kotovalexarian-likes-github/ruby--ruby
1
0
Fork 0
mirror of https://github.com/ruby/ruby.git synced 2022-11-09 12:17:21 -05:00
Code Releases Activity

* lib/tsort.rb (TSort.each_strongly_connected_component_from):

Browse source 
Extracted from TSort#each_strongly_connected_component_from.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43326 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
akr 2013-10-17 03:32:15 +00:00
parent 209376034f
commit ed6231195b
4 changed files with 44 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

28
lib/tsort.rb
View file

@ -195,18 +195,40 @@ module TSort
#
# #each_strongly_connected_component_from doesn't call #tsort_each_node.
#
def each_strongly_connected_component_from(node, id_map={}, stack=[]) # :yields: nodes
def each_strongly_connected_component_from(node, id_map={}, stack=[], &block) # :yields: nodes
TSort.each_strongly_connected_component_from(node, method(:tsort_each_child), id_map, stack, &block)
end
# Iterates over strongly connected components in a graph.
# The graph is represented by _node_ and _each_child_.
#
# _node_ is the first node.
# _each_child_ should have +call+ method which takes a node argument
# and yields for each adjacent node.
#
# Return value is unspecified.
#
# #TSort.each_strongly_connected_component_from is a class method and
# it doesn't need a class to represent a graph which includes TSort.
#
# graph = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
# each_child = lambda {|n, &b| graph[n].each(&b) }
# TSort.each_strongly_connected_component_from(1, each_child) {|scc|
# p scc #=> [4], [2, 3], [1]
# }
#
def TSort.each_strongly_connected_component_from(node, each_child, id_map={}, stack=[]) # :yields: nodes
minimum_id = node_id = id_map[node] = id_map.size
stack_length = stack.length
stack << node
tsort_each_child(node) {|child|
each_child.call(node) {|child|
if id_map.include? child
child_id = id_map[child]
minimum_id = child_id if child_id && child_id < minimum_id
else
sub_minimum_id =
each_strongly_connected_component_from(child, id_map, stack) {|c|
TSort.each_strongly_connected_component_from(child, each_child, id_map, stack) {|c|
yield c
}
minimum_id = sub_minimum_id if sub_minimum_id < minimum_id