Config::Model::Searcher(3pm)

NAME
Config::Model::Searcher - Search an element in a configuration model

SYNOPSIS
 use Config::Model ;

 # create your config model
 my $model = Config::Model -> new ;
 $model->create_config_class( ... ) ;

 # create instance
 my $inst = $model->instance (root_class_name => 'FooBar',
                              instance_name => 'test1');

 # create root of config
 my $root = $inst -> config_root ;

 # create searcher for manual search
 my $searcher = $root->searcher();
 $searcher -> prepare (element => 'X') ;
 my $step1 = $searcher->next_step() ; # return possibilities
 my $obj1 = $searcher->choose($step1->[0]) ;
 my $step2 = $searcher->next_step() ; # return possibilities
 my $target = $searcher->choose($step2->[1]) ;

 # automatic search
 my $element_call_back = sub { ... ; return 'foo' ;} ;
 my $id_call_back      = sub { ... ; return 'bar' ;} ;

 $searcher->reset ;
 my $target = $searcher->auto_choose($element_call_back, $id_call_back) ;

DESCRIPTION
This modules provides a way to search for a configuration element in a configuration tree.

For instance, suppose that you have a xorg.conf model and you know that you need to tune the "MergedXinerama" parameter, but you don't remember where is this parameter in the configuration tree. This module will guide you through the tree to the(s) node(s) that contain this parameter.

This class should be invaluable to construct interactive GUIs.

This module provides 2 search modes:

•   A manual search where you are guided step by step to the element you're looking for. At each step, the module will return you the possible paths to choose from. The user will have to choose the correct path from the available paths. Most of the time, only one possibility will be returned, so the user choice should be straightforward. In other case (more that one choice), the user will have to decide the next step.

•   An automatic search where you provide call-back that will resolve the ambiguities in case of multiple paths.

CONSTRUCTOR
The constructor should be used only by Config::Model::Node.

Methods

  get_searchable_elements
Return the list of elements found in model that can be searched in the configuration tree.

  prepare(element => ...)
Prepare the searcher to look for the element passed in the argument. Returns the searcher object (i.e. $self).

  reset
Re-initialise the search engine to redo the search from start

  searched
Returns the searched element name.

Manual search

  next_step()
Returns an array ref containing the next possible step to find the element you're looking for. The array ref can contain 1 or more elements.

If the array ref is empty, you can get the target element with "current_object()".

  next_choice()
Returns an array ref containing the next non-obvious choice to find the element you're looking for.

If the array ref is empty, you can get the target element with "current_object()".

  choose( <chosen_element_name> )
Tell the search engine your choice. The chosen element name must be one of the possibilities given by "next_step()".

  current_object()
Returns the object where the search engine is. It can be a node, a list, a hash, or a leaf element.

Automatic search

  auto_choose ( element_callback, id_call_back)
Finds the searched element with minimal user interaction.

"element_callback" will be called when the search engine finds a node where more than one element can lead to the searched item.

"id_call_back" will be called when the search engine finds a hash element or a list element which contain no or more than 1 elements. In this case the call-back will have return an id that will be used by the search engine to get the target element.

Both call-back arguments will be:

•   The current object (as returned by "current_object()")

•   A list of possible choices

For instances, your callback will be :

 my $id_cb = sub {
    my ($object,@choices) = @_ ;
    ....
    return $choice[1] ;
 }

Both call-back are expected to return a scalar value that is either:

•   An element name

•   An id valid for the list or hash element returned by "current_object()".

AUTHOR
Dominique Dumont, (ddumont at cpan dot org)

SEE ALSO
Config::Model, Config::Model::Node, Config::Model::AnyId, Config::Model::ListId, Config::Model::HashId, Config::Model::Value,