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 raw_width
243 my ( $raw_min, $raw_max ) = $self->raw_width();
244 This public method returns the minimum and maximum width matched by the
246 element before taking into account such details as what the element
247 actually is and how it is quantified. Either or both elements can be
248 "undef" if the width can not be determined, and the maximum can be
249 "Inf".
250 This method was added in version 0.085_01.
252 remove_insignificant
254 This method returns a new object manufactured from the invocant, but
255 containing only elements for which "$elem->significant()" returns a
256 true value.
257 If you call this method on a PPIx::Regexp::Node you will get back a
259 deep clone, but without the insignificant elements.
260 If you call this method on any other PPIx::Regexp class you will get
262 back either the invocant or nothing. This may change to a clone of the
263 invocant or nothing if unforeseen problems arise with returning the
264 invocant, or if objects become mutable (unlikely, but not impossible.)
265 requirements_for_perl
267 say $token->requirements_for_perl();
268 This method returns a string representing the Perl requirements for a
270 given module. This should only be used for informational purposes, as
271 the format of the string may be subject to change.
272 At the moment, the returns may be:
274 version <= $]
276 version <= $] < version
277 two or more of the above joined by '||'
278 ! $]
279 The last means that, although all the components of the regular
281 expression can be compiled by some version of Perl, there is no version
282 that will compile all of them.
283 I reiterate: the returned string may be subject to change, maybe
285 without warning.
286 This method was added in version 0.051_01.
288 scontent
290 This method returns the significant content of the element. That is, if
291 called on the parse of '/ f u b a r /x', it returns '/fubar/x'. If the
292 invocant contains no insignificant elements, it is the same as
293 content(). If called on an insignificant element, it returns nothing --
294 that is, "undef" in scalar context, and an empty list in list context.
295 This method was inspired by jb's question on Perl Monks about stripping
297 comments and white space from a regular expression:
298 <https://www.perlmonks.org/?node_id=1207556>
299 This method was added in version 0.053_01
301 significant
303 This method returns true if the element is significant and false
304 otherwise.
305 snext_element
307 This method returns the next significant element, or nothing if there
308 is none.
309 Unlike snext_sibling(), this will cross from the content of a structure
311 into the elements that define the structure, or vice versa.
312 snext_sibling
314 This method returns the element's next significant sibling, or nothing
315 if there is none.
316 This method is analogous to the same-named PPI::Element method, in that
318 it will not cross from the content of a structure into the elements
319 that define the structure.
320 sprevious_element
322 This method returns the previous significant element, or nothing if
323 there is none.
324 Unlike sprevious_sibling(), this will cross from the content of a
326 structure into the elements that define the structure, or vice versa.
327 sprevious_sibling
329 This method returns the element's previous significant sibling, or
330 nothing if there is none.
331 This method is analogous to the same-named PPI::Element method, in that
333 it will not cross from the content of a structure into the elements
334 that define the structure.
335 statement
337 This method returns the PPI::Statement that contains this element, or
338 nothing if the statement can not be determined.
339 In general this method will return something only under the following
341 conditions:
342 • The element is contained in a PPIx::Regexp object;
344 • That object was initialized from a PPI::Element;
346 • The PPI::Element is contained in a statement.
348 tokens
350 This method returns all tokens contained in the element.
351 top
353 This method returns the top of the hierarchy.
354 unescaped_content
356 This method returns the content of the element, unescaped.
357 visual_column_number
359 This method returns the visual column number (taking tabs into account)
360 of the first character in the element, or "undef" if that can not be
361 determined.
362 whitespace
364 This method returns true if the element is whitespace and false
365 otherwise.
366 width
368 my ( $min, $max ) = $self->width();
369 This method returns the minimum and maximum number of characters this
371 element can match.
372 Either element can be "undef" if it cannot be determined. For example,
374 for "/$foo/" both elements will be "undef". Recursions will return
375 "undef" because they can not be analyzed statically -- or at least I am
376 not smart enough to do so. Back references may return "undef" if the
377 referred-to group can not be uniquely determined.
378 It is possible for $max to be "Inf". For example, for "/x*/" $max will
380 be "Inf".
381 Elements that do not actually match anything will return zeroes.
383 Note: This method was added because I wanted better detection of
385 variable-length look-behinds. Both it and raw_width() (above) should be
386 considered somewhat experimental.
387 This method was added in version 0.085_01.
389 nav
391 This method returns navigation information from the top of the
392 hierarchy to this node. The return is a list of names of methods and
393 references to their argument lists. The idea is that given $elem which
394 is somewhere under $top,
395 my @nav = $elem->nav();
397 my $obj = $top;
398 while ( @nav ) {
399 my $method = shift @nav;
400 my $args = shift @nav;
401 $obj = $obj->$method( @{ $args } ) or die;
402 }
403 # At this point, $obj should contain the same object
404 # as $elem.
405
407 Support is by the author. Please file bug reports at
408 <https://rt.cpan.org/Public/Dist/Display.html?Name=PPIx-Regexp>,
409 <https://github.com/trwyant/perl-PPIx-Regexp/issues>, or in electronic
410 mail to the author.
411
413 Thomas R. Wyant, III wyant at cpan dot org
414
416 Copyright (C) 2009-2023 by Thomas R. Wyant, III
417 This program is free software; you can redistribute it and/or modify it
419 under the same terms as Perl 5.10.0. For more details, see the full
420 text of the licenses in the directory LICENSES.
421 This program is distributed in the hope that it will be useful, but
423 without any warranty; without even the implied warranty of
424 merchantability or fitness for a particular purpose.
425perl v5.36.0 2023-01-30 PPIx::Regexp::Element(3)