diff --git a/lib/rubygems/dependency_list.rb b/lib/rubygems/dependency_list.rb
index 8f61869874..10e08fc703 100644
--- a/lib/rubygems/dependency_list.rb
+++ b/lib/rubygems/dependency_list.rb
@@ -5,7 +5,7 @@
# See LICENSE.txt for permissions.
#++
-require 'tsort'
+require_relative 'tsort'
require_relative 'deprecate'
##
@@ -20,7 +20,7 @@ class Gem::DependencyList
attr_reader :specs
include Enumerable
- include TSort
+ include Gem::TSort
##
# Allows enabling/disabling use of development dependencies
diff --git a/lib/rubygems/request_set.rb b/lib/rubygems/request_set.rb
index 9286c54221..01b01599a8 100644
--- a/lib/rubygems/request_set.rb
+++ b/lib/rubygems/request_set.rb
@@ -1,5 +1,5 @@
# frozen_string_literal: true
-require 'tsort'
+require_relative 'tsort'
##
# A RequestSet groups a request to activate a set of dependencies.
@@ -15,7 +15,7 @@ require 'tsort'
# #=> ["nokogiri-1.6.0", "mini_portile-0.5.1", "pg-0.17.0"]
class Gem::RequestSet
- include TSort
+ include Gem::TSort
##
# Array of gems to install even if already installed
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
index 16430a79f5..95f8416b96 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
@@ -1,6 +1,6 @@
# frozen_string_literal: true
-require 'tsort'
+require_relative '../../../../tsort'
require_relative 'dependency_graph/log'
require_relative 'dependency_graph/vertex'
@@ -17,7 +17,7 @@ module Gem::Resolver::Molinillo
vertices.values.each { |v| yield v }
end
- include TSort
+ include Gem::TSort
# @!visibility private
alias tsort_each_node each
diff --git a/lib/rubygems/tsort.rb b/lib/rubygems/tsort.rb
new file mode 100644
index 0000000000..ebe7c3364b
--- /dev/null
+++ b/lib/rubygems/tsort.rb
@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require_relative 'tsort/lib/tsort'
diff --git a/lib/rubygems/tsort/lib/tsort.rb b/lib/rubygems/tsort/lib/tsort.rb
new file mode 100644
index 0000000000..f68c5947d3
--- /dev/null
+++ b/lib/rubygems/tsort/lib/tsort.rb
@@ -0,0 +1,454 @@
+# frozen_string_literal: true
+
+#--
+# tsort.rb - provides a module for topological sorting and strongly connected components.
+#++
+#
+
+#
+# Gem::TSort implements topological sorting using Tarjan's algorithm for
+# strongly connected components.
+#
+# Gem::TSort is designed to be able to be used with any object which can be
+# interpreted as a directed graph.
+#
+# Gem::TSort requires two methods to interpret an object as a graph,
+# tsort_each_node and tsort_each_child.
+#
+# * tsort_each_node is used to iterate for all nodes over a graph.
+# * tsort_each_child is used to iterate for child nodes of a given node.
+#
+# The equality of nodes are defined by eql? and hash since
+# Gem::TSort uses Hash internally.
+#
+# == A Simple Example
+#
+# The following example demonstrates how to mix the Gem::TSort module into an
+# existing class (in this case, Hash). Here, we're treating each key in
+# the hash as a node in the graph, and so we simply alias the required
+# #tsort_each_node method to Hash's #each_key method. For each key in the
+# hash, the associated value is an array of the node's child nodes. This
+# choice in turn leads to our implementation of the required #tsort_each_child
+# method, which fetches the array of child nodes and then iterates over that
+# array using the user-supplied block.
