be executed as expected.
64 Returns the basic code as a string (excluding here-doc content).
66 parent
68 Elements themselves are not intended to contain other Elements, that is
70 left to the PPI::Node abstract class, a subclass of "PPI::Element".
71 However, all Elements can be contained within a parent Node.
72 If an Element is within a parent Node, the "parent" method returns the
74 Node.
75 statement
77 For a "PPI::Element" that is contained (at some depth) within a
79 PPI::Statment, the "statement" method will return the first parent
80 Statement object lexically 'above' the Element.
81 Returns a PPI::Statement object, which may be the same Element if the
83 Element is itself a PPI::Statement object.
84 Returns false if the Element is not within a Statement and is not
86 itself a Statement.
87 top
89 For a "PPI::Element" that is contained within a PDOM tree, the "top"
91 method will return the top-level Node in the tree. Most of the time
92 this should be a PPI::Document object, however this will not always be
93 so. For example, if a subroutine has been removed from its Document, to
94 be moved to another Document.
95 Returns the top-most PDOM object, which may be the same Element, if it
97 is not within any parent PDOM object.
98 For an Element that is contained within a PPI::Document object, the
100 "document" method will return the top-level Document for the Element.
101 Returns the PPI::Document for this Element, or false if the Element is
103 not contained within a Document.
104 next_sibling
106 All PPI::Node objects (specifically, our parent Node) contain a number
108 of "PPI::Element" objects. The "next_sibling" method returns the
109 "PPI::Element" immediately after the current one, or false if there is
110 no next sibling.
111 snext_sibling
113 As per the other 's' methods, the "snext_sibling" method returns the
115 next significant sibling of the "PPI::Element" object.
116 Returns a "PPI::Element" object, or false if there is no 'next' signif‐
118 icant sibling.
119 previous_sibling
121 All PPI::Node objects (specifically, our parent Node) contain a number
123 of "PPI::Element" objects. The "previous_sibling" method returns the
124 Element immediately before the current one, or false if there is no
125 'previous' "PPI::Element" object.
126 sprevious_sibling
128 As per the other 's' methods, the "sprevious_sibling" method returns
130 the previous significant sibling of the "PPI::Element" object.
131 Returns a "PPI::Element" object, or false if there is no 'previous'
133 significant sibling.
134 first_token
136 As a support method for higher-order algorithms that deal specifically
138 with tokens and actual Perl content, the "first_token" method finds the
139 first PPI::Token object within or equal to this one.
140 That is, if called on a PPI::Node subclass, it will descend until it
142 finds a PPI::Token. If called on a PPI::Token object, it will return
143 the same object.
144 Returns a PPI::Token object, or dies on error (which should be
146 extremely rare and only occur if an illegal empty PPI::Statement exists
147 below the current Element somewhere.
148 last_token
150 As a support method for higher-order algorithms that deal specifically
152 with tokens and actual Perl content, the "last_token" method finds the
153 last PPI::Token object within or equal to this one.
154 That is, if called on a PPI::Node subclass, it will descend until it
156 finds a PPI::Token. If called on a PPI::Token object, it will return
157 the itself.
158 Returns a PPI::Token object, or dies on error (which should be
160 extremely rare and only occur if an illegal empty PPI::Statement exists
161 below the current Element somewhere.
162 next_token
164 As a support method for higher-order algorithms that deal specifically
166 with tokens and actual Perl content, the "next_token" method finds the
167 PPI::Token object that is immediately after the current Element, even
168 if it is not within the same parent PPI::Node as the one for which the
169 method is being called.
170 Note that this is not defined as a PPI::Token-specific method, because
172 it can be useful to find the next token that is after, say, a
173 PPI::Statement, although obviously it would be useless to want the next
174 token after a PPI::Document.
175 Returns a PPI::Token object, or false if there are no more tokens after
177 the Element.
178 previous_token
180 As a support method for higher-order algorithms that deal specifically
182 with tokens and actual Perl content, the "previous_token" method finds
183 the PPI::Token object that is immediately before the current Element,
184 even if it is not within the same parent PPI::Node as this one.
