gem, specs, README, and general consistency

lib/tee.rb

@@ -0,0 +1,107 @@
+require 'digest/sha1'
+require 'digest/sha2'
+
+module Enumerable
+  module Tee
+    def tee(*procs)
+      procs.map { |p| p.call(each) }
+    end
+  end
+end
+
+class IO
+  module Chunkable
+    CHUNK_SIZE = 1024
+
+    def chunks(chunk_size = nil)
+      chunk_size ||= CHUNK_SIZE
+
+      Enumerator.new { |y| y << read(chunk_size) until eof? }
+    end
+
+    def each_chunk(chunk_size = nil)
+      return chunks.each unless block_given?
+
+      chunks.each { |*args| yield(*args) }
+    end
+  end
+
+  module Digestable
+    def digest_with(digest, chunk_size = nil)
+      chunks(chunk_size).each { |chunk| digest << chunk }
+
+      digest
+    end
+
+    def sha256(chunk_size = nil)
+      digest_with(Digest::SHA2.new(256), chunk_size)
+    end
+  end
+
+  module Tee
+    def fiber_tee(*procs)
+      ios = procs.map { |proc| FiberChunkedIO.new(&proc) }
+
+      chunks.each do |chunk|
+        ios.each do |io|
+          io.write chunk
+        end
+      end
+      ios.each { |io| io.close }
+
+      ios.map { |io| io.result }
+    end
+    alias_method :tee, :fiber_tee
+  end
+end
+
+class FiberChunkedIO
+  def initialize(chunk_size = 1024, &block)
+    @chunk_size = chunk_size
+    @chunks = []
+    @eof = false
+    @fiber = Fiber.new do
+      @result = block.call self
+    end
+    @fiber.resume
+  end
+
+  # Being a stream, it behaves like IO#eof? and blocks until the other end
+  # sends some data or closes it.
+  def eof?
+    Fiber.yield
+
+    @eof
+  end
+
+  def close
+    @eof = true
+    @fiber.resume
+  end
+
+  attr_reader :result
+
+  def write(chunk)
+    if chunk.size > @chunk_size
+      raise ArgumentError.new('chunk size mismatch: ' <<
+                              "expected #{@chunk_size}, got #{chunk.size}")
+    end
+
+    @chunks << chunk
+    @eof = false
+    @fiber.resume
+
+    chunk.size
+  end
+
+  def read(chunk_size)
+    unless chunk_size == @chunk_size
+      raise ArgumentError.new('chunk size mismatch:' <<
+                              " expected #{@chunk_size}, got #{chunk_size}")
+    end
+
+    @chunks.shift
+  end
+
+  include IO::Chunkable
+end