Work on Diagnostics

Upsilon/Diagnostics.cs

@@ -0,0 +1,86 @@
+using System.Collections.Generic;
+using Upsilon.Text;
+
+namespace Upsilon
+{
+    public class Diagnostics
+    {
+        public SourceText ScriptString { get; }
+        public readonly List<DiagnosticsMessage> Messages = new List<DiagnosticsMessage>();
+
+        public Diagnostics(SourceText scriptString)
+        {
+            ScriptString = scriptString;
+        }
+
+        public void Log(DiagnosticLevel level, string message, TextSpan location)
+        {
+            Messages.Add(new DiagnosticsMessage(this, level, message, location));
+        }
+
+        public void LogError(string message, TextSpan location)
+        {
+            Log(DiagnosticLevel.Error, message, location);
+        }
+
+        public void LogBadCharacter(TextSpan location)
+        {
+            LogError($"Invalid character found", location);
+        }
+
+        public void LogUnknownVariable(TextSpan span, string variable)
+        {
+            LogError($"Unknown variable '{variable}'", span);
+        }
+
+        public void LogNullReferenceError(TextSpan span)
+        {
+            LogError($"Null Reference Encountered", span);
+        }
+    }
+
+    public class DiagnosticsMessage
+    {
+        public Diagnostics Diagnostics { get; }
+        private readonly DiagnosticLevel _diagnosticLevel;
+        public string Message { get; }
+        public TextSpan Span { get; }
+
+        public DiagnosticsMessage(Diagnostics diagnostics, DiagnosticLevel diagnosticLevel, string message, TextSpan span)
+        {
+            _diagnosticLevel = diagnosticLevel;
+            Diagnostics = diagnostics;
+            Message = message;
+            Span = span;
+        }
+
+        public override string ToString()
+        {
+            return $"{Message} at {Span.Start}\n{Diagnostics.ScriptString.GetSpan(Span)}";
+        }
+
+        public string BeforeError(int i = 5)
+        {
+            return Diagnostics.ScriptString.GetSpan(Span.Start - i, i);
+        }
+
+        public string AtError()
+        {
+            return Diagnostics.ScriptString.GetSpan(Span);
+        }
+
+        public string AfterError(int i = 5)
+        {
+            return Diagnostics.ScriptString.GetSpan(Span.Start + 1, i);
+        }
+
+    }
+
+    public enum DiagnosticLevel
+    {
+        Information,
+        Warning,
+        Error,
+    }
+
+}

Upsilon/Evaluator/Evaluator.cs

@@ -5,11 +5,13 @@ namespace Upsilon.Evaluator
 {
     public class Evaluator
     {
+        private readonly Diagnostics _diagnostics;
         public Script Script { get; }
         public VariableScope Scope { get; }
 
-        public Evaluator(Script script, VariableScope scope)
+        public Evaluator(Script script, VariableScope scope, Diagnostics diagnostics)
         {
+            _diagnostics = diagnostics;
             Script = script;
             Scope = scope;
         }
@@ -65,6 +67,8 @@ namespace Upsilon.Evaluator
         {
             var left  = EvaluateExpression(e.Left);
             var right = EvaluateExpression(e.Right);
+            try
+            {
                 switch (e.Operator.Kind)
                 {
                     case SyntaxKind.Plus:
@@ -87,6 +91,12 @@ namespace Upsilon.Evaluator
                         throw new Exception("Invalid Binary Operator: " + e.Operator.Kind);
                 }
             }
+            catch (NullReferenceException)
+            {
+                _diagnostics.LogNullReferenceError(e.Span);
+                return null;
+            }
+        }
 
         private object EvaluateAssignmentExpression(AssignmentExpressionSyntax e)
         {
@@ -110,7 +120,9 @@ namespace Upsilon.Evaluator
             {
                 return value;
             }
-            throw new Exception("Unknown variable: " + varName);
+
+            _diagnostics.LogUnknownVariable(e.Span, varName);
+            return null;
         }
 
