Class: Tangle::Graph

Inherits:
Object
  • Object
show all
Defined in:
lib/tangle/graph.rb

Overview

Base class for all kinds of graphs

Direct Known Subclasses

Simple::Graph

Constant Summary collapse

Edge = 
Tangle::Edge

Instance Method Summary collapse

Constructor Details

#initialize(vertices: nil, edges: nil) ⇒ Graph

Initialize a new graph, optionally preloading it with vertices and edges

Graph.new() => Graph Graph.new(vertices: array_or_hash) => Graph Graph.new(vertices: array_or_hash, edges: array_or_hash) => Graph

When array_or_hash is a hash, it contains the objects as values and their names as keys. When array_or_hash is an array the objects will get assigned unique names (within the graph).

vertices can contain anything, and the Vertex object that is created will delegate all missing methods to its content.

edges can contain an array of exactly two, either names of vertices or vertices.

Any subclass of Graph should also subclass Edge to manage its unique constraints.



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# File 'lib/tangle/graph.rb', line 30

def initialize(vertices: nil, edges: nil)
  @vertices_by_id = {}
  @vertices_by_name = {}
  @edges ||= []

  initialize_vertices(vertices)
  initialize_edges(edges)
end

Instance Method Details

#add_edge(*vertices, **kvargs) ⇒ Object

Add a new edge to the graph

add_edge(vtx1, vtx2, …) => Edge



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# File 'lib/tangle/graph.rb', line 55

def add_edge(*vertices, **kvargs)
  vertices = vertices.map { |v| get_vertex(v) }
  insert_edge(self.class::Edge.new(*vertices, graph: self, **kvargs))
end

#add_vertex(**kvargs) ⇒ Object

Add a new vertex to the graph

add_vertex(…) => Vertex

Optional named arguments:

name: unique name or label for vertex
contents: delegate object for missing methods



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# File 'lib/tangle/graph.rb', line 80

def add_vertex(**kvargs)
  insert_vertex(Vertex.new(graph: self, **kvargs))
end

#edges(&selector) ⇒ Object

Get all edges.

edges => Array



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# File 'lib/tangle/graph.rb', line 43

def edges(&selector)
  if block_given?
    @edges.select(&selector)
  else
    @edges.to_a
  end
end

#get_vertex(name_or_vertex) ⇒ Object 



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# File 'lib/tangle/graph.rb', line 84

def get_vertex(name_or_vertex)
  case name_or_vertex
  when Vertex
    name_or_vertex
  else
    @vertices_by_name[name_or_vertex] ||
      @vertices_by_id.fetch(name_or_vertex)
  end
end

#subgraph(&selector) ⇒ Object Also known as: dup

Return a subgraph, optionally filtered by a vertex selector block

subgraph => Graph subgraph { |vertex| … } => Graph

Unless a selector is provided, the subgraph contains the entire graph.



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# File 'lib/tangle/graph.rb', line 101

def subgraph(&selector)
  graph = self.class.new

  dup_vertices_into(graph, &selector)
  dup_edges_into(graph)

  graph
end

#vertices ⇒ Object

Get all vertices.

vertices => Array



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# File 'lib/tangle/graph.rb', line 64

def vertices
  if block_given?
    @vertices_by_id.select { |_, vertex| yield(vertex) }
  else
    @vertices_by_id
  end.values
end