Removed unnecessary Regex constructors for #353

src/Humanizer/StringHumanizeExtensions.cs

@@ -9,37 +9,37 @@ namespace Humanizer
     /// </summary>
     public static class StringHumanizeExtensions
     {
+        private static readonly Regex PascalCaseWordPartsRegex;
+        private static readonly Regex FreestandingSpacingCharRegex;
+
+        static StringHumanizeExtensions()
+        {
+            PascalCaseWordPartsRegex = new Regex(@"[A-Z]?[a-z]+|[0-9]+|[A-Z]+(?=[A-Z][a-z]|[0-9]|\b)",
+                RegexOptions.IgnorePatternWhitespace | RegexOptions.ExplicitCapture);
+            FreestandingSpacingCharRegex = new Regex(@"\s[-_]|[-_]\s");
+        }
+
         static string FromUnderscoreDashSeparatedWords (string input)
         {
             return String.Join(" ", input.Split(new[] {'_', '-'}));
         }
 
         static string FromPascalCase(string input)
         {
-            var pascalCaseWordBoundaryRegex = new Regex(@"
-(?# word to word, number or acronym)
-(?<=[a-z])(?=[A-Z0-9])|
-(?# number to word or acronym)
-(?<=[0-9])(?=[A-Za-z])|
-(?# acronym to number)
-(?<=[A-Z])(?=[0-9])|
-(?# acronym to word)
-(?<=[A-Z])(?=[A-Z][a-z])|
-(?# words/acronyms/numbers separated by space)
-(?<=[^\s])(?=[\s])
-", RegexOptions.IgnorePatternWhitespace);
+            if (input.Length == 1)
+                return Char.ToUpper(input[0]).ToString();
 
-            var result = pascalCaseWordBoundaryRegex
-                .Split(input)
-                .Select(word =>
-                    word.Trim().ToCharArray().All(Char.IsUpper) && word.Length > 1
-                        ? word
-                        : word.ToLower())
-                .Aggregate((res, word) => res + " " + word.Trim());
+            var result = PascalCaseWordPartsRegex
+                .Matches(input).Cast<Match>()
+                .Select(match => match.Value.ToCharArray().All(Char.IsUpper) &&
+                    (match.Value.Length > 1 || (match.Index > 0 && input[match.Index - 1] == ' ') || match.Value == "I")
+                    ? match.Value
+                    : match.Value.ToLower())
+                .Aggregate((res, word) => res + " " + word);
 
             result = Char.ToUpper(result[0]) +
                 result.Substring(1, result.Length - 1);
-            return result.Replace(" i ", " I "); // I is an exception
+            return result;
         }
 
         /// <summary>
@@ -55,8 +55,7 @@ public static string Humanize(this string input)
 
             // if input contains a dash or underscore which preceeds or follows a space (or both, i.g. free-standing)
             // remove the dash/underscore and run it through FromPascalCase
-            Regex r = new Regex(@"[\s]{1}[-_]|[-_][\s]{1}", RegexOptions.IgnoreCase);
-            if (r.IsMatch(input))
+            if (FreestandingSpacingCharRegex.IsMatch(input))
                 return FromPascalCase(FromUnderscoreDashSeparatedWords(input));
 
             if (input.Contains("_") || input.Contains("-"))

src/Humanizer/Transformer/ToTitleCase.cs

@@ -1,6 +1,6 @@
 using System;
 using System.Collections.Generic;
-using System.Text.RegularExpressions;
+using System.Linq;
 
 namespace Humanizer
 {
@@ -25,7 +25,7 @@ public string Transform(string input)
 
         static bool AllCapitals(string input)
         {
-            return Regex.IsMatch(input, @"^[A-Z]+$");
+            return input.ToCharArray().All(Char.IsUpper);
         }
     }
 }