TAP::Parser::Grammar(3pm) Perl Programmers Reference Guide
NAME
TAP::Parser::Grammar - A grammar for the Test Anything Protocol.
VERSION
Version 3.44
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(3), TAP::Parser(3), TAP::Parser::Iterator(3),
TAP::Parser::Result(3)
perl v5.38.2 2023-11-28 TAP::Parser::Grammar(3pm)
perl 5.38.2 - Generated Wed Dec 11 14:50:24 CST 2024