feat: add ProgramVariable and ProgramVariableManager for macro variable declarations

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

OpenNest.Posts.Cincinnati/ProgramVariable.cs

@@ -0,0 +1,18 @@
+namespace OpenNest.Posts.Cincinnati
+{
+    public sealed class ProgramVariable
+    {
+        public int Number { get; }
+        public string Name { get; }
+        public string Expression { get; set; }
+
+        public ProgramVariable(int number, string name, string expression = null)
+        {
+            Number = number;
+            Name = name;
+            Expression = expression;
+        }
+
+        public string Reference => $"#{Number}";
+    }
+}

OpenNest.Posts.Cincinnati/ProgramVariableManager.cs

@@ -0,0 +1,43 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace OpenNest.Posts.Cincinnati
+{
+    public sealed class ProgramVariableManager
+    {
+        private readonly Dictionary<int, ProgramVariable> _variables = new();
+
+        public ProgramVariable GetOrCreate(string name, int number, string expression = null)
+        {
+            if (_variables.TryGetValue(number, out var existing))
+                return existing;
+
+            var variable = new ProgramVariable(number, name, expression);
+            _variables[number] = variable;
+            return variable;
+        }
+
+        public List<string> EmitDeclarations()
+        {
+            return _variables.Values
+                .Where(v => v.Expression != null)
+                .OrderBy(v => v.Number)
+                .Select(v => $"{v.Reference}={v.Expression} ({FormatComment(v.Name)})")
+                .ToList();
+        }
+
+        private static string FormatComment(string name)
+        {
+            // "LeadInFeedrate" -> "LEAD IN FEEDRATE"
+            var sb = new StringBuilder();
+            foreach (var c in name)
+            {
+                if (char.IsUpper(c) && sb.Length > 0)
+                    sb.Append(' ');
+                sb.Append(char.ToUpper(c));
+            }
+            return sb.ToString();
+        }
+    }
+}

OpenNest.Tests/Cincinnati/ProgramVariableManagerTests.cs

@@ -0,0 +1,71 @@
+using OpenNest.Posts.Cincinnati;
+
+namespace OpenNest.Tests.Cincinnati;
+
+public class ProgramVariableManagerTests
+{
+    [Fact]
+    public void GetOrCreate_ReturnsNewVariable()
+    {
+        var mgr = new ProgramVariableManager();
+        var v = mgr.GetOrCreate("LeadInFeedrate", 126);
+        Assert.Equal(126, v.Number);
+        Assert.Equal("LeadInFeedrate", v.Name);
+    }
+
+    [Fact]
+    public void GetOrCreate_ReturnsSameVariable_WhenCalledTwice()
+    {
+        var mgr = new ProgramVariableManager();
+        var v1 = mgr.GetOrCreate("LeadInFeedrate", 126);
+        var v2 = mgr.GetOrCreate("LeadInFeedrate", 126);
+        Assert.Same(v1, v2);
+    }
+
+    [Fact]
+    public void GetOrCreate_WithExpression_SetsExpression()
+    {
+        var mgr = new ProgramVariableManager();
+        var v = mgr.GetOrCreate("LeadInFeedrate", 126, "[#148*0.5]");
+        Assert.Equal("[#148*0.5]", v.Expression);
+    }
+
+    [Fact]
+    public void GetOrCreate_WithLiteral_SetsExpression()
+    {
+        var mgr = new ProgramVariableManager();
+        var v = mgr.GetOrCreate("CircleFeedrate", 128, ".8");
+        Assert.Equal(".8", v.Expression);
+    }
+
+    [Fact]
+    public void Reference_ReturnsHashNumber()
+    {
+        var v = new ProgramVariable(126, "LeadInFeedrate");
+        Assert.Equal("#126", v.Reference);
+    }
+
+    [Fact]
+    public void EmitDeclarations_ProducesCorrectLines()
+    {
+        var mgr = new ProgramVariableManager();
+        mgr.GetOrCreate("LeadInFeedrate", 126, "[#148*0.5]");
+        mgr.GetOrCreate("CircleFeedrate", 128, ".8");
+
+        var lines = mgr.EmitDeclarations();
+
+        Assert.Contains("#126=[#148*0.5] (LEAD IN FEEDRATE)", lines);
+        Assert.Contains("#128=.8 (CIRCLE FEEDRATE)", lines);
+    }
+
+    [Fact]
+    public void EmitDeclarations_SkipsVariablesWithNoExpression()
+    {
+        var mgr = new ProgramVariableManager();
+        mgr.GetOrCreate("ProcessFeedrate", 148);
+
+        var lines = mgr.EmitDeclarations();
+
+        Assert.Empty(lines);
+    }
+}