lib/glimmer/data_binding/observer.rb
# Copyright (c) 2007-2024 Andy Maleh
#
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# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
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#
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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require 'glimmer/error'
module Glimmer
module DataBinding
# Mixin representing Observer trait from Observer Design Pattern
# Allows classes to include without interfering with their
# inheritance hierarchy.
#
# Includes a default implementation that can receive an observer block
# Example: Observer.proc {|new_value| puts new_value}
# Subclasses may override
module Observer
# Observer Proc default implementation that takes an observer block to process updates
# via call method
class Proc
include Observer
def initialize(&observer_block)
@observer_block = observer_block
end
# Called by observables once updates occur sending in the new_value if any
def call(new_value=nil, *extra_args)
@observer_block.call(new_value, *extra_args)
end
end
Registration = Struct.new(:observer, :observable, :args, keyword_init: true) do
def deregister
observer.unobserve(observable, *args)
end
alias unregister deregister
alias unobserve deregister
end
class << self
def proc(&observer_block)
Proc.new(&observer_block)
end
end
def registrations
@registrations ||= Concurrent::Hash.new
end
def registration_for(observable, *args)
args = compact_args(args)
registrations[[observable.object_id, args]] ||= Registration.new(observer: self, observable: observable, args: args)
end
alias ensure_registration_for! registration_for
# mapping of registrations to dependents
# {[observable, property] => [[dependent, dependent_observable, dependent_property], ...]}
def dependents
@dependents ||= Concurrent::Hash.new
end
def dependents_for(registration)
dependents[registration.object_id] ||= Concurrent::Set.new
end
# registers observer in an observable on args usually containing a property and options (optional)
# observer maintains registration list to unregister later
def observe(observable, *args)
options = args.last.is_a?(Hash) ? args.last : {}
return if observable.nil?
return if options[:ignore_frozen] && observable.frozen?
unless observable.is_a?(Observable)
# TODO refactor code to be more smart/polymorphic/automated and honor open/closed principle (e.g. for SomeClass, search if there is ObservableSomeClass)
if observable.is_a?(Array)
observable.extend(ObservableArray)
elsif observable.is_a?(Hash)
observable.extend(ObservableHash)
else
observable.extend(ObservableModel)
end
end
args = compact_args(args)
observable.add_observer(self, *args)
ensure_registration_for!(observable, *args)
end
alias register observe
def unobserve(observable, *args)
return unless observable.is_a?(Observable)
args = compact_args(args)
registration = registration_for(observable, *args)
registrations.delete([observable.object_id, args])
registration.tap do |registration|
dependents_for(registration).each do |dependent|
remove_dependent(registration => dependent)
dependent.deregister if dependent != registration
end
observable.remove_observer(self, *args)
end
end
alias unregister unobserve
alias deregister unobserve
def unobserve_dependents_with_observable(registration, dependent_observable)
thedependents = dependents_for(registration).select do |thedependent|
thedependent.observable == dependent_observable
end
thedependents.each(&:deregister)
end
alias unregister_dependents_with_observable unobserve_dependents_with_observable
alias deregister_dependents_with_observable unobserve_dependents_with_observable
# cleans up all registrations in observables
def unobserve_all_observables
registrations.values.dup.each do |registration|
registration.deregister
registrations.delete([registration.observable.object_id, registration.args])
end
end
alias unregister_all_observables unobserve_all_observables
alias deregister_all_observables unobserve_all_observables
# add dependent observer to unregister when unregistering observer
def add_dependent(parent_to_dependent_hash)
registration = parent_to_dependent_hash.keys.first
dependent = parent_to_dependent_hash.values.first
dependents_for(registration) << dependent
end
def remove_dependent(parent_to_dependent_hash)
registration = parent_to_dependent_hash.keys.first
dependent = parent_to_dependent_hash.values.first
dependents_for(registration).delete(dependent).tap do
dependents.delete([registration.object_id]) if dependents_for(registration).empty?
end
end
def call(new_value = nil, *extra_args)
raise Error, 'Not implemented!'
end
def compact_args(args)
args = args[0...-1] if args.last == {}
args = args[0...-1] if args.last == []
args.compact
end
end
end
end
require 'glimmer/data_binding/observable_model'
require 'glimmer/data_binding/observable_array'
require 'glimmer/data_binding/observable_hash'