Fix nested conditional preprocessors

lib/bitclust/preprocessor.rb

@@ -149,7 +149,7 @@ def current_cond
     end
 
     def cond_init
-      @state_stack = [State.new(nil, :toplevel)]
+      @state_stack = [State.new(true, :toplevel)]
     end
 
     def cond_toplevel?
@@ -158,13 +158,13 @@ def cond_toplevel?
 
     def cond_push(bool)
       last = @state_stack.last
-      @state_stack.push(State.new(last.current, bool))
+      @state_stack.push(last.next(bool, :condition))
     end
 
     def cond_invert
       b = @state_stack.pop.processing?
       last = @state_stack.last
-      @state_stack.push(State.new(last.current, !b))
+      @state_stack.push(last.next(!b, :condition))
     end
 
     def cond_pop
@@ -254,7 +254,7 @@ def samplecode_end
 
     def samplecode_push(description)
       last = @state_stack.last
-      @state_stack.push(State.new(last.current, :samplecode))
+      @state_stack.push(last.next(true, :samplecode))
     end
 
     def samplecode_pop
@@ -276,24 +276,25 @@ def scan_error(msg)
     class State
       attr_reader :current
 
-      def initialize(previous, current)
-        @previous = previous
-        @current = current
+      def initialize(is_processing, label)
+        @is_processing = is_processing
+        @label = label
+      end
+
+      def next(is_processing, label)
+        State.new(@is_processing && is_processing, label)
       end
 
       def toplevel?
-        @current == :toplevel
+        @label == :toplevel
       end
 
       def processing?
-        toplevel? ||
-          (@current == true && @previous != false) ||
-          (@current == :samplecode && @previous == true) ||
-          (@current == :samplecode && @previous == :toplevel)
+        @is_processing
       end
 
       def samplecode?
-        @current == :samplecode
+        @label == :samplecode
       end
     end
   end

test/test_preprocessor.rb

@@ -109,6 +109,27 @@ def test_complex_condition
     assert_equal(expected, ret.join)
   end
 
+  def test_nested_condition
+    params = { 'version' => '2.4.0' }
+    src = <<~'HERE'
+      #@until 2.4.0
+      #@since 1.8.7
+      #@since 1.9.3
+      #@since 2.0.0
+      Not display here!
+      #@end
+      #@end
+      #@end
+      #@end
+      Display here!
+    HERE
+    expected = <<~HERE
+      Display here!
+    HERE
+    ret = Preprocessor.wrap(StringIO.new(src), params).to_a
+    assert_equal(expected, ret.join)
+  end
+
   sub_test_case("samplecode") do
 
     def test_samplecode