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,
+    }
+
+}