adjacency.rb in rgl-0.2.3

- old
+ new
@@ -1,151 +1,184 @@
+# adjacency.rb
 # 
-# $Id: adjacency.rb,v 1.4 2002/11/10 21:21:20 monora Exp $
+# $Id: adjacency.rb,v 1.7 2005/03/30 21:25:34 monora Exp $
 # 
 # The DirectedAdjacencyGraph class implements a generalized adjacency list
-# graph structure. An AdjacencyGraph is basically a two-dimensional structure,
-# where each element of the first dimension represents a vertex, and each of
-# the vertices contains a one-dimensional structure that is the list of all
-# adjacent vertices.
+# graph structure.  An AdjacencyGraph is basically a two-dimensional structure
+# (ie, a list of lists).  Each element of the first dimension represents a
+# vertex.  Each of the vertices contains a one-dimensional structure that is
+# the list of all adjacent vertices.
 #
-# The class for representing the adjacency list of a vertex is by default a
-# Set, but can be configured by the client when a AdjacencyGraph is created.
+# The class for representing the adjacency list of a vertex is, by default, a
+# Set.  This can be configured by the client, however, when an AdjacencyGraph
+# is created.
 
 require 'rgl/mutable'
 require 'set'
 
 module RGL
+
   class DirectedAdjacencyGraph
-	include MutableGraph
 
-	# Shortcut for creating a DirectedAdjacencyGraph:
-	#
-	#  RGL::DirectedAdjacencyGraph[1,2, 2,3, 2,4, 4,5].edges.to_a.to_s =>
-	#    "(1-2)(2-3)(2-4)(4-5)"
-	def self.[](*a)
-	  result = new
-	  0.step(a.size-1,2) { |i| result.add_edge(a[i],a[i+1])}
-	  result
-	end
+    include MutableGraph
 
-	# Returns a new empty DirectedAdjacencyGraph which has as edgelist class the
-	# given class. The default edgelist class is Set to ensure set semantics for
-	# edges and vertices.
-	def initialize(edgelist_class=Set)
-	  @edgelist_class = edgelist_class
-	  @vertice_dict = Hash.new
-	end
+    # Shortcut for creating a DirectedAdjacencyGraph:
+    #
+    #  RGL::DirectedAdjacencyGraph[1,2, 2,3, 2,4, 4,5].edges.to_a.to_s =>
+    #    "(1-2)(2-3)(2-4)(4-5)"
 
-	# Iterator for the keys of the vertice list hash.
-	def each_vertex(&b)
-	  @vertice_dict.each_key(&b)
-	end
+    def self.[] (*a)
+      result = new
+      0.step(a.size-1, 2) { |i| result.add_edge(a[i], a[i+1]) }
+      result
+    end
 
-	def each_adjacent(v, &b)	# :nodoc:
-	  adjacency_list = @vertice_dict[v] or raise NoVertexError, "No vertex #{v}."
-	  adjacency_list.each(&b)
-	end
+    # Returns a new empty DirectedAdjacencyGraph which has as its edgelist
+    # class the given class.  The default edgelist class is Set, to ensure
+    # set semantics for edges and vertices.
 
-	# Returns true.
-	def directed?; true; end
+    def initialize (edgelist_class = Set)
+      @edgelist_class = edgelist_class
+      @vertice_dict   = Hash.new
+    end
 
-	# Complexity is O(1), since the vertices are kept in a Hash containing as
-	# value the list of adjacent vertices of _v_.
-	def has_vertex?(v); @vertice_dict.has_key?(v); end
+    # Iterator for the keys of the vertice list hash.
 
-	# Complexity is O(1), if a Set is used as adjacency list, otherwise
-	# O(out_degree(v)) 
-	#
-	# ---
-	# MutableGraph interface.
-	def has_edge? (u, v)
-	  has_vertex?(u) and @vertice_dict[u].include? v
-	end
+    def each_vertex (&b)
+      @vertice_dict.each_key(&b)
+    end
 
-	# See MutableGraph#add_vertex.
-	#
-	# If the vertex is already in (using eql?) the method does nothing.
-	def add_vertex(v)
-	  @vertice_dict[v] ||= @edgelist_class.new
-	end
+    def each_adjacent (v, &b)			# :nodoc:
+      adjacency_list = @vertice_dict[v] or
+        raise NoVertexError, "No vertex #{v}."
+      adjacency_list.each(&b)
+    end
 
-	# See MutableGraph#add_edge.
-	def add_edge (u,v)
-	  add_vertex(u)				# ensure key
-	  add_vertex(v)				# ensure key
-	  basic_add_edge(u,v)
-	end
+    # Returns true.
 
-	# See MutableGraph#remove_vertex.
-	def remove_vertex(v)
-	  @vertice_dict.delete(v)
-	  
-	  # remove v from all adjacency lists
-	  @vertice_dict.each_value { |adjList| adjList.delete(v) }
-	end
+    def directed?
+      true
+    end
 
-	# See MutableGraph::remove_edge.
-	def remove_edge (u,v)
-	  @vertice_dict[u].delete(v) unless @vertice_dict[u].nil?
-	end
+    # Complexity is O(1), because the vertices are kept in a Hash containing
+    # as values the lists of adjacent vertices of _v_.
 
