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Contents
# frozen_string_literal: true
module Redd
module Utilities
# A forward-expading listing of items that can be enumerated forever.
class Stream
# A simple fixed-size ring buffer.
class RingBuffer
def initialize(size)
@size = size
@backing_array = Array.new(size)
@pointer = 0
end
def include?(el)
@backing_array.include?(el)
end
def add(el)
@backing_array[@pointer] = el
@pointer = (@pointer + 1) % @size
end
end
# Create a streamer.
# @yield [latest]
# @yieldparam latest [String, nil] the fullname of the latest model requested
# @yieldreturn [Listing] the models after the latest one
def initialize(&block)
@loader = block
@buffer = RingBuffer.new(100)
@latest = nil
end
# Make another request to reddit, yielding new elements.
# @yield [element] an element from the listings returned by the loader
def next_request
# Get the elements from the loader before the `latest` element
listing = @loader.call(@latest)
# If there's nothing new to process, request again.
return if listing.empty?
# Set the latest element to the latest one to be processed.
@latest = listing.first.name
# Iterate over the new elements, oldest to newest.
listing.reverse_each do |el|
next if @buffer.include?(el.name)
yield el
@buffer.add(el.name)
end
end
# Loop forever, yielding the elements from the loader
# @yield [element] an element from the listings returned by the loader
def stream
loop do
next_request { |el| yield el }
end
end
end
end
end
Version data entries
8 entries across 8 versions & 1 rubygems