NAME¶
TAP::Parser::Grammar - A grammar for the Test Anything Protocol.
VERSION¶
Version 3.25
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,