Endpoint markers on start in addition to end of ranges

lib/treetop/runtime/interval_skip_list.rb

@@ -1,6 +1,7 @@
 class IntervalSkipList
   def initialize
     @head = HeadNode.new(max_height)
+    @ranges = {}
   end
 
   def max_height
@@ -27,7 +28,9 @@ def containing(n)
   end
 
   def insert(range, marker)
+    ranges[marker] = range
     first_node = insert_node(range.first)
+    first_node.endpoint_of.push(marker)
     last_node = insert_node(range.last)
     last_node.endpoint_of.push(marker)
 
@@ -48,8 +51,37 @@ def insert(range, marker)
     end
   end
 
+  def delete(marker)
+    range = ranges[marker]
+    first_node = find(range.first)
+
+    cur_node = first_node
+    cur_level = first_node.height - 1
+    while next_node_at_level_inside_range?(cur_node, cur_level, range)
+      while can_ascend_from?(cur_node, cur_level) && next_node_at_level_inside_range?(cur_node, cur_level + 1, range)
+        cur_level += 1
+      end
+      cur_node = unmark_forward_path_at_level(cur_node, cur_level, marker)
+    end
+
+    while node_inside_range?(cur_node, range)
+      while can_descend_from?(cur_level) && next_node_at_level_outside_range?(cur_node, cur_level, range)
+        cur_level -= 1
+      end
+      cur_node = unmark_forward_path_at_level(cur_node, cur_level, marker)
+    end
+    last_node = cur_node
+
+
+    first_node.endpoint_of.delete(marker)
+    delete_node(first_node) if first_node.endpoint_of.empty?
+
+    last_node.endpoint_of.delete(marker)
+    delete_node(first_node) if first_node.endpoint_of.empty?
+  end
+
   protected
-  attr_reader :head
+  attr_reader :head, :ranges
 
   def insert_node(key)
     path = make_path
@@ -61,19 +93,19 @@ def insert_node(key)
     end
   end
 
-  def delete(key)
+  def delete_node(key)
     path = make_path
     found_node = find(key, path)
     found_node.remove(path) if found_node.key == key
-  end  
+  end
 
-  def find(key, path)
+  def find(key, path = nil)
     cur_node = head
     (max_height - 1).downto(0) do |cur_level|
       while (next_node = cur_node.forward[cur_level]) && next_node.key < key
         cur_node = next_node
       end
-      path[cur_level] = cur_node
+      path[cur_level] = cur_node if path
     end
     cur_node.forward[0]
   end

spec/runtime/interval_skip_list_spec.rb

@@ -2,7 +2,7 @@
 require File.expand_path("#{File.dirname(__FILE__)}/interval_skip_list_spec_helper")
 
 class IntervalSkipList
-  public :insert_node, :delete, :head, :nodes
+  public :insert_node, :delete_node, :head, :nodes
 end
 
 describe "#next_node_height is deterministic", :shared => true do
@@ -90,8 +90,8 @@ def confirm_containing_intervals(range, *markers)
         node.markers.should be_empty
       end
 
-      it "is not an endpoint of any interval" do
-        node.endpoint_of.should be_empty
+      it "is not an endpoint of only :a" do
+        node.endpoint_of.should have_marker(:a)
       end
     end
 
@@ -162,8 +162,8 @@ def confirm_containing_intervals(range, *markers)
           node.markers.should be_empty
         end
 
-        it "is not an endpoint of any interval" do
-          node.endpoint_of.should be_empty
+        it "is an endpoint of only :a and :b" do
+          node.endpoint_of.should have_markers(:a, :b)
         end
       end
 
@@ -177,7 +177,7 @@ def confirm_containing_intervals(range, *markers)
           node.height.should == 2
         end
 
-        it "has :a as its only marker at level 1" do
+        it "has :a as its only forward marker at level 1" do
           node.forward_markers[1].should have_marker(:a)
         end
 
@@ -265,8 +265,8 @@ def confirm_containing_intervals(range, *markers)
             node.markers.should be_empty
           end
 
-          it "is not an endpoint of any interval" do
-            node.endpoint_of.should be_empty
+          it "is an endpoint of only :a, :b, :c" do
+            node.endpoint_of.should have_markers(:a, :b, :c)
           end
         end
 
@@ -280,11 +280,11 @@ def confirm_containing_intervals(range, *markers)
             node.height.should == 3
           end
 
