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Contents
require 'set'
module Volt
# Dependencies are used to track the current computation so it can be re-run
# at a later point if this dependency changes.
#
# You can also pass an on_dep and on_stop_dep proc's to #initialize.
class Dependency
# Setup a new dependency.
#
# @param on_dep [Proc] a proc to be called the first time a computation depends
# on this dependency.
# @param on_stop_dep [Proc] a proc to be called when no computations are depending
# on this dependency anymore.
def initialize(on_dep = nil, on_stop_dep = nil)
@dependencies = Set.new
@on_dep = on_dep
@on_stop_dep = on_stop_dep
end
def depend
# If there is no @dependencies, don't depend because it has been removed
return unless @dependencies
current = Computation.current
if current
added = @dependencies.add?(current)
if added
# The first time the dependency is depended on by this computation, we call on_dep
@on_dep.call if @on_dep && @dependencies.size == 1
current.on_invalidate do
# If @dependencies is nil, this Dependency has been removed
if @dependencies
# For set, .delete returns a boolean if it was deleted
deleted = @dependencies.delete(current)
# Call on stop dep if no more deps
@on_stop_dep.call if @on_stop_dep && deleted && @dependencies.size == 0
end
end
end
end
end
def changed!
deps = @dependencies
# If no deps, dependency has been removed
return unless deps
@dependencies = Set.new
deps.each(&:invalidate!)
@on_stop_dep.call if @on_stop_dep
end
# Called when a dependency is no longer needed
def remove
changed!
@dependencies = nil
end
end
end
Version data entries
21 entries across 21 versions & 1 rubygems