fix edge case of nested tp_chain

lib/sscharter.rb

@@ -343,6 +343,7 @@ def init_state
 		@bpm_changes = nil
 		@tip_point_mode_stack = [:none]
 		@current_tip_point_stack = []
+		@current_tip_point_group_stack = []
 		@tip_point_peak = 0
 		@current_duplicate = 0
 		@tip_point_start_to_add_stack = [nil]
@@ -476,13 +477,13 @@ def tip_point mode, *args, preserve_beat: true, **opts, &block
 			@tip_point_peak += 1
 		end
 		result = group preserve_beat: do
-			@current_tip_point_group = @groups.last
+			@current_tip_point_group_stack.push @groups.last
 			instance_eval &block
 		end
 		@tip_point_start_to_add_stack.pop
 		@tip_point_mode_stack.pop
 		@current_tip_point_stack.pop
-		@current_tip_point_group = nil
+		@current_tip_point_group_stack.pop
 		result
 	end
 
@@ -515,7 +516,7 @@ def push_tip_point_start start_event
 		return unless tip_point_start
 		@groups.each do |group|
 			group.push tip_point_start
-			break if group.equal?(@current_tip_point_group) && @tip_point_mode_stack.last != :drop
+			break if group.equal?(@current_tip_point_group_stack.last) && @tip_point_mode_stack.last != :drop
 		end
 	end
 

test/test_sscharter.rb

@@ -553,4 +553,29 @@ def test_group_nested_in_tip_point_drop
 		assert_equal group1.first(2), group2
 	end
 
+	def test_group_nested_in_tip_point_chain_twice
+		chart = Charter.open __method__
+		chart.offset offset = rand
+		chart.bpm bpm = rand * 300
+
+		group1 = group2 = group3 = note1 = note2 = note3 = nil
+		chart.tip_point_chain rand, rand, rand do
+			group2 = tp_chain rand, rand, rand do
+				group3 = group do
+					note3 = t rand(100), rand(100)
+				end
+				note2 = t rand(100), rand(100)
+			end
+			group1 = group do
+				note1 = t rand(100), rand(100)
+			end
+		end
+		assert_equal chart.events.length, 5
+		assert_equal note1[:tip_point], chart.events[4][:tip_point]
+		assert_equal note2[:tip_point], note3[:tip_point]
+		assert_equal note3[:tip_point], group2[1][:tip_point]
+		assert_equal group3, [note3]
+		assert_equal group1, [note1]
+	end
+
 end