Class: EnumStateMachine::NodeCollection

Inherits:
Object
  • Object
show all
Includes:
Assertions, Enumerable
Defined in:
lib/enum_state_machine/node_collection.rb

Overview

Represents a collection of nodes in a state machine, be it events or states. Nodes will not differentiate between the String and Symbol versions of the values being indexed.

Direct Known Subclasses

EventCollection, StateCollection

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Assertions

#assert_exclusive_keys, #assert_valid_keys

Constructor Details

#initialize(machine, options = {}) ⇒ NodeCollection

Creates a new collection of nodes for the given state machine. By default, the collection is empty.

Configuration options:

  • :index - One or more attributes to automatically generate hashed indices for in order to perform quick lookups. Default is to index by the :name attribute



21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
 
# File 'lib/enum_state_machine/node_collection.rb', line 21

def initialize(machine, options = {})
  assert_valid_keys(options, :index)
  options = {:index => :name}.merge(options)
  
  @machine = machine
  @nodes = []
  @index_names = Array(options[:index])
  @indices = @index_names.inject({}) do |indices, name|
    indices[name] = {}
    indices[:"#{name}_to_s"] = {}
    indices[:"#{name}_to_sym"] = {}
    indices
  end
  @default_index = Array(options[:index]).first
  @contexts = []
end

Instance Attribute Details

#machine ⇒ Object

The machine associated with the nodes



12
13
14
 
# File 'lib/enum_state_machine/node_collection.rb', line 12

def machine
  @machine
end

Instance Method Details

#<<(node) ⇒ Object

Adds a new node to the collection. By doing so, this will also add it to the configured indices. This will also evaluate any existings contexts that match the new node.



88
89
90
91
92
93
 
# File 'lib/enum_state_machine/node_collection.rb', line 88

def <<(node)
  @nodes << node
  @index_names.each {|name| add_to_index(name, value(node, name), node)}
  @contexts.each {|context| eval_context(context, node)}
  self
end

#[](key, index_name = @default_index) ⇒ Object

Gets the node indexed by the given key. By default, this will look up the key in the first index configured for the collection. A custom index can be specified like so:

collection['parked', :value]

The above will look up the “parked” key in a hash indexed by each node’s value attribute.

If the key cannot be found, then nil will be returned.



145
146
147
148
149
150
 
# File 'lib/enum_state_machine/node_collection.rb', line 145

def [](key, index_name = @default_index)
  self.index(index_name)[key] ||
  self.index(:"#{index_name}_to_s")[key.to_s] ||
  to_sym?(key) && self.index(:"#{index_name}_to_sym")[:"#{key}"] ||
  nil
end

#at(index) ⇒ Object

Gets the node at the given index.

states = EnumStateMachine::NodeCollection.new
states << EnumStateMachine::State.new(machine, :parked)
states << EnumStateMachine::State.new(machine, :idling)

states.at(0).name    # => :parked
states.at(1).name    # => :idling



131
132
133
 
# File 'lib/enum_state_machine/node_collection.rb', line 131

def at(index)
  @nodes[index]
end

#concat(nodes) ⇒ Object

Appends a group of nodes to the collection



96
97
98
 
# File 'lib/enum_state_machine/node_collection.rb', line 96

def concat(nodes)
  nodes.each {|node| self << node}
end

#context(nodes, &block) ⇒ Object

Tracks a context that should be evaluated for any nodes that get added which match the given set of nodes. Matchers can be used so that the context can get added once and evaluated after multiple adds.



75
76
77
78
79
80
81
82
83
 
# File 'lib/enum_state_machine/node_collection.rb', line 75

def context(nodes, &block)
  nodes = nodes.first.is_a?(Matcher) ? nodes.first : WhitelistMatcher.new(nodes)
  @contexts << context = {:nodes => nodes, :block => block}
  
  # Evaluate the new context for existing nodes
  each {|node| eval_context(context, node)}
  
  context
end

#each ⇒ Object

Calls the block once for each element in self, passing that element as a parameter.

states = EnumStateMachine::NodeCollection.new
states << EnumStateMachine::State.new(machine, :parked)
states << EnumStateMachine::State.new(machine, :idling)
states.each {|state| puts state.name, ' -- '}

…produces:

parked -- idling --



118
119
120
121
 
# File 'lib/enum_state_machine/node_collection.rb', line 118

def each
  @nodes.each {|node| yield node}
  self
end

#fetch(key, index_name = @default_index) ⇒ Object

Gets the node indexed by the given key. By default, this will look up the key in the first index configured for the collection. A custom index can be specified like so:

collection['parked', :value]

The above will look up the “parked” key in a hash indexed by each node’s value attribute.

If the key cannot be found, then an IndexError exception will be raised:

collection['invalid', :value]   # => IndexError: "invalid" is an invalid value



164
165
166
 
# File 'lib/enum_state_machine/node_collection.rb', line 164

def fetch(key, index_name = @default_index)
  self[key, index_name] || raise(IndexError, "#{key.inspect} is an invalid #{index_name}")
end

#initialize_copy(orig) ⇒ Object

Creates a copy of this collection such that modifications don’t affect the original collection



40
41
42
43
44
45
46
47
48
49
50
51
52
53
 
# File 'lib/enum_state_machine/node_collection.rb', line 40

def initialize_copy(orig) #:nodoc:
  super
  
  nodes = @nodes
  contexts = @contexts
  @nodes = []
  @contexts = []
  @indices = @indices.inject({}) {|indices, (name, *)| indices[name] = {}; indices}
  
  # Add nodes *prior* to copying over the contexts so that they don't get
  # evaluated multiple times
  concat(nodes.map {|n| n.dup})
  @contexts = contexts.dup
end

#keys(index_name = @default_index) ⇒ Object

Gets the set of unique keys for the given index



68
69
70
 
# File 'lib/enum_state_machine/node_collection.rb', line 68

def keys(index_name = @default_index)
  index(index_name).keys
end

#length ⇒ Object

Gets the number of nodes in this collection



63
64
65
 
# File 'lib/enum_state_machine/node_collection.rb', line 63

def length
  @nodes.length
end

#update(node) ⇒ Object

Updates the indexed keys for the given node. If the node’s attribute has changed since it was added to the collection, the old indexed keys will be replaced with the updated ones.



103
104
105
 
# File 'lib/enum_state_machine/node_collection.rb', line 103

def update(node)
  @index_names.each {|name| update_index(name, node)}
end