Some initial work for debugging

Upsilon/Binder/BoundStatements/BoundStatement.cs

@@ -7,5 +7,7 @@ namespace Upsilon.Binder
         protected BoundStatement(TextSpan span) : base(span)
         {
         }
+
+        internal bool HasBreakpoint { get; set; }
     }
 }

Upsilon/Evaluator/Debugging/BreakpointInfo.cs

@@ -0,0 +1,22 @@
+using System.Collections.Generic;
+
+namespace Upsilon.Evaluator.Debugging
+{
+    public class BreakpointInfo
+    {
+        private Dictionary<string, object> _variables;
+        public BreakpointInfo(EvaluationScope scope)
+        {
+            _variables = new Dictionary<string, object>();
+            while (scope != null)
+            {
+                foreach (var v in scope.Variables)
+                {
+                    _variables.Add(v.Key, v.Value);
+                }
+
+                scope = scope.ParentScope;
+            }
+        }
+    }
+}

Upsilon/Evaluator/Debugging/DebugFile.cs

@@ -0,0 +1,14 @@
+using System.Collections.Generic;
+
+namespace Upsilon.Evaluator.Debugging
+{
+    public class DebugFile
+    {
+        public List<Breakpoint> Breakpoints = new List<Breakpoint>();
+    }
+
+    public class Breakpoint
+    {
+        public int Line { get; set; }
+    }
+}

Upsilon/Evaluator/Debugging/DebugSession.cs

@@ -0,0 +1,54 @@
+using System.Collections.Generic;
+using System.Xml.Linq;
+
+namespace Upsilon.Evaluator.Debugging
+{
+    public static class DebugSession
+    {
+        public static bool DebuggerAttached { get; set; }
+        internal static bool Debugging { get; set; }
+        private static Dictionary<string, DebugFile> Files { get; set; }
+
+        public static void AttachDebugger()
+        {
+            DebuggerAttached = true;
+        }
+
+        public static DebugFile GetFileInfo(string file)
+        {
+            return Files.TryGetValue(file, out var info) ? info : null;
+        }
+
+        public static void SetBreakpoint(string file, int line)
+        {
+            if (!Files.TryGetValue(file, out var fileObj))
+            {
+                fileObj = new DebugFile();
+                Files.Add(file, fileObj);
+            }
+            fileObj.Breakpoints.Add(new Breakpoint()
+            {
+                Line = line
+            });
+        }
+
+        public static void RemoveBreakpoint(string file, int line)
+        {
+            if (Files.TryGetValue(file, out var fileObj))
+            {
+                fileObj = new DebugFile();
+                fileObj.Breakpoints.RemoveAll(x => x.Line == line);
+                if (fileObj.Breakpoints.Count <= 0)
+                    Files.Remove(file);
+            }
+        }
+
+        internal static void TriggerBreakpoint(EvaluationScope scope)
+        {
+            OnBreakpoint?.Invoke(new BreakpointInfo(scope));
+        }
+
+        public delegate void BreakpointEvent(BreakpointInfo info);
+        public static event BreakpointEvent OnBreakpoint;
+    }
+}

Upsilon/Evaluator/EvaluationScope.cs

@@ -8,7 +8,7 @@ namespace Upsilon.Evaluator
 {
     public class EvaluationScope : IDisposable
     {
-        private EvaluationScope _parentScope;
+        public EvaluationScope ParentScope { get; private set; }
         private EvaluationScope _getOnlyParentScope;
 
         public readonly Dictionary<string, ScriptType> Variables;
@@ -16,7 +16,7 @@ namespace Upsilon.Evaluator
 
         internal EvaluationScope(EvaluationScope parentScope)
         {
-            _parentScope = parentScope;
+            ParentScope = parentScope;
             Variables = new Dictionary<string, ScriptType>();
         }
 
@@ -33,8 +33,8 @@ namespace Upsilon.Evaluator
 
         public void Dispose()
         {
-            _parentScope?.Dispose();
+            ParentScope?.Dispose();
-            _parentScope = null;
+            ParentScope = null;
             Variables.Clear();
         }
 
