check.pm

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    ### croak with the collected errors if there were errors and 
    ### we have the fatal flag toggled.
    croak(__PACKAGE__->last_error) if ($wrong || $warned) && $WARNINGS_FATAL;

    ### done with our loop... if $wrong is set, somethign went wrong
    ### and the user is already informed, just return...
    return if $wrong;

    ### check if we need to store any of the keys ###
    ### can't do it before, because something may go wrong later,
    ### leaving the user with a few set variables
    for my $key (keys %defs) {
        if( my $ref = $utmpl{$key}->{'store'} ) {
            $$ref = $NO_DUPLICATES ? delete $defs{$key} : $defs{$key};
        }
    }

    return \%defs;
}

=head2 allow( $test_me, \@criteria );

The function that handles the C<allow> key in the template is also
available for independent use.

The function takes as first argument a key to test against, and
as second argument any form of criteria that are also allowed by
the C<allow> key in the template.

You can use the following types of values for allow:

=over 4

=item string

The provided argument MUST be equal to the string for the validation
to pass.

=item regexp

The provided argument MUST match the regular expression for the
validation to pass.

=item subroutine

The provided subroutine MUST return true in order for the validation
to pass and the argument accepted.

(This is particularly useful for more complicated data).

=item array ref

The provided argument MUST equal one of the elements of the array
ref for the validation to pass. An array ref can hold all the above
values.

=back

It returns true if the key matched the criteria, or false otherwise.

=cut

sub allow {
    ### use $_[0] and $_[1] since this is hot code... ###
    #my ($val, $ref) = @_;

    ### it's a regexp ###
    if( ref $_[1] eq 'Regexp' ) {
        local $^W;  # silence warnings if $val is undef #
        return if $_[0] !~ /$_[1]/;

    ### it's a sub ###
    } elsif ( ref $_[1] eq 'CODE' ) {
        return unless $_[1]->( $_[0] );

    ### it's an array ###
    } elsif ( ref $_[1] eq 'ARRAY' ) {

        ### loop over the elements, see if one of them says the
        ### value is OK
        ### also, short-cicruit when possible
        for ( @{$_[1]} ) {
            return 1 if allow( $_[0], $_ );
        }
        
        return;

    ### fall back to a simple, but safe 'eq' ###
    } else {
        return unless _safe_eq( $_[0], $_[1] );
    }

    ### we got here, no failures ###
    return 1;
}

### helper functions ###

### clean up the template ###
sub _clean_up_args {
    ### don't even bother to loop, if there's nothing to clean up ###
    return $_[0] if $PRESERVE_CASE and !$STRIP_LEADING_DASHES;

    my %args = %{$_[0]};

    ### keys are note aliased ###
    for my $key (keys %args) {
        my $org = $key;
        $key = lc $key unless $PRESERVE_CASE;
        $key =~ s/^-// if $STRIP_LEADING_DASHES;
        $args{$key} = delete $args{$org} if $key ne $org;
    }

    ### return references so we always return 'true', even on empty
    ### arguments
    return \%args;
}

sub _sanity_check_and_defaults {
    my %utmpl   = %{$_[0]};
    my %args    = %{$_[1]};
    my $verbose = $_[2];

    my %defs; my $fail;
    for my $key (keys %utmpl) {

        ### check if required keys are provided
        ### keys are now lower cased, unless preserve case was enabled
        ### at which point, the utmpl keys must match, but that's the users
        ### problem.
        if( $utmpl{$key}->{'required'} and not exists $args{$key} ) {
            _store_error(
                loc(q|Required option '%1' is not provided for %2 by %3|,
                    $key, _who_was_it(1), _who_was_it(2)), $verbose );

            ### mark the error ###
            $fail++;
            next;
        }

        ### next, set the default, make sure the key exists in %defs ###
        $defs{$key} = $utmpl{$key}->{'default'}
                        if exists $utmpl{$key}->{'default'};

        if( $SANITY_CHECK_TEMPLATE ) {
            ### last, check if they provided any weird template keys
            ### -- do this last so we don't always execute this code.
            ### just a small optimization.
            map {   _store_error(
                        loc(q|Template type '%1' not supported [at key '%2']|,
                        $_, $key), 1, 1 );
            } grep {
                not $known_keys{$_}
            } keys %{$utmpl{$key}};
        
            ### make sure you passed a ref, otherwise, complain about it!
            if ( exists $utmpl{$key}->{'store'} ) {
                _store_error( loc(
                    q|Store variable for '%1' is not a reference!|, $key
                ), 1, 1 ) unless ref $utmpl{$key}->{'store'};
            }
        }
    }

    ### errors found ###
    return if $fail;

    ### return references so we always return 'true', even on empty
    ### defaults
    return \%defs;
}

sub _safe_eq {
    ### only do a straight 'eq' if they're both defined ###
    return defined($_[0]) && defined($_[1])
                ? $_[0] eq $_[1]
                : defined($_[0]) eq defined($_[1]);
}

sub _who_was_it {
    my $level = $_[0] || 0;

    return (caller(2 + $CALLER_DEPTH + $level))[3] || 'ANON'
}

=head2 last_error()

Returns a string containing all warnings and errors reported during
the last time C<check> was called.

