diff options
Diffstat (limited to 'lib/bundler/vendor/tsort/lib/tsort.rb')
| -rw-r--r-- | lib/bundler/vendor/tsort/lib/tsort.rb | 455 |
1 files changed, 455 insertions, 0 deletions
diff --git a/lib/bundler/vendor/tsort/lib/tsort.rb b/lib/bundler/vendor/tsort/lib/tsort.rb new file mode 100644 index 0000000000..cf8731f760 --- /dev/null +++ b/lib/bundler/vendor/tsort/lib/tsort.rb @@ -0,0 +1,455 @@ +# frozen_string_literal: true + +#-- +# tsort.rb - provides a module for topological sorting and strongly connected components. +#++ +# + +# +# Bundler::TSort implements topological sorting using Tarjan's algorithm for +# strongly connected components. +# +# Bundler::TSort is designed to be able to be used with any object which can be +# interpreted as a directed graph. +# +# Bundler::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 +# Bundler::TSort uses Hash internally. +# +# == A Simple Example +# +# The following example demonstrates how to mix the Bundler::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 'bundler/vendor/tsort/lib/tsort' +# +# class Hash +# include Bundler::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 'bundler/vendor/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 Bundler::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 Bundler::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", +# <em>SIAM Journal on Computing</em>, Vol. 1, No. 2, pp. 146-160, June 1972. +# + +module Bundler::TSort + + VERSION = "0.2.0" + + 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, Bundler::TSort::Cyclic is raised. + # + # class G + # include Bundler::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 Bundler::TSort::Cyclic + # + def tsort + each_node = method(:tsort_each_node) + each_child = method(:tsort_each_child) + Bundler::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, Bundler::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 Bundler::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 Bundler::TSort.tsort(each_node, each_child) # raises Bundler::TSort::Cyclic + # + def self.tsort(each_node, each_child) + tsort_each(each_node, each_child).to_a + end + + # The iterator version of the #tsort method. + # <tt><em>obj</em>.tsort_each</tt> is similar to <tt><em>obj</em>.tsort.each</tt>, but + # modification of _obj_ during the iteration may lead to unexpected results. + # + # #tsort_each returns +nil+. + # If there is a cycle, Bundler::TSort::Cyclic is raised. + # + # class G + # include Bundler::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) + Bundler::TSort.tsort_each(each_node, each_child, &block) + end + + # The iterator version of the Bundler::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) } + # Bundler::TSort.tsort_each(each_node, each_child) {|n| p n } + # #=> 4 + # # 2 + # # 3 + # # 1 + # + def self.tsort_each(each_node, each_child) # :yields: node + return to_enum(__method__, each_node, each_child) unless block_given? + + 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 Bundler::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) + Bundler::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 Bundler::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 Bundler::TSort.strongly_connected_components(each_node, each_child) + # #=> [[4], [2, 3], [1]] + # + def self.strongly_connected_components(each_node, each_child) + each_strongly_connected_component(each_node, each_child).to_a + end + + # The iterator version of the #strongly_connected_components method. + # <tt><em>obj</em>.each_strongly_connected_component</tt> is similar to + # <tt><em>obj</em>.strongly_connected_components.each</tt>, but + # modification of _obj_ during the iteration may lead to unexpected results. + # + # #each_strongly_connected_component returns +nil+. + # + # class G + # include Bundler::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) + Bundler::TSort.each_strongly_connected_component(each_node, each_child, &block) + end + + # The iterator version of the Bundler::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) } + # Bundler::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) } + # Bundler::TSort.each_strongly_connected_component(each_node, each_child) {|scc| p scc } + # #=> [4] + # # [2, 3] + # # [1] + # + def self.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 + 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 Bundler::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 + Bundler::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. + # + # #Bundler::TSort.each_strongly_connected_component_from is a class method and + # it doesn't need a class to represent a graph which includes Bundler::TSort. + # + # graph = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]} + # each_child = lambda {|n, &b| graph[n].each(&b) } + # Bundler::TSort.each_strongly_connected_component_from(1, each_child) {|scc| + # p scc + # } + # #=> [4] + # # [2, 3] + # # [1] + # + def self.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 = + 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 |