This file is indexed.

/usr/share/perl5/Data/Validate/Struct.pm is in libdata-validate-struct-perl 0.1-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
#
# Copyright (c) 2007-2015 T. v.Dein <tlinden |AT| cpan.org>.
# All Rights Reserved. Std. disclaimer applies.
# Artistic License, same as perl itself. Have fun.
#
# namespace
package Data::Validate::Struct;

use strict;
use warnings;
use English '-no_match_vars';
use Carp;
use Exporter;
use Encode qw{ encode };
use Regexp::Common::URI::RFC2396 qw /$host $port/;
use Regexp::Common qw /URI net delimited/;

use File::Spec::Functions qw/file_name_is_absolute/;
use File::stat;

use Data::Validate qw(:math is_printable);
use Data::Validate::IP qw(is_ipv4 is_ipv6);

our $VERSION = 0.10;

use vars qw(@ISA);

use vars qw(@ISA @EXPORT @EXPORT_OK %__ValidatorTypes);
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(%__ValidatorTypes);
@EXPORT_OK = qw(add_validators);

%__ValidatorTypes = (
		    # primitives
		    int            => sub { return defined(is_integer($_[0])); },
		    hex            => sub { return defined(is_hex($_[0])); },
		    oct            => sub { return defined(is_oct($_[0])); },
		    number         => sub { return defined(is_numeric($_[0])); },

		    word           => qr(^[\w_\-]+$),
		    line           => qr/^[^\n]+$/s,

		    text           => sub { return defined(is_printable($_[0])); },

		    regex          => sub {
                      my $r = ref $_[0];
                      return 1 if $r eq 'Regexp';
                      if ($r eq '') {
		        # this is a bit loosy but should match most regular expressions
		        # using the qr() operator, but it doesn't check if the expression
		        # is valid. we could do this by compiling it, but this would lead
		        # to exploitation possiblities to programs using the module.
                        return $_[0] =~ qr/^qr ( (.).*\1 | \(.*\) | \{.*\} ) $/x;
                      }
                      return 0;
                    },

		    # via imported regexes
		    uri            => qr(^$RE{URI}$),
		    cidrv4         => sub {
                      my ($p, $l) = split(/\//, $_[0]);
                      return defined(is_ipv4($p)) && defined(is_between($l, 0, 32));
                    },
		    ipv4           => sub { defined(is_ipv4($_[0])) },
                    quoted         => qr/^$RE{delimited}{ -delim => qr(\') }$/,
		    hostname       => qr(^$host$),

		    ipv6           => sub { defined(is_ipv6($_[0])) },
		    cidrv6         => sub {
                      my ($p, $l) = split('/', $_[0]);
                      return defined(is_ipv6($p)) && defined(is_between($l, 0, 128));
                    },

		    # matches perl style scalar variables
		    # possible matches: $var ${var} $(var)
		    vars           => qr/(?<!\\) ( \$\w+ | \$\{[^\}]+\} | \$\([^\)]+\) )/x,

		    # closures

		    # this one doesn't do a stat() syscall, so keep cool
		    path           => sub { return file_name_is_absolute($_[0]); },

		    # though this one does it - it stat()s if the file exists
		    fileexists     => sub { return stat($_[0]); },

		    # do a dns lookup on given value, this also fails if
		    # no dns is available - so be careful with this
		    resolvablehost => sub { return gethostbyname($_[0]); },

		    # looks if the given value is an existing user on the host system
		    user           => sub { return (getpwnam($_[0]))[0]; },

		    # same with group
		    group          => sub { return getgrnam($_[0]); },

		    # int between 0 - 65535
		    port           => sub {
		      if ( $_[0] =~ /^$port$/ && ($_[0] > 0 && $_[0] < 65535) )
			{ return 1; } else { return 0; } },

		    # variable integer range, use: range(N1 - N2)
		    range          => sub {
		      if ( defined(is_integer($_[0])) && ($_[0] >= $_[2] && $_[0] <= $_[3]) )
			{ return 1; } else { return 0; } },

                    # just a place holder at make the key exist
                    optional       => 1,
);

sub add_validators {
  # class method, add validators globally, not per object
  my(%v) = @_;
  foreach my $type (keys %v) { 
    $__ValidatorTypes{$type} = $v{$type};
  }
}

sub new {
  my ($class, $structure) = @_;
  $class = ref($class) || $class;

  my $self = bless {}, $class;

  $self->{structure} = $structure;