+#
+# require 'rubygems/tsort/lib/tsort'
+#
+# class Hash
+# include Gem::TSort
+# alias tsort_each_node each_key
+# def tsort_each_child(node, &block)
+# fetch(node).each(&block)
+# end
+# end
+#
+# {1=>[2, 3], 2=>[3], 3=>[], 4=>[]}.tsort
+# #=> [3, 2, 1, 4]
+#
+# {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}.strongly_connected_components
+# #=> [[4], [2, 3], [1]]
+#
+# == A More Realistic Example
+#
+# A very simple `make' like tool can be implemented as follows:
+#
+# require 'rubygems/tsort/lib/tsort'
+#
+# class Make
+# def initialize
+# @dep = {}
+# @dep.default = []
+# end
+#
+# def rule(outputs, inputs=[], &block)
+# triple = [outputs, inputs, block]
+# outputs.each {|f| @dep[f] = [triple]}
+# @dep[triple] = inputs
+# end
+#
+# def build(target)
+# each_strongly_connected_component_from(target) {|ns|
+# if ns.length != 1
+# fs = ns.delete_if {|n| Array === n}
+# raise Gem::TSort::Cyclic.new("cyclic dependencies: #{fs.join ', '}")
+# end
+# n = ns.first
+# if Array === n
+# outputs, inputs, block = n
+# inputs_time = inputs.map {|f| File.mtime f}.max
+# begin
+# outputs_time = outputs.map {|f| File.mtime f}.min
+# rescue Errno::ENOENT
+# outputs_time = nil
+# end
+# if outputs_time == nil ||
+# inputs_time != nil && outputs_time <= inputs_time
+# sleep 1 if inputs_time != nil && inputs_time.to_i == Time.now.to_i
+# block.call
+# end
+# end
+# }
+# end
+#
+# def tsort_each_child(node, &block)
+# @dep[node].each(&block)
+# end
+# include Gem::TSort
+# end
+#
+# def command(arg)
+# print arg, "\n"
+# system arg
+# end
+#
+# m = Make.new
+# m.rule(%w[t1]) { command 'date > t1' }
+# m.rule(%w[t2]) { command 'date > t2' }
+# m.rule(%w[t3]) { command 'date > t3' }
+# m.rule(%w[t4], %w[t1 t3]) { command 'cat t1 t3 > t4' }
+# m.rule(%w[t5], %w[t4 t2]) { command 'cat t4 t2 > t5' }
+# m.build('t5')
+#
+# == Bugs
+#
+# * 'tsort.rb' is wrong name because this library uses
+# Tarjan's algorithm for strongly connected components.
+# Although 'strongly_connected_components.rb' is correct but too long.
+#
+# == References
+#
+# R. E. Tarjan, "Depth First Search and Linear Graph Algorithms",
+# SIAM Journal on Computing, Vol. 1, No. 2, pp. 146-160, June 1972.
+#
+
+module Gem
+ module TSort
+ class Cyclic < StandardError
+ end
+
+ # Returns a topologically sorted array of nodes.
+ # The array is sorted from children to parents, i.e.
+ # the first element has no child and the last node has no parent.
+ #
+ # If there is a cycle, Gem::TSort::Cyclic is raised.
+ #
+ # class G
+ # include Gem::TSort
+ # def initialize(g)
+ # @g = g
+ # end
+ # def tsort_each_child(n, &b) @g[n].each(&b) end
+ # def tsort_each_node(&b) @g.each_key(&b) end
+ # end
+ #
+ # graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+ # p graph.tsort #=> [4, 2, 3, 1]
+ #
+ # graph = G.new({1=>[2], 2=>[3, 4], 3=>[2], 4=>[]})
+ # p graph.tsort # raises Gem::TSort::Cyclic
+ #
+ def tsort
+ each_node = method(:tsort_each_node)
+ each_child = method(:tsort_each_child)
+ Gem::TSort.tsort(each_node, each_child)
+ end
+
+ # Returns a topologically sorted array of nodes.
+ # The array is sorted from children to parents, i.e.
+ # the first element has no child and the last node has no parent.
+ #
+ # The graph is represented by _each_node_ and _each_child_.
+ # _each_node_ should have +call+ method which yields for each node in the graph.
+ # _each_child_ should have +call+ method which takes a node argument and yields for each child node.
+ #
+ # If there is a cycle, Gem::TSort::Cyclic is raised.
+ #
+ # g = {1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]}
+ # each_node = lambda {|&b| g.each_key(&b) }
+ # each_child = lambda {|n, &b| g[n].each(&b) }
+ # p Gem::TSort.tsort(each_node, each_child) #=> [4, 2, 3, 1]
+ #
+ # g = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
+ # each_node = lambda {|&b| g.each_key(&b) }
+ # each_child = lambda {|n, &b| g[n].each(&b) }
+ # p Gem::TSort.tsort(each_node, each_child) # raises Gem::TSort::Cyclic
+ #
+ def TSort.tsort(each_node, each_child)
+ Gem::TSort.tsort_each(each_node, each_child).to_a
+ end
+
+ # The iterator version of the #tsort method.
+ # obj.tsort_each is similar to obj.tsort.each, but
+ # modification of _obj_ during the iteration may lead to unexpected results.
