Graph::Traversal(3) User Contributed Perl Documentation Graph::Traversal(3)NAMEGraph::Traversal - traverse graphs
SYNOPSIS
Don't use Graph::Traversal directly, use Graph::Traversal::DFS or
Graph::Traversal::BFS instead.
use Graph;
my $g = Graph->new;
$g->add_edge(...);
use Graph::Traversal::...;
my $t = Graph::Traversal::...->new(%opt);
$t->...
DESCRIPTION
You can control how the graph is traversed by the various callback
parameters in the %opt. In the parameters descriptions below the $u
and $v are vertices, and the $self is the traversal object itself.
Callback parameters
The following callback parameters are available:
tree_edge
Called when traversing an edge that belongs to the traversal tree.
Called with arguments ($u, $v, $self).
non_tree_edge
Called when an edge is met which either leads back to the traversal
tree (either a "back_edge", a "down_edge", or a "cross_edge").
Called with arguments ($u, $v, $self).
pre_edge
Called for edges in preorder. Called with arguments ($u, $v,
$self).
post_edge
Called for edges in postorder. Called with arguments ($u, $v,
$self).
back_edge
Called for back edges. Called with arguments ($u, $v, $self).
down_edge
Called for down edges. Called with arguments ($u, $v, $self).
cross_edge
Called for cross edges. Called with arguments ($u, $v, $self).
pre
pre_vertex
Called for vertices in preorder. Called with arguments ($v,
$self).
post
post_vertex
Called for vertices in postorder. Called with arguments ($v,
$self).
first_root
Called when choosing the first root (start) vertex for traversal.
Called with arguments ($self, $unseen) where $unseen is a hash
reference with the unseen vertices as keys.
next_root
Called when choosing the next root (after the first one) vertex for
traversal (useful when the graph is not connected). Called with
arguments ($self, $unseen) where $unseen is a hash reference with
the unseen vertices as keys. If you want only the first reachable
subgraph to be processed, set the next_root to "undef".
start
Identical to defining "first_root" and undefining "next_root".
next_alphabetic
Set this to true if you want the vertices to be processed in
alphabetic order (and leave first_root/next_root undefined).
next_numeric
Set this to true if you want the vertices to be processed in
numeric order (and leave first_root/next_root undefined).
next_successor
Called when choosing the next vertex to visit. Called with
arguments ($self, $next) where $next is a hash reference with the
possible next vertices as keys. Use this to provide a custom
ordering for choosing vertices, as opposed to "next_numeric" or
"next_alphabetic".
The parameters "first_root" and "next_successor" have a 'hierarchy' of
how they are determined: if they have been explicitly defined, use that
value. If not, use the value of "next_alphabetic", if that has been
defined. If not, use the value of "next_numeric", if that has been
defined. If not, the next vertex to be visited is chose randomly.
Methods
The following methods are available:
unseen
Return the unseen vertices in random order.
seen
Return the seen vertices in random order.
seeing
Return the active fringe vertices in random order.
preorder
Return the vertices in preorder traversal order.
postorder
Return the vertices in postorder traversal order.
vertex_by_preorder
$v = $t->vertex_by_preorder($i)
Return the ith (0..$V-1) vertex by preorder.
preorder_by_vertex
$i = $t->preorder_by_vertex($v)
Return the preorder index (0..$V-1) by vertex.
vertex_by_postorder
$v = $t->vertex_by_postorder($i)
Return the ith (0..$V-1) vertex by postorder.
postorder_by_vertex
$i = $t->postorder_by_vertex($v)
Return the postorder index (0..$V-1) by vertex.
preorder_vertices
Return a hash with the vertices as the keys and their preorder
indices as the values.
postorder_vertices
Return a hash with the vertices as the keys and their postorder
indices as the values.
tree
Return the traversal tree as a graph.
has_state
$t->has_state('s')
Test whether the traversal has state 's' attached to it.
get_state
$t->get_state('s')
Get the state 's' attached to the traversal ("undef" if none).
set_state
$t->set_state('s', $s)
Set the state 's' attached to the traversal.
delete_state
$t->delete_state('s')
Delete the state 's' from the traversal.
Backward compatibility
The following parameters are for backward compatibility to Graph 0.2xx:
get_next_root
Like "next_root".
successor
Identical to having "tree_edge" both "non_tree_edge" defined to be
the same.
unseen_successor
Like "tree_edge".
seen_successor
Like "seed_edge".
Special callbacks
If in a callback you call the special "terminate" method, the traversal
is terminated, no more vertices are traversed.
SEE ALSO
Graph::Traversal::DFS, Graph::Traversal::BFS
AUTHOR AND COPYRIGHT
Jarkko Hietaniemi jhi@iki.fi
LICENSE
This module is licensed under the same terms as Perl itself.
perl v5.14.0 2008-11-28 Graph::Traversal(3)