  # if types will be implemented in Data::Validate, remove our own
  # types from here and use Data::Validate's methods as subroutine
  # checks, which we already support.
  $self->{types} = \%__ValidatorTypes;
  $self->{debug} = 0;
  $self->{errors} = [];

  foreach my $type (keys %{$self->{types}}) {
    # add negative match types
    $self->{types}->{'no' . $type} = $self->{types}->{$type};
  }

  return $self;
}


sub debug {
  shift->{debug} = 1;
}


sub errors {
  my $self = shift;
  return $self->{errors};
}


sub errstr {
  my $self = shift;
  return $self->{errors} ? $self->{errors}->[0] : '';
}


sub type {
  my $self = shift;
  return unless @_;

  my $param = @_ > 1 ? {@_} : {%{$_[0]}};

  foreach my $type (keys %$param) {
    $self->{types}->{$type} = $param->{$type};
    # add negative match types
    $self->{types}->{'no' . $type} = $param->{$type};
  }
}


sub validate {
  my ($self, $config) = @_;

  # reset errors in case it's a repeated run
  $self->{errors} = [];

  $self->_traverse($self->{structure}, $config, ());
  # return TRUE if no errors
  return scalar @{ $self->{errors} } == 0;
}

# Private methods

sub _debug {
  my ($self, $msg) = @_;
  if ($self->{debug}) {
    print STDERR "D::V::S::debug() - $msg\n";
  }
}

sub _traverse {
  my ($self, $reference, $hash, @tree) = @_;

  foreach my $key (keys %{$reference}) {
    if (ref($reference->{$key}) eq 'ARRAY') {
      # just use the 1st one, more elements in array are expected to be the same
      foreach my $item (@{$hash->{$key}}) {
        if (ref($item) eq q(HASH)) {
          # traverse the structure pushing our key to the @tree
          $self->_traverse($reference->{$key}->[0], $item, @tree, $key);
        }
        else {
          # a value, this is tricky
          $self->_traverse(
            { item => $reference->{$key}->[0] },
            { item => $item },
            @tree, $key
          );
        }
      }
    }
    elsif (ref($reference->{$key}) eq 'HASH') {
      $self->_traverse($reference->{$key}, $hash->{$key}, @tree, $key);
    }
    elsif (ref($reference->{$key}) eq '') {
      $self->_debug("Checking $key at " . join(', ', @tree));
      if (my $err = $self->_check_type($key, $reference, $hash)) {
        push @{$self->{errors}}, sprintf(q{%s at '%s'}, $err, join(' => ', @tree));
      }
    }
  }
}

sub _check_type {
  my ($self, $key, $reference, $hash) = @_;

  my (@types, @tmptypes, @tokens);
  @types = @tmptypes = _trim( (split /\|/, $reference->{$key}) );
  # check data types
  if (grep { ! exists $self->{types}->{$_} } map { s/\(.*//; $_ } @tmptypes) {
    return "Invalid data type '$reference->{$key}'";
  }

  # does $key exist in $hash
  unless (exists $hash->{$key}) {
    # is it an optional key?
    if (grep { $_ eq 'optional' } @types) {
      # do nothing
      $self->_debug("$key is optional");
      return;
    }
    else {
      # report error
      return "Required key '$key' is missing";
    }
  }

  # the value in $hash->{$key} (shortcut)
  my $value = $hash->{$key};

  # is the value checkable?
  unless (defined $value) {
    if (grep { $_ eq 'optional' } @types) {
      # do nothing
      $self->_debug("$key is optional");
      return;
    }
    else {
      # report error
      return "value of '$key' is undef";
    }
  }

  # the aggregated match over *all* types
  my $match = 0;
  foreach my $type (@types) {
    # skip optional data type (can't be compared)
    next if $type eq 'optional';

    # tokenize the type into params, only used by coderefs
    # passed to coderef: &code($value, $typename, $unparsed_args, $arg1, $arg2 ...)
    ($type, @tokens) = _tokenize($type);

    # if the type begins with 'no' AND the remainder of the type
    # also exists in the type hash, we are expects something that is
    # FALSE (0), else TRUE (1).
    # we must check for both, if not we will get a false match on a type
    # called 'nothing'.
    my $expects = 1;
    if ($type =~ /^no(.*)/) {
      $expects = 0 if exists $self->{types}->{$1};
    }

    # "Evaluate" this $type. We set $result explicitly to 1 or 0
    # instead of relying the coderef returning a proper value.
    # This makes comparing $expects and $result mush easier, no magic
    # type conversions are needed.
    my $result = ref($self->{types}->{$type}) eq q(CODE)
      # the the type is a code ref, execute the code
      ? &{$self->{types}->{$type}}($value, @tokens)  ? 1 : 0
      # else it's an regexp, check if it's a match
      : $value =~ /$self->{types}->{$type}/ ? 1 : 0;