+ #
+ # #tsort_each returns +nil+.
+ # If there is a cycle, Gem::TSort::Cyclic is raised.
+ #
+ # class G
+ # include Gem::TSort
+ # def initialize(g)
+ # @g = g
+ # end
+ # def tsort_each_child(n, &b) @g[n].each(&b) end
+ # def tsort_each_node(&b) @g.each_key(&b) end
+ # end
+ #
+ # graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+ # graph.tsort_each {|n| p n }
+ # #=> 4
+ # # 2
+ # # 3
+ # # 1
+ #
+ def tsort_each(&block) # :yields: node
+ each_node = method(:tsort_each_node)
+ each_child = method(:tsort_each_child)
+ Gem::TSort.tsort_each(each_node, each_child, &block)
+ end
+
+ # The iterator version of the Gem::TSort.tsort method.
+ #
+ # The graph is represented by _each_node_ and _each_child_.
+ # _each_node_ should have +call+ method which yields for each node in the graph.
+ # _each_child_ should have +call+ method which takes a node argument and yields for each child node.
+ #
+ # g = {1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]}
+ # each_node = lambda {|&b| g.each_key(&b) }
+ # each_child = lambda {|n, &b| g[n].each(&b) }
+ # Gem::TSort.tsort_each(each_node, each_child) {|n| p n }
+ # #=> 4
+ # # 2
+ # # 3
+ # # 1
+ #
+ def TSort.tsort_each(each_node, each_child) # :yields: node
+ return to_enum(__method__, each_node, each_child) unless block_given?
+
+ Gem::TSort.each_strongly_connected_component(each_node, each_child) {|component|
+ if component.size == 1
+ yield component.first
+ else
+ raise Cyclic.new("topological sort failed: #{component.inspect}")
+ end
+ }
+ end
+
+ # Returns strongly connected components as an array of arrays of nodes.
+ # The array is sorted from children to parents.
+ # Each elements of the array represents a strongly connected component.
+ #
+ # class G
+ # include Gem::TSort
+ # def initialize(g)
+ # @g = g
+ # end
+ # def tsort_each_child(n, &b) @g[n].each(&b) end
+ # def tsort_each_node(&b) @g.each_key(&b) end
+ # end
+ #
+ # graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+ # p graph.strongly_connected_components #=> [[4], [2], [3], [1]]
+ #
+ # graph = G.new({1=>[2], 2=>[3, 4], 3=>[2], 4=>[]})
+ # p graph.strongly_connected_components #=> [[4], [2, 3], [1]]
+ #
+ def strongly_connected_components
+ each_node = method(:tsort_each_node)
+ each_child = method(:tsort_each_child)
+ Gem::TSort.strongly_connected_components(each_node, each_child)
+ end
+
+ # Returns strongly connected components as an array of arrays of nodes.
+ # The array is sorted from children to parents.
+ # Each elements of the array represents a strongly connected component.
+ #
+ # The graph is represented by _each_node_ and _each_child_.
+ # _each_node_ should have +call+ method which yields for each node in the graph.
+ # _each_child_ should have +call+ method which takes a node argument and yields for each child node.
+ #
+ # g = {1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]}
+ # each_node = lambda {|&b| g.each_key(&b) }
+ # each_child = lambda {|n, &b| g[n].each(&b) }
+ # p Gem::TSort.strongly_connected_components(each_node, each_child)
+ # #=> [[4], [2], [3], [1]]
+ #
+ # g = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
+ # each_node = lambda {|&b| g.each_key(&b) }
+ # each_child = lambda {|n, &b| g[n].each(&b) }
+ # p Gem::TSort.strongly_connected_components(each_node, each_child)
+ # #=> [[4], [2, 3], [1]]
+ #
+ def TSort.strongly_connected_components(each_node, each_child)
+ Gem::TSort.each_strongly_connected_component(each_node, each_child).to_a
+ end
+
+ # The iterator version of the #strongly_connected_components method.
+ # obj.each_strongly_connected_component is similar to
+ # obj.strongly_connected_components.each, but
+ # modification of _obj_ during the iteration may lead to unexpected results.
+ #
+ # #each_strongly_connected_component returns +nil+.
