PPIx::Regexp::Element(3)
NAME
PPIx::Regexp::Element - Base of the PPIx::Regexp hierarchy.
SYNOPSIS
No user-serviceable parts inside.
INHERITANCE
"PPIx::Regexp::Element" is not descended from any other class.
"PPIx::Regexp::Element" is the parent of PPIx::Regexp::Node and
PPIx::Regexp::Token.
DESCRIPTION
This class is the base of the PPIx::Regexp object hierarchy. It
provides the same kind of navigational functionality that is provided
by PPI::Element.
METHODS
This class provides the following public methods. Methods not
documented here are private, and unsupported in the sense that the
author reserves the right to change or remove them without notice.
accepts_perl
$token->accepts_perl( '5.020' )
and say 'This works under Perl 5.20';
This method returns a true value if the token is acceptable under the
specified version of Perl, and a false value otherwise. Unless the
token (or its contents) have been equivocated on, the result is simply
what you would expect based on testing the results of
perl_version_introduced() and perl_version_removed() versus the given
Perl version number.
This method was added in version 0.051_01.
ancestor_of
This method returns true if the object is an ancestor of the argument,
and false otherwise. By the definition of this method, $self is its own
ancestor.
can_be_quantified
$token->can_be_quantified()
and print "This element can be quantified.\n";
This method returns true if the element can be quantified.
class
This method returns the class name of the element. It is the same as
"ref $self".
comment
This method returns true if the element is a comment and false
otherwise.
content
This method returns the content of the element.
descendant_of
This method returns true if the object is a descendant of the argument,
and false otherwise. By the definition of this method, $self is its own
descendant.
explain
This method returns a brief explanation of what the element does. The
return will be either a string or "undef" in scalar context, but may be
multiple values or an empty array in list context.
This method should be considered experimental. What it returns may
change without notice as my understanding of what all the pieces/parts
of a Perl regular expression evolves. The worst case is that it will
prove entirely infeasible to implement satisfactorily, in which case it
will be put through a deprecation cycle and retracted.
error
say $token->error();
If an element is one of the classes that represents a parse error, this
method may return a brief message saying why. Otherwise it will return
"undef".
in_regex_set
This method returns a true value if the invocant is contained in an
extended bracketed character class (also known as a regex set), and a
false value otherwise. This method returns true if the invocant is a
PPIx::Regexp::Structure::RegexSet.
is_quantifier
$token->is_quantifier()
and print "This element is a quantifier.\n";
This method returns true if the element is a quantifier. You can not
tell this from the element's class, because a right curly bracket may
represent a quantifier for the purposes of figuring out whether a
greediness token is possible.
main_structure
This method returns the PPIx::Regexp::Structure::Main that contains the
element. In practice this will be a PPIx::Regexp::Structure::Regexp or
a PPIx::Regexp::Structure::Replacement,
If the element is not contained in any such structure, "undef" is
returned. This will happen if the element is a PPIx::Regexp or one of
its immediate children.
modifier_asserted
$token->modifier_asserted( 'i' )
and print "Matched without regard to case.\n";
This method returns true if the given modifier is in effect for the
element, and false otherwise.
What it does is to walk backwards from the element until it finds a
modifier object that specifies the modifier, whether asserted or
negated. and returns the specified value. If nobody specifies the
modifier, it returns "undef".
This method will not work reliably if called on tokenizer output.
next_element
This method returns the next element, or nothing if there is none.
Unlike next_sibling(), this will cross from the content of a structure
into the elements that define the structure, or vice versa.
next_sibling
This method returns the element's next sibling, or nothing if there is
none.
parent
This method returns the parent of the element, or undef if there is
none.
perl_version_introduced
This method returns the version of Perl in which the element was
introduced. This will be at least 5.000. Before 5.006 I am relying on
the perldelta, perlre, and perlop documentation, since I have been
unable to build earlier Perls. Since I have found no documentation
before 5.003, I assume that anything found in 5.003 is also in 5.000.
Since this all depends on my ability to read and understand masses of
documentation, the results of this method should be viewed with
caution, if not downright skepticism.
There are also cases which are ambiguous in various ways. For those see
the PPIx::Regexp documentation, particularly Changes in Syntax.
Very occasionally, a construct will be removed and then added back. If
this happens, this method will return the lowest version in which the
construct appeared. For the known instances of this, see the
PPIx::Regexp documentation, particularly Equivocation.
perl_version_removed
This method returns the version of Perl in which the element was
removed. If the element is still valid the return is "undef".
