NAME

       Config::Model::Iterator - Iterates forward or backward a configuration tree

VERSION

       version 2.082

SYNOPSIS

        use Config::Model;

        # define configuration tree object
        my $model = Config::Model->new;
        $model->create_config_class(
           name    => "Foo",
           element => [
               [qw/bar baz/] => {
                   type       => 'leaf',
                   value_type => 'string',
                   level => 'important' ,
               },
           ]
        );
        $model->create_config_class(
           name    => "MyClass",
           element => [
               foo_nodes => {
                   type       => 'hash',     # hash id
                   index_type => 'string',
                   level => 'important' ,
                   cargo      => {
                       type              => 'node',
                       config_class_name => 'Foo'
                   },
               },
           ],
        );

        my $inst = $model->instance( root_class_name => 'MyClass' );
        # create some Foo objects
        $inst->config_root->load("foo_nodes:foo1 - foo_nodes:foo2  ") ;

        my $my_leaf_cb = sub {
           my ($iter, $data_r,$node,$element,$index, $leaf_object) = @_ ;
           print "leaf_cb called for ",$leaf_object->location,"\n" ;
        } ;
        my $my_hash_cb = sub {
           my ($iter, $data_r,$node,$element,@keys) = @_ ;
           print "hash_element_cb called for element $element with keys @keys\n" ;
        } ;

        my $iterator = $inst -> iterator (
           leaf_cb         => $my_leaf_cb,
           hash_element_cb => $my_hash_cb ,
        );

        $iterator->start ;
        ### prints
        # hash_element_cb called for element foo_nodes with keys foo1 foo2
        # leaf_cb called for foo_nodes:foo1 bar
        # leaf_cb called for foo_nodes:foo1 baz
        # leaf_cb called for foo_nodes:foo2 bar
        # leaf_cb called for foo_nodes:foo2 baz

DESCRIPTION

       This module provides a class that is able to iterate forward or backward a configuration
       tree.  The iterator will stop and call back user defined subroutines on one of the
       following condition:

       •   A configuration item contains an error (mostly undefined mandatory values)

       •   A configuration item contains warnings and the constructor's argument
           "call_back_on_warning" was set.

       •   A configuration item has a "important" level and the constructor's argument
           "call_back_on_important" was set.. See level parameter for details.

       The iterator supports going forward and backward (to support "back" and "next" buttons on
       a wizard widget).

CONSTRUCTOR

       The constructor should be used only by Config::Model::Instance with the iterator method.

Creating an iterator

       A iterator requires at least two kind of call-back: a call-back for leaf elements and a
       call-back for hash elements (which will be also used for list elements).

       These call-back must be passed when creating the iterator (the parameters are named
       "leaf_cb" and "hash_element_cb")

       Here are the the parameters accepted by "iterator":

   call_back_on_important
       Whether to call back when an important element is found (default 0).

   call_back_on_warning
       Whether to call back when an item with warnings is found (default 0).

   status
       Specifies the status of the element scanned by the wizard (default 'standard').

   leaf_cb
       Subroutine called backed for leaf elements. See "Callback prototypes" in
       Config::Model::ObjTreeScanner for signature and details. (mandatory)

   hash_element_cb
       Subroutine called backed for hash elements. See "Callback prototypes" in
       Config::Model::ObjTreeScanner for signature and details. (mandatory)

Custom callbacks

       By default, "leaf_cb" will be called for all types of leaf elements (i.e enum. integer,
       strings, ...). But you can provide dedicated call-back for each type of leaf:

        enum_value_cb, integer_value_cb, number_value_cb, boolean_value_cb,
        uniline_value_cb, string_value_cb

       Likewise, you can also provide a call-back dedicated to list elements with
       "list_element_cb"

Methods

   start
       Start the scan and perform call-back when needed. This function will return when the scan
       is completely done.

   bail_out
       When called, a variable is set so that all call_backs will return as soon as possible.
       Used to abort wizard.

   go_forward
       Set wizard in forward (default) mode.

   go_backward
       Set wizard in backward mode.

AUTHOR

       Dominique Dumont, (ddumont at cpan dot org)

SEE ALSO

       Config::Model, Config::Model::Instance, Config::Model::Node, Config::Model::HashId,
       Config::Model::ListId, Config::Model::Value, Config::Model::CheckList,
       Config::Model::ObjTreeScanner,

AUTHOR

       Dominique Dumont

COPYRIGHT AND LICENSE

       This software is Copyright (c) 2005-2016 by Dominique Dumont.

       This is free software, licensed under:

         The GNU Lesser General Public License, Version 2.1, February 1999