[ruby-dev:28159] Re: thread based generator.rb

山本です。

>こちらはインタプリタの話になるので私にはわかりませんが、
>ファイナライザでどうにかできないかといじってみた結果、それらしく動くように
>なりました。（まだ適当なコードで、コミットできる状態ではありません）

とりあえず改善してみました。ただ、

>    g = Generator.new { |g2|
>      for i in 'A'..'C'
>        g2.yield i
>      end
>
>      g2.yield 'Z'
>    }

は、ブロック引数に Generator ではなく、他のオブジェクトが渡るように
なっています。ブロック内では元々 Generator#yield しか呼べない（はず）
なので、この方がいいと思うのですが、前述のスコープの問題があります。

本当は

    g = Generator.new {
      for i in 'A'..'C'
        yield i
      end

      yield 'Z'
    }

としたほうがわかりやすいと思うのですが、うまくいきませんでした。

あと、メモリは sleep 0 を入れるのでも使用量が変化しなくなりました。（？？？）

Index: generator.rb
===================================================================
RCS file: /src/ruby/lib/generator.rb,v
retrieving revision 1.5
diff -u -w -b -p -r1.5 generator.rb
--- generator.rb	29 Dec 2005 02:29:26 -0000	1.5
+++ generator.rb	29 Dec 2005 05:34:18 -0000
@@ -56,16 +56,23 @@
 class Generator
   include Enumerable
 
-  # Creates a new generator either from an Enumerable object or from a
-  # block.
-  #
-  # In the former, block is ignored even if given.
-  #
-  # In the latter, the given block is called with the generator
-  # itself, and expected to call the +yield+ method for each element.
+  class GeneratorProxy
+    def initialize(impl)
+      @impl = impl
+    end
+
+    # Yields an element to the generator.
+    def yield(value)
+      @impl.yield(value)
+      nil # ???
+    end
+  end
+
+  class GeneratorImpl # internal use only
+
   def initialize(enum = nil, &block)
     if enum
-      @block = proc{|g| enum.each{|value| g.yield value}}
+        @block = proc{|proxy| enum.each{|value| proxy.yield value}}
     else
       @block = block
     end
@@ -75,7 +82,7 @@ class Generator
       Thread.stop
       Thread.critical = true
       begin
-        @block.call(self) # exception safe?
+          @block.call(GeneratorProxy.new(self))
       rescue
         @main_thread.raise $!
       ensure
@@ -83,22 +90,19 @@ class Generator
         Thread.critical = false
       end
     end
-    self
   end
 
-  # Yields an element to the generator.
+    # should be called on @loop_thread
+
   def yield(value)
-    if Thread.current != @loop_thread
-      raise RuntimeError.new("Generator#yield must be called in Generator.new{|g| ... }")
-    end
     @queue << value
     @main_thread.wakeup
     Thread.stop
     Thread.critical = true
-    self
   end
 
-  # Returns true if the generator has reached the end.
+    # should be called on @main_thread
+
   def end?
     if @queue.empty?
       Thread.critical = true
@@ -116,37 +120,77 @@ class Generator
     @queue.empty?
   end
 
+    def index
+      @index
+    end
+
+    def next
+      raise EOFError.new("no more elements available") if end?
+      @index += 1
+      @queue.shift
+    end
+
+    def current
+      raise EOFError.new("no more elements available") if end?
+      @queue.first
+    end
+
+    def rewind
+      initialize(nil, &@block) if @index.nonzero?
+    end
+
+    def create_finalizer
+      proc { @loop_thread.kill }
+    end
+
+  end
+
+  # Creates a new generator either from an Enumerable object or from a
+  # block.
+  #
+  # In the former, block is ignored even if given.
+  #
+  # In the latter, the given block is called with the generator
+  # itself, and expected to call the +yield+ method for each element.
+  def initialize(enum = nil, &block)
+    @impl = GeneratorImpl.new(enum, &block)
+    ObjectSpace.define_finalizer(self, @impl.create_finalizer)
+    self
+  end
+
+  # Returns true if the generator has reached the end.
+  def end?
+    @impl.end?
+  end
+
   # Returns true if the generator has not reached the end yet.
   def next?
-    !end?
+    !@impl.end?
   end
 
   # Returns the current index (position) counting from zero.
   def index
-    @index
+    @impl.index
   end
 
   # Returns the current index (position) counting from zero.
   def pos
-    @index
+    @impl.index
   end
 
   # Returns the element at the current position and moves forward.
   def next
-    raise EOFError.new("no more elements available") if end?
-    @index += 1
-    @queue.shift
+    @impl.next
   end
 
   # Returns the element at the current position.
   def current
-    raise EOFError.new("no more elements available") if end?
-    @queue.first
+    @impl.current
   end
 
   # Rewinds the generator.
   def rewind
-    initialize(nil, &@block) if @index.nonzero?
+    @impl.rewind
     self
   end
 
@@ -251,12 +295,12 @@ class TC_Generator < Test::Unit::TestCas
   end
 
   def test_block2
-    g = Generator.new { |g|
+    g = Generator.new { |y|
       for i in 'A'..'C'
-        g.yield i
+        y.yield i
       end
 
-      g.yield 'Z'
+      y.yield 'Z'
     }
 
     assert_equal(0, g.pos)