refactor: extract shared feature utilities and sub-program registry from CincinnatiPostProcessor

Consolidate duplicated static methods (SplitFeatures, ComputeCutDistance,
IsFeatureEtch, feature ordering) from CincinnatiSheetWriter and
CincinnatiPartSubprogramWriter into a shared FeatureUtils class. Move
inline sub-program registry building from Post() into
CincinnatiPartSubprogramWriter.BuildRegistry().

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest.Posts.Cincinnati/CincinnatiPartSubprogramWriter.cs

@@ -29,12 +29,12 @@ public sealed class CincinnatiPartSubprogramWriter
     public void Write(TextWriter w, Program normalizedProgram, string drawingName,
         int subNumber, string cutLibrary, string etchLibrary, double sheetDiagonal)
     {
-        var allFeatures = SplitFeatures(normalizedProgram.Codes);
+        var allFeatures = FeatureUtils.SplitByRapids(normalizedProgram.Codes);
         if (allFeatures.Count == 0)
             return;
 
         // Classify and order: etch features first, then cut features
-        var ordered = OrderFeatures(allFeatures);
+        var ordered = FeatureUtils.ClassifyAndOrder(allFeatures);
 
         w.WriteLine("(*****************************************************)");
         w.WriteLine($":{subNumber}");
@@ -46,7 +46,7 @@ public sealed class CincinnatiPartSubprogramWriter
             var featureNumber = i == 0
                 ? _config.FeatureLineNumberStart
                 : 1000 + i + 1;
-            var cutDistance = ComputeCutDistance(codes);
+            var cutDistance = FeatureUtils.ComputeCutDistance(codes);
 
             var ctx = new FeatureContext
             {
@@ -70,81 +70,43 @@ public sealed class CincinnatiPartSubprogramWriter
         w.WriteLine($"M99 (END OF {drawingName})");
     }
 
-    internal static List<(List<ICode> codes, bool isEtch)> OrderFeatures(List<List<ICode>> features)
-    {
-        var result = new List<(List<ICode>, bool)>();
-        var etch = new List<List<ICode>>();
-        var cut = new List<List<ICode>>();
-
-        foreach (var f in features)
-        {
-            if (CincinnatiSheetWriter.IsFeatureEtch(f))
-                etch.Add(f);
-            else
-                cut.Add(f);
-        }
-
-        foreach (var f in etch)
-            result.Add((f, true));
-        foreach (var f in cut)
-            result.Add((f, false));
-
-        return result;
-    }
-
     /// <summary>
     /// Creates a sub-program key for matching parts to their sub-programs.
     /// </summary>
     internal static (int drawingId, long rotationKey) SubprogramKey(Part part) =>
         (part.BaseDrawing.Id, (long)System.Math.Round(part.Rotation * 1e6));
 
-    internal static List<List<ICode>> SplitFeatures(List<ICode> codes)
+    /// <summary>
+    /// Scans all plates and builds a mapping of unique part geometries to sub-program numbers,
+    /// along with their normalized programs for writing.
+    /// </summary>
+    internal static (Dictionary<(int, long), int> mapping, List<(int subNum, string name, Program program)> entries)
+        BuildRegistry(IEnumerable<Plate> plates, int startNumber)
     {
-        var features = new List<List<ICode>>();
-        List<ICode> current = null;
+        var mapping = new Dictionary<(int, long), int>();
+        var entries = new List<(int, string, Program)>();
+        var nextSubNum = startNumber;
 
-        foreach (var code in codes)
+        foreach (var plate in plates)
         {
-            if (code is RapidMove)
+            foreach (var part in plate.Parts)
             {
-                if (current != null)
-                    features.Add(current);
-                current = new List<ICode> { code };
-            }
-            else
-            {
-                current ??= new List<ICode>();
-                current.Add(code);
+                if (part.BaseDrawing.IsCutOff) continue;
+                var key = SubprogramKey(part);
+                if (!mapping.ContainsKey(key))
+                {
+                    var subNum = nextSubNum++;
+                    mapping[key] = subNum;
+
+                    var pgm = part.Program.Clone() as Program;
+                    var bbox = pgm.BoundingBox();
+                    pgm.Offset(-bbox.Location.X, -bbox.Location.Y);
+
+                    entries.Add((subNum, part.BaseDrawing.Name, pgm));
+                }
             }
         }
 
