1 files changed, 165 insertions, 0 deletions
diff --git a/src/change_vectors.adb b/src/change_vectors.adb
new file mode 100644
index 0000000..65a1f99
--- /dev/null
+++ b/src/change_vectors.adb
@@ -0,0 +1,165 @@
+
+
+with FLTK.Text_Buffers;
+with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
+use type FLTK.Text_Buffers.Modification;
+use type FLTK.Text_Buffers.Position;
+
+
+with Ada.Text_IO;
+
+
+package body Change_Vectors is
+
+
+    procedure Push
+           (This : in out Change_Vector;
+            Item : in     Change)
+    is
+        procedure App (Ch : in out Change) is
+        begin
+            Ch.Length := Ch.Length + 1;
+            Append (Ch.Text, Item.Text);
+        end App;
+        procedure Pre (Ch : in out Change) is
+        begin
+            Ch.Length := Ch.Length + 1;
+            Ch.Text := Item.Text & Ch.Text;
+            Ch.Place := Ch.Place - 1;
+        end Pre;
+    begin
+        if Item.Action = FLTK.Text_Buffers.Insert then
+            if This.Near > 0 and then
+                This.List.Element (This.Near).Action = FLTK.Text_Buffers.Insert and then
+                Integer (This.List.Element (This.Near).Place) + This.List.Element (This.Near).Length = Integer (Item.Place) and then
+                Item.Length = 1 and then
+                (Element (This.List.Element (This.Near).Text, This.List.Element (This.Near).Length) /= ' ' or else
+                    Element (Item.Text, (1)) = ' ') then
+                This.List.Update_Element (This.Near, App'Access);
+            else
+                This.Near := This.Near + 1;
+                This.List.Insert (This.Near, Item);
+            end if;
+        elsif Item.Action = FLTK.Text_Buffers.Delete then
+            if This.Near > 0 then
+                if This.List.Element (This.Near).Action = FLTK.Text_Buffers.Delete and then
+                    This.List.Element (This.Near).Place = Item.Place and then Item.Length = 1 then
+                    This.List.Update_Element (This.Near, App'Access);
+                elsif This.List.Element (This.Near).Action = FLTK.Text_Buffers.Delete and then
+                    This.List.Element (This.Near).Place = Item.Place + 1 and then Item.Length = 1 then
+                    This.List.Update_Element (This.Near, Pre'Access);
+                else
+                    This.Near := This.Near + 1;
+                    This.List.Insert (This.Near, Item);
+                end if;
+            end if;
+        end if;
+        This.Far := This.Near;
+        while Integer (This.List.Length) > This.Far loop
+            This.List.Delete_Last;
+        end loop;
+    end Push;
+
+
+
+
+    function Pop
+           (This : in out Change_Vector)
+        return Boolean is
+    begin
+        if This.Near > 0 then
+            This.Near := This.Near - 1;
+            return True;
+        else
+            return False;
+        end if;
+    end Pop;
+
+
+
+
+    procedure Pop
+           (This : in out Change_Vector) is
+    begin
+        if This.Near > 0 then
+            This.Near := This.Near - 1;
+        end if;
+    end Pop;
+
+
+
+
+    function Peek
+           (This : in     Change_Vector;
+            Item :    out Change)
+        return Boolean is
+    begin
+        if This.Near > 0 then
+            Item := This.List.Element (This.Near);
+            return True;
+        else
+            return False;
+        end if;
+    end Peek;
+
+
+
+
+    procedure Peek
+           (This : in     Change_Vector;
+            Item :    out Change) is
+    begin
+        if This.Near > 0 then
+            Item := This.List.Element (This.Near);
+        end if;
+    end Peek;
+
+
+
+
+    function Re_Push
+           (This : in out Change_Vector)
+        return Boolean is
+    begin
+        if This.Near < This.Far then
+            This.Near := This.Near + 1;
+            return True;
+        else
+            return False;
+        end if;
+    end Re_Push;
+
+
+
+
+    procedure Re_Push
+           (This : in out Change_Vector) is
+    begin
+        if This.Near < This.Far then
+            This.Near := This.Near + 1;
+        end if;
+    end Re_Push;
+
+
+
+
+    function At_Start
+           (This : in Change_Vector)
+        return Boolean is
+    begin
+        return This.Near = 0;
+    end At_Start;
+
+
+
+
+    function At_End
+           (This : in Change_Vector)
+        return Boolean is
+    begin
+        return This.Near >= This.Far;
+    end At_End;
+
+
+end Change_Vectors;
+