1PPIx::Regexp::Element(3U)ser Contributed Perl DocumentatiPoPnIx::Regexp::Element(3)
2
6 PPIx::Regexp::Element - Base of the PPIx::Regexp hierarchy.
7
9 No user-serviceable parts inside.
10
12 "PPIx::Regexp::Element" is not descended from any other class.
13 "PPIx::Regexp::Element" is the parent of PPIx::Regexp::Node and
15 PPIx::Regexp::Token.
16
18 This class is the base of the PPIx::Regexp object hierarchy. It
19 provides the same kind of navigational functionality that is provided
20 by PPI::Element.
21
23 This class provides the following public methods. Methods not
24 documented here are private, and unsupported in the sense that the
25 author reserves the right to change or remove them without notice.
26 accepts_perl
28 $token->accepts_perl( '5.020' )
29 and say 'This works under Perl 5.20';
30 This method returns a true value if the token is acceptable under the
32 specified version of Perl, and a false value otherwise. Unless the
33 token (or its contents) have been equivocated on, the result is simply
34 what you would expect based on testing the results of
35 perl_version_introduced() and perl_version_removed() versus the given
36 Perl version number.
37 This method was added in version 0.051_01.
39 ancestor_of
41 This method returns true if the object is an ancestor of the argument,
42 and false otherwise. By the definition of this method, $self is its own
43 ancestor.
44 can_be_quantified
46 $token->can_be_quantified()
47 and print "This element can be quantified.\n";
48 This method returns true if the element can be quantified.
50 class
52 This method returns the class name of the element. It is the same as
53 "ref $self".
54 column_number
56 This method returns the column number of the first character in the
57 element, or "undef" if that can not be determined.
58 comment
60 This method returns true if the element is a comment and false
61 otherwise.
62 content
64 This method returns the content of the element.
65 descendant_of
67 This method returns true if the object is a descendant of the argument,
68 and false otherwise. By the definition of this method, $self is its own
69 descendant.
70 explain
72 This method returns a brief explanation of what the element does. The
73 return will be either a string or "undef" in scalar context, but may be
74 multiple values or an empty array in list context.
75 This method should be considered experimental. What it returns may
77 change without notice as my understanding of what all the pieces/parts
78 of a Perl regular expression evolves. The worst case is that it will
79 prove entirely infeasible to implement satisfactorily, in which case it
80 will be put through a deprecation cycle and retracted.
81 error
83 say $token->error();
84 If an element is one of the classes that represents a parse error, this
86 method may return a brief message saying why. Otherwise it will return
87 "undef".
88 is_matcher
90 This method reports on whether the element potentially matches
91 something. Possible returns are a true value if it does, a false (but
92 defined) value if it does not, or "undef" if this can not be
93 determined.
94 The idea is to classify elements based on whether they potentially
96 match something in the target string.
97 This method is overridden to return "undef" in
99 PPIx::Regexp::Token::Code, PPIx::Regexp::Token::Interpolation, and
100 PPIx::Regexp::Token::Unknown.
101 This method is overridden to return a true value in
103 PPIx::Regexp::Token::Assertion, PPIx::Regexp::Token::CharClass,
104 PPIx::Regexp::Token::Literal, and PPIx::Regexp::Token::Reference.
105 For PPIx::Regexp::Node, this method is overridden to return a value
107 computed from the node's children.
108 For anything else this method returns a false (but defined) value.
110 in_regex_set
112 This method returns a true value if the invocant is contained in an
113 extended bracketed character class (also known as a regex set), and a
114 false value otherwise. This method returns true if the invocant is a
115 PPIx::Regexp::Structure::RegexSet.
116 is_quantifier
118 $token->is_quantifier()
119 and print "This element is a quantifier.\n";
120 This method returns true if the element is a quantifier. You can not
122 tell this from the element's class, because a right curly bracket may
123 represent a quantifier for the purposes of figuring out whether a
124 greediness token is possible.
125 line_number
127 This method returns the line number of the first character in the
128 element, or "undef" if that can not be determined.
