Google Api

Yavsc/GoogleApiSupport/Google.Apis.Core/Util/Utilities.cs

@@ -0,0 +1,175 @@
+/*
+Copyright 2010 Google Inc
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+using Google.Apis.Testing;
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Reflection;
+using System.Text.RegularExpressions;
+
+namespace Google.Apis.Util
+{
+    /// <summary>A utility class which contains helper methods and extension methods.</summary>
+    public static class Utilities
+    {
+        /// <summary>Returns the version of the core library.</summary>
+        [VisibleForTestOnly]
+        public static string GetLibraryVersion()
+        {
+            return Regex.Match(typeof(Utilities).GetTypeInfo().Assembly.FullName, "Version=([\\d\\.]+)").Groups[1].ToString();
+        }
+
+        /// <summary>
+        /// A Google.Apis utility method for throwing an <see cref="System.ArgumentNullException"/> if the object is
+        /// <c>null</c>.
+        /// </summary>
+        public static T ThrowIfNull<T>(this T obj, string paramName)
+        {
+            if (obj == null)
+            {
+                throw new ArgumentNullException(paramName);
+            }
+
+            return obj;
+        }
+
+        /// <summary>
+        /// A Google.Apis utility method for throwing an <see cref="System.ArgumentNullException"/> if the string is
+        /// <c>null</c> or empty.
+        /// </summary>
+        /// <returns>The original string.</returns>
+        public static string ThrowIfNullOrEmpty(this string str, string paramName)
+        {
+            if (string.IsNullOrEmpty(str))
+            {
+                throw new ArgumentException("Parameter was empty", paramName);
+            }
+            return str;
+        }
+
+        /// <summary>Returns <c>true</c> in case the enumerable is <c>null</c> or empty.</summary>
+        internal static bool IsNullOrEmpty<T>(this IEnumerable<T> coll)
+        {
+            return coll == null || coll.Count() == 0;
+        }
+
+        /// <summary>
+        /// A Google.Apis utility method for returning the first matching custom attribute (or <c>null</c>) of the specified member.
+        /// </summary>
+        public static T GetCustomAttribute<T>(this MemberInfo info) where T : Attribute
+        {
+            object[] results = info.GetCustomAttributes(typeof(T), false).ToArray();
+            return results.Length == 0 ? null : (T)results[0];
+        }
+
+        /// <summary>Returns the defined string value of an Enum.</summary>
+        internal static string GetStringValue(this Enum value)
+        {
+            FieldInfo entry = value.GetType().GetField(value.ToString());
+            entry.ThrowIfNull("value");
+
+            // If set, return the value.
+            var attribute = entry.GetCustomAttribute<StringValueAttribute>();
+            if (attribute != null)
+            {
+                return attribute.Text;
+            }
+
+            // Otherwise, throw an exception.
+            throw new ArgumentException(
+                string.Format("Enum value '{0}' does not contain a StringValue attribute", entry), "value");
+        }
+
+        /// <summary>
+        /// Returns the defined string value of an Enum. Use for test purposes or in other Google.Apis projects.
+        /// </summary>
+        public static string GetEnumStringValue(Enum value)
+        {
+            return value.GetStringValue();
+        }
+
+        /// <summary>
+        /// Tries to convert the specified object to a string. Uses custom type converters if available.
+        /// Returns null for a null object.
+        /// </summary>
+        [VisibleForTestOnly]
+        public static string ConvertToString(object o)
+        {
+            if (o == null)
+            {
+                return null;
+            }
+
+            if (o.GetType().GetTypeInfo().IsEnum)
+            {
+                // Try to convert the Enum value using the StringValue attribute.
+                var enumType = o.GetType();
+                FieldInfo field = enumType.GetField(o.ToString());
+                StringValueAttribute attribute = field.GetCustomAttribute<StringValueAttribute>();
+                return attribute != null ? attribute.Text : o.ToString();
+            }
+
+            if (o is DateTime)
+            {
+                // Honor RFC3339.
+                return ConvertToRFC3339((DateTime)o);
+            }
+
+            if (o is bool)
+            {
+                return o.ToString().ToLowerInvariant();
+            }
+
+            return o.ToString();
+        }
+
+        /// <summary>Converts the input date into a RFC3339 string (http://www.ietf.org/rfc/rfc3339.txt).</summary>
+        internal static string ConvertToRFC3339(DateTime date)
+        {
+            if (date.Kind == DateTimeKind.Unspecified)
+            {
+                date = date.ToUniversalTime();
+            }
+            return date.ToString("yyyy-MM-dd'T'HH:mm:ss.fffK", DateTimeFormatInfo.InvariantInfo);
+        }
+
+        /// <summary>
+        /// Parses the input string and returns <see cref="System.DateTime"/> if the input is a valid 
+        /// representation of a date. Otherwise it returns <c>null</c>.
+        /// </summary>
+        public static DateTime? GetDateTimeFromString(string raw)
+        {
+            DateTime result;
+            if (!DateTime.TryParse(raw, out result))
+            {
+                return null;
+            }
+            return result;
+        }
+
+        /// <summary>Returns a string (by RFC3339) form the input <see cref="DateTime"/> instance.</summary>
+        public static string GetStringFromDateTime(DateTime? date)
+        {
+            if (!date.HasValue)
+            {
+                return null;
+            }
+            return ConvertToRFC3339(date.Value);
+        }
+    }
+}