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StateMachine::NodeCollection

Represents a collection of nodes in a state machine, be it events or states.

Attributes

machine[R]

The machine associated with the nodes

Public Instance Methods

<<(node) click to toggle source

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.

# File lib/state_machine/node_collection.rb, line 80
def <<(node)
  @nodes << node
  @indices.each {|attribute, index| index[value(node, attribute)] = node}
  @contexts.each {|context| eval_context(context, node)}
  self
end
[](key, index_name = @default_index) click to toggle source

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.

# File lib/state_machine/node_collection.rb, line 146
def [](key, index_name = @default_index)
  index = self.index(index_name)
  if index.include?(key)
    index[key]
  elsif @indices.include?(:"#{index_name}_to_s")
    self[key.to_s, :"#{index_name}_to_s"]
  end
end
at(index) click to toggle source

Gets the node at the given index.

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

states.at(0).name    # => :parked
states.at(1).name    # => :idling
# File lib/state_machine/node_collection.rb, line 132
def at(index)
  @nodes[index]
end
concat(nodes) click to toggle source

Appends a group of nodes to the collection

# File lib/state_machine/node_collection.rb, line 88
def concat(nodes)
  nodes.each {|node| self << node}
end
context(nodes, &block) click to toggle source

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.

# File lib/state_machine/node_collection.rb, line 67
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() click to toggle source

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

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

…produces:

parked -- idling --
# File lib/state_machine/node_collection.rb, line 119
def each
  @nodes.each {|node| yield node}
  self
end
fetch(key, index_name = @default_index) click to toggle source

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
# File lib/state_machine/node_collection.rb, line 167
def fetch(key, index_name = @default_index)
  self[key, index_name] || raise(IndexError, "#{key.inspect} is an invalid #{index_name}")
end
keys(index_name = @default_index) click to toggle source

Gets the set of unique keys for the given index

# File lib/state_machine/node_collection.rb, line 60
def keys(index_name = @default_index)
  index(index_name).keys
end
length() click to toggle source

Gets the number of nodes in this collection

# File lib/state_machine/node_collection.rb, line 55
def length
  @nodes.length
end
machine=(new_machine) click to toggle source

Changes the current machine associated with the collection. In turn, this will change the state machine associated with each node in the collection.

# File lib/state_machine/node_collection.rb, line 49
def machine=(new_machine)
  @machine = new_machine
  each {|node| node.machine = new_machine}
end
update(node) click to toggle source

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.

# File lib/state_machine/node_collection.rb, line 95
def update(node)
  @indices.each do |attribute, index|
    old_key = RUBY_VERSION < '1.9' ? index.index(node) : index.key(node)
    new_key = value(node, attribute)
    
    # Only replace the key if it's changed
    if old_key != new_key
      index.delete(old_key)
      index[new_key] = node
    end
  end
end

Protected Instance Methods

eval_context(context, node) click to toggle source

Evaluates the given context for a particular node. This will only evaluate the context if the node matches.

# File lib/state_machine/node_collection.rb, line 186
def eval_context(context, node)
  node.context(&context[:block]) if context[:nodes].matches?(node.name)
end
index(name) click to toggle source

Gets the given index. If the index does not exist, then an ArgumentError is raised.

# File lib/state_machine/node_collection.rb, line 174
def index(name)
  raise ArgumentError, 'No indices configured' unless @indices.any?
  @indices[name] || raise(ArgumentError, "Invalid index: #{name.inspect}")
end
value(node, attribute) click to toggle source

Gets the value for the given attribute on the node

# File lib/state_machine/node_collection.rb, line 180
def value(node, attribute)
  node.send(attribute)
end

Public Class Methods

new(machine, options = {}) click to toggle source

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

# File lib/state_machine/node_collection.rb, line 19
def initialize(machine, options = {})
  assert_valid_keys(options, :index)
  options = {:index => :name}.merge(options)
  
  @machine = machine
  @nodes = []
  @indices = Array(options[:index]).inject({}) {|indices, attribute| indices[attribute] = {}; indices}
  @default_index = Array(options[:index]).first
  @contexts = []
end

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