Moved nesting to SawCut library

SawCut/Fraction.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Text.RegularExpressions;
+using System.Text;
+using System.Linq;
+
+namespace SawCut
+{
+    public static class Fraction
+    {
+        public static readonly Regex FractionRegex = new Regex(@"((?<WholeNum>\d+)(\ |-))?(?<Fraction>\d+\/\d+)");
+
+        public static bool IsValid(string s)
+        {
+            return FractionRegex.IsMatch(s);
+        }
+
+        public static double Parse(string s)
+        {
+            var match = FractionRegex.Match(s);
+
+            if (!match.Success)
+                throw new Exception("Invalid format.");
+
+            var value = 0.0;
+
+            var wholeNumGroup = match.Groups["WholeNum"];
+            var fractionGroup = match.Groups["Fraction"];
+
+            if (wholeNumGroup.Success)
+            {
+                value = double.Parse(wholeNumGroup.Value);
+            }
+
+            if (fractionGroup.Success)
+            {
+                var parts = fractionGroup.Value.Split('/');
+                var numerator = double.Parse(parts[0]);
+                var denominator = double.Parse(parts[1]);
+
+                value += Math.Round(numerator / denominator, 8);
+            }
+
+            return value;
+        }
+
+        public static string ReplaceFractionsWithDecimals(string input)
+        {
+            var sb = new StringBuilder(input);
+
+            // find all matches and sort by descending index number to avoid
+            // changing all previous index numbers when the fraction is replaced
+            // with the decimal equivalent.
+            var fractionMatches = FractionRegex.Matches(sb.ToString())
+                .Cast<Match>()
+                .OrderByDescending(m => m.Index);
+
+            foreach (var fractionMatch in fractionMatches)
+            {
+                // convert the fraction to a decimal value
+                var decimalValue = Parse(fractionMatch.Value);
+
+                // remove the fraction and insert the decimal value in its place.
+                sb.Remove(fractionMatch.Index, fractionMatch.Length);
+                sb.Insert(fractionMatch.Index, decimalValue);
+            }
+
+            return sb.ToString();
+        }
+
+        public static bool TryParse(string s, out double fraction)
+        {
+            try
+            {
+                fraction = Parse(s);
+            }
+            catch
+            {
+                fraction = 0;
+                return false;
+            }
+
+            return true;
+        }
+    }
+}