Merge from branch giga

StgSharp.Model/Step/SyntaxNode/StepEntityInstanceNode.cs

@@ -28,37 +28,78 @@
 //     
 //-----------------------------------------------------------------------
 //-----------------------------------------------------------------------
-using StgSharp.Modeling.Step;
+using StgSharp.Model.Step;
 using StgSharp.Script;
 using StgSharp.Script.Express;
 
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Net.Http.Headers;
 using System.Text;
 using System.Threading.Tasks;
 
-namespace StgSharp.Modeling.Step
+namespace StgSharp.Model.Step
 {
     public class StepEntityInstanceNode : ExpSyntaxNode
     {
 
-        private int id;
-        private StepModel _model;
-
-        public StepEntityInstanceNode( Token source, StepModel model ) : base( source ) { }
+        private StepEntityInstanceNode( Token source ) : base( source ) { }
 
         public override ExpSyntaxNode Left => Empty;
 
         public override ExpSyntaxNode Right => Empty;
 
-        public override IExpElementSource EqualityTypeConvert => throw new NotImplementedException();
+        public override IExpElementSource EqualityTypeConvert => StepEntityType.Source;
 
-        private void GetInstance()
+        public int Id { get; init; }
+
+        public static StepEntityInstanceNode Register( Token t )
         {
-            _model 
+            if( t.Value[ 0 ] != '#' ) {
+                throw new ExpInvalidSyntaxException( "Entity label in STEP should be # + number" );
+            }
+            StepEntityInstanceNode node = new StepEntityInstanceNode( t )
+            {
+                Id = int.Parse( t.Value.AsSpan( 1 ) ),
+            };
+            return node;
+        }
 
+        public static StepEntityInstanceNode RegisterNull( Token t )
+        {
+            if( t.Value != "$" ) {
+                throw new ExpInvalidSyntaxException(
+                    $"Token {t.Value} does not represent a null entity" );
+            }
+            StepEntityInstanceNode node = new StepEntityInstanceNode( t )
+            {
+                Id = 0,
+            };
+            return node;
+        }
+
+        public static StepEntityInstanceNode RegisterRuntimeInference( Token t )
+        {
+            if( t.Value != "*" ) {
+                throw new ExpInvalidSyntaxException(
+                    $"Token {t.Value} does not represent a runtime inferences entity" );
+            }
+            StepEntityInstanceNode node = new StepEntityInstanceNode( t )
+            {
+                Id = -1,
+            };
+            return node;
         }
 
     }
+
+    internal class StepEntityType : ExpTypeSource
+    {
+
+        private StepEntityType( string typeName ) : base( typeName ) { }
+
+        public static StepEntityType Source { get; } = new StepEntityType( "ENTITY" );
+
+    }
 }