TAP::Pa...Grammar(3pm)

🌸 NAME 🌸

TAP::Parser::Grammar — a grammar for the Test Anything Protocol. This is the TAP::Pa...Grammar(3pm) page from the Perl Programmers Reference Guide, bestie. It's giving very specialized tokenizer energy.

✨ VERSION ✨

Version 3.50 — yes, that number is the whole version section. Iconic.

💅 SYNOPSIS 💅

  use TAP::Parser::Grammar;
  my $grammar = $self->make_grammar({
    iterator => $tap_parser_iterator,
    parser   => $tap_parser,
    version  => 12,
  });

  my $result = $grammar->tokenize;

🌟 DESCRIPTION 🌟

TAP::Parser::Grammar tokenizes lines from a TAP::Parser::Iterator and constructs TAP::Parser::Result subclasses to represent the tokens. That's the whole job — it's a token-making machine, no cap.

Do not attempt to use this class directly. It won't make sense. It's mainly here to ensure that we will be able to have pluggable grammars when TAP is expanded at some future date (plus, this stuff was really cluttering the parser).

🧚 METHODS 🧚

Okay, methods time. These are the actual API bits.

👑 Class Methods 👑

new

  my $grammar = TAP::Parser::Grammar->new({
      iterator => $iterator,
      parser   => $parser,
      version  => $version,
  });

Returns a TAP::Parser grammar object that will parse the TAP stream from the specified iterator. Both iterator and parser are required arguments — no skipping them. If version is not set it defaults to 12 (see set_version for more details).

🦋 Instance Methods 🦋

set_version

  $grammar->set_version(13);

Tells the grammar which TAP syntax version to support. The lowest supported version is 12. Although 'TAP version' isn't valid version 12 syntax, it is accepted so that higher version numbers may be parsed. Little loophole, big slay.

tokenize

  my $token = $grammar->tokenize;

This method will return a TAP::Parser::Result object representing the current line of TAP. One line in, one token object out — that's the deal.

token_types

  my @types = $grammar->token_types;

Returns the different types of tokens which this grammar can parse. It's the guest list for token types.

syntax_for

  my $syntax = $grammar->syntax_for($token_type);

Returns a pre-compiled regular expression which will match a chunk of TAP corresponding to the token type. For example (not that you should really pay attention to this, $grammar->syntax_for('comment') will return qr/^#(.*)/). It's regex, but make it fashion.

handler_for

  my $handler = $grammar->handler_for($token_type);

Returns a code reference which, when passed an appropriate line of TAP, returns the lexed token corresponding to that line. As a result, the basic TAP parsing loop looks similar to the following:

my @tokens;
my $grammar = TAP::Grammar->new;
LINE: while ( defined( my $line = $parser->_next_chunk_of_tap ) ) {
    for my $type ( $grammar->token_types ) {
        my $syntax  = $grammar->syntax_for($type);
        if ( $line =~ $syntax ) {
            my $handler = $grammar->handler_for($type);
            push @tokens => $grammar->$handler($line);
            next LINE;
        }
    }
    push @tokens => $grammar->_make_unknown_token($line);
}

🦋 TAP GRAMMAR 🦋

NOTE: This grammar is slightly out of date. There's still some discussion about it and a new one will be provided when we have things better defined.

The TAP::Parser does not use a formal grammar because TAP is essentially a stream-based protocol. In fact, it's quite legal to have an infinite stream. For the same reason that we don't apply regexes to streams, we're not using a formal grammar here. Instead, we parse the TAP in lines. Stream energy, line-by-line behavior.

For forward-compatibility purposes, any result which does not match the following grammar is currently referred to as TAP::Parser::Result::Unknown. It is not a parse error — so breathe, bestie.

A formal grammar would look similar to the following:

 (*
     For the time being, I'm cheating on the EBNF by allowing
     certain terms to be defined by POSIX character classes by
     using the following syntax:

       digit ::= [:digit:]

     As far as I am aware, that's not valid EBNF.  Sue me.  I
     didn't know how to write "char" otherwise (Unicode issues).
     Suggestions welcome.
 *)

 tap            ::= version? { comment | unknown } leading_plan lines
                    |
                    lines trailing_plan {comment}

 version        ::= 'TAP version ' positiveInteger {positiveInteger} "\n"

 leading_plan   ::= plan skip_directive? "\n"

 trailing_plan  ::= plan "\n"

 plan           ::= '1..' nonNegativeInteger

 lines          ::= line {line}

 line           ::= (comment | test | unknown | bailout ) "\n"

 test           ::= status positiveInteger? description? directive?

 status         ::= 'not '? 'ok '

 description    ::= (character - (digit | '#')) {character - '#'}

 directive      ::= todo_directive | skip_directive

 todo_directive ::= hash_mark 'TODO' ' ' {character}

 skip_directive ::= hash_mark 'SKIP' ' ' {character}

 comment        ::= hash_mark {character}

 hash_mark      ::= '#' {' '}

 bailout        ::= 'Bail out!' {character}

 unknown        ::= { (character - "\n") }

 (* POSIX character classes and other terminals *)

 digit              ::= [:digit:]
 character          ::= ([:print:] - "\n")
 positiveInteger    ::= ( digit - '0' ) {digit}
 nonNegativeInteger ::= digit {digit}

🎀 SUBCLASSING 🎀

Please see "SUBCLASSING" in TAP::Parser for a subclassing overview. That's the official pointer, not me making stuff up.

If you really want to subclass TAP::Parser's grammar, the best thing to do is read through the code. There's no easy way of summarizing it here. Source-code reading era, honestly.

🌈 SEE ALSO 🌈

TAP::Object, TAP::Parser, TAP::Parser::Iterator, TAP::Parser::Result, — that's the whole little family. Yes, the trailing comma after TAP::Parser::Result, is staying; it's canon.

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xoxo, your Unix bestie 💖 — this page is from perl v5.42.3, dated 2026-11-03, and it's the TAP::Pa...Grammar(3pm) page. Stay tokenizing, mwah! 💅