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_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_sibling
       This method returns the element's previous sibling, or nothing if there is none.

   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.

       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_sibling
       This method returns the element's next significant sibling, or nothing if there is none.

   sprevious_sibling
       This method returns the element's previous significant sibling, or nothing if there is
       none.

   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) 2009-2018 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.