Graph Append and Prepend functions should now work

2 files changed, 102 insertions, 6 deletions

diff --git a/src/packrat-graphs.adb b/src/packrat-graphs.adb
index 1cc21b3..f32c628 100644
--- a/src/packrat-graphs.adb
+++ b/src/packrat-graphs.adb
@@ -97,6 +97,14 @@ package body Packrat.Graphs is
 
 
 
+    function Is_Nothing
+           (This : in Node)
+        return Boolean is
+    begin
+        return This.Kind = Null_Node;
+    end Is_Nothing;
+
+
     function Is_Leaf
            (This : in Node)
         return Boolean is
@@ -825,19 +833,103 @@ package body Packrat.Graphs is
 
 
 
-    procedure Append
+    procedure Add_Nodes
            (Container : in out Graph;
-            Addition  : in     Graph) is
+            Addition  : in     Node_Vectors.Vector;
+            Mapping   :    out Index_Maps.Map) is
+    begin
+        Mapping := Index_Maps.Empty_Map;
+        for C in Addition.Iterate loop
+            Mapping.Insert (Node_Vectors.To_Index (C), Container.Add_Place);
+            if Container.Add_Place > Container.Node_List.Last_Index then
+                Container.Node_List.Append (Node_Vectors.Element (C));
+            else
+                Container.Node_List.Replace_Element (Container.Add_Place, Node_Vectors.Element (C));
+            end if;
+            while Container.Add_Place <= Container.Node_List.Last_Index and then
+                not Is_Nothing (Container.Node_List.Element (Container.Add_Place))
+            loop
+                Container.Add_Place := Container.Add_Place + 1;
+            end loop;
+        end loop;
+    end Add_Nodes;
+
+
+    procedure Add_Edges
+           (Container : in out Graph;
+            Addition  : in     Graph;
+            Mapping   : in     Index_Maps.Map)
+    is
+        Targets : Index_Vectors.Vector := Index_Vectors.Empty_Vector;
     begin
-        null;
+        --  Up edges
+        for E in Addition.Up_Edges.Iterate loop
+            Targets.Clear;
+            for T of Edge_Up_Maps.Element (E) loop
+                Targets.Append (Mapping.Element (T));
+            end loop;
+            Container.Up_Edges.Insert
+               (Mapping.Element (Edge_Up_Maps.Key (E)), Targets);
+        end loop;
+
+        --  Down edges
+        for E in Addition.Down_Edges.Iterate loop
+            Targets.Clear;
+            for T of Edge_Down_Maps.Element (E) loop
+                Targets.Append (Mapping.Element (T));
+            end loop;
+            Container.Down_Edges.Insert
+               ((Mapping.Element (Edge_Down_Maps.Key (E).From), Edge_Down_Maps.Key (E).Choice),
+                Targets);
+        end loop;
+
+        --  Choices
+        for C in Addition.Choices.Iterate loop
+            Container.Choices.Insert
+               (Mapping.Element (Choice_Maps.Key (C)), Choice_Maps.Element (C));
+        end loop;
+    end Add_Edges;
+
+
+    procedure Append
+           (Container : in out Graph;
+            Addition  : in     Graph)
+    is
+        Mapping : Index_Maps.Map;
+    begin
+        --  Add the nodes and edges from the addition to the graph,
+        --  making sure to handle the conversion of the index each node
+        --  is stored at. If index conversion wasn't required this bit would
+        --  be much simpler.
+        Add_Nodes (Container, Addition.Node_List, Mapping);
+        Add_Edges (Container, Addition, Mapping);
+
+        --  Append the root list of the addition to the graph
+        for R of Addition.Root_List loop
+            Container.Root_List.Append (Mapping.Element (R));
+        end loop;
     end Append;
 
 
     procedure Prepend
            (Container : in out Graph;
-            Addition  : in     Graph) is
-    begin
-        null;
+            Addition  : in     Graph)
+    is
+        Mapping : Index_Maps.Map;
+        Converted_Roots : Index_Vectors.Vector := Index_Vectors.Empty_Vector;
+    begin
+        --  Add the nodes and edges from the addition to the graph,
+        --  making sure to handle the conversion of the index each node
+        --  is stored at. If index conversion wasn't required this bit would
+        --  be much simpler.
+        Add_Nodes (Container, Addition.Node_List, Mapping);
+        Add_Edges (Container, Addition, Mapping);
+
+        --  Prepend the root list of the addition to the graph
+        for R of Addition.Root_List loop
+            Converted_Roots.Append (Mapping.Element (R));
+        end loop;
+        Container.Root_List.Prepend (Converted_Roots);
     end Prepend;
 
 
diff --git a/src/packrat-graphs.ads b/src/packrat-graphs.ads
index 76be2e4..5074485 100644
--- a/src/packrat-graphs.ads
+++ b/src/packrat-graphs.ads
@@ -469,6 +469,10 @@ private
        (Index_Type   => Positive,
         Element_Type => Node_Index);
 
+    package Index_Maps is new Ada.Containers.Ordered_Maps
+       (Key_Type     => Node_Index,
+        Element_Type => Node_Index);
+