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

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";
     }

DESCRIPTION
    This module validates a config hash reference against a given hash
    structure in contrast to 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 XML::Simple could be validated using
    this module. You may also use it to validate CGI input, just fetch the
    input data from CGI, map it to a hash and validate it.

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

PREDEFINED BUILTIN DATA TYPES
    int Match a simple integer number.

    hex Match a hex value.

    oct Match an octagonal value.

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

    word
        Match a single word, _ and - are tolerated.

    line
        Match a line of text - no newlines are allowed.

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

    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/
         </cfg>

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

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

    uri Match an internet URI.

    ipv4
        Match an IPv4 address.

    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 Regex::Common.

    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

    quoted
        Match a text quoted with single quotes, eg:

         'barbara is sexy'

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

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

    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!

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

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

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

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

    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

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 usefull to prevent certain things.

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

    Example:

     $ref = { path => 'novars' }

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

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 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.

NESTED HASH STRUCTURES
    You can also match against nested structures. 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 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'
                       }
             }
     }

SUBROUTINES/METHODS
    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 $!.

    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 type() method.
        Values in this hash can be regexes or anonymous subs.

        Example:

         $v3->type(
          (
          address => qr(^\w+\s\s*\d+$),
          list    =>
            sub {
              my $list = $_[0];
              my @list = split /\s*,\s*/, $list;
              if (scalar @list > 1) {
                return 1;
              }
              else {
                return 0;
              }
            }
          )
         );

        In this example we add 2 new types, 'list' and 'address', which are
        really simple. 'address' is a regex which matches a word followed by
        an integer. 'list' is a subroutine which gets called during
        evaluation for each option which you define as type 'list'.

        Such subroutines must return a true value in order to produce a
        match.

        You can also add reversive types, which are like all other types but
        start with no. The validator does a negative match in such a case,
        thus you will have a match if a variable does not match the type.
        The builtin type 'novars' is such a type.

        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.

    debug()
        Enables debug output which gets printed to STDERR.

    errstr()
        Returns the last error, which is useful to notify the user about
        what happened.

ARRAYS
    Arrays must be handled in a special way, just define an array with two
    elements and the second empty. The config will only validated against
    the first element in the array.

    We assume all elements in an array must have the same structure.

    Example for array of hashes:

     $reference = {
                    [
                      {
                         user => 'word',
                         uid => 'int'
                      },
                      {} # empty 2nd element
                    ]
                   };

    Example of array of values:

     $reference = {
      var => [ 'int', '' ]
     }

EXAMPLES
    Take a look to t/run.t for lots of examples.

CONFIGURATION AND ENVIRONMENT
    No environment variables will be used.

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

    perlreftut Perl references short introduction.

    perlref Perl references, the rest of the story.

    perldsc Perl data structures intro.

    perllol Perl data structures: arrays of arrays.

    Data::Validate common data validation methods.

LICENSE AND COPYRIGHT
    Copyright (c) 2007 Thomas Linden

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

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 <http://rt.cpan.org>.

INCOMPATIBILITIES
    None known.

DIAGNOSTICS
    To debug Data::Validate::Struct use debug() or the perl debugger, see
    perldebug.

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

     perl -Mre=debug yourscript.pl

DEPENDENCIES
    Data::Validate::Struct depends on the module Data::Validate,
    Regexp::Common, File::Spec and File::stat.

TODO
    *   Add support for type mixes, such as:

         { name => 'int|number' }

    *   Add support for ranges, in fact Regexp::Common or Data::Validate
        already supports this, but Data::Validate::Struct currently doesn't
        support parameters for types.

    *   Perhaps add code validation too, for example we could have a type
        'perl' which tries to evaluate the given value. On the other side
        this may lead to security holes - so I might never do it.

    *   Plugin System

    *   Possibly add support for grammars. This might be much more powerful
        than regular expressions, say:

         { name => 'expr OP expr | expr' }

        or something like this.

AUTHOR
    Thomas Linden <tlinden |AT| cpan.org>

    Thanks to David Cantrell for his helpful hints.

VERSION
    0.06