Class: Agama::Graph

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

Instance Method Summary collapse

Constructor Details

#initialize(params) ⇒ Graph

Initialises variables and sets the path



6
7
8
9
 
# File 'lib/agama/graph.rb', line 6

def initialize(params)
  @db_path  = params[:path] || "./"
  @db       = params[:db]
end

Instance Method Details

#clean_edge(edge) ⇒ Object 



254
255
256
257
258
259
260
261
262
 
# File 'lib/agama/graph.rb', line 254

def clean_edge(edge)
  new_edge = {}
  edge.each do |key, value|
    next if (key == :type or key == :from or key == :to or key == :directed)
    new_edge[key] = value
  end

  return new_edge
end

#clean_node(node) ⇒ Object

Methods to seperate key from the value



244
245
246
247
248
249
250
251
252
 
# File 'lib/agama/graph.rb', line 244

def clean_node(node)
  new_node = {}
  node.each do |key, value|
    next if (key == :type or key == :name)
    new_node[key] = value
  end

  return new_node
end

#close ⇒ Object

Closes the database connection



29
30
31
 
# File 'lib/agama/graph.rb', line 29

def close
  @db.close
end

#edge_count(type = nil) ⇒ Object 



230
231
232
233
234
235
236
237
238
239
240
 
# File 'lib/agama/graph.rb', line 230

def edge_count(type = nil)
  if type
    value = @db.m_get("edge#{type}")
    if value
      etype = Marshal.load(value)
      etype[:count]
    end
  else
    Marshal.load(@db.m_get("m"))
  end
end

#get_edge(edge) ⇒ Object

Fetches the value assigned to the edge from the from node to the to node



148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
 
# File 'lib/agama/graph.rb', line 148

def get_edge(edge)
  return nil unless edge[:from][:name]
  return nil unless edge[:to][:name]

  #Get the type of the edge
  type = edge[:type] || Config::DEFAULT_TYPE
  edge[:type] = type

  #Check if the edge type exists
  etype = Marshal.load(@db.m_get("edge#{type}")) if @db.m_get("edge#{type}")

  #Integrity check: Check whether the edge direction is not contradictory
  if edge[:directed]
    if etype
      if etype[:directed] != edge[:directed]
        return false
      end
    else
      #If there is no edge of that type then pre-empt the result
      return false
    end
  else
    if etype
      edge[:directed] = etype[:directed]
    else
      #If there is no edge of that type then pre-empt the result
      return false
    end
  end

  #Convert the edge into a Key string and fetch the corresponding data
  key, reverse_key = Keyify.edge(edge)
  value = @db.e_get(key)

  if value
    new_edge            = Marshal.load(value)
    new_edge[:from]     = self.get_node(edge[:from])
    new_edge[:to]       = self.get_node(edge[:to])
    new_edge[:type]     = edge[:type]
    new_edge[:directed] = etype[:directed] #Pick direction alone from the meta_db for consistency
    new_edge
  end
end

#get_node(node) ⇒ Object

Fetches the node requested



71
72
73
74
75
76
77
78
79
80
81
82
83
84
 
# File 'lib/agama/graph.rb', line 71

def get_node(node)
  return nil unless node[:name]

  #Convert the node into a Key string and fetch the corresponding data
  key = Keyify.node(node)
  value = @db.n_get(key)

  if value
    new_node        = Marshal.load(value)
    new_node[:name] = node[:name]
    new_node[:type] = node[:type] || Config::DEFAULT_TYPE
    new_node
  end
end

#neighbours(node) ⇒ Object 



192
193
194
195
 
# File 'lib/agama/graph.rb', line 192

def neighbours(node)
  traverser = Traverser.new(@db, self)
  traverser.set(:from => node)
end

#node_count(type = nil) ⇒ Object

Accessors for meta values



219
220
221
222
223
224
225
226
227
228
 
# File 'lib/agama/graph.rb', line 219

def node_count(type = nil)
  if type
    value = @db.m_get("node#{type}")
    if value
      Marshal.load(value)
    end
  else
    Marshal.load(@db.m_get("n"))
  end
end

#open ⇒ Object

Opens the database for access



13
14
15
16
17
18
19
20
21
22
23
24
25
26
 
# File 'lib/agama/graph.rb', line 13

def open
  @db.open(@db_path)

  #Create meta variables if they are absent
  unless @db.m_get("n")
    @db.m_put("n", Marshal.dump(0))             #Total node count
    @db.m_put("m", Marshal.dump(0))             #Total edge count
    @db.m_put("node#{Config::DEFAULT_TYPE}", 
              Marshal.dump(0))                  #Node count for default type
    @db.m_put("edge#{Config::DEFAULT_TYPE}", 
              Marshal.dump({:directed => false, :count => 0})) #Edge count for default type
  end

end

#set_edge(edge) ⇒ Object

Creates/Updates an edge



88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
 
# File 'lib/agama/graph.rb', line 88

def set_edge(edge)
  return false unless edge
  return false unless edge[:from][:name]
  return false unless edge[:to][:name]

  #Get the type of the edge
  type = edge[:type] || Config::DEFAULT_TYPE
  edge[:type] = type

  #Check if the edge type exists
  etype = Marshal.load(@db.m_get("edge#{type}")) if @db.m_get("edge#{type}")

  #Integrity check: Check whether the edge direction is not contradictory
  if edge[:directed]
    if etype
      if etype[:directed] != edge[:directed]
        raise "Edge creation error: edge direction contradicting existing edges"
        return
      end
    end
  else
    if etype
      edge[:directed] = etype[:directed]
    else
      edge[:directed] = false
    end
  end

  #Convert the edge into Key, Reversed Key and Value strings for storage
  key, reverse_key = Keyify.edge(edge)
  value = Marshal.dump(clean_edge(edge))

  #Integrity check: Check if the incident nodes are defined
  unless (self.get_node(edge[:from]) and self.get_node(edge[:to]))
    raise "Edge creation error: node(s) not defined"
    return
  end

  #Check whether the operation is an insert (not an update), if so increment count
  unless @db.e_get(key)
    if etype
      etype[:count] += 1
      @db.m_put("edge#{type}", Marshal.dump(etype))
    else
      @db.m_put("edge#{type}", 
                Marshal.dump({:directed => edge[:directed], :count => 1}))
    end

    #Increment global count
    @db.m_put("m", Marshal.dump(Marshal.load(@db.m_get("m")) + 1))
  end

  #Add the edge and the reversed edge
  if @db.e_put(key, value) and @db.e_put(reverse_key, value)
    return edge
  end
end

#set_node(node) ⇒ Object

Creates/Updates a node



35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
 
# File 'lib/agama/graph.rb', line 35

def set_node(node)
  return nil unless node[:name]

  #Get the type of the node
  type = node[:type] || Config::DEFAULT_TYPE
  node[:type] = type

  #Convert the node into Key and Value strings for storage
  key = Keyify.node(node)
  value = Marshal.dump(self.clean_node(node)) #remove key items from value

  #Check if the node type exists, and if so get its count
  count = Marshal.load(@db.m_get("node#{type}")) if @db.m_get("node#{type}")

  #Check whether the operation is an insert (not an update), if so increment count
  unless @db.n_get(key)
    #Increment type-specific count
    if count
      count += 1
      @db.m_put("node#{type}", Marshal.dump(count))
    else
      @db.m_put("node#{type}", Marshal.dump(1))
    end

    #Increment global count
    @db.m_put("n", Marshal.dump(Marshal.load(@db.m_get("n")) + 1))
  end

  #Store the node
  if @db.n_put(key, value)
    node
  end
end