/ 
Config-Model-2.012
River stage two • 11 direct dependents • 11 total dependents
/ Config::Model::SearchElement

NAME

Config::Model::SearchElement - Search an element in a configuration model

VERSION

version 2.012

SYNOPSIS

use Config::Model;
use Log::Log4perl qw(:easy);
Log::Log4perl->easy_init($WARN);

# define configuration tree object
my $model = Config::Model->new;
 $model->create_config_class(
   name    => "Foo",
   element => [
       [qw/foo bar/] => {
           type       => 'leaf',
           value_type => 'string'
       },
   ]
); 
$model ->create_config_class (
   name => "MyClass",

   element => [ 

       [qw/foo bar/] => {
           type       => 'leaf',
           value_type => 'string'
       },
       hash_of_nodes => {
           type       => 'hash',     # hash id
           index_type => 'string',
           cargo      => {
               type              => 'node',
               config_class_name => 'Foo'
           },
       },
   ],
) ;

my $inst = $model->instance(root_class_name => 'MyClass' );

my $root = $inst->config_root ;

# put data
my $step = 'foo=FOO hash_of_nodes:fr foo=bonjour -
  hash_of_nodes:en foo=hello ';
$root->load( step => $step );

# create searcher for manual search
my $searcher = $root->searcher();

# looking for foo element in the tree
$searcher -> prepare (element => 'foo') ;
my @next = $searcher->next_step() ; 

print "next possible steps: @next\n";
# next possible steps: foo hash_of_nodes

# Looking for foo below hash_of_nodes
$searcher->choose('hash_of_nodes') ;
@next = $searcher->next_step() ; 

print "next possible steps: @next\n";
# next possible steps: en fr

# Looking for foo below fr
$searcher->choose('fr') ;
@next = $searcher->next_step() ; 

print "next possible steps: @next\n";
# next possible steps: foo

# last step
$searcher->choose('foo') ;
my $target = $searcher->current_object;

print "Found '",$target->location,"'\n";
# Found 'hash_of_nodes:fr foo'

# automatic search setup
my $element_call_back = sub { return 'hash_of_nodes' ;} ;
my $id_call_back      = sub { return 'en' ;} ;

$searcher->reset ;
$target = $searcher->auto_choose($element_call_back, $id_call_back) ;
 print "Automatic search found '",$target->location,"'\n";
# Automatic search found 'hash_of_nodes:en foo'

DESCRIPTION

This modules provides a way to search for a configuration element in a configuration tree by exploring the configuration model.

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 user interfaces.

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-initialize the search engine to redo the search from start

searched

Returns the searched element name.

Manual search

next_step()

Returns an array (or a ref depending on context) 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:

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,