-        if (current != null && current.Count > 0)
-            features.Add(current);
-
-        return features;
-    }
-
-    internal static double ComputeCutDistance(List<ICode> codes)
-    {
-        var distance = 0.0;
-        var currentPos = Vector.Zero;
-
-        foreach (var code in codes)
-        {
-            if (code is RapidMove rapid)
-                currentPos = rapid.EndPoint;
-            else if (code is LinearMove linear)
-            {
-                distance += currentPos.DistanceTo(linear.EndPoint);
-                currentPos = linear.EndPoint;
-            }
-            else if (code is ArcMove arc)
-            {
-                distance += currentPos.DistanceTo(arc.EndPoint);
-                currentPos = arc.EndPoint;
-            }
-        }
-
-        return distance;
+        return (mapping, entries);
     }
 }

OpenNest.Posts.Cincinnati/CincinnatiPostProcessor.cs

@@ -84,32 +84,7 @@ namespace OpenNest.Posts.Cincinnati
             List<(int subNum, string name, Program program)> subprogramEntries = null;
 
             if (Config.UsePartSubprograms)
-            {
-                partSubprograms = new Dictionary<(int, long), int>();
-                subprogramEntries = new List<(int, string, Program)>();
-                var nextSubNum = Config.PartSubprogramStart;
-
-                foreach (var plate in plates)
-                {
-                    foreach (var part in plate.Parts)
-                    {
-                        if (part.BaseDrawing.IsCutOff) continue;
-                        var key = CincinnatiPartSubprogramWriter.SubprogramKey(part);
-                        if (!partSubprograms.ContainsKey(key))
-                        {
-                            var subNum = nextSubNum++;
-                            partSubprograms[key] = subNum;
-
-                            // Create normalized program at origin
-                            var pgm = part.Program.Clone() as Program;
-                            var bbox = pgm.BoundingBox();
-                            pgm.Offset(-bbox.Location.X, -bbox.Location.Y);
-
-                            subprogramEntries.Add((subNum, part.BaseDrawing.Name, pgm));
-                        }
-                    }
-                }
-            }
+                (partSubprograms, subprogramEntries) = CincinnatiPartSubprogramWriter.BuildRegistry(plates, Config.PartSubprogramStart);
 
             // 5. Create writers
             var preamble = new CincinnatiPreambleWriter(Config);

OpenNest.Posts.Cincinnati/CincinnatiSheetWriter.cs

@@ -4,7 +4,6 @@ using System.IO;
 using System.Linq;
 using System.Text;
 using OpenNest.CNC;
-using OpenNest.Geometry;
 
 namespace OpenNest.Posts.Cincinnati;
 
@@ -128,7 +127,7 @@ public sealed class CincinnatiSheetWriter
             else
             {
                 // Inline features for cutoffs or parts without sub-programs
-                var features = SplitAndOrderFeatures(part);
+                var features = FeatureUtils.SplitAndClassify(part);
                 for (var f = 0; f < features.Count; f++)
                 {
                     var (codes, isEtch) = features[f];
@@ -137,7 +136,7 @@ public sealed class CincinnatiSheetWriter
                         : 1000 + featureIndex + 1;
 
                     var isLastFeature = isLastPart && f == features.Count - 1;
-                    var cutDistance = ComputeCutDistance(codes);
+                    var cutDistance = FeatureUtils.ComputeCutDistance(codes);
 
                     var ctx = new FeatureContext
                     {
@@ -205,7 +204,7 @@ public sealed class CincinnatiSheetWriter
         var features = new List<(Part part, List<ICode> codes, bool isEtch)>();
         foreach (var part in allParts)
         {
-            var partFeatures = SplitAndOrderFeatures(part);
+            var partFeatures = FeatureUtils.SplitAndClassify(part);
             foreach (var (codes, isEtch) in partFeatures)
                 features.Add((part, codes, isEtch));
         }
@@ -224,7 +223,7 @@ public sealed class CincinnatiSheetWriter
                 ? _config.FeatureLineNumberStart
                 : 1000 + i + 1;
 
