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require 'set'
require 'tsort'
module Bundler::Molinillo
# A directed acyclic graph that is tuned to hold named dependencies
class DependencyGraph
include Enumerable
# Enumerates through the vertices of the graph.
# @return [Array<Vertex>] The graph's vertices.
def each
vertices.values.each { |v| yield v }
end
include TSort
alias_method :tsort_each_node, :each
def tsort_each_child(vertex, &block)
vertex.successors.each(&block)
end
# Topologically sorts the given vertices.
# @param [Enumerable<Vertex>] vertices the vertices to be sorted, which must
# all belong to the same graph.
# @return [Array<Vertex>] The sorted vertices.
def self.tsort(vertices)
TSort.tsort(
lambda { |b| vertices.each(&b) },
lambda { |v, &b| (v.successors & vertices).each(&b) }
)
end
# A directed edge of a {DependencyGraph}
# @attr [Vertex] origin The origin of the directed edge
# @attr [Vertex] destination The destination of the directed edge
# @attr [Array] requirements The requirements the directed edge represents
Edge = Struct.new(:origin, :destination, :requirements)
# @return [{String => Vertex}] vertices that have no {Vertex#predecessors},
# keyed by by {Vertex#name}
attr_reader :root_vertices
# @return [{String => Vertex}] the vertices of the dependency graph, keyed
# by {Vertex#name}
attr_reader :vertices
# @return [Set<Edge>] the edges of the dependency graph
attr_reader :edges
def initialize
@vertices = {}
@edges = Set.new
@root_vertices = {}
end
# Initializes a copy of a {DependencyGraph}, ensuring that all {#vertices}
# have the correct {Vertex#graph} set
def initialize_copy(other)
super
@vertices = other.vertices.reduce({}) do |vertices, (name, vertex)|
vertices.tap do |hash|
hash[name] = vertex.dup.tap { |v| v.graph = self }
end
end
@root_vertices = Hash[vertices.select { |n, _v| other.root_vertices[n] }]
@edges = other.edges.map do |edge|
Edge.new(
vertex_named(edge.origin.name),
vertex_named(edge.destination.name),
edge.requirements.dup
)
end
end
# @return [String] a string suitable for debugging
def inspect
"#{self.class}:#{vertices.values.inspect}"
end
# @return [Boolean] whether the two dependency graphs are equal, determined
# by a recursive traversal of each {#root_vertices} and its
# {Vertex#successors}
def ==(other)
root_vertices == other.root_vertices
end
# @param [String] name
# @param [Object] payload
# @param [Array<String>] parent_names
# @param [Object] requirement the requirement that is requiring the child
# @return [void]
def add_child_vertex(name, payload, parent_names, requirement)
is_root = parent_names.include?(nil)
parent_nodes = parent_names.compact.map { |n| vertex_named(n) }
vertex = vertex_named(name) || if is_root
add_root_vertex(name, payload)
else
add_vertex(name, payload)
end
vertex.payload ||= payload
parent_nodes.each do |parent_node|
add_edge(parent_node, vertex, requirement)
end
vertex
end
# @param [String] name
# @param [Object] payload
# @return [Vertex] the vertex that was added to `self`
def add_vertex(name, payload)
vertex = vertices[name] ||= Vertex.new(self, name, payload)
vertex.tap { |v| v.payload = payload }
end
# @param [String] name
# @param [Object] payload
# @return [Vertex] the vertex that was added to `self`
def add_root_vertex(name, payload)
add_vertex(name, payload).tap { |v| root_vertices[name] = v }
end
# Detaches the {#vertex_named} `name` {Vertex} from the graph, recursively
# removing any non-root vertices that were orphaned in the process
# @param [String] name
# @return [void]
def detach_vertex_named(name)
vertex = vertex_named(name)
return unless vertex
successors = vertex.successors
vertices.delete(name)
edges.reject! { |e| e.origin == vertex || e.destination == vertex }
successors.each { |v| detach_vertex_named(v.name) unless root_vertices[v.name] || v.predecessors.any? }
end
# @param [String] name
# @return [Vertex,nil] the vertex with the given name
def vertex_named(name)
vertices[name]
end
# @param [String] name
# @return [Vertex,nil] the root vertex with the given name
def root_vertex_named(name)
root_vertices[name]
end
# Adds a new {Edge} to the dependency graph
# @param [Vertex] origin
# @param [Vertex] destination
# @param [Object] requirement the requirement that this edge represents
# @return [Edge] the added edge
def add_edge(origin, destination, requirement)
if origin == destination || destination.path_to?(origin)
raise CircularDependencyError.new([origin, destination])
end
Edge.new(origin, destination, [requirement]).tap { |e| edges << e }
end
# A vertex in a {DependencyGraph} that encapsulates a {#name} and a
# {#payload}
class Vertex
# @return [DependencyGraph] the graph this vertex is a node of
attr_accessor :graph
# @return [String] the name of the vertex
attr_accessor :name
# @return [Object] the payload the vertex holds
attr_accessor :payload
# @return [Arrary<Object>] the explicit requirements that required
# this vertex
attr_reader :explicit_requirements
# @param [DependencyGraph] graph see {#graph}
# @param [String] name see {#name}
# @param [Object] payload see {#payload}
def initialize(graph, name, payload)
@graph = graph
@name = name
@payload = payload
@explicit_requirements = []
end
# @return [Array<Object>] all of the requirements that required
# this vertex
def requirements
incoming_edges.map(&:requirements).flatten + explicit_requirements
end
# @return [Array<Edge>] the edges of {#graph} that have `self` as their
# {Edge#origin}
def outgoing_edges
graph.edges.select { |e| e.origin.shallow_eql?(self) }
end
# @return [Array<Edge>] the edges of {#graph} that have `self` as their
# {Edge#destination}
def incoming_edges
graph.edges.select { |e| e.destination.shallow_eql?(self) }
end
# @return [Set<Vertex>] the vertices of {#graph} that have an edge with
# `self` as their {Edge#destination}
def predecessors
incoming_edges.map(&:origin).to_set
end
# @return [Set<Vertex>] the vertices of {#graph} that have an edge with
# `self` as their {Edge#origin}
def successors
outgoing_edges.map(&:destination).to_set
end
# @return [Set<Vertex>] the vertices of {#graph} where `self` is an
# {#ancestor?}
def recursive_successors
successors + successors.map(&:recursive_successors).reduce(Set.new, &:+)
end
# @return [String] a string suitable for debugging
def inspect
"#{self.class}:#{name}(#{payload.inspect})"
end
# @return [Boolean] whether the two vertices are equal, determined
# by a recursive traversal of each {Vertex#successors}
def ==(other)
shallow_eql?(other) &&
successors == other.successors
end
# @return [Boolean] whether the two vertices are equal, determined
# solely by {#name} and {#payload} equality
def shallow_eql?(other)
other &&
name == other.name &&
payload == other.payload
end
alias_method :eql?, :==
# @return [Fixnum] a hash for the vertex based upon its {#name}
def hash
name.hash
end
# Is there a path from `self` to `other` following edges in the
# dependency graph?
# @return true iff there is a path following edges within this {#graph}
def path_to?(other)
successors.include?(other) || successors.any? { |v| v.path_to?(other) }
end
alias_method :descendent?, :path_to?
# Is there a path from `other` to `self` following edges in the
# dependency graph?
# @return true iff there is a path following edges within this {#graph}
def ancestor?(other)
predecessors.include?(other) || predecessors.any? { |v| v.ancestor?(other) }
end
alias_method :is_reachable_from?, :ancestor?
end
end
end
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