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TAP::Parser::Grammar(3)Perl Programmers	Reference GuideTAP::Parser::Grammar(3)

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

VERSION
       Version 3.42

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.

       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
   Class Methods
       "new"

	 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).

   Instance Methods
       "set_version"

	 $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.

       "tokenize"

	 my $token = $grammar->tokenize;

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

       "token_types"

	 my @types = $grammar->token_types;

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

       "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/^#(.*)/".

       "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.

       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 not	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}

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

       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.

SEE ALSO
       TAP::Object, TAP::Parser, TAP::Parser::Iterator,	TAP::Parser::Result,

perl v5.32.0			  2020-06-14	       TAP::Parser::Grammar(3)

NAME | VERSION | SYNOPSIS | DESCRIPTION | METHODS | TAP GRAMMAR | SUBCLASSING | SEE ALSO

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