Merge from branch giga

StgSharp.Model/Step/ExpressStepUtil.cs

@@ -28,7 +28,9 @@
 //     
 //-----------------------------------------------------------------------
 //-----------------------------------------------------------------------
-using StgSharp.Modeling.Step;
+using CommunityToolkit.HighPerformance.Buffers;
+
+using StgSharp.Model.Step;
 using StgSharp.Script;
 using StgSharp.Script.Express;
 
@@ -37,7 +39,7 @@ using System.Collections.Frozen;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
 
-namespace StgSharp.Modeling.Step
+namespace StgSharp.Model.Step
 {
     public class ExpressStepUtil : ExpSchema
     {
@@ -58,6 +60,7 @@ namespace StgSharp.Modeling.Step
         public const string LineText = "LINE";
         public const string OrientedEdgeText = "ORIENTED_EDGE";
         public const string PlaneText = "PLANE";
+        public const string RepresentationItemText = "REPRESENTATION_ITEM";
         public const string VectorText = "VECTOR";
         public const string VertexPointText = "VERTEX_POINT";
 
@@ -79,15 +82,22 @@ namespace StgSharp.Modeling.Step
                 LineText,
                 OrientedEdgeText,
                 PlaneText,
+                RepresentationItemText,
                 VectorText,
                 VertexPointText,
                 ];
 
-        private FrozenDictionary<string, ExpTypeSource> entitiesDefine;
+        private FrozenDictionary<string, ExpEntitySource> entitiesDefine;
+        private StringPool _entityNamePool = new StringPool();
 
         public ExpressStepUtil()
         {
-            Dictionary<string, ExpTypeSource> tIndex = new Dictionary<string, ExpTypeSource>();
+            IEnumerable<KeyValuePair<string, ExpEntitySource>> defineSource = [];
+            entitiesDefine = new Dictionary<string, ExpEntitySource>( defineSource )
+                .ToFrozenDictionary();
+            foreach( string item in names ) {
+                _entityNamePool.Add( item );
+            }
         }
 
         internal StepModel Current { get; set; }
@@ -105,13 +115,13 @@ namespace StgSharp.Modeling.Step
 
         public override bool TryGetEntity( string name, out ExpEntitySource e )
         {
-            e = null!;
-            return false;
+            return entitiesDefine.TryGetValue( name, out e! );
         }
 
         public override bool TryGetFunction( string name, out ExpFunctionSource f )
         {
-            throw new NotImplementedException();
+            f = null!;
+            return false;
         }
 
         public override bool TryGetProcedure( string name, out ExpProcedureSource p )