PPI::Token::HereDoc(3)User Contributed Perl DocumentatioPPI::Token::HereDoc(3)NAMEPPI::Token::HereDoc - Token class for the here-doc
INHERITANCEPPI::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 strong 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.
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 v5.16.2 2011-02-25 PPI::Token::HereDoc(3)
