unify exceptions

Lexer/Automaton/AutomatonConstructionException.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Lexer.Automaton
+{
+    public class AutomatonConstructionException : Exception
+    {
+        public AutomatonConstructionException(string message) : base(message)
+        {
+        }
+    }
+}

Lexer/Automaton/Impl/AutomatonBuilder.cs

@@ -39,9 +39,9 @@ public void AcceptState(int state)
         public IAutomaton Build()
         {
             if(StateCounter == 0)
-                throw new InvalidOperationException("No states defined!");
+                throw new AutomatonConstructionException("No states defined!");
             if(startState == -1)
-                throw new InvalidOperationException("No start defined!");
+                throw new AutomatonConstructionException("No start defined!");
             return new Automaton(StateCounter, startState, acceptingStates, 
                 transitions.ToDictionary(kv => kv.Key, kv => (ITransitionTargets)kv.Value));
         }

Lexer/LexerExecutionException.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Runtime.Serialization;
+
+namespace Lexer
+{
+    public class LexerExecutionException : Exception
+    {
+        public LexerExecutionException(string message) : base(message)
+        {
+        }
+    }
+}

Lexer/LexerExtensions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Text;
 
 namespace Lexer
 {
@@ -15,7 +16,20 @@ public static IEnumerable<IToken> Read(this ILexer lexer, string input)
                 index += token.Value.Length;
             }
             if (index < input.Length)
-                throw new InvalidOperationException("EOF not reached!");
+                throw new LexerExecutionException("EOF not reached!");
+        }
+
+        public static string Times(this string str, int factor)
+        {
+            if (factor < 0)
+                throw new ArgumentException("Factor must be non-negative!", nameof(factor));
+            var builder = new StringBuilder(str.Length*factor);
+            while(factor > 0)
+            {
+                builder.Append(str);
+                factor--;
+            }
+            return builder.ToString();
         }
     }
 }

Lexer/RegexParser.cs

@@ -255,7 +255,7 @@ private IAutomaton PrimaryExpression()
             private int Number()
             {
                 if(Lookahead < '0' || Lookahead > '9')
-                    throw new InvalidOperationException("Digit expected, but '"+Lookahead+"' found!");
+                    throw new RegexParserException(index, "Digit expected, but '"+Lookahead+"' found!");
                 var num = "";
                 while (Lookahead >= '0' && Lookahead <= '9')
                 {
@@ -290,7 +290,7 @@ private bool MayConsume(string str)
             private void Consumes(char c)
             {
                 if(Lookahead != c)
-                    throw new InvalidOperationException("'"+c+"' expected, but '"+Lookahead+"' found.");
+                    throw new RegexParserException(index, "'"+c+"' expected, but '"+Lookahead+"' found.");
                 index++;
             }
 
@@ -330,7 +330,7 @@ private ICharSet CharRange()
                 {
                     var last = Char();
                     if (last.Length != 1)
-                        throw new InvalidOperationException("Invalid upper bound for character range!");
+                        throw new RegexParserException(index, "Invalid upper bound for character range!");
                     result = new CharSet(new CharRange(first.First().First(), last.First().First()));
                 }
                 else
@@ -348,7 +348,7 @@ private ICharSet Char()
                     switch(asciiTable[Lookahead])
                     {
                         case CharType.Invalid:
-                            throw new InvalidOperationException("Invalid character!");
+                            throw new RegexParserException(index, "Invalid character: "+Lookahead+"!");
                         case CharType.Literal:
                             var first = Lookahead;
                             index++;
@@ -382,11 +382,11 @@ private ICharSet Char()
                                         }
                                     }
                                     if (!found)
-                                        throw new InvalidOperationException("Invalid escape character: " + Lookahead);
+                                        throw new RegexParserException(index, "Invalid escape character: " + Lookahead);
                                 }
                             }
                             else
-                                throw new InvalidOperationException("Invalid character!");
+                                throw new RegexParserException(index, "Invalid character: "+Lookahead+"!");
                             break;
                     }
                 }

Lexer/RegexParserException.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Lexer
+{
+    public class RegexParserException : Exception
+    {
+        public RegexParserException(int index, string message) : base(message)
+        {
+            Index = index;
+        }
+        public int Index { get; }
+    }
+}

Main/Program.cs

@@ -21,11 +21,12 @@ public static void Main(string[] args)
                     var automaton = parser.Parse(input);
                     automaton.Print();
                 }
-                catch (Exception e)
+                catch (RegexParserException e)
                 {
+                    Console.WriteLine("  "+(" ".Times(e.Index))+"^");
                     Console.Error.WriteLine(e.Message);
-                    Console.Error.WriteLine(e.StackTrace);
                 }
+                Console.WriteLine();
             } while (true);
         }
     }