-            var cutDistance = ComputeCutDistance(codes);
+            var cutDistance = FeatureUtils.ComputeCutDistance(codes);
 
             var ctx = new FeatureContext
             {
@@ -246,91 +245,4 @@ public sealed class CincinnatiSheetWriter
         }
     }
 
-    /// <summary>
-    /// Splits a part's program into features (by rapids), classifies each as etch or cut,
-    /// and orders etch features before cut features.
-    /// </summary>
-    public static List<(List<ICode> codes, bool isEtch)> SplitAndOrderFeatures(Part part)
-    {
-        var etchFeatures = new List<List<ICode>>();
-        var cutFeatures = new List<List<ICode>>();
-        List<ICode> current = null;
-
-        foreach (var code in part.Program.Codes)
-        {
-            if (code is RapidMove)
-            {
-                if (current != null)
-                    ClassifyAndAdd(current, etchFeatures, cutFeatures);
-                current = new List<ICode> { code };
-            }
-            else
-            {
-                current ??= new List<ICode>();
-                current.Add(code);
-            }
-        }
-
-        if (current != null && current.Count > 0)
-            ClassifyAndAdd(current, etchFeatures, cutFeatures);
-
-        // Etch features first, then cut features
-        var result = new List<(List<ICode>, bool)>();
-        foreach (var f in etchFeatures)
-            result.Add((f, true));
-        foreach (var f in cutFeatures)
-            result.Add((f, false));
-
-        return result;
-    }
-
-    private static void ClassifyAndAdd(List<ICode> codes,
-        List<List<ICode>> etchFeatures, List<List<ICode>> cutFeatures)
-    {
-        if (IsFeatureEtch(codes))
-            etchFeatures.Add(codes);
-        else
-            cutFeatures.Add(codes);
-    }
-
-    /// <summary>
-    /// A feature is etch if any non-rapid move has LayerType.Scribe.
-    /// </summary>
-    public static bool IsFeatureEtch(List<ICode> codes)
-    {
-        foreach (var code in codes)
-        {
-            if (code is LinearMove linear && linear.Layer == LayerType.Scribe)
-                return true;
-            if (code is ArcMove arc && arc.Layer == LayerType.Scribe)
-                return true;
-        }
-        return false;
-    }
-
-    private static double ComputeCutDistance(List<ICode> codes)
-    {
-        var distance = 0.0;
-        var currentPos = Vector.Zero;
-
-        foreach (var code in codes)
-        {
-            if (code is RapidMove rapid)
-            {
-                currentPos = rapid.EndPoint;
-            }
-            else if (code is LinearMove linear)
-            {
-                distance += currentPos.DistanceTo(linear.EndPoint);
-                currentPos = linear.EndPoint;
-            }
-            else if (code is ArcMove arc)
-            {
-                distance += currentPos.DistanceTo(arc.EndPoint);
-                currentPos = arc.EndPoint;
-            }
-        }
-
-        return distance;
-    }
 }