     }

Upsilon/Evaluator/Script.cs

@@ -1,27 +1,31 @@
 using System.Collections.Generic;
 using Upsilon.Parser;
+using Upsilon.Text;
 
 namespace Upsilon.Evaluator
 {
     public class Script : VariableScope
     {
-        private string ScriptString { get; }
+        private SourceText ScriptString { get; }
         private Evaluator Evaluator { get; }
         public readonly ScriptSyntax Parsed;
+        public Diagnostics Diagnostics { get; }
 
         public Script(string scriptString)
         {
-            ScriptString = scriptString;
+            ScriptString = new SourceText(scriptString);
-            Evaluator = new Evaluator(this, this);
+            Diagnostics = new Diagnostics(ScriptString);
-            Parsed = Parser.Parser.Parse(scriptString);
+            Parsed = Parser.Parser.Parse(scriptString, Diagnostics);
+            Evaluator = new Evaluator(this, this, Diagnostics);
         }
 
         public Script(string scriptString, Dictionary<string, object> variables = null)
         :base(variables: variables)
         {
-            ScriptString = scriptString;
+            ScriptString = new SourceText(scriptString);
-            Evaluator    = new Evaluator(this, this);
+            Diagnostics = new Diagnostics(ScriptString);
-            Parsed      = Parser.Parser.Parse(scriptString);
+            Evaluator    = new Evaluator(this, this, Diagnostics);
+            Parsed      = Parser.Parser.Parse(scriptString, Diagnostics);
         }
 
         public object Evaluate()

Upsilon/Evaluator/VariableScope.cs

@@ -47,7 +47,7 @@ namespace Upsilon.Evaluator
             {
                 return _parentScope.TryGetVariable(key, out result);
             }
-            throw new Exception("Variable not found: " + key);
+            return false;
         }
     }
 }

Upsilon/Parser/ExpressionSyntax/BadExpressionSyntax.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+
+namespace Upsilon.Parser
+{
+    public class BadExpressionSyntax : ExpressionSyntax
+    {
+        public override SyntaxKind Kind => SyntaxKind.BadExpression;
+        public override IEnumerable<SyntaxNode> ChildNodes()
+        {
+            throw new System.NotImplementedException();
+        }
+    }
+}

Upsilon/Parser/Lexer.cs

@@ -1,22 +1,24 @@
-using System;
 using System.Collections.Immutable;
 using System.Text;
+using Upsilon.Text;
 
 namespace Upsilon.Parser
 {
     public class Lexer
     {
         private readonly string _text;
+        private readonly Diagnostics _diagnostics;
         private int _position;
 
-        private Lexer(string text)
+        private Lexer(string text, Diagnostics diagnostics)
         {
             _text = text;
+            _diagnostics = diagnostics;
         }
 
-        public static ImmutableArray<SyntaxToken> Lex(string text)
+        public static ImmutableArray<SyntaxToken> Lex(string text, Diagnostics diagnostics)
         {
-            var lexer = new Lexer(text);
+            var lexer = new Lexer(text, diagnostics);
             return lexer.Lex();
         }
 
@@ -97,7 +99,8 @@ namespace Upsilon.Parser
                 default:
                     if (char.IsLetter(Current))
                         return LexIdentifierOrKeyword();
-                    throw new Exception("Unknown token character: " + Current);
+                    _diagnostics.LogBadCharacter(new TextSpan(_position, 1));
+                    return new SyntaxToken(SyntaxKind.BadToken, _position, "", null);
             }
         }
 
@@ -113,7 +116,8 @@ namespace Upsilon.Parser
                 {
                     if (hasDecimalPoint)
                     {
-                        throw new Exception("No second decimal allowed there");
+                        _diagnostics.LogBadCharacter(new TextSpan(_position, 1));
+                        return new SyntaxToken(SyntaxKind.BadToken, _position, "", null);
                     }
                     hasDecimalPoint = true;
                 }

Upsilon/Parser/Parser.cs

@@ -1,22 +1,25 @@
 using System;
 using System.Collections.Immutable;
+using Upsilon.Text;
 
 namespace Upsilon.Parser
 {
     public class Parser
     {
         private readonly ImmutableArray<SyntaxToken> _tokens;
+        private readonly Diagnostics _diagnostics;
         private int _position;
 
-        private Parser(ImmutableArray<SyntaxToken> tokens)
+        private Parser(ImmutableArray<SyntaxToken> tokens, Diagnostics diagnostics)
         {
             _tokens = tokens;
+            _diagnostics = diagnostics;
         }
 
