Class: CouchProxy::RowFilter

Inherits:
JSON::Stream::Builder
  • Object
show all
Defined in:
lib/couchproxy/row_filter.rb

Overview

A JSON::Stream::Parser listener that listens for the ‘rows’ key in a CouchDB map/reduce result stream. As row objects are parsed they are sent to callbacks for processing. Typically the callback will perform some kind of reduce on the rows before sending them to the client.

Example usage: parser = JSON::Stream::Parser.new filter = CouchProxy::RowFilter.new(parser) do

total_rows {|total| puts total }
rows do |rows, complete|
  # process rows, complete tells us if this is the last row
end

end

Constant Summary collapse

TOTAL_ROWS = 
'total_rows'.freeze
MAX_ROWS = 
100

Instance Method Summary collapse

Constructor Details

#initialize(parser, &block) ⇒ RowFilter

Returns a new instance of RowFilter.



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# File 'lib/couchproxy/row_filter.rb', line 23

def initialize(parser, &block)
  @listeners = Hash.new {|h, k| h[k] = [] }
  @total_rows_key = false
  super(parser)
  instance_eval(&block) if block_given?
end

Instance Method Details

#end_document ⇒ Object 



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# File 'lib/couchproxy/row_filter.rb', line 56

def end_document
  notify_rows(@stack.pop.obj['rows'], true)
end

#end_object ⇒ Object 



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# File 'lib/couchproxy/row_filter.rb', line 60

def end_object
  super
  # row object complete
  if @stack.size == 2 && @stack[-1].obj.size >= MAX_ROWS
    notify_rows(@stack.pop.obj, false)
    @stack.push(JSON::Stream::ArrayNode.new)
  end
end

#key(key) ⇒ Object 



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# File 'lib/couchproxy/row_filter.rb', line 43

def key(key)
  super
  @total_rows_key = (@stack.size == 1 && key == TOTAL_ROWS)
end

#value(value) ⇒ Object 



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# File 'lib/couchproxy/row_filter.rb', line 48

def value(value)
  super
  if @total_rows_key
    @total_rows_key = false
    notify_total_rows(value)
  end
end