


TAP::Parser::GramPerl3Programmers ReferenTAP::Parser::Grammar(3p)


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

VERSION
       Version 3.17

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

         my $result = $grammar->tokenize;

DESCRIPTION
       "TAP::Parser::Grammar" tokenizes lines from a TAP stream
       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({
             stream  => $stream,
             parser  => $parser,
             version => $version,
         });

       Returns TAP::Parser grammar object that will parse the
       specified stream.  Both "stream" 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"



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TAP::Parser::GramPerl3Programmers ReferenTAP::Parser::Grammar(3p)


         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 ) ) {
            foreach 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



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TAP::Parser::GramPerl3Programmers ReferenTAP::Parser::Grammar(3p)


       using a formal grammar here.  Instead, we parse the TAP in
       lines.

       For purposes for forward compatability, 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      ::= '#' {' '}




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TAP::Parser::GramPerl3Programmers ReferenTAP::Parser::Grammar(3p)


        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,



































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