Rewrite lexer from scratch

src/UI/CSConsole/Lexer/StringLexer.cs

@@ -0,0 +1,59 @@
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace UnityExplorer.UI.CSharpConsole.Lexers
+{
+    public class StringLexer : Lexer
+    {
+        protected override Color HighlightColor => new Color(0.79f, 0.52f, 0.32f, 1.0f);
+
+        public override IEnumerable<char> Delimiters => new[] { '"' };
+
+        public override bool TryMatchCurrent(LexerBuilder lexer)
+        {
+            if (lexer.Current != '"')
+                return false;
+
+            if (lexer.Previous == '@')
+            {
+                // verbatim string, continue until un-escaped quote.
+                while (!lexer.EndOfInput)
+                {
+                    lexer.Commit();
+                    if (lexer.PeekNext() == '"')
+                    {
+                        lexer.Commit();
+                        // possibly the end, check for escaped quotes.
+                        // commit the character and flip the escape bool for each quote.
+                        bool escaped = false;
+                        while (lexer.PeekNext() == '"')
+                        {
+                            lexer.Commit();
+                            escaped = !escaped;
+                        }
+                        // if the last quote wasnt escaped, that was the end of the string.
+                        if (!escaped)
+                            break;
+                    }
+                }
+            }
+            else
+            {
+                // normal string
+                // continue until a quote which is not escaped, or end of input
+
+                while (!lexer.EndOfInput)
+                {
+                    lexer.Commit();
+                    if (lexer.PeekNext() == '"' && lexer.Previous != '\\')
+                    {
+                        lexer.Commit();
+                        break;
+                    }
+                }
+            }
+
+            return true;
+        }
+    }
+}