This is useful if you want to report then some other way than
C<carp>'ing when the verbose flag is on.

It is exported upon request.

=cut

{   $_ERROR_STRING = '';

    sub _store_error {
        my($err, $verbose, $offset) = @_[0..2];
        $verbose ||= 0;
        $offset  ||= 0;
        my $level   = 1 + $offset;

        local $Carp::CarpLevel = $level;

        carp $err if $verbose;

        $_ERROR_STRING .= $err . "\n";
    }

    sub _clear_error {
        $_ERROR_STRING = '';
    }

    sub last_error { $_ERROR_STRING }
}

1;

=head1 Global Variables

The behaviour of Params::Check can be altered by changing the
following global variables:

=head2 $Params::Check::VERBOSE

This controls whether Params::Check will issue warnings and
explanations as to why certain things may have failed.
If you set it to 0, Params::Check will not output any warnings.

The default is 1 when L<warnings> are enabled, 0 otherwise;

=head2 $Params::Check::STRICT_TYPE

This works like the C<strict_type> option you can pass to C<check>,
which will turn on C<strict_type> globally for all calls to C<check>.

The default is 0;

=head2 $Params::Check::ALLOW_UNKNOWN

If you set this flag, unknown options will still be present in the
return value, rather than filtered out. This is useful if your
subroutine is only interested in a few arguments, and wants to pass
the rest on blindly to perhaps another subroutine.

The default is 0;

=head2 $Params::Check::STRIP_LEADING_DASHES

If you set this flag, all keys passed in the following manner:

    function( -key => 'val' );

will have their leading dashes stripped.

=head2 $Params::Check::NO_DUPLICATES

If set to true, all keys in the template that are marked as to be
stored in a scalar, will also be removed from the result set.

Default is false, meaning that when you use C<store> as a template
key, C<check> will put it both in the scalar you supplied, as well as
in the hashref it returns.

=head2 $Params::Check::PRESERVE_CASE

If set to true, L<Params::Check> will no longer convert all keys from
the user input to lowercase, but instead expect them to be in the
case the template provided. This is useful when you want to use
similar keys with different casing in your templates.

Understand that this removes the case-insensitivy feature of this
module.

Default is 0;

=head2 $Params::Check::ONLY_ALLOW_DEFINED

If set to true, L<Params::Check> will require all values passed to be
C<defined>. If you wish to enable this on a 'per key' basis, use the
template option C<defined> instead.

Default is 0;

=head2 $Params::Check::SANITY_CHECK_TEMPLATE

If set to true, L<Params::Check> will sanity check templates, validating
for errors and unknown keys. Although very useful for debugging, this
can be somewhat slow in hot-code and large loops.

To disable this check, set this variable to C<false>.

Default is 1;

=head2 $Params::Check::WARNINGS_FATAL

If set to true, L<Params::Check> will C<croak> when an error during 
template validation occurs, rather than return C<false>.

Default is 0;

=head2 $Params::Check::CALLER_DEPTH

This global modifies the argument given to C<caller()> by
C<Params::Check::check()> and is useful if you have a custom wrapper
function around C<Params::Check::check()>. The value must be an
integer, indicating the number of wrapper functions inserted between
the real function call and C<Params::Check::check()>.

Example wrapper function, using a custom stacktrace:

    sub check {
        my ($template, $args_in) = @_;

        local $Params::Check::WARNINGS_FATAL = 1;
        local $Params::Check::CALLER_DEPTH = $Params::Check::CALLER_DEPTH + 1;
        my $args_out = Params::Check::check($template, $args_in);

        my_stacktrace(Params::Check::last_error) unless $args_out;

        return $args_out;
    }

Default is 0;

=head1 AUTHOR

This module by
Jos Boumans E<lt>[e-mail]<gt>.

=head1 Acknowledgements

Thanks to Richard Soderberg for his performance improvements.

=head1 COPYRIGHT

This module is
copyright (c) 2003,2004 Jos Boumans E<lt>[e-mail]<gt>.
All rights reserved.

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

=cut

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