Class: Turbine::Pipeline::JournalFilter

Inherits:
Filter show all
Includes:
Turbine::Pipeline::Journal::Read
Defined in:
lib/turbine/pipeline/journal_filter.rb

Overview

A filter which uses an upstream Journal as a basis for determining which values should be emitted.

Instance Attribute Summary

Attributes inherited from Segment

#source

Instance Method Summary collapse

Methods included from Turbine::Pipeline::Journal::Read

#journal

Methods inherited from Filter

#next

Methods included from Trace::Transparent

#trace

Methods inherited from Segment

#append, #each, #inspect, #next, #rewind, #trace, #tracing=

Constructor Details

#initialize(mode, name) ⇒ JournalFilter

Public: Creates a new JournalFilter.

mode - The filter mode to be used. :only will cause the filter to emit

only values which were seen in the journal, while :except will
emit only those which were *not* seen.

name - The name of the Journal whose values will be used.

Returns a JournalFilter.



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# File 'lib/turbine/pipeline/journal_filter.rb', line 16

def initialize(mode, name)
  unless mode == :only || mode == :except
    raise ArgumentError, 'JournalFilter mode must be :only or :except'
  end

  @mode = mode
  @journal_name = name

  super(&method(:"filter_#{ mode }"))
end

Instance Method Details

#source=(source) ⇒ Object

Public: Sets the previous segment in the pipeline.

Raises NoSuchJournalError if the Journal required by the filter is not present in the source pipeline.

Returns the source.



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# File 'lib/turbine/pipeline/journal_filter.rb', line 33

def source=(source)
  super
  @journal = journal(@journal_name)
end

#to_s ⇒ Object

Public: Describes the segments through which each input will pass.

Return a string.



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# File 'lib/turbine/pipeline/journal_filter.rb', line 41

def to_s
  "#{ source_to_s } | #{ @mode }(#{ @journal_name.inspect })"
end