PPI::Token::HereDoc(3)                     User Contributed Perl Documentation


NAME
       PPI::Token::HereDoc - Token class for the here-doc

INHERITANCE
         PPI::Token::HereDoc
         isa PPI::Token
             isa PPI::Element

DESCRIPTION
       Here-docs are incredibly handy when writing Perl, but incredibly tricky
       when parsing it, primarily because they don't follow the general flow
       of input.

       They jump ahead and nab lines directly off the input buffer. Whitespace
       and newlines may not matter in most Perl code, but they matter in here-
       docs.

       They are also tricky to store as an object. They look sort of like an
       operator and a string, but they don't act like it. And they have a
       second section that should be something like a separate token, but
       isn't because a string can span from above the here-doc content to
       below it.

       So when parsing, this is what we do.

       Firstly, the PPI::Token::HereDoc object, does not represent the "<<"
       operator, or the "END_FLAG", or the content, or even the terminator.

       It represents all of them at once.

       The token itself has only the declaration part as its "content".

         # This is what the content of a HereDoc token is
         <<FOO

         # Or this
         <<"FOO"

         # Or even this
         <<      'FOO'

       That is, the "operator", any whitespace separator, and the quoted or
       bare terminator. So when you call the "content" method on a HereDoc
       token, you get '<< "FOO"'.

       As for the content and the terminator, when treated purely in "content"
       terms they do not exist.

       The content is made available with the "heredoc" method, and the name
       of the terminator with the "terminator" method.

       To make things work in the way you expect, PPI has to play some games
       when doing line/column location calculation for tokens, and also during
       the content parsing and generation processes.

       Documents cannot simply by recreated by stitching together the token
       contents, and involve a somewhat more expensive procedure, but the
       extra expense should be relatively negligible unless you are doing huge
       quantities of them.

       Please note that due to the immature nature of PPI in general, we
       expect "HereDocs" to be a rich (bad) source of corner-case bugs for
       quite a while, but for the most part they should more or less DWYM.

   Comparison to other string types
       Although technically it can be considered a quote, for the time being
       "HereDocs" are being treated as a completely separate "Token" subclass,
       and will not be found in a search for PPI::Token::Quote or
       PPI::Token::QuoteLike objects.

       This may change in the future, with it most likely to end up under
       QuoteLike.

METHODS
       Although it has the standard set of "Token" methods, "HereDoc" objects
       have a relatively large number of unique methods all of their own.

   heredoc
       The "heredoc" method is the authoritative method for accessing the
       contents of the "HereDoc" object.

       It returns the contents of the here-doc as a list of newline-terminated
       strings. If called in scalar context, it returns the number of lines in
       the here-doc, excluding the terminator line.

   indentation
       The "indentation" method returns the indentation string of an indented
       here-doc if that can be determined. If the indented here-doc is damaged
       (say, missing terminator) or the here-doc was not indented, it returns
       "undef".

   terminator
       The "terminator" method returns the name of the terminating string for
       the here-doc.

       Returns the terminating string as an unescaped string (in the rare case
       the terminator has an escaped quote in it).

TO DO
       - Implement PPI::Token::Quote interface compatibility

       - Check CPAN for any use of the null here-doc or here-doc-in-s///e

       - Add support for the null here-doc

       - Add support for here-doc in s///e

SUPPORT
       See the support section in the main module.

AUTHOR
       Adam Kennedy <adamk@cpan.org>

COPYRIGHT
       Copyright 2001 - 2011 Adam Kennedy.

       This program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.

       The full text of the license can be found in the LICENSE file included
       with this module.

perl v5.38.2                      2024-05-12            PPI::Token::HereDoc(3)