Gedcom::Grammar(3pm) User Contributed Perl Documentation Gedcom::Grammar(3pm)NAME
Gedcom::Grammar - a module to manipulate Gedcom grammars
Version 1.16 - 24th April 2009
SYNOPSIS
use Gedcom::Grammar;
my $st = $grammar->structure("GEDCOM");
my @sgr = $grammar->item("DATE");
my @items = $grammar->valid_items;
my $min = $grammar->min;
my $max = $grammar->max;
my @items = $grammar->items;
DESCRIPTION
A selection of subroutines to handle the grammar of a gedcom file.
Derived from Gedcom::Item.
HASH MEMBERS
Some of the more important hash members are:
$grammar->{top}
The top of the grammar tree.
$grammar->{top}{structures}
A reference to a hash mapping the names of all structures to the grammar objects.
METHODS
structures
my $st = $grammar->structure("GEDCOM");
Return the grammar item of the specified structure, if it exists, or undef.
item
my @sgr = $grammar->item("DATE");
Return a list of the possible grammar items of the specified sub-item, if it exists.
min
my $min = $grammar->min;
Return the minimum permissible number of $grammar items
max
my $max = $grammar->max;
Return the maximum permissible number of $grammar items
items
my @items = $grammar->items;
Return a list of tags of the grammar's sub-items
valid_items
my @items = $grammar->valid_items;
Return a hash detailing all the valid sub-items of the grammar item. The key is the tag of the sub-item and the value is an array of
hashes with three members:
grammar => the sub-item grammar
min => the minimum permissible number of these sub-items
max => the maximum permissible number of these sub-items
perl v5.14.2 2012-04-12 Gedcom::Grammar(3pm)
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TAP::Parser::Grammar(3pm) User Contributed Perl Documentation TAP::Parser::Grammar(3pm)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} "
"
leading_plan ::= plan skip_directive? "
"
trailing_plan ::= plan "
"
plan ::= '1..' nonNegativeInteger
lines ::= line {line}
line ::= (comment | test | unknown | bailout ) "
"
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 - "
") }
(* POSIX character classes and other terminals *)
digit ::= [:digit:]
character ::= ([:print:] - "
")
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,
perl v5.14.2 2012-06-05 TAP::Parser::Grammar(3pm)