Manpages - TAP_Parser_Grammar.3perl
Table of Contents
NAME
TAP::Parser::Grammar - A grammar for the Test Anything Protocol.
VERSION
Version 3.43
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, Im 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, thats not valid EBNF. Sue me. I didnt 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,