GUID Pattern support in RegexMatcher (#699)

* Add the RegexGuid class

* Use of RegexGuid in the RegexMatcher

* Fix up the CodeFactor violations

* Rename RegexGuid --> RegexExtended

src/WireMock.Net/Matchers/RegexMatcher.cs

@@ -5,6 +5,7 @@ using AnyOfTypes;
 using JetBrains.Annotations;
 using WireMock.Extensions;
 using WireMock.Models;
+using WireMock.RegularExpressions;
 using WireMock.Validation;
 
 namespace WireMock.Matchers
@@ -17,7 +18,7 @@ namespace WireMock.Matchers
     public class RegexMatcher : IStringMatcher, IIgnoreCaseMatcher
     {
         private readonly AnyOf<string, StringPattern>[] _patterns;
-        private readonly Regex[] _expressions;
+        private readonly RegexExtended[] _expressions;
 
         /// <inheritdoc cref="IMatcher.MatchBehaviour"/>
         public MatchBehaviour MatchBehaviour { get; }
@@ -76,7 +77,7 @@ namespace WireMock.Matchers
                 options |= RegexOptions.IgnoreCase;
             }
 
-            _expressions = patterns.Select(p => new Regex(p.GetPattern(), options)).ToArray();
+            _expressions = patterns.Select(p => new RegexExtended(p.GetPattern(), options)).ToArray();
         }
 
         /// <inheritdoc cref="IStringMatcher.IsMatch"/>

src/WireMock.Net/RegularExpressions/RegexExtended.cs

@@ -0,0 +1,72 @@
+using System;
+using System.Collections.Generic;
+using System.Text.RegularExpressions;
+using WireMock.Validation;
+
+namespace WireMock.RegularExpressions
+{
+    /// <summary>
+    /// Extension to the <see cref="Regex"/> object, adding support for GUID tokens for matching on.
+    /// </summary>
+    public class RegexExtended : Regex
+    {
+        /// <inheritdoc cref="Regex"/>
+        public RegexExtended(string pattern) : this(pattern, RegexOptions.None)
+        {
+        }
+
+        /// <inheritdoc cref="Regex"/>
+        public RegexExtended(string pattern,
+                         RegexOptions options)
+          : this(pattern, options, Regex.InfiniteMatchTimeout)
+        {
+        }
+
+        /// <inheritdoc cref="Regex"/>
+        public RegexExtended(string pattern,
+                         RegexOptions options,
+                         TimeSpan matchTimeout)
+          : base(ReplaceGuidPattern(pattern), options, matchTimeout)
+        {
+        }
+
+        // Dictionary of various Guid tokens with a corresponding regular expression pattern to use instead.
+        private static readonly Dictionary<string, string> GuidTokenPatterns = new Dictionary<string, string>
+        {
+            // Lower case format `B` Guid pattern
+            { @"\guidb", @"(\{[a-z0-9]{8}-([a-z0-9]{4}-){3}[a-z0-9]{12}\})" },
+            // Upper case format `B` Guid pattern
+            { @"\GUIDB", @"(\{[A-Z0-9]{8}-([A-Z0-9]{4}-){3}[A-Z0-9]{12}\})" },
+            // Lower case format `D` Guid pattern
+            { @"\guidd", "([a-z0-9]{8}-([a-z0-9]{4}-){3}[a-z0-9]{12})" },
+            // Upper case format `D` Guid pattern
+            { @"\GUIDD", "([A-Z0-9]{8}-([A-Z0-9]{4}-){3}[A-Z0-9]{12})" },
+            // Lower case format `N` Guid pattern
+            { @"\guidn", "([a-z0-9]{32})" },
+            // Upper case format `N` Guid pattern
+            { @"\GUIDN", "([A-Z0-9]{32})" },
+            // Lower case format `P` Guid pattern
+            { @"\guidp", @"(\([a-z0-9]{8}-([a-z0-9]{4}-){3}[a-z0-9]{12}\))" },
+            // Upper case format `P` Guid pattern
+            { @"\GUIDP", @"(\([A-Z0-9]{8}-([A-Z0-9]{4}-){3}[A-Z0-9]{12}\))" },
+            // Lower case format `X` Guid pattern
+            { @"\guidx", @"(\{0x[a-f0-9]{8},0x[a-f0-9]{4},0x[a-f0-9]{4},\{(0x[a-f0-9]{2},){7}(0x[a-f0-9]{2})\}\})" },
+            // Upper case format `X` Guid pattern
+            { @"\GUIDX", @"(\{0x[A-F0-9]{8},0x[A-F0-9]{4},0x[A-F0-9]{4},\{(0x[A-F0-9]{2},){7}(0x[A-F0-9]{2})\}\})" },
+        };
+
+        /// <summary>
+        /// Replaces all instances of valid GUID tokens with the correct regular expression to match.
+        /// </summary>
+        /// <param name="pattern">Pattern to replace token for.</param>
+        private static string ReplaceGuidPattern(string pattern)
+        {
+            Check.NotNull(pattern, nameof(pattern));
+            foreach (var tokenPattern in GuidTokenPatterns)
+            {
+                pattern = pattern.Replace(tokenPattern.Key, tokenPattern.Value);
+            }
+            return pattern;
+        }
+    }
+}