91 lines
2.8 KiB
Ruby
91 lines
2.8 KiB
Ruby
# :nodoc:
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#
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# Author:: Nathaniel Talbott.
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# Copyright:: Copyright (c) 2000-2002 Nathaniel Talbott. All rights reserved.
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# License:: Ruby license.
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require 'test/unit/util/procwrapper'
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module Test
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module Unit
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module Util # :nodoc:
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# This is a utility class that allows anything mixing
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# it in to notify a set of listeners about interesting
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# events.
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module Observable
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# We use this for defaults since nil might mean something
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NOTHING = "NOTHING/#{__id__}"
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# Adds the passed proc as a listener on the
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# channel indicated by channel_name. listener_key
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# is used to remove the listener later; if none is
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# specified, the proc itself is used.
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#
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# Whatever is used as the listener_key is
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# returned, making it very easy to use the proc
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# itself as the listener_key:
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#
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# listener = add_listener("Channel") { ... }
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# remove_listener("Channel", listener)
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def add_listener(channel_name, listener_key=NOTHING, &listener) # :yields: value
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unless(block_given?)
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raise ArgumentError.new("No callback was passed as a listener")
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end
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key = listener_key
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if (listener_key == NOTHING)
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listener_key = listener
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key = ProcWrapper.new(listener)
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end
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channels[channel_name] ||= {}
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channels[channel_name][key] = listener
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return listener_key
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end
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# Removes the listener indicated by listener_key
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# from the channel indicated by
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# channel_name. Returns the registered proc, or
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# nil if none was found.
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def remove_listener(channel_name, listener_key)
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channel = channels[channel_name]
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return nil unless (channel)
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key = listener_key
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if (listener_key.instance_of?(Proc))
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key = ProcWrapper.new(listener_key)
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end
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if (channel.has_key?(key))
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return channel.delete(key)
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end
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return nil
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end
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# Calls all the procs registered on the channel
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# indicated by channel_name. If value is
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# specified, it is passed in to the procs,
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# otherwise they are called with no arguments.
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#
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#--
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#
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# Perhaps this should be private? Would it ever
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# make sense for an external class to call this
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# method directly?
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def notify_listeners(channel_name, *arguments)
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channel = channels[channel_name]
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return 0 unless (channel)
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listeners = channel.values
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listeners.each { |listener| listener.call(*arguments) }
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return listeners.size
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end
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private
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def channels # :nodoc:
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@channels ||= {}
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return @channels
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end
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end
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end
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end
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end
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