-          it "has :a as its only marker at level 2" do
+          it "has :a as its only forward marker at level 2" do
             node.forward_markers[2].should have_marker(:a)
           end
 
-          it "has :b as its only marker at level 1" do
+          it "has :b as its only forward marker at level 1" do
             node.forward_markers[1].should have_marker(:b)
           end
 
@@ -406,8 +406,8 @@ def confirm_containing_intervals(range, *markers)
               node.markers.should be_empty
             end
 
-            it "is not an endpoint of any interval" do
-              node.endpoint_of.should be_empty
+            it "is an endpoint of only :a, :b, :c, and :d" do
+              node.endpoint_of.should have_markers(:a, :b, :c, :d)
             end
           end
 
@@ -516,6 +516,95 @@ def confirm_containing_intervals(range, *markers)
               node.endpoint_of.should have_marker(:d)
             end
           end
+
+#          describe ", and then :d is deleted" do
+#            before do
+#              list.delete(:d)
+#            end
+#
+#            it "has only 4 nodes" do
+#              list.nodes.size.should == 4
+#            end
+#
+#            describe " #nodes[0]" do
+#              before do
+#                @node = list.nodes[0]
+#              end
+#
+#              it "has :a, :b, and :c as its only forward markers at level 1" do
+#                node.forward_markers[1].should have_markers(:a, :b, :c)
+#              end
+#
+#              it "has no forward markers at level 0" do
+#                node.forward_markers[0].should be_empty
+#              end
+#            end
+#
+#            describe " #nodes[1]" do
+#              before do
+#                @node = list.nodes[1]
+#              end
+#
+#              it "has :a as its only forward marker at level 2" do
+#                node.forward_markers[2].should have_marker(:a)
+#              end
+#
+#              it "has :b as its only forward marker at level 1" do
+#                node.forward_markers[1].should have_marker(:b)
+#              end
+#
+#              it "has no forward markers at level 0" do
+#                node.forward_markers[0].should be_empty
+#              end
+#
+#              it "has :a, :b, and :c as its only markers" do
+#                node.markers.should have_markers(:a, :b, :c)
+#              end
+#
+#              it "is the endpoint of only :c" do
+#                node.endpoint_of.should have_marker(:c)
+#              end
+#            end
+#
+#            describe " #nodes[2]" do
+#              before do
+#                @node = list.nodes[2]
+#              end
+#
+#              it "has no forward markers at any level" do
+#                node.forward_markers[0].should be_empty
+#                node.forward_markers[1].should be_empty
+#              end
+#
+#              it "has :b as its only marker" do
+#                node.markers.should have_marker(:b)
+#              end
+#
+#              it "is the endpoint of only :b" do
+#                node.markers.endpoint_of.should have_marker(:b)
+#              end
+#            end
+#
+#            describe " #nodes[3]" do
+#              before do
+#                @node = list.nodes[3]
+#              end
+#
+#              it "has no forward markers at any level" do
+#                node.forward_markers[0].should be_empty
+#                node.forward_markers[1].should be_empty
+#                node.forward_markers[2].should be_empty
+#              end
+#
+#              it "has :a as its only marker" do
+#                node.markers.should have_marker(:a)
+#              end
+#
+#              it "is the endpoint of only :a" do
+#                node.markers.endpoint_of.should have_marker(:a)
+#              end
+#            end
+#          end
         end
       end
     end
@@ -602,7 +691,7 @@ def expected_node_heights
 
     describe "and subsequently deleted" do
       before do
-        list.delete(1)
+        list.delete_node(1)
       end
 
       specify "#empty? returns true" do
@@ -669,7 +758,7 @@ def expected_node_heights
 
     describe "and 1 is subsequently deleted" do
       before do
-        list.delete(1)
+        list.delete_node(1)
       end
 
       describe "the remaining node" do
@@ -689,7 +778,7 @@ def expected_node_heights
 
     describe "and 3 is subsequently deleted" do
       before do
-        list.delete(3)
+        list.delete_node(3)
       end
 
       describe "the remaining node" do
@@ -791,7 +880,7 @@ def expected_node_heights
 
     describe "and 3 is subsequently deleted" do
       before do
-        list.delete(3)
+        list.delete_node(3)
       end
 
       specify "#head points at nil at levels 1 and 2" do