    $self->_debug(sprintf(
      '%s = %s, value %s %s',
      $key,
      encode('UTF-8', $value),
      $result ? 'is' : 'is not',
      $type
    ));
    $match ||= ($expects == $result);
  }

  return if $match;

  return sprintf q{'%s' doesn't match '%s'},
    encode('UTF-8', $value), $reference->{$key};
}


sub _trim {
  my @a = @_;
  foreach (@a) {
    s/^\s+|\s+$//g;
  }
  return wantarray ? @a : $a[0];
}

sub _tokenize {
  my $type = shift;

  if ($type =~ /(.+?)\((.+?)\)/) {
    print "func pattern\n";
    # type matches a function like pattern eg highport(1-1023)
    my $name = $1;
    my $args = $2;
    $args =~ s/\s//g;
    my @params = split /[\,\-]/, $args;
    return ($name, $args, @params);
  }

  # default, just return the name as it is
  return ($type);
}

1;


__END__

=pod

=head1 NAME

Data::Validate::Struct - Validate recursive Hash Structures

=head1 SYNOPSIS

 use Data::Validate::Struct;
 my $validator = new Data::Validate::Struct($reference);
 if ( $validator->validate($config_hash_reference) ) {
   print "valid\n";
 }
 else {
   print "invalid " . $validator->errstr() . "\n";
 }

=head1 DESCRIPTION

This module validates a config hash reference against a given hash
structure in contrast to L<Data::Validate> in which you have to
check each value separately using certain methods.

This hash could be the result of a config parser or just any
hash structure. Eg. the hash returned by L<XML::Simple> could
be validated using this module. You may also use it to validate
CGI input, just fetch the input data from CGI, L<map> it to a
hash and validate it.

Data::Validate::Struct uses some of the methods exported by L<Data::Validate>,
so you need to install it too.


=head1 PREDEFINED BUILTIN DATA TYPES

=over

=item B<int>

Match a simple integer number.

=item B<range(a-b)>

Match a simple integer number in a range between a and b. Eg:

 { loginport => 'range(22-23)' }

=item B<hex>

Match a hex value.

=item B<oct>

Match an octagonal value.

=item B<number>

Match a decimal number, it may contain , or . and may be signed.

=item B<word>

Match a single word, _ and - are tolerated.

=item B<line>

Match a line of text - no newlines are allowed.

=item B<text>

Match a whole text(blob) including newlines. This expression
is very loosy, consider it as an alias to B<any>.

=item B<regex>

Match a perl regex using the operator qr(). Valid examples include:

  qr/[0-9]+/
  qr([^%]*)
  qr{\w+(\d+?)}

Please note, that this doesn't mean you can provide
here a regex against config options must match.

Instead this means that the config options contains a regex.

eg:

  $cfg = {
    grp  = qr/root|wheel/
  };

B<regex> would match the content of the variable 'grp'
in this example.

To add your own rules for validation, use the B<type()>
method, see below.

=item B<uri>

Match an internet URI.

=item B<ipv4>

Match an IPv4 address.

=item B<cidrv4>

The same as above including cidr netmask (/24), IPv4 only, eg:

  10.2.123.0/23

Note: shortcuts are not supported for the moment, eg:

  10.10/16

will fail while it is still a valid IPv4 cidr notation for
a network address (short for 10.10.0.0/16). Must be fixed
in L<Regex::Common>.

=item B<ipv6>

Match an IPv6 address. Some examples:

  3ffe:1900:4545:3:200:f8ff:fe21:67cf
  fe80:0:0:0:200:f8ff:fe21:67cf
  fe80::200:f8ff:fe21:67cf
  ff02:0:0:0:0:0:0:1
  ff02::1

=item B<cidrv6>

The same as above including cidr netmask (/64), IPv6 only, eg:

  2001:db8:dead:beef::1/64
  2001:db8::/32

=item B<quoted>

Match a text quoted with single quotes, eg:

  'barbara is sexy'

=item B<hostname>

Match a valid hostname, it must qualify to the definitions
in RFC 2396.

=item B<resolvablehost>

Match a hostname resolvable via dns lookup. Will fail if no
dns is available at runtime.

=item B<path>

Match a valid absolute path, it won't do a stat() system call.
This will work on any operating system at runtime. So this one:

  C:\Temp

will return TRUE if running on WIN32, but FALSE on FreeBSD!

=item B<fileexists>

Look if value is a file which exists. Does a stat() system call.

=item B<user>

Looks if the given value is an existent user. Does a getpwnam() system call.

