From 74df6241cc6e5cf46f965f3dfc3755e317ed2625 Mon Sep 17 00:00:00 2001
From: Brychan Dempsey <brychand@hotmail.com>
Date: Fri, 12 Mar 2021 12:46:00 +1300
Subject: [PATCH] Added a center-string function

---
 Assignment 1/Program.cs | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/Assignment 1/Program.cs b/Assignment 1/Program.cs
index aa6e0af..24c0177 100644
--- a/Assignment 1/Program.cs	
+++ b/Assignment 1/Program.cs	
@@ -30,6 +30,11 @@ namespace Assignment_1
                 { "NEWLINE", new Tuple<string, VariableFlags>("\n", VariableFlags.Reserved | VariableFlags.NoPrint) },
                 { "CARRIAGE_RETURN", new Tuple<string, VariableFlags>("\r", VariableFlags.Reserved | VariableFlags.NoPrint) }
             };
+
+        static List<char> ForbiddenChars = new List<char>
+        {
+            '$', '\\', '\"', '\''
+        };
         static void Main(string[] args)
         {
             Console.WriteLine("┌──────────────────────────────────────────┐");
@@ -197,7 +202,7 @@ namespace Assignment_1
             void List()
             {
                 Console.WriteLine("┌" + new string('─', 15) + "┬" + new string('─', 25) + "┬" + new string('─', 9) + "┐");
-                Console.WriteLine("│{0,-15}│{1,-25}│{2,9}│", "Symbol", "Value", "Flags");
+                Console.WriteLine("│{0}│{1}│{2}│", CenterString("Symbol",15), CenterString("Value",25), CenterString("Flags",9));
                 Console.WriteLine("├" + new string('─', 15) + "┼" + new string('─', 25) + "┼" + new string('─', 9) + "┤");
                 int keyPos = 0;
                 foreach (var item in Symbols)
@@ -267,9 +272,15 @@ namespace Assignment_1
                 }
                 string identifier;
                 long identifierEndPos = FindIdentifier(source, out identifier);
-                if (identifierEndPos <= source.Position + 1 )
+                if (identifierEndPos <= source.Position + 1 || identifier.Trim().Length == 0)
                 {
-                    WriteDebugLine(lineStart, "set ".Length, "???", source);
+                    WriteDebugLine(lineStart, "set ".Length, "expected an identifier", source);
+                    return false;
+                }
+                else if (ForbiddenChars.Exists((c) => identifier.Contains(c)))
+                {
+                    char fbChar = ForbiddenChars.Find((c) => identifier.Contains(c));
+                    WriteDebugLine(lineStart, "set ".Length, string.Format("character {0} is not valid for an identifier", fbChar), source);
                     return false;
                 }
                 source.Position = identifierEndPos;
@@ -531,7 +542,7 @@ namespace Assignment_1
             long originalPos = s.Position;
             string tempstring;
             long nextWSOccurance = FindNextOccurance(s, (c, s) => Char.IsWhiteSpace(c), out tempstring);
-            while (tempstring.Length == 0)
+            while (tempstring.Length == 0 && s.Position < s.Length)
             {
                 nextWSOccurance = FindNextOccurance(s, (c, s) => Char.IsWhiteSpace(c), out tempstring);
                 s.Position++;
@@ -635,5 +646,17 @@ namespace Assignment_1
             }
             s.Position--;
         }
+
+        static string CenterString(string source, int totalPadding, char paddingChar=' ')
+        {
+            if (source.Length >= totalPadding) return source;
+            int leftHalf = (int)Math.Floor(source.Length / 2.0);
+            int rightHalf = (int)Math.Ceiling(source.Length / 2.0);
+            int leftHalfPad = (int)Math.Floor(totalPadding / 2.0);
+            int rightHalfPad = (int)Math.Ceiling(totalPadding / 2.0);
+            string t = "{0," + leftHalfPad + "}{1," + -1 * rightHalfPad + "}";
+            string result = string.Format(t, source.Substring(0,leftHalf+1), source.Substring(rightHalf,source.Length-rightHalf));
+            return result;
+        }
     }
 }