Graph layout attribute

Sources/DotNetGraph.Tests/BasicGraphTests.cs

@@ -1,3 +1,4 @@
+using DotNetGraph.Core;
 using DotNetGraph.Extensions;
 using DotNetGraph.Node;
 using NFluent;
@@ -64,5 +65,18 @@ public void GraphWithoutStringsFormat()
 
             Check.That(compiled).HasSameValueAs("digraph \"TestGraph\" { \"TestNode\"[label=\"\\lTesting\"]; }");
         }
+
+        [Fact]
+        public void GraphWithLayout()
+        {
+            var graph = new DotGraph("TestGraph", true)
+            {
+                Layout = DotGraphLayout.Neato
+            };
+
+            var compiled = graph.Compile(false, false);
+
+            Check.That(compiled).HasSameValueAs("digraph \"TestGraph\" { layout=neato; }");
+        }
     }
 }

Sources/DotNetGraph/Attributes/DotGraphLayoutAttribute.cs

@@ -0,0 +1,19 @@
+using DotNetGraph.Core;
+
+namespace DotNetGraph.Attributes
+{
+    public class DotGraphLayoutAttribute : IDotAttribute
+    {
+        public DotGraphLayout Layout { get; set; }
+
+        public DotGraphLayoutAttribute(DotGraphLayout layout = DotGraphLayout.Dot)
+        {
+            Layout = layout;
+        }
+
+        public static implicit operator DotGraphLayoutAttribute(DotGraphLayout? layout)
+        {
+            return layout.HasValue ? new DotGraphLayoutAttribute(layout.Value) : null;
+        }
+    }
+}

Sources/DotNetGraph/Compiler/DotCompiler.cs

@@ -44,6 +44,8 @@ private void CompileGraph(StringBuilder builder, bool indented, bool formatStrin
 
             indentationLevel++;
 
+            CompileGraphAttributes(builder, _graph.Attributes, formatStrings);
+
             foreach (var element in _graph.Elements)
             {
                 if (element is DotEdge edge)
@@ -256,6 +258,24 @@ private void CompileAttributes(StringBuilder builder, ReadOnlyCollection<IDotAtt
             builder.Append("]");
         }
 
+        private void CompileGraphAttributes(StringBuilder builder, ReadOnlyCollection<IDotAttribute> attributes, bool formatStrings)
+        {
+            if (attributes.Count == 0)
+                return;
+
+            foreach (var attribute in attributes)
+            {
+                if (attribute is DotGraphLayoutAttribute graphLayoutAttribute)
+                {
+                    builder.Append($"layout={graphLayoutAttribute.Layout.ToString().ToLowerInvariant()}; ");
+                }
+                else
+                {
+                    throw new DotException($"Attribute type not supported: {attribute.GetType()}");
+                }
+            }
+        }
+
         internal static string FormatString(string value, bool format)
         {
             if (!format)

Sources/DotNetGraph/Core/DotGraphLayout.cs

@@ -0,0 +1,12 @@
+namespace DotNetGraph.Core
+{
+    public enum DotGraphLayout
+    {
+        Dot = 0,
+        Neato = 1,
+        Fdp = 2,
+        Sfdp = 3,
+        Twopi = 4,
+        Circo= 5
+    }
+}

Sources/DotNetGraph/DotGraph.cs

@@ -1,16 +1,23 @@
 using System.Collections.Generic;
+using DotNetGraph.Attributes;
 using DotNetGraph.Core;
 
 namespace DotNetGraph
 {
-    public class DotGraph : IDotElement
+    public class DotGraph : DotElementWithAttributes
     {
         public bool Directed { get; set; }
 
         public string Identifier { get; set; }
 
         public bool Strict { get; set; }
 
+        public DotGraphLayoutAttribute Layout
+        {
+            get => GetAttribute<DotGraphLayoutAttribute>();
+            set => SetAttribute(value);
+        }
+
         public List<IDotElement> Elements { get; }
 
         public DotGraph()