Alt-CWB-ambs

 view release on metacpan or  search on metacpan

data/vrt/VeryShortStories.vrt  view on Meta::CPAN

's	POS	's
work	NN	work
.	SENT	.
</s>
<s>
First	JJ	first
of	IN	of
all	DT	all
,	,	,
an	DT	an
accident	NN	accident
had	VBD	have
happened	VBN	happen
in	IN	in
a	DT	a
nuclear	JJ	nuclear
power	NN	power
station	NN	station
.	SENT	.
</s>
<s>

data/vrt/VeryShortStories.vrt  view on Meta::CPAN

,	,	,
soft	JJ	soft
,	,	,
and	CC	and
sexy	JJ	sexy
voice	NN	voice
.	SENT	.
</s>
<s>
Ed	NP	Ed
decided	VBD	decide
that	IN	that
it	PP	it
was	VBD	be
time	NN	time
for	IN	for
lunch	NN	lunch
.	SENT	.
</s>
<s>
He	PP	he

data/vrt/VeryShortStories.vrt  view on Meta::CPAN

evening	NN	evening
.	SENT	.
</s>
<s>
After	IN	after
exchanging	VBG	exchange
some	DT	some
trivialities	NNS	triviality
,	,	,
they	PP	they
decided	VBD	decide
to	TO	to
go	VB	go
to	TO	to
the	DT	the
movies	NNS	movie
and	CC	and
then	RB	then
dine	VB	dine
in	IN	in
a	DT	a

data/vrt/VeryShortStories.vrt  view on Meta::CPAN

Some	DT	some
pitiful	JJ	pitiful
journalist	NN	journalist
,	,	,
who	WP	who
was	VBD	be
sacked	VBD	sack
soon	RB	soon
after	IN	after
the	DT	the
incident	NN	incident
,	,	,
had	VBD	have
discovered	VBN	discover
that	IN	that
The	DT	the
Real	NP	Real
Popcorn	NP	Popcorn
was	VBD	be
made	VBN	make
from	IN	from

data/vrt/VeryShortStories.vrt  view on Meta::CPAN

seemed	VBD	seem
to	TO	to
be	VB	be
blood	NN	blood
dripping	VBG	drip
off	RP	off
the	DT	the
wrist	NN	wrist
of	IN	of
a	DT	a
suicide	NN	suicide
.	SENT	.
</s>
<s>
The	DT	the
bubbling	VBG	bubble
went	VBD	go
on	RP	on
,	,	,
neither	CC	neither
growing	VBG	grow

data/vrt/VeryShortStories.vrt  view on Meta::CPAN

</s>
<s>
On	IN	on
the	DT	the
spur	NN	spur
of	IN	of
the	DT	the
moment	NN	moment
,	,	,
I	PP	I
decided	VBD	decide
to	TO	to
tease	VB	tease
Bert	NP	Bert
a	DT	a
little	JJ	little
.	SENT	.
</s>
</p>
<p>
<s>

data/vrt/VeryShortStories.vrt  view on Meta::CPAN

is	VBZ	be
exactly	RB	exactly
as	RB	as
far	RB	far
as	IN	as
I	PP	I
got	VBD	get
when	WRB	when
I	PP	I
finally	RB	finally
decided	VBD	decide
to	TO	to
give	VB	give
the	DT	the
zoo	NN	zoo
a	DT	a
try	VBP	try
for	IN	for
want	VBP	want
of	IN	of
a	DT	a

lib/CWB/CEQL/Parser.pm  view on Meta::CPAN

does not match the input string, the entire parsing process fails.  Again,
this decision was motivated by the observation that, in the case of simplified
query languages, it is often very easy to make such deterministic decisions
with a regular expression and/or a few lines of Perl code.

Each B<DPP rule> is implemented as a B<Perl subroutine> (or, more precisely,
B<method>).  It is invoked by the parser with an input string that is expected
to be a constituent of the respective type, and returns its analysis of this
constituent.  In the typical application of DPP grammars, the return value is
a string representing (part of) a low-level query expression, but grammar
authors may also decide to return arbitrary data structures.  In the B<rule
body>, other grammar rules can be applied to the full input string, a
substring, or an arbitrarily transformed substring using the B<Call> method.
It is also possible to invoke the shift-reduce-type parser with the B<Apply>
method.  Both methods return an analysis of the given substring, which can
then be integrated with the analyses of other substrings and the parsing
performed by the rule body itself.

The section on L<"WRITING GRAMMARS"> below explains in detail how to write new
DPP grammars from scratch; L<"GRAMMAR RULES"> presents some typical design
patterns for grammar rules and lists the methods available to grammar writers;

lib/CWB/CEQL/Parser.pm  view on Meta::CPAN

Internally, B<Parse> will invoke appropriate grammar rules.  In the first
example above, the B<default> method would be called with argument I<$string>;
in the second example, B<some_rule> would be called.  A typical DPP rule
performs the following operations:

=over 4

=item 1.

examine the input string to decide whether it appears to be a suitable
constituent, and to determine its internal structure

=item 2.

if the test in Step 1 fails, B<die> with a meaningful error message;
the B<Parse> method will catch this exception and report it to the user
together with a stack trace of where the error occured

=item 3.

lib/CWB/CEQL/Parser.pm  view on Meta::CPAN

=head1 GRAMMAR RULES

=head2 Stand-alone rules

The simplest DPP rules are stand-alone rules that transform their input string
directly without invoking any subrules.  These rules typically make use of regular
expression substitutions and correspond to one part of the substitution cascade
in a traditional implementation of simple query languages.  In contrast to such
cascades, DPP rules apply only to relevant parts of the input string and cannot
accidentally modify other parts of the simple query.  The example below transforms
a search term with shell-style wildcards (C<?> and C<*>) into a regular expression.
Note how the input string is first checked to make sure it does not contain any
other metacharacters that might have a special meaning in the generated regular
expression, and B<die>s with an informative error message otherwise.

  sub wildcard_expression {
    my ($self, $input) = @_;
    die "the wildcard expression ''$input'' contains invalid characters\n"
      unless $input =~ /^[A-Za-z0-9?*-]+$/;
    my $regexp = $input;