-        public static ScriptSyntax Parse(string text)
+        public static ScriptSyntax Parse(string text, Diagnostics diagnostics)
         {
-            var tokens = Lexer.Lex(text);
+            var tokens = Lexer.Lex(text, diagnostics);
-            return new Parser(tokens).ParseScriptSyntax();
+            return new Parser(tokens, diagnostics).ParseScriptSyntax();
         }
 
         private SyntaxToken Current => Get(0);
@@ -41,6 +44,7 @@ namespace Upsilon.Parser
             if (Current.Kind == kind)
                 return NextToken();
 
+            _diagnostics.LogBadCharacter(new TextSpan(_position, 1));
             return new SyntaxToken(kind, Current.Span.Start, "", null);
         }
 
@@ -121,7 +125,9 @@ namespace Upsilon.Parser
                     var token = MatchToken(SyntaxKind.Identifier);
                     return new VariableExpressionSyntax((IdentifierToken) token);
                 default:
-                    throw new Exception("Unknown primary expression type: " + Current.Kind);
+                    _diagnostics.LogBadCharacter(new TextSpan(_position, 1));
+                    NextToken();
+                    return new BadExpressionSyntax();
             }
         }
 

Upsilon/Parser/SyntaxKind.cs

@@ -2,10 +2,12 @@ namespace Upsilon.Parser
 {
     public enum SyntaxKind
     {
-        // tokens
+        // misc
         EndOfFile,
         WhiteSpace,
+        BadToken,
 
+        // tokens
         Number,
         Plus,
         Minus,
@@ -35,6 +37,7 @@ namespace Upsilon.Parser
         ParenthesizedExpression,
         AssignmentExpression,
         VariableExpression,
+        BadExpression,
 
         // script unit
         ScriptUnit,

Upsilon/Text/SourceText.cs

@@ -0,0 +1,30 @@
+using System;
+
+namespace Upsilon.Text
+{
+    public class SourceText
+    {
+        private readonly string _text;
+
+        public SourceText(string text)
+        {
+            _text = text;
+        }
+
+        public string GetSpan(int start, int length)
+        {
+            if (start < 0)
+            {
+                length += start;
+                start = 0;
+            };
+            if (start + length >= _text.Length) length = _text.Length - start;
+            return _text.Substring(start, length);
+        }
+
+        public string GetSpan(TextSpan span)
+        {
+            return GetSpan(span.Start, span.Length);
+        }
+    }
+}

Yc/Program.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
+using Upsilon;
 using Upsilon.Evaluator;
-using Upsilon.Utilities;
 
 namespace Yc
 {
@@ -21,10 +21,51 @@ namespace Yc
                 }
 
                 var parsed = new Script(input, variables);
-                //Console.WriteLine(parsed.Parsed.Print());
+                if (parsed.Diagnostics.Messages.Count > 0)
-                Console.WriteLine(parsed.Evaluate());
+                {
+                    Console.ForegroundColor = ConsoleColor.Red;
+                    Console.WriteLine("Errors were found during parsing");
+                    foreach (var diagnosticsMessage in parsed.Diagnostics.Messages)
+                    {
+                        LogError(diagnosticsMessage);
+                    }
+                    Console.ResetColor();
+                    continue;
+                }
+
+                var evaluate = parsed.Evaluate();
+                if (parsed.Diagnostics.Messages.Count > 0)
+                {
+                    Console.ForegroundColor = ConsoleColor.Red;
+                    Console.WriteLine("Errors were found during evaluating");
+                    foreach (var diagnosticsMessage in parsed.Diagnostics.Messages)
+                    {
+                        LogError(diagnosticsMessage);
+                    }
+                    Console.ResetColor();
+                }
+                else
+                {
+                    Console.WriteLine(evaluate);
                     variables = parsed.Variables;
                 }
             }
         }
+
+        public static void LogError(DiagnosticsMessage message)
+        {
+            Console.ForegroundColor = ConsoleColor.Red;
+            Console.WriteLine(message.Message);
+
+            Console.ForegroundColor = ConsoleColor.Gray;
+            Console.Write(message.BeforeError());
+
+            Console.ForegroundColor = ConsoleColor.Red;
+            Console.Write(message.AtError());
+
+            Console.ForegroundColor = ConsoleColor.Gray;
+            Console.Write(message.AfterError());
+            Console.WriteLine();
+        }
+    }
 }