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# frozen_string_literal: true
module Molinillo
class DependencyGraph
# A vertex in a {DependencyGraph} that encapsulates a {#name} and a
# {#payload}
class Vertex
# @return [String] the name of the vertex
attr_accessor :name
# @return [Object] the payload the vertex holds
attr_accessor :payload
# @return [Array<Object>] the explicit requirements that required
# this vertex
attr_reader :explicit_requirements
# @return [Boolean] whether the vertex is considered a root vertex
attr_accessor :root
alias root? root
# Initializes a vertex with the given name and payload.
# @param [String] name see {#name}
# @param [Object] payload see {#payload}
def initialize(name, payload)
@name = name.frozen? ? name : name.dup.freeze
@payload = payload
@explicit_requirements = []
@outgoing_edges = []
@incoming_edges = []
end
# @return [Array<Object>] all of the requirements that required
# this vertex
def requirements
(incoming_edges.map(&:requirement) + explicit_requirements).uniq
end
# @return [Array<Edge>] the edges of {#graph} that have `self` as their
# {Edge#origin}
attr_accessor :outgoing_edges
# @return [Array<Edge>] the edges of {#graph} that have `self` as their
# {Edge#destination}
attr_accessor :incoming_edges
# @return [Array<Vertex>] the vertices of {#graph} that have an edge with
# `self` as their {Edge#destination}
def predecessors
incoming_edges.map(&:origin)
end
# @return [Set<Vertex>] the vertices of {#graph} where `self` is a
# {#descendent?}
def recursive_predecessors
_recursive_predecessors
end
# @param [Set<Vertex>] vertices the set to add the predecessors to
# @return [Set<Vertex>] the vertices of {#graph} where `self` is a
# {#descendent?}
def _recursive_predecessors(vertices = new_vertex_set)
incoming_edges.each do |edge|
vertex = edge.origin
next unless vertices.add?(vertex)
vertex._recursive_predecessors(vertices)
end
vertices
end
protected :_recursive_predecessors
# @return [Array<Vertex>] the vertices of {#graph} that have an edge with
# `self` as their {Edge#origin}
def successors
outgoing_edges.map(&:destination)
end
# @return [Set<Vertex>] the vertices of {#graph} where `self` is an
# {#ancestor?}
def recursive_successors
_recursive_successors
end
# @param [Set<Vertex>] vertices the set to add the successors to
# @return [Set<Vertex>] the vertices of {#graph} where `self` is an
# {#ancestor?}
def _recursive_successors(vertices = new_vertex_set)
outgoing_edges.each do |edge|
vertex = edge.destination
next unless vertices.add?(vertex)
vertex._recursive_successors(vertices)
end
vertices
end
protected :_recursive_successors
# @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)
return true if equal?(other)
shallow_eql?(other) &&
successors.to_set == other.successors.to_set
end
# @param [Vertex] other the other vertex to compare to
# @return [Boolean] whether the two vertices are equal, determined
# solely by {#name} and {#payload} equality
def shallow_eql?(other)
return true if equal?(other)
other &&
name == other.name &&
payload == other.payload
end
alias 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 whether there is a path following edges within this {#graph}
def path_to?(other)
_path_to?(other)
end
alias descendent? path_to?
# @param [Vertex] other the vertex to check if there's a path to
# @param [Set<Vertex>] visited the vertices of {#graph} that have been visited
# @return [Boolean] whether there is a path to `other` from `self`
def _path_to?(other, visited = new_vertex_set)
return false unless visited.add?(self)
return true if equal?(other)
successors.any? { |v| v._path_to?(other, visited) }
end
protected :_path_to?
# Is there a path from `other` to `self` following edges in the
# dependency graph?
# @return whether there is a path following edges within this {#graph}
def ancestor?(other)
other.path_to?(self)
end
alias is_reachable_from? ancestor?
def new_vertex_set
require 'set'
Set.new
end
private :new_vertex_set
end
end
end
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