Represents a directed graph. It is used by the dependency tracker for storing and querying dependencies between items.
@example Creating and using a directed graph
# Create a graph with three vertices graph = DirectedGraph.new(%w( a b c d )) # Add edges graph.add_edge('a', 'b') graph.add_edge('b', 'c') graph.add_edge('c', 'd') # Get (direct) predecessors graph.direct_predecessors_of('d').sort # => %w( c ) graph.predecessors_of('d').sort # => %w( a b c ) # Modify edges graph.remove_edge('a', 'b') # Get (direct) predecessors again graph.direct_predecessors_of('d').sort # => %w( c ) graph.predecessors_of('d').sort # => %w( b c )
Creates a new directed graph with the given vertices.
# File lib/nanoc3/base/directed_graph.rb, line 41 def initialize(vertices) @vertices = vertices @from_graph = {} @to_graph = {} @vertice_indexes = {} vertices.each_with_index do |v, i| @vertice_indexes[v] = i end invalidate_caches end
Adds an edge from the first vertex to the second vertex.
@param from Vertex where the edge should start @param to Vertex where the edge should end
@return [void]
# File lib/nanoc3/base/directed_graph.rb, line 61 def add_edge(from, to) @from_graph[from] ||= Set.new @from_graph[from] << to @to_graph[to] ||= Set.new @to_graph[to] << from invalidate_caches end
Deletes all edges going to the given vertex.
@param to Vertex to which all edges should be removed
@return [void]
# File lib/nanoc3/base/directed_graph.rb, line 93 def delete_edges_to(to) @to_graph[to] ||= Set.new @to_graph[to].each do |from| @from_graph[from].delete(to) end @to_graph.delete(to) end
Returns the direct predecessors of the given vertex, i.e. the vertices x where there is an edge from x to the given vertex y.
@param to The vertex of which the predecessors should be calculated
@return [Array] Direct predecessors of the given vertex
# File lib/nanoc3/base/directed_graph.rb, line 107 def direct_predecessors_of(to) @to_graph[to].to_a end
Returns the direct successors of the given vertex, i.e. the vertices y where there is an edge from the given vertex x to y.
@param from The vertex of which the successors should be calculated
@return [Array] Direct successors of the given vertex
# File lib/nanoc3/base/directed_graph.rb, line 117 def direct_successors_of(from) @from_graph[from].to_a end
Returns an array of tuples representing the edges. The result of this method may take a while to compute and should be cached if possible.
@return [Array] The list of all edges in this graph.
# File lib/nanoc3/base/directed_graph.rb, line 145 def edges result = [] @vertices.each_with_index do |v, i| direct_successors_of(v).map { |v2| @vertice_indexes[v2] }.each do |i2| result << [ i, i2 ] end end result end
Returns the predecessors of the given vertex, i.e. the vertices x for which there is a path from x to the given vertex y.
@param to The vertex of which the predecessors should be calculated
@return [Array] Predecessors of the given vertex
# File lib/nanoc3/base/directed_graph.rb, line 127 def predecessors_of(to) @predecessors[to] ||= recursively_find_vertices(to, :direct_predecessors_of) end
Removes the edge from the first vertex to the second vertex. If the edge does not exist, nothing is done.
@param from Start vertex of the edge @param to End vertex of the edge
@return [void]
# File lib/nanoc3/base/directed_graph.rb, line 78 def remove_edge(from, to) @from_graph[from] ||= Set.new @from_graph[from].delete(to) @to_graph[to] ||= Set.new @to_graph[to].delete(from) invalidate_caches end
Returns the successors of the given vertex, i.e. the vertices y for which there is a path from the given vertex x to y.
@param from The vertex of which the successors should be calculated
@return [Array] Successors of the given vertex
# File lib/nanoc3/base/directed_graph.rb, line 137 def successors_of(from) @successors[from] ||= recursively_find_vertices(from, :direct_successors_of) end
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