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Contents
require_relative("accumulator")
module Wukong
class Processor
# A processor which counts the total number of its input records.
#
# On it's own, this widget is really just a poor man's `wc -l`.
# It's really intended to serve as a superclass for more complex
# accumulators.
#
# @example Count the total number of input records on the command-line.
#
# $ wc -l input
# 283 input
# $ cat input | wu-local count
# 283
class Count < Accumulator
description <<EOF
This processor counts the number of input records it receives.
$ wc -l input
283 input
$ cat input | wu-local count
283
This processor will not output any records until it receives its final
input record.
EOF
# The total size of the input recors.
attr_accessor :size
# Initializes the count to 0.
def setup
super()
@size = 0
end
# Accumulate a `record` by incrmenting the total size.
#
# @param [Object] record
def accumulate record
self.size += 1
end
# Keeps all records in the same group so that one count is
# emitted at the end.
#
# Overriding this method and returning different keys for
# different records is the beginning of constructing a "group
# by" type widget.
#
# @param [Object] record
# @return [:__first__group__]
# @see Group
def get_key record
:__first_group__
end
# Yields the total size.
#
# @yield [size]
# @yieldparam [Integer] size
def finalize
yield self.size
end
register
end
end
end
Version data entries
5 entries across 5 versions & 2 rubygems