function Graph::searchAndSort

Performs a depth-first search and sort on the directed acyclic graph.

Return value

The given $graph with more secondary keys filled in:

• 'paths': Contains a list of vertices than can be reached on a path from this vertex.
• 'reverse_paths': Contains a list of vertices that has a path from them to this vertex.
• 'weight': If there is a path from a vertex to another then the weight of the latter is higher.
• 'component': Vertices in the same component have the same component identifier.

File

core/lib/Drupal/Component/Graph/Graph.php, line 58

Class

Graph

Directed acyclic graph manipulation.

Namespace

Code

public function searchAndSort() {
    $state = [
        // The order of last visit of the depth first search. This is the reverse
        // of the topological order if the graph is acyclic.
'last_visit_order' => [],
        // The components of the graph.
'components' => [],
    ];
    // Perform the actual search.
    foreach ($this->graph as $start => $data) {
        $this->depthFirstSearch($state, $start);
    }
    // We do such a numbering that every component starts with 0. This is useful
    // for module installs as we can install every 0 weighted module in one
    // request, and then every 1 weighted etc.
    $component_weights = [];
    foreach ($state['last_visit_order'] as $vertex) {
        $component = $this->graph[$vertex]['component'];
        if (!isset($component_weights[$component])) {
            $component_weights[$component] = 0;
        }
        $this->graph[$vertex]['weight'] = $component_weights[$component]--;
    }
    return $this->graph;
}