Class: Command::Results::Presenter

Inherits:
Object
  • Object
show all
Defined in:
lib/command-set/results.rb

Overview

Gets item and list events from Collectors, and emits two kinds of events to Formatters:

saw events

occur in chronological order, with no guarantee regarding timing.

closed events

occur in tree order.

In general, saw events are good for immediate feedback to the user, not so good in terms of making sense of things. They’re generated as soon as the relevant output element enters the system.

On the other hand, closed events will be generated in the natural order you’d expect the output to appear in. Most Formatter subclasses use closed events.

A list which has not received a “list_end” event from upstream will block lists later in tree order until it closes. A Formatter that listens only to closed events can present them to the user in a way that should be reasonable, although output might be halting for any process that takes noticeable time.

Defined Under Namespace

Classes: Exception

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Presenter

Returns a new instance of Presenter.



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# File 'lib/command-set/results.rb', line 275

def initialize
  @results = List.new("")
  @leading_edge = @results
  @formatters = []
  @list_lock = Mutex.new
end

Instance Method Details

#begin_list(home, name, options = {}) ⇒ Object 



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# File 'lib/command-set/results.rb', line 304

def begin_list( home, name, options={} )
  list = List.new(name)

  add_item(home, list, options)

  notify(:saw_begin, list)
  return list
end

#create_collector ⇒ Object 



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# File 'lib/command-set/results.rb', line 282

def create_collector
  return Collector.new(self, @results)
end

#done ⇒ Object 



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# File 'lib/command-set/results.rb', line 323

def done
  @results.close
  advance_leading_edge
  notify(:done, nil)
end

#end_list(list) ⇒ Object 



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# File 'lib/command-set/results.rb', line 313

def end_list( list )
  @list_lock.synchronize do
    list.close
    advance_leading_edge
  end

  notify(:saw_end, list)
  return nil
end

#item(home, value, options = {}) ⇒ Object 



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# File 'lib/command-set/results.rb', line 295

def item( home, value, options={} )
  item = ListItem.new(value)

  add_item(home, item, options)

  notify(:saw, item)
  return nil
end

#leading_edge?(list) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/command-set/results.rb', line 291

def leading_edge?(list)
  return list == @leading_edge
end

#output ⇒ Object

Returns the current list of results. A particularly advanced Formatter might treat saw_* events like notifications, and then use the List#filter functionality to discover the specifics about the item or list just closed.



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# File 'lib/command-set/results.rb', line 333

def output
  @results
end

#register_formatter(formatter) ⇒ Object 



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# File 'lib/command-set/results.rb', line 286

def register_formatter(formatter)
  @formatters << formatter
  formatter.notify(:start, nil)
end