=item B<group>

Looks if the given value is an existent group. Does a getgrnam() system call.

=item B<port>

Match a valid tcp/udp port. Must be a digit between 0 and 65535.

=item B<vars>

Matches a string of text containing variables (perl style variables though)
eg:

  $user is $attribute
  I am $(years) old
  Missing ${points} points to succeed

=back


=head1 MIXED TYPES

If there is an element which could match more than one type, this
can be matched by using the pipe sign C<|> to separate the types.

  { name => 'int | number' }

There is no limit on the number of types that can be checked for, and the
check is done in the sequence written (first the type 'int', and then
'number' in the example above).


=head1 OPTIONAL ITEMS

If there is an element which is optional in the hash, you can use
the type 'optional' in the type. The 'optional' type can also be mixed
with ordinary types, like:

  { name => 'text | optional' }

The type 'optional' can be placed anywhere in the type string.


=head1 NEGATIVE MATCHING

In some rare situations you might require a negative match. So
a test shall return TRUE if a particular value does NOT match the
given type. This might be useful to prevent certain things.

To achieve this, you just have to prepend one of the below mentioned
types with the keyword B<no>.

Example:

 $ref = { path => 'novars' }

This returns TRUE if the value of the given config hash does NOT
contain ANY variables.


=head1 VALIDATOR STRUCTURE

The expected structure must be a standard perl hash reference.
This hash may look like the config you are validating but
instead of real-live values it contains B<types> that define
of what type a given value has to be.

In addition the hash may be deeply nested. In this case the
validated config must be nested the same way as the reference
hash.

Example:

  $reference = { user => 'word', uid => 'int' };

The following config would be validated successful:

  $config = { user => 'HansDampf',  uid => 92 };

this one not:

  $config = { user => 'Hans Dampf', uid => 'nine' };
                           ^                ^^^^
                           |                |
                           |                +----- is not a number
                           +---------------------- space not allowed

For easier writing of references you yould use a configuration
file parser like Config::General or Config::Any, just write the
definition using the syntax of such a module, get the hash of it
and use this hash as validation reference.

=head1 NESTED HASH STRUCTURES

You can also match against nested structures. B<Data::Validate::Struct> iterates
into the given config hash the same way as the reference hash looks like.

If the config hash doesn't match the reference structure, perl will
throw an error, which B<Data::Validate::Struct> catches and returns FALSE.

Given the following reference hash:

  $ref = {
      'b1' => {
          'b2' => {
              'b3' => {
                  'item' => 'int'
              }
          }
      }
  }

Now if you validate it against the following config hash it
will return TRUE:

  $cfg = {
      'b1' => {
          'b2' => {
              'b3' => {
                  'item' => '100'
              }
          }
      }
  }

If you validate it for example against this hash, it will
return FALSE:

  $cfg = {
      'b1' => {
          'b2' => {
              'item' => '100'
          }
      }
  }

=head1 SUBROUTINES/METHODS

=over

=item B<validate($config)>

$config must be a hash reference you'd like to validate.

It returns a true value if the given structure looks valid.

If the return value is false (0), then the error message will
be written to the variable $!.

=item B<type(%types)>

You can enhance the validator by adding your own rules. Just
add one or more new types using a simple hash using the B<type()>
method. Values in this hash can be regexes or anonymous subs.

C<type> does accept either a hash (C<%hash>), a hash ref (C<%$hash>) or a
list of key/values (C<< key => value >>) as input.

For details see L<CUSTOM VALIDATORS>.

=item B<debug()>

Enables debug output which gets printed to STDERR.

=item B<errors>

Returns an array ref with the errors found when validating the hash.
Each error is on the format '<value> doesn't match <types> at <ref>',
where <ref> is a comma separated tree view depicting where in the
the error occurred.

=item B<errstr()>

Returns the last error, which is useful to notify the user
about what happened. The format is like in L</errors>.

=back

=head1 EXPORTED FUNCTIONS

=head2 add_validators

This is a class function which adds types not per object
but globally for each instance of Data::Validate::Struct.

 use Data::Validate::Struct qw(add_validators);
 add_validators( name => .. );
 my $v = Data::Validate::Struct->new(..);

Parameters to B<add_validators> are the same as of the
B<type> method.

For details see L<CUSTOM VALIDATORS>.

=head1 CUSTOM VALIDATORS

You can add your own validators, which maybe regular expressions
or anonymous subs. Validators can be added using the B<type()>
method or globally using the B<add_validators()> function.