OpenNest.Posts.Cincinnati/FeatureUtils.cs

@@ -0,0 +1,115 @@
+using System.Collections.Generic;
+using OpenNest.CNC;
+using OpenNest.Geometry;
+
+namespace OpenNest.Posts.Cincinnati;
+
+/// <summary>
+/// Shared utilities for splitting CNC programs into features and classifying them.
+/// </summary>
+public static class FeatureUtils
+{
+    /// <summary>
+    /// Splits a flat list of codes into feature groups, breaking on rapid moves.
+    /// Each feature starts with a rapid move followed by cutting/etching moves.
+    /// </summary>
+    public static List<List<ICode>> SplitByRapids(List<ICode> codes)
+    {
+        var features = new List<List<ICode>>();
+        List<ICode> current = null;
+
+        foreach (var code in codes)
+        {
+            if (code is RapidMove)
+            {
+                if (current != null)
+                    features.Add(current);
+                current = new List<ICode> { code };
+            }
+            else
+            {
+                current ??= new List<ICode>();
+                current.Add(code);
+            }
+        }
+
+        if (current != null && current.Count > 0)
+            features.Add(current);
+
+        return features;
+    }
+
+    /// <summary>
+    /// Classifies features as etch or cut and orders etch features before cut features.
+    /// </summary>
+    public static List<(List<ICode> codes, bool isEtch)> ClassifyAndOrder(List<List<ICode>> features)
+    {
+        var result = new List<(List<ICode>, bool)>();
+        var etch = new List<List<ICode>>();
+        var cut = new List<List<ICode>>();
+
+        foreach (var f in features)
+        {
+            if (IsEtch(f))
+                etch.Add(f);
+            else
+                cut.Add(f);
+        }
+
+        foreach (var f in etch)
+            result.Add((f, true));
+        foreach (var f in cut)
+            result.Add((f, false));
+
+        return result;
+    }
+
+    /// <summary>
+    /// Splits a part's program into features by rapids, classifies each as etch or cut,
+    /// and orders etch features before cut features.
+    /// </summary>
+    public static List<(List<ICode> codes, bool isEtch)> SplitAndClassify(Part part) =>
+        ClassifyAndOrder(SplitByRapids(part.Program.Codes));
+
+    /// <summary>
+    /// Returns true if any non-rapid move in the feature has LayerType.Scribe.
+    /// </summary>
+    public static bool IsEtch(List<ICode> codes)
+    {
+        foreach (var code in codes)
+        {
+            if (code is LinearMove linear && linear.Layer == LayerType.Scribe)
+                return true;
+            if (code is ArcMove arc && arc.Layer == LayerType.Scribe)
+                return true;
+        }
+        return false;
+    }
+
+    /// <summary>
+    /// Computes the total cut distance of a feature by summing segment lengths.
+    /// </summary>
+    public static double ComputeCutDistance(List<ICode> codes)
+    {
+        var distance = 0.0;
+        var currentPos = Vector.Zero;
+
+        foreach (var code in codes)
+        {
+            if (code is RapidMove rapid)
+                currentPos = rapid.EndPoint;
+            else if (code is LinearMove linear)
+            {
+                distance += currentPos.DistanceTo(linear.EndPoint);
+                currentPos = linear.EndPoint;
+            }
+            else if (code is ArcMove arc)
+            {
+                distance += currentPos.DistanceTo(arc.EndPoint);
+                currentPos = arc.EndPoint;
+            }
+        }
+
+        return distance;
+    }
+}

OpenNest.Tests/Cincinnati/CincinnatiSheetWriterTests.cs

@@ -152,7 +152,7 @@ public class CincinnatiSheetWriterTests
             new LinearMove(1, 1) { Layer = LayerType.Scribe }
         };
 
-        Assert.True(CincinnatiSheetWriter.IsFeatureEtch(codes));
+        Assert.True(FeatureUtils.IsEtch(codes));
     }
 
     [Fact]
@@ -165,7 +165,7 @@ public class CincinnatiSheetWriterTests
             new LinearMove(1, 1) { Layer = LayerType.Cut }
         };
 
-        Assert.False(CincinnatiSheetWriter.IsFeatureEtch(codes));
+        Assert.False(FeatureUtils.IsEtch(codes));
     }
 
     [Fact]
@@ -176,7 +176,7 @@ public class CincinnatiSheetWriterTests
             new RapidMove(0, 0)
         };
 
-        Assert.False(CincinnatiSheetWriter.IsFeatureEtch(codes));
+        Assert.False(FeatureUtils.IsEtch(codes));
     }
 
     private static Program CreateSimpleProgram()