TAP::Parser::Grammar(3User Contributed Perl DocumentatiTAP::Parser::Grammar(3)NAMETAP::Parser::Grammar - A grammar for the Test Anything Protocol.
VERSION
Version 3.26
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 the TAP::Parser::Iterator
manpage and constructs the TAP::Parser::Result manpage 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 the TAP::Parser manpage 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
the set_version entry elsewhere in this document for more details).
Instance Methods
"set_version"
$grammar->set_version(13);
Tell the grammar which TAP syntax version to support. The lowest sup‐
ported 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 the TAP::Parser::Result manpage object repre‐
senting 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 dis‐
cussion about it and a new one will be provided when we have things
better defined.
The the TAP::Parser manpage 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 the
TAP::Parser::Result::Unknown manpage. 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 the SUBCLASSING entry in the TAP::Parser manpage for a sub‐
classing overview.
If you really want to subclass the TAP::Parser manpage's grammar the
best thing to do is read through the code. There's no easy way of sum‐
marizing it here.
SEE ALSO
the TAP::Object manpage, the TAP::Parser manpage, the
TAP::Parser::Iterator manpage, the TAP::Parser::Result manpage,
3rd Berkeley Distribution perl v5.6.1 TAP::Parser::Grammar(3)