185 Note that this is not defined as a PPI::Token-only method, because it
187 can be useful to find the token is before, say, a PPI::Statement,
188 although obviously it would be useless to want the next token before a
189 PPI::Document.
190 Returns a PPI::Token object, or false if there are no more tokens
192 before the "Element".
193 clone
195 As per the Clone module, the "clone" method makes a perfect copy of an
197 Element object. In the generic case, the implementation is done using
198 the Clone module's mechanism itself. In higher-order cases, such as for
199 Nodes, there is more work involved to keep the parent-child links
200 intact.
201 insert_before @Elements
203 The "insert_before" method allows you to insert lexical perl content,
205 in the form of "PPI::Element" objects, before the calling "Element".
206 You need to be very careful when modifying perl code, as it's easy to
207 break things.
208 In its initial incarnation, this method allows you to insert a single
210 Element, and will perform some basic checking to prevent you inserting
211 something that would be structurally wrong (in PDOM terms).
212 In future, this method may be enhanced to allow the insertion of multi‐
214 ple Elements, inline-parsed code strings or PPI::Document::Fragment
215 objects.
216 Returns true if the Element was inserted, false if it can not be
218 inserted, or "undef" if you do not provide a PPI::Element object as a
219 parameter.
220 insert_after @Elements
222 The "insert_after" method allows you to insert lexical perl content, in
224 the form of "PPI::Element" objects, after the calling "Element". You
225 need to be very careful when modifying perl code, as it's easy to break
226 things.
227 In its initial incarnation, this method allows you to insert a single
229 Element, and will perform some basic checking to prevent you inserting
230 something that would be structurally wrong (in PDOM terms).
231 In future, this method may be enhanced to allow the insertion of multi‐
233 ple Elements, inline-parsed code strings or PPI::Document::Fragment
234 objects.
235 Returns true if the Element was inserted, false if it can not be
237 inserted, or "undef" if you do not provide a PPI::Element object as a
238 parameter.
239 remove
241 For a given "PPI::Element", the "remove" method will remove it from its
243 parent intact, along with all of its children.
244 Returns the "Element" itself as a convenience, or "undef" if an error
246 occurs while trying to remove the "Element".
247 delete
249 For a given "PPI::Element", the "remove" method will remove it from its
251 parent, immediately deleting the "Element" and all of its children (if
252 it has any).
253 Returns true if the "Element" was successfully deleted, or "undef" if
255 an error occurs while trying to remove the "Element".
256 replace $Element
258 Although some higher level class support more exotic forms of replace,
260 at the basic level the "replace" method takes a single "Element" as an
261 argument and replaces the current "Element" with it.
262 To prevent accidental damage to code, in this initial implementation
264 the replacement element must be of the same class (or a subclass) as
265 the one being replaced.
266 location
268 If the Element exists within a PPI::Document that has indexed the Ele‐
270 ment locations using "PPI::Document::index_locations", the "location"
271 method will return the location of the first character of the Element
272 within the Document.
273 Returns the location as a reference to a three-element array in the
275 form "[ $line, $rowchar, $col ]". The values are in a human format,
276 with the first character of the file located at "[ 1, 1, 1 ]".
277 The second and third numbers are similar, except that the second is the
279 literal horizontal character, and the third is the visual column, tak‐
280 ing into account tabbing.
281 Returns "undef" on error, or if the PPI::Document object has not been
283 indexed.
284
286 It would be nice if "location" could be used in an ad-hoc manner. That
287 is, if called on an Element within a Document that has not been
288 indexed, it will do a one-off calculation to find the location. It
289 might be very painful if someone started using it a lot, without remem‐
290 bering to index the document, but it would be handy for things that are
291 only likely to use it once, such as error handlers.
292
294 See the support section in the main module.
295
297 Adam Kennedy <adamk@cpan.org>
298
300 Copyright 2001 - 2006 Adam Kennedy.
301 This program is free software; you can redistribute it and/or modify it
303 under the same terms as Perl itself.
304 The full text of the license can be found in the LICENSE file included
306 with this module.
307perl v5.8.8 2006-09-23 PPI::Element(3)