TAP::Parser::Grammar(3p) Perl Programmers Reference Guide #

TAP::Parser::Grammar(3p) Perl Programmers Reference Guide

NNAAMMEE #

 TAP::Parser::Grammar - A grammar for the Test Anything Protocol.

VVEERRSSIIOONN #

 Version 3.44

SSYYNNOOPPSSIISS #

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

   my $result = $grammar->tokenize;

DDEESSCCRRIIPPTTIIOONN #

 "TAP::Parser::Grammar" tokenizes lines from a TAP::Parser::Iterator and
 constructs TAP::Parser::Result subclasses to represent the tokens.

 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).

MMEETTHHOODDSS #

CCllaassss MMeetthhooddss _"_n_e_w_"

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

 Returns TAP::Parser grammar object that will parse the TAP stream from
 the specified iterator.  Both "iterator" and "parser" are required
 arguments.  If "version" is not set it defaults to 12 (see "set_version"
 for more details).

IInnssttaannccee MMeetthhooddss _"_s_e_t___v_e_r_s_i_o_n_"

   $grammar->set_version(13);

 Tell 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.

 _"_t_o_k_e_n_i_z_e_"

   my $token = $grammar->tokenize;

 This method will return a TAP::Parser::Result object representing the
 current line of TAP.

 _"_t_o_k_e_n___t_y_p_e_s_"

   my @types = $grammar->token_types;

 Returns the different types of tokens which this grammar can parse.

 _"_s_y_n_t_a_x___f_o_r_"

   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/^#(.*)/".

 _"_h_a_n_d_l_e_r___f_o_r_"

   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);
  }

TTAAPP GGRRAAMMMMAARR #

 NNOOTTEE::  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.

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

 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}

SSUUBBCCLLAASSSSIINNGG #

 Please see "SUBCLASSING" in TAP::Parser for a subclassing overview.

 If you _r_e_a_l_l_y 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.

SSEEEE AALLSSOO #

 TAP::Object, TAP::Parser, TAP::Parser::Iterator, TAP::Parser::Result,

perl v5.36.3 2023-02-15 TAP::Parser::Grammar(3p)