@@ -44,9 +44,9 @@ namespace Upsilon.Evaluator
             {
                 Variables[symbol.Name] = value;
             }
-            else if (_parentScope != null)
+            else if (ParentScope != null)
             {
-                _parentScope.AssignToNearest(symbol, value);
+                ParentScope.AssignToNearest(symbol, value);
             }
             else
             {
@@ -74,8 +74,8 @@ namespace Upsilon.Evaluator
         {
             if (Variables.TryGetValue(symbol.Name, out obj))
                 return true;
-            if (_parentScope != null)
+            if (ParentScope != null)
-                if (_parentScope.TryGet(symbol, out obj))
+                if (ParentScope.TryGet(symbol, out obj))
                     return true;
             if (_getOnlyParentScope != null)
                 if (_getOnlyParentScope.TryGet(symbol, out obj))
@@ -87,8 +87,8 @@ namespace Upsilon.Evaluator
         {
             if (Variables.TryGetValue(variable, out obj))
                 return true;
-            if (_parentScope != null)
+            if (ParentScope != null)
-                if (_parentScope.TryGet(variable, out obj))
+                if (ParentScope.TryGet(variable, out obj))
                     return true;
             if (_getOnlyParentScope != null)
                 if (_getOnlyParentScope.TryGet(variable, out obj))

Upsilon/Evaluator/Evaluator.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Threading;
 using Upsilon.BaseTypes;
 using Upsilon.BaseTypes.Number;
 using Upsilon.BaseTypes.ScriptFunction;
@@ -8,8 +9,10 @@ using Upsilon.BaseTypes.ScriptTypeInterfaces;
 using Upsilon.BaseTypes.UserData;
 using Upsilon.Binder;
 using Upsilon.Binder.VariableSymbols;
+using Upsilon.Evaluator.Debugging;
 using Upsilon.Exceptions;
 using Upsilon.Text;
+using Upsilon.Utilities;
 using Type = Upsilon.BaseTypes.Type;
 
 namespace Upsilon.Evaluator
@@ -57,6 +60,19 @@ namespace Upsilon.Evaluator
 
         public ScriptType Evaluate(BoundScript e)
         {
+            if (DebugSession.DebuggerAttached && !string.IsNullOrWhiteSpace(e.FileName))
+            {
+                var file = DebugSession.GetFileInfo(e.FileName);
+                if (file != null)
+                {
+                    foreach (var breakpoint in file.Breakpoints)
+                    {
+                        var lineStart = _script.ScriptString.GetLineInfo(breakpoint.Line).Start;
+                        var debugStatement = e.GetBottomStatementAtPosition(lineStart);
+                        debugStatement.HasBreakpoint = true;
+                    }
+                }
+            }
             EvaluateNode(e.Statement);
             if (_returnValue == null)
                 return _lastValue;
@@ -474,14 +490,30 @@ namespace Upsilon.Evaluator
             throw new Exception($"Cannot find variable: '{e.Variable.VariableSymbol.Name}'");
         }
 
+        private Queue<BoundStatement> _todoStatements;
+
         private void EvaluateBoundBlockStatement(BoundBlockStatement boundBlockStatement)
         {
-            foreach (var boundStatement in boundBlockStatement.Statements)
+            _todoStatements = new Queue<BoundStatement>(boundBlockStatement.Statements);
+            while (true)
             {
+                if (DebugSession.Debugging)
+                {
+                    Thread.Sleep(10);
+                    continue;
+                }
                 if (HasReturned)
                     return;
                 if (HasBroken)
                     return;
+                if (_todoStatements.Count == 0)
+                    return;
+                var boundStatement = _todoStatements.Dequeue();
+                if (DebugSession.DebuggerAttached && boundStatement.HasBreakpoint)
+                {
+                    DebugSession.TriggerBreakpoint(Scope);
+                    continue;
+                }
                 EvaluateStatement(boundStatement);
             }
         }

Upsilon/Utilities/SearchHelper.cs

@@ -24,6 +24,11 @@ namespace Upsilon.Utilities
             return node.GetNodeAtPosition(characterPosition).First();
         }
         
+        public static BoundStatement GetBottomStatementAtPosition(this BoundNode node, int characterPosition)
+        {
+            return (BoundStatement) node.GetNodeAtPosition(characterPosition).First(x => x is BoundStatement);
+        }
+
         public static Dictionary<string, VariableSymbol> GetBoundScopeVisibleVariables(this BoundScope scope)
         {
             IEnumerable<KeyValuePair<string, VariableSymbol>> dictionary = scope.Variables;