class StateMachines::NodeCollection
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.
Attributes
The machine associated with the nodes
Public Class Methods
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_machines/node_collection.rb, line 18 def initialize(machine, options = {}) options.assert_valid_keys(:index) options = { index: :name }.merge(options) @machine = machine @nodes = [] @index_names = Array(options[:index]) @indices = @index_names.reduce({}) do |indices, name| indices[name] = {} indices[:"#{name}_to_s"] = {} indices[:"#{name}_to_sym"] = {} indices end @default_index = Array(options[:index]).first @contexts = [] end
Public Instance Methods
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_machines/node_collection.rb, line 85 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
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_machines/node_collection.rb, line 142 def [](key, index_name = @default_index) index(index_name)[key] || index(:"#{index_name}_to_s")[key.to_s] || to_sym?(key) && index(:"#{index_name}_to_sym")[:"#{key}"] || nil end
Gets the node at the given index.
states = StateMachines::NodeCollection.new states << StateMachines::State.new(machine, :parked) states << StateMachines::State.new(machine, :idling) states.at(0).name # => :parked states.at(1).name # => :idling
# File lib/state_machines/node_collection.rb, line 128 def at(index) @nodes[index] end
Appends a group of nodes to the collection
# File lib/state_machines/node_collection.rb, line 93 def concat(nodes) nodes.each { |node| self << node } end
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_machines/node_collection.rb, line 72 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
Calls the block once for each element in self, passing that element as a parameter.
states = StateMachines::NodeCollection.new states << StateMachines::State.new(machine, :parked) states << StateMachines::State.new(machine, :idling) states.each {|state| puts state.name, ' -- '}
…produces:
parked -- idling --
# File lib/state_machines/node_collection.rb, line 115 def each @nodes.each { |node| yield node } self end
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_machines/node_collection.rb, line 161 def fetch(key, index_name = @default_index) self[key, index_name] || fail(IndexError, "#{key.inspect} is an invalid #{index_name}") end
Gets the set of unique keys for the given index
# File lib/state_machines/node_collection.rb, line 65 def keys(index_name = @default_index) index(index_name).keys end
Gets the number of nodes in this collection
# File lib/state_machines/node_collection.rb, line 60 def length @nodes.length end
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_machines/node_collection.rb, line 54 def machine=(new_machine) @machine = new_machine each { |node| node.machine = new_machine } end
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_machines/node_collection.rb, line 100 def update(node) @index_names.each { |name| update_index(name, node) } end
Protected Instance Methods
Adds the given key / node combination to an index, including the string and symbol versions of the index
# File lib/state_machines/node_collection.rb, line 180 def add_to_index(name, key, node) index(name)[key] = node index(:"#{name}_to_s")[key.to_s] = node index(:"#{name}_to_sym")[:"#{key}"] = node if to_sym?(key) end
Evaluates the given context for a particular node. This will only evaluate the context if the node matches.
# File lib/state_machines/node_collection.rb, line 215 def eval_context(context, node) node.context(&context[:block]) if context[:nodes].matches?(node.name) end
Gets the given index. If the index does not exist, then an ArgumentError is raised.
# File lib/state_machines/node_collection.rb, line 168 def index(name) fail ArgumentError, 'No indices configured' unless @indices.any? @indices[name] || fail(ArgumentError, "Invalid index: #{name.inspect}") end
Removes the given key from an index, including the string and symbol versions of the index
# File lib/state_machines/node_collection.rb, line 188 def remove_from_index(name, key) index(name).delete(key) index(:"#{name}_to_s").delete(key.to_s) index(:"#{name}_to_sym").delete(:"#{key}") if to_sym?(key) end
Determines whether the given value can be converted to a symbol
# File lib/state_machines/node_collection.rb, line 209 def to_sym?(value) "#{value}" != '' end
Updates the node for the given index, including the string and symbol versions of the index
# File lib/state_machines/node_collection.rb, line 196 def update_index(name, node) index = self.index(name) old_key = index.key(node) new_key = value(node, name) # Only replace the key if it's changed if old_key != new_key remove_from_index(name, old_key) add_to_index(name, new_key, node) end end
Gets the value for the given attribute on the node
# File lib/state_machines/node_collection.rb, line 174 def value(node, attribute) node.send(attribute) end