* cont.c: support Fiber. Check test/ruby/test_fiber.rb for detail.

Fiber is known as "Micro Thread", "Coroutine", and other terms.
  At this time, only Fiber#pass is supported to change context.
  I want to know more suitable method name/API for Fiber (... do you
  know more suitable class name instead of Fiber?) as "suspend/resume",
  "call", "yield", "start/kick/stop/restart", ....
* eval.c, eval_intern.h, thread.c, yarvcore.c, yarvcore.h: ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12395 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_fiber.rb

@@ -0,0 +1,66 @@
+require 'test/unit'
+
+class TestFiber < Test::Unit::TestCase
+  def test_normal
+    f = Fiber.current
+    assert_equal(:ok2,
+      Fiber.new(:ok1){|e|
+        assert_equal(:ok1, e)
+        assert_equal(f, Fiber.prev)
+        Fiber.pass :ok2
+      }.pass)
+  end
+
+  def test_term
+    assert_equal(:ok, Fiber.new{:ok}.pass)
+    assert_equal([:a, :b, :c, :d, :e],
+      Fiber.new{
+        Fiber.new{
+          Fiber.new{
+            Fiber.new{
+              [:a]
+            }.pass + [:b]
+          }.pass + [:c]
+        }.pass + [:d]
+      }.pass + [:e])
+  end
+
+  def test_many_fibers
+    max = 10000
+    assert_equal(max, max.times{
+      Fiber.new{}
+    })
+    assert_equal(max,
+      max.times{|i|
+        Fiber.new{
+        }.pass
+      }
+    )
+  end
+
+  def test_error
+    assert_raise(ArgumentError){
+      Fiber.new # Fiber without block
+    }
+    assert_raise(RuntimeError){
+      f = Fiber.new{}
+      Thread.new{f.pass}.join # Fiber passing across thread
+    }
+  end
+
+  def test_loop
+    ary = []
+    f2 = nil
+    f1 = Fiber.new{
+      ary << f2.pass(:foo)
+      :bar
+    }
+    f2 = Fiber.new{
+      ary << f1.pass(:baz)
+      :ok
+    }
+    assert_equal(:ok, f1.pass)
+    assert_equal([:baz, :bar], ary)
+  end
+end
+