All the caveats to perl_version_introduced() apply here also, though
perhaps less severely since although many features have been introduced
since 5.0, few have been removed.
Very occasionally, a construct will be removed and then added back. If
this happens, this method will return the "undef" if the construct is
present in the highest-numbered version of Perl (whether production or
development), or the version after the highest-numbered version in
which it appeared otherwise. For the known instances of this, see the
PPIx::Regexp documentation, particularly Equivocation.
previous_element
This method returns the previous element, or nothing if there is none.
Unlike previous_sibling(), this will cross from the content of a
structure into the elements that define the structure, or vice versa.
previous_sibling
This method returns the element's previous sibling, or nothing if there
is none.
This method is analogous to the same-named PPI::Element method, in that
it will not cross from the content of a structure into the elements
that define the structure.
remove_insignificant
This method returns a new object manufactured from the invocant, but
containing only elements for which "$elem->significant()" returns a
true value.
If you call this method on a PPIx::Regexp::Node you will get back a
deep clone, but without the insignificant elements.
If you call this method on any other PPIx::Regexp class you will get
back either the invocant or nothing. This may change to a clone of the
invocant or nothing if unforseen problems arise with returning the
invocant, or if objects become mutable (unlikely, but not impossible.)
requirements_for_perl
say $token->requirements_for_perl();
This method returns a string representing the Perl requirements for a
given module. This should only be used for informational purposes, as
the format of the string may be subject to change.
At the moment, the returns may be:
version <= $]
version <= $] < version
two or more of the above joined by '||'
! $]
The last means that, although all the components of the regular
expression can be compiled by some version of Perl, there is no version
that will compile all of them.
I reiterate: the returned string may be subject to change, maybe
without warning.
This method was added in version 0.051_01.
scontent
This method returns the significant content of the element. That is, if
called on the parse of '/ f u b a r /x', it returns '/fubar/x'. If the
invocant contains no insignificant elements, it is the same as
content(). If called on an insignificant element, it returns nothing --
that is, "undef" in scalar context, and an empty list in list context.
This method was inspired by jb's question on Perl Monks about stripping
comments and white space from a regular expression:
<http://www.perlmonks.org/?node_id=1207556>
This method was added in version 0.053_01
significant
This method returns true if the element is significant and false
otherwise.
snext_element
This method returns the next significant element, or nothing if there
is none.
Unlike snext_sibling(), this will cross from the content of a structure
into the elements that define the structure, or vice versa.
snext_sibling
This method returns the element's next significant sibling, or nothing
if there is none.
This method is analogous to the same-named PPI::Element method, in that
it will not cross from the content of a structure into the elements
that define the structure.
sprevious_element
This method returns the previous significant element, or nothing if
there is none.
Unlike sprevious_sibling(), this will cross from the content of a
structure into the elements that define the structure, or vice versa.
sprevious_sibling
This method returns the element's previous significant sibling, or
nothing if there is none.
This method is analogous to the same-named PPI::Element method, in that
it will not cross from the content of a structure into the elements
that define the structure.
tokens
This method returns all tokens contained in the element.
top
This method returns the top of the hierarchy.
unescaped_content
This method returns the content of the element, unescaped.
whitespace
This method returns true if the element is whitespace and false
otherwise.
nav
This method returns navigation information from the top of the
hierarchy to this node. The return is a list of names of methods and
references to their argument lists. The idea is that given $elem which
is somewhere under $top,
my @nav = $elem->nav();
my $obj = $top;
while ( @nav ) {
my $method = shift @nav;
my $args = shift @nav;
$obj = $obj->$method( @{ $args } ) or die;
}
# At this point, $obj should contain the same object
# as $elem.
SUPPORT
Support is by the author. Please file bug reports at
<http://rt.cpan.org>, or in electronic mail to the author.
AUTHOR
Thomas R. Wyant, III wyant at cpan dot org
COPYRIGHT AND LICENSE
Copyright (C) 2009-2019 by Thomas R. Wyant, III
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl 5.10.0. For more details, see the full
text of the licenses in the directory LICENSES.
This program is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of
merchantability or fitness for a particular purpose.
perl v5.28.1 2019-04-04 PPIx::Regexp::Element(3)
ppix-regexp 0.64.0 - Generated Thu Apr 4 16:00:15 CDT 2019