129 location
131 This method returns a reference to an array describing the position of
132 the element in the regular expression, or "undef" if locations were not
133 indexed.
134 The array is compatible with the corresponding PPI::Element method.
136 logical_filename
138 This method returns the logical file name (taking "#line" directives
139 into account) of the file containing first character in the element, or
140 "undef" if that can not be determined.
141 logical_line_number
143 This method returns the logical line number (taking "#line" directives
144 into account) of the first character in the element, or "undef" if that
145 can not be determined.
146 main_structure
148 This method returns the PPIx::Regexp::Structure::Main that contains the
149 element. In practice this will be a PPIx::Regexp::Structure::Regexp or
150 a PPIx::Regexp::Structure::Replacement,
151 If the element is not contained in any such structure, "undef" is
153 returned. This will happen if the element is a PPIx::Regexp or one of
154 its immediate children.
155 modifier_asserted
157 $token->modifier_asserted( 'i' )
158 and print "Matched without regard to case.\n";
159 This method returns true if the given modifier is in effect for the
161 element, and false otherwise.
162 What it does is to walk backwards from the element until it finds a
164 modifier object that specifies the modifier, whether asserted or
165 negated. and returns the specified value. If nobody specifies the
166 modifier, it returns "undef".
167 This method will not work reliably if called on tokenizer output.
169 next_element
171 This method returns the next element, or nothing if there is none.
172 Unlike next_sibling(), this will cross from the content of a structure
174 into the elements that define the structure, or vice versa.
175 next_sibling
177 This method returns the element's next sibling, or nothing if there is
178 none.
179 next_token
181 This method returns the next token, or nothing if there is none.
182 Unlike next_element(), this will walk the parse tree.
184 parent
186 This method returns the parent of the element, or undef if there is
187 none.
188 perl_version_introduced
190 This method returns the version of Perl in which the element was
191 introduced. This will be at least 5.000. Before 5.006 I am relying on
192 the perldelta, perlre, and perlop documentation, since I have been
193 unable to build earlier Perls. Since I have found no documentation
194 before 5.003, I assume that anything found in 5.003 is also in 5.000.
195 Since this all depends on my ability to read and understand masses of
197 documentation, the results of this method should be viewed with
198 caution, if not downright skepticism.
199 There are also cases which are ambiguous in various ways. For those see
201 the PPIx::Regexp documentation, particularly Changes in Syntax.
202 Very occasionally, a construct will be removed and then added back. If
204 this happens, this method will return the lowest version in which the
205 construct appeared. For the known instances of this, see the
206 PPIx::Regexp documentation, particularly Equivocation.
207 perl_version_removed
209 This method returns the version of Perl in which the element was
210 removed. If the element is still valid the return is "undef".
211 All the caveats to perl_version_introduced() apply here also, though
213 perhaps less severely since although many features have been introduced
214 since 5.0, few have been removed.
215 Very occasionally, a construct will be removed and then added back. If
217 this happens, this method will return the "undef" if the construct is
218 present in the highest-numbered version of Perl (whether production or
219 development), or the version after the highest-numbered version in
220 which it appeared otherwise. For the known instances of this, see the
221 PPIx::Regexp documentation, particularly Equivocation.
222 previous_element
224 This method returns the previous element, or nothing if there is none.
225 Unlike previous_sibling(), this will cross from the content of a
227 structure into the elements that define the structure, or vice versa.
228 previous_sibling
230 This method returns the element's previous sibling, or nothing if there
231 is none.
232 This method is analogous to the same-named PPI::Element method, in that
234 it will not cross from the content of a structure into the elements
235 that define the structure.
236 previous_token
238 This method returns the previous token, or nothing if there is none.
239 Unlike previous_element(), this will walk the parse tree.
241 remove_insignificant
243 This method returns a new object manufactured from the invocant, but
244 containing only elements for which "$elem->significant()" returns a
245 true value.
246 If you call this method on a PPIx::Regexp::Node you will get back a
248 deep clone, but without the insignificant elements.
