Improve HttpStatusCodeParser efficiency, basic validation of non-standard regular expressions, provide a default implementation (HttpStatusCodeParser.Default)

Author: sharwell

src/corelib/Core/HttpStatusCodeParser.cs

@@ -1,16 +1,83 @@
-using System.Text.RegularExpressions;
+using System;
+using System.Linq;
+using System.Text.RegularExpressions;
 using net.openstack.Core.Domain;
 
 namespace net.openstack.Core
 {
+    /// <summary>
+    /// A status parser for HTTP status codes.
+    /// </summary>
     public class HttpStatusCodeParser : IStatusParser
     {
-        private const string RegEx = @"(?<StatusCode>\d*)\s*(?<Status>\w*)";
-        public Status Parse(string value)
+        /// <summary>
+        /// The default regular expression to use for matching HTTP status codes.
+        /// </summary>
+        protected static readonly string DefaultPattern = @"(?<StatusCode>\d*)\s*(?<Status>\w*)";
+
+        /// <summary>
+        /// A singleton instance of the default <see cref="HttpStatusCodeParser"/>.
+        /// </summary>
+        private static readonly HttpStatusCodeParser _default = new HttpStatusCodeParser(DefaultPattern);
+
+        /// <summary>
+        /// The compiled regular expression to use for matching HTTP status codes.
+        /// </summary>
+        private readonly Regex _expression;
+
+        /// <summary>
+        /// Constructs a new instance of <see cref="HttpStatusCodeParser"/> for the default regular
+        /// expression.
+        /// </summary>
+        [Obsolete("Use HttpStatusCodeParser.Default instead.")]
+        public HttpStatusCodeParser()
+            : this(DefaultPattern)
         {
-            var regex = new Regex(RegEx);
+        }
+
+        /// <summary>
+        /// Constructs a new instance of <see cref="HttpStatusCodeParser"/> for the specified regular
+        /// expression.
+        /// </summary>
+        /// <param name="pattern">
+        /// The regular expression pattern to use.
+        ///
+        /// <para><paramref name="pattern"/> should contain the named capturing grounds <c>StatusCode</c> and <c>status</c>.</para>
+        /// </param>
+        /// <exception cref="ArgumentNullException"><paramref name="pattern"/> is <c>null</c>.</exception>
+        /// <exception cref="ArgumentException">
+        /// <paramref name="pattern"/> does not contain a capturing group named <c>StatusCode</c>.
+        /// <para>-or-</para>
+        /// <para><paramref name="pattern"/> does not contain a capturing group named <c>Status</c>.</para>
+        /// </exception>
+        protected HttpStatusCodeParser(string pattern)
+        {
+            if (pattern == null)
+                throw new ArgumentNullException("pattern");
+
+            _expression = new Regex(pattern, RegexOptions.Compiled);
 
-            var match = regex.Match(value);
+            string[] groupNames = _expression.GetGroupNames();
+            if (!groupNames.Contains("StatusCode", StringComparer.Ordinal))
+                throw new ArgumentException("The pattern does not contain a StatusCode named capturing group.", "pattern");
+            if (!groupNames.Contains("Status", StringComparer.Ordinal))
+                throw new ArgumentException("The pattern does not contain a Status named capturing group.", "pattern");
+        }
+
+        /// <summary>
+        /// Gets a default <see cref="HttpStatusCodeParser"/>.
+        /// </summary>
+        public static HttpStatusCodeParser Default
+        {
+            get
+            {
+                return _default;
+            }
+        }
+
+        public Status Parse(string value)
+        {
+            var match = _expression.Match(value);
             if (!match.Success)
                 return null;
 

src/corelib/Providers/Rackspace/CloudFilesProvider.cs

@@ -99,7 +99,7 @@ public CloudFilesProvider(CloudIdentity identity, IRestService restService)
         /// <param name="identityProvider">An instance of an <see cref="IIdentityProvider"/> to override the default <see cref="CloudIdentity"/></param>
         /// <param name="restService">An instance of an <see cref="IRestService"/> to override the default <see cref="JsonRestServices"/></param>
         public CloudFilesProvider(CloudIdentity identity, IIdentityProvider identityProvider, IRestService restService)
-            : this(identity, identityProvider, restService, CloudFilesValidator.Default, CloudFilesMetadataProcessor.Default, EncodeDecodeProvider.Default, new HttpStatusCodeParser(), new BulkDeletionResultMapper(new HttpStatusCodeParser())) { }
+            : this(identity, identityProvider, restService, CloudFilesValidator.Default, CloudFilesMetadataProcessor.Default, EncodeDecodeProvider.Default, HttpStatusCodeParser.Default, new BulkDeletionResultMapper(HttpStatusCodeParser.Default)) { }
 
         internal CloudFilesProvider(IIdentityProvider cloudIdentityProvider, IRestService restService, IObjectStorageValidator cloudFilesValidator, IObjectStorageMetadataProcessor cloudFilesMetadataProcessor, IEncodeDecodeProvider encodeDecodeProvider, IStatusParser statusParser, IObjectMapper<BulkDeleteResponse, BulkDeletionResults> mapper)
             : this(null, cloudIdentityProvider, restService, cloudFilesValidator, cloudFilesMetadataProcessor, encodeDecodeProvider, statusParser, mapper) { }