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86530b38 AT |
1 | package Graph::Directed; |
2 | ||
3 | use strict; | |
4 | local $^W = 1; | |
5 | ||
6 | use Graph::Base; | |
7 | ||
8 | use vars qw(@ISA); | |
9 | @ISA = qw(Graph::Base); | |
10 | ||
11 | use overload '""' => \&stringify; | |
12 | ||
13 | =head1 NAME | |
14 | ||
15 | Graph::Directed - directed graphs | |
16 | ||
17 | =head1 SYNOPSIS | |
18 | ||
19 | use Graph::Directed; | |
20 | ||
21 | $g = new Graph::Directed; | |
22 | ||
23 | =head1 DESCRIPTION | |
24 | ||
25 | See Graph::Base for the available methods. | |
26 | ||
27 | =head1 COPYRIGHT | |
28 | ||
29 | Copyright 1999, O'Reilly & Associates. | |
30 | ||
31 | This code is distributed under the same copyright terms as Perl itself. | |
32 | ||
33 | =cut | |
34 | ||
35 | # new | |
36 | # | |
37 | # $D = Graph::Directed->new(@V) | |
38 | # | |
39 | # The Constructor. Returns a new directed graph $D, possibly | |
40 | # populated with the optional initial vertices @V. | |
41 | # | |
42 | sub new { | |
43 | my $class = shift; | |
44 | ||
45 | my $G = Graph::Base->new(@_); | |
46 | ||
47 | bless $G, $class; | |
48 | ||
49 | $G->directed(1); | |
50 | ||
51 | return $G; | |
52 | } | |
53 | ||
54 | # _edges | |
55 | # | |
56 | # @e = $G->_edges($u, $v) | |
57 | # | |
58 | # (INTERNAL USE ONLY) | |
59 | # Both vertices undefined: | |
60 | # returns all the edges of the graph. | |
61 | # Both vertices defined: | |
62 | # returns all the edges between the vertices. | |
63 | # Only 1st vertex defined: | |
64 | # returns all the edges leading out of the vertex. | |
65 | # Only 2nd vertex defined: | |
66 | # returns all the edges leading into the vertex. | |
67 | # Edges @e are returned as ($start_vertex, $end_vertex) pairs. | |
68 | # | |
69 | sub _edges { | |
70 | my ($G, $u, $v) = @_; | |
71 | my @e; | |
72 | ||
73 | if (defined $u and defined $v) { | |
74 | @e = ($u, $v) | |
75 | if exists $G->{ Succ }->{ $u }->{ $v }; | |
76 | } elsif (defined $u) { | |
77 | foreach $v ($G->successors($u)) { | |
78 | push @e, $G->_edges($u, $v); | |
79 | } | |
80 | } elsif (defined $v) { # not defined $u and defined $v | |
81 | foreach $u ($G->predecessors($v)) { | |
82 | push @e, $G->_edges($u, $v); | |
83 | } | |
84 | } else { # not defined $u and not defined $v | |
85 | foreach $u ($G->vertices) { | |
86 | push @e, $G->_edges($u); | |
87 | } | |
88 | } | |
89 | ||
90 | return @e; | |
91 | } | |
92 | ||
93 | sub stringify { | |
94 | my $G = shift; | |
95 | ||
96 | return $G->_stringify("-", ","); | |
97 | } | |
98 | ||
99 | 1; |