249 If you call this method on any other PPIx::Regexp class you will get
251 back either the invocant or nothing. This may change to a clone of the
252 invocant or nothing if unforseen problems arise with returning the
253 invocant, or if objects become mutable (unlikely, but not impossible.)
254 requirements_for_perl
256 say $token->requirements_for_perl();
257 This method returns a string representing the Perl requirements for a
259 given module. This should only be used for informational purposes, as
260 the format of the string may be subject to change.
261 At the moment, the returns may be:
263 version <= $]
265 version <= $] < version
266 two or more of the above joined by '||'
267 ! $]
268 The last means that, although all the components of the regular
270 expression can be compiled by some version of Perl, there is no version
271 that will compile all of them.
272 I reiterate: the returned string may be subject to change, maybe
274 without warning.
275 This method was added in version 0.051_01.
277 scontent
279 This method returns the significant content of the element. That is, if
280 called on the parse of '/ f u b a r /x', it returns '/fubar/x'. If the
281 invocant contains no insignificant elements, it is the same as
282 content(). If called on an insignificant element, it returns nothing --
283 that is, "undef" in scalar context, and an empty list in list context.
284 This method was inspired by jb's question on Perl Monks about stripping
286 comments and white space from a regular expression:
287 <https://www.perlmonks.org/?node_id=1207556>
288 This method was added in version 0.053_01
290 significant
292 This method returns true if the element is significant and false
293 otherwise.
294 snext_element
296 This method returns the next significant element, or nothing if there
297 is none.
298 Unlike snext_sibling(), this will cross from the content of a structure
300 into the elements that define the structure, or vice versa.
301 snext_sibling
303 This method returns the element's next significant sibling, or nothing
304 if there is none.
305 This method is analogous to the same-named PPI::Element method, in that
307 it will not cross from the content of a structure into the elements
308 that define the structure.
309 sprevious_element
311 This method returns the previous significant element, or nothing if
312 there is none.
313 Unlike sprevious_sibling(), this will cross from the content of a
315 structure into the elements that define the structure, or vice versa.
316 sprevious_sibling
318 This method returns the element's previous significant sibling, or
319 nothing if there is none.
320 This method is analogous to the same-named PPI::Element method, in that
322 it will not cross from the content of a structure into the elements
323 that define the structure.
324 statement
326 This method returns the PPI::Statement that contains this element, or
327 nothing if the statement can not be determined.
328 In general this method will return something only under the following
330 conditions:
331 · The element is contained in a PPIx::Regexp object;
333 · That object was initialized from a PPI::Element;
335 · The PPI::Element is contained in a statement.
337 tokens
339 This method returns all tokens contained in the element.
340 top
342 This method returns the top of the hierarchy.
343 unescaped_content
345 This method returns the content of the element, unescaped.
346 visual_column_number
348 This method returns the visual column number (taking tabs into account)
349 of the first character in the element, or "undef" if that can not be
350 determined.
351 whitespace
353 This method returns true if the element is whitespace and false
354 otherwise.
355 nav
357 This method returns navigation information from the top of the
358 hierarchy to this node. The return is a list of names of methods and
359 references to their argument lists. The idea is that given $elem which
360 is somewhere under $top,
361 my @nav = $elem->nav();
363 my $obj = $top;
364 while ( @nav ) {
365 my $method = shift @nav;
366 my $args = shift @nav;
367 $obj = $obj->$method( @{ $args } ) or die;
368 }
369 # At this point, $obj should contain the same object
370 # as $elem.
371
373 Support is by the author. Please file bug reports at
374 <https://rt.cpan.org>, or in electronic mail to the author.
375
377 Thomas R. Wyant, III wyant at cpan dot org
378
380 Copyright (C) 2009-2020 by Thomas R. Wyant, III
381 This program is free software; you can redistribute it and/or modify it
383 under the same terms as Perl 5.10.0. For more details, see the full
384 text of the licenses in the directory LICENSES.
385 This program is distributed in the hope that it will be useful, but
387 without any warranty; without even the implied warranty of
388 merchantability or fitness for a particular purpose.
389perl v5.32.0 2020-07-29 PPIx::Regexp::Element(3)