-	protected
+    def has_vertex? (v)
+      @vertice_dict.has_key?(v)
+    end
 
-	def basic_add_edge(u,v)
-	  @vertice_dict[u].add v
-	end
-  end							# class AdjacencyGraph
+    # Complexity is O(1), if a Set is used as adjacency list.  Otherwise,
+    # complexity is O(out_degree(v)).
+    #
+    # ---
+    # MutableGraph interface.
 
-  # AdjacencyGraph is an undirected Graph. The methods add_edge and remove_edge
-  # are reimplemented: If an edge (u,v) is added or removed then the reverse
-  # edge (v,u) is also added or removed.
-  class AdjacencyGraph < DirectedAdjacencyGraph
-	# Always returns false.
-	def directed?; false; end
-	
-	# Also removes (v,u)
-	def remove_edge (u,v)
-	  super
-	  @vertice_dict[v].delete(u) unless @vertice_dict[v].nil?
-	end
+    def has_edge? (u, v)
+      has_vertex?(u) and @vertice_dict[u].include?(v)
+    end
 
-	protected
-	def basic_add_edge(u,v)
-	  super
-	  # Insert backwards edge
-	  @vertice_dict[v].add u
-	end
-  end
+    # See MutableGraph#add_vertex.
+    #
+    # If the vertex is already in the graph (using eql?), the method does
+    # nothing.
 
+    def add_vertex (v)
+      @vertice_dict[v] ||= @edgelist_class.new
+    end
+
+    # See MutableGraph#add_edge.
+
+    def add_edge (u, v)
+      add_vertex(u)                         # ensure key
+      add_vertex(v)                         # ensure key
+      basic_add_edge(u, v)
+    end
+
+    # See MutableGraph#remove_vertex.
+
+    def remove_vertex (v)
+      @vertice_dict.delete(v)
+          
+      # remove v from all adjacency lists
+
+      @vertice_dict.each_value { |adjList| adjList.delete(v) }
+    end
+
+    # See MutableGraph::remove_edge.
+
+    def remove_edge (u, v)
+      @vertice_dict[u].delete(v) unless @vertice_dict[u].nil?
+    end
+
+    protected
+
+    def basic_add_edge (u, v)
+      @vertice_dict[u].add(v)
+    end
+
+  end		# class DirectedAdjacencyGraph
+
+  # AdjacencyGraph is an undirected Graph.  The methods add_edge and
+  # remove_edge are reimplemented:  If an edge (u,v) is added or removed,
+  # then the reverse edge (v,u) is also added or removed.
+
+  class AdjacencyGraph < DirectedAdjacencyGraph 
+
+    def directed?				# Always returns false.
+      false
+    end
+        
+    # Also removes (v,u)
+
+    def remove_edge (u, v)
+      super
+      @vertice_dict[v].delete(u) unless @vertice_dict[v].nil?
+    end
+
+    protected
+
+    def basic_add_edge (u,v)
+      super
+      @vertice_dict[v].add(u)			# Insert backwards edge
+    end
+
+  end		# class AdjacencyGraph
+
   module Graph
-	# Convert a general graph to an AdjacencyGraph. If the graph is directed
-	# returns a DirectedAdjacencyGraph else a AdjacencyGraph.
-	def to_adjacency
-	  result = (directed? ? DirectedAdjacencyGraph : AdjacencyGraph).new
-	  each_edge { |u,v| result.add_edge u,v }
-	  result
-	end
 
-	# Return a new DirectedAdjacencyGraph which has the same set of vertices. If
-	# (u,v) is an edge of the graph then (v,u) is an edge of the result.
-	#
-	# If the graph is undirected the result is self.
-	def reverse
-	  reurn self unless directed?
-	  result = DirectedAdjacencyGraph.new
-	  each_edge { |u,v| result.add_edge v,u }
-	  result
-	end
+    # Convert a general graph to an AdjacencyGraph.  If the graph is directed,
+    # returns a DirectedAdjacencyGraph; otherwise, returns an AdjacencyGraph.
 
-	# Return a new AdjacencyGraph which has the same set of vertices. If (u,v)
-	# is an edge of the graph (u,v) and (v,u) (which are the same edges) is an
-	# edge of the result.
-	#
-	# If the graph is undirected the result is self.
-	def to_undirected
-	  return self unless directed?
-	  result = AdjacencyGraph.new
-	  each_edge { |u,v| result.add_edge u,v }
-	  result
-	end
-  end
-end
+    def to_adjacency
+      result = (directed? ? DirectedAdjacencyGraph : AdjacencyGraph).new
+      each_edge { |u,v| result.add_edge(u, v) }
+      result
+    end
+
+    # Return a new DirectedAdjacencyGraph which has the same set of vertices.
+    # If (u,v) is an edge of the graph, then (v,u) is an edge of the result.
+    #
+    # If the graph is undirected, the result is self.
+
+    def reverse
+      return self unless directed?
+      result = DirectedAdjacencyGraph.new
+      each_vertex { |v| result.add_vertex v }
+      each_edge { |u,v| result.add_edge(v, u) }
+      result
+    end
+
+    # Return a new AdjacencyGraph which has the same set of vertices.  If (u,v)
+    # is an edge of the graph, then (u,v) and (v,u) (which are the same edges)
+    # are edges of the result.
+    #
+    # If the graph is undirected, the result is self.
+
+    def to_undirected
+      return self unless directed?
+      result = AdjacencyGraph.new
+      each_edge { |u,v| result.add_edge(u, v) }
+      result
+    end
+
+  end		# module Graph
+end		# module RGL