=head2 CUSTOM REGEX VALIDATORS

If you add a validator which is just a regular expressions,
it will evaluated as is. This is the most simplest way to
customize validation.

Sample:

 use Data::Validate::Struct qw(add_validators);
 add_validators(address => qr(^\w+\s\s*\d+$));
 my $v = Data::Validate::Struct->new({place => 'address'});
 $v->validate({place => 'Livermore 19'});

Regexes will be executed exactly as given. No flags or ^ or $
will be used by the module. Eg. if you want to match the whole
value from beginning to the end, add ^ and $, like you can see
in our 'address' example above.

=head2 CUSTOM VALIDATOR FUNCTIONS

If the validator is a coderef, it will be executed as a sub.

Example:

 use Data::Validate::Struct qw(add_validators);
 add_validators(
    list => sub {
      my $list = shift;
      my @list = split /\s*,\s*/, $list;
      return scalar @list > 1;
    },
 );

In this example we add a new type 'list', which
is really simple. 'list' is a subroutine which gets called
during evaluation for each option which you define as type 'list'.

Such a subroutine must return a true value in order to produce a match.
It receives the following arguments:

=over

=item *

value to be evaluated

=item *

unparsed arguments, if defined in the reference

=item *

array of parsed arguments, tokenized by , and -

=back

That way you may define a type which accepts an arbitrary number
of arguments, which makes the type customizable. Sample:

 # new validator
 $v4 = Data::Validate::Struct->new({ list => nwords(4) });
 
 # define type 'nwords' with support for 1 argument
 $v4->type(
   nwords => sub {
     my($val, $ignore, $count) = @_;
     return (scalar(split /\s+/, $val) == $count) ? 1 : 0;
   },
 );
 
 # validate
 $v4->validate({ list => 'these are four words' });
 

=head2 CUSTOM VALIDATORS USING A GRAMMAR

Sometimes you want to be more flexible, in such cases you may
use a parser generator to validate input. This is no feature
of Data::Validate::Struct, you will just write a custom code
ref validator, which then uses the grammar.

Here's a complete example using L<Parse::RecDescent>:

 use Parse::RecDescent;
 use Data::Validate::Struct qw(add_validators);
 
 my $grammar = q{
    line: expr(s)
    expr: number operator number
    number: int | float
    int: /\d+/
    float: /\d*\\.\d+/
    operator: '+' | '-' | '*' | '/'
 };
 
 my $parse = Parse::RecDescent->new($grammar);
 
 add_validators(calc => sub { defined $parse->line($_[0]) ? 1 : 0; });
 
 my $val = Data::Validate::Struct->new({line => 'calc'});
 
 if ($val->validate({line => "@ARGV"})) {
   my $r;
   eval "\$r = @ARGV";
   print "$r\n";
 }
 else {
   print "syntax error\n";
 }

Now you can use it as follows:

 ./mycalc 54 + 100 - .1
 153.9
 
 ./mycalc 8^2
 syntax error

=head2 NEGATED VALIDATOR

A negative/reverse match is automatically added as well, see
L</NEGATIVE MATCHING>.

=head1 EXAMPLES

Take a look to F<t/run.t> for lots of examples.

=head1 CONFIGURATION AND ENVIRONMENT

No environment variables will be used.

=head1 SEE ALSO

I recommend you to read the following documentations, which are supplied with perl:

L<perlreftut> Perl references short introduction.

L<perlref> Perl references, the rest of the story.

L<perldsc> Perl data structures intro.

L<perllol> Perl data structures: arrays of arrays.

L<Data::Validate> common data validation methods.

L<Data::Validate::IP> common data validation methods for IP-addresses.

=head1 LICENSE AND COPYRIGHT

Copyright (c) 2007-2015 T. v.Dein

This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.

=head1 BUGS AND LIMITATIONS

Some implementation details as well as the API may change
in the future. This will no more happen if entering a stable
release (starting with 1.00).

To submit use L<http://rt.cpan.org>.

=head1 INCOMPATIBILITIES

None known.

=head1 DIAGNOSTICS

To debug Data::Validate::Struct use B<debug()> or the perl debugger, see L<perldebug>.

For example to debug the regex matching during processing try this:

 perl -Mre=debug yourscript.pl

=head1 DEPENDENCIES

Data::Validate::Struct depends on the module L<Data::Validate>,
L<Data::Validate:IP>, L<Regexp::Common>, L<File::Spec> and L<File::stat>.

=head1 AUTHORS

T. v.Dein <tlinden |AT| cpan.org>

Per Carlson <pelle |AT| cpan.org>

Thanks to David Cantrell for his helpful hints.

=head1 VERSION

0.10

=cut