+ #
+ # class G
+ # include Gem::TSort
+ # def initialize(g)
+ # @g = g
+ # end
+ # def tsort_each_child(n, &b) @g[n].each(&b) end
+ # def tsort_each_node(&b) @g.each_key(&b) end
+ # end
+ #
+ # graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+ # graph.each_strongly_connected_component {|scc| p scc }
+ # #=> [4]
+ # # [2]
+ # # [3]
+ # # [1]
+ #
+ # graph = G.new({1=>[2], 2=>[3, 4], 3=>[2], 4=>[]})
+ # graph.each_strongly_connected_component {|scc| p scc }
+ # #=> [4]
+ # # [2, 3]
+ # # [1]
+ #
+ def each_strongly_connected_component(&block) # :yields: nodes
+ each_node = method(:tsort_each_node)
+ each_child = method(:tsort_each_child)
+ Gem::TSort.each_strongly_connected_component(each_node, each_child, &block)
+ end
+
+ # The iterator version of the Gem::TSort.strongly_connected_components method.
+ #
+ # The graph is represented by _each_node_ and _each_child_.
+ # _each_node_ should have +call+ method which yields for each node in the graph.
+ # _each_child_ should have +call+ method which takes a node argument and yields for each child node.
+ #
+ # g = {1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]}
+ # each_node = lambda {|&b| g.each_key(&b) }
+ # each_child = lambda {|n, &b| g[n].each(&b) }
+ # Gem::TSort.each_strongly_connected_component(each_node, each_child) {|scc| p scc }
+ # #=> [4]
+ # # [2]
+ # # [3]
+ # # [1]
+ #
+ # g = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
+ # each_node = lambda {|&b| g.each_key(&b) }
+ # each_child = lambda {|n, &b| g[n].each(&b) }
+ # Gem::TSort.each_strongly_connected_component(each_node, each_child) {|scc| p scc }
+ # #=> [4]
+ # # [2, 3]
+ # # [1]
+ #
+ def TSort.each_strongly_connected_component(each_node, each_child) # :yields: nodes
+ return to_enum(__method__, each_node, each_child) unless block_given?
+
+ id_map = {}
+ stack = []
+ each_node.call {|node|
+ unless id_map.include? node
+ Gem::TSort.each_strongly_connected_component_from(node, each_child, id_map, stack) {|c|
+ yield c
+ }
+ end
+ }
+ nil
+ end
+
+ # Iterates over strongly connected component in the subgraph reachable from
+ # _node_.
+ #
+ # Return value is unspecified.
+ #
+ # #each_strongly_connected_component_from doesn't call #tsort_each_node.
+ #
+ # class G
+ # include Gem::TSort
+ # def initialize(g)
+ # @g = g
+ # end
+ # def tsort_each_child(n, &b) @g[n].each(&b) end
+ # def tsort_each_node(&b) @g.each_key(&b) end
+ # end
+ #
+ # graph = G.new({1=>[2, 3], 2=>[4], 3=>[2, 4], 4=>[]})
+ # graph.each_strongly_connected_component_from(2) {|scc| p scc }
+ # #=> [4]
+ # # [2]
+ #
+ # graph = G.new({1=>[2], 2=>[3, 4], 3=>[2], 4=>[]})
+ # graph.each_strongly_connected_component_from(2) {|scc| p scc }
+ # #=> [4]
+ # # [2, 3]
+ #
+ def each_strongly_connected_component_from(node, id_map={}, stack=[], &block) # :yields: nodes
+ Gem::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 child node.
+ #
+ # Return value is unspecified.
+ #
+ # #Gem::TSort.each_strongly_connected_component_from is a class method and
+ # it doesn't need a class to represent a graph which includes Gem::TSort.
+ #
+ # graph = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
+ # each_child = lambda {|n, &b| graph[n].each(&b) }
+ # Gem::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
+ return to_enum(__method__, node, each_child, id_map, stack) unless block_given?
+
+ minimum_id = node_id = id_map[node] = id_map.size
+ stack_length = stack.length
+ stack << node
+
+ 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 =
+ Gem::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
+ end
+ }
+
+ if node_id == minimum_id
+ component = stack.slice!(stack_length .. -1)
+ component.each {|n| id_map[n] = nil}
+ yield component
+ end
+
+ minimum_id
+ end
+
+ # Should be implemented by a extended class.
+ #
+ # #tsort_each_node is used to iterate for all nodes over a graph.
+ #
+ def tsort_each_node # :yields: node
+ raise NotImplementedError.new
+ end
+
+ # Should be implemented by a extended class.
+ #
+ # #tsort_each_child is used to iterate for child nodes of _node_.
+ #
+ def tsort_each_child(node) # :yields: child
+ raise NotImplementedError.new
+ end
+ end
+end