1 files changed, 58 insertions, 0 deletions
diff --git a/src/mscorlib/shared/System/Runtime/CompilerServices/FormattableStringFactory.cs b/src/mscorlib/shared/System/Runtime/CompilerServices/FormattableStringFactory.cs
new file mode 100644
index 0000000000..23d03860ed
--- /dev/null
+++ b/src/mscorlib/shared/System/Runtime/CompilerServices/FormattableStringFactory.cs
@@ -0,0 +1,58 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+/*============================================================
+**
+**
+**
+** Purpose: implementation of the FormattableStringFactory
+** class.
+**
+===========================================================*/
+
+namespace System.Runtime.CompilerServices
+{
+    /// <summary>
+    /// A factory type used by compilers to create instances of the type <see cref="FormattableString"/>.
+    /// </summary>
+    public static class FormattableStringFactory
+    {
+        /// <summary>
+        /// Create a <see cref="FormattableString"/> from a composite format string and object
+        /// array containing zero or more objects to format.
+        /// </summary>
+        public static FormattableString Create(string format, params object[] arguments)
+        {
+            if (format == null)
+            {
+                throw new ArgumentNullException(nameof(format));
+            }
+
+            if (arguments == null)
+            {
+                throw new ArgumentNullException(nameof(arguments));
+            }
+
+            return new ConcreteFormattableString(format, arguments);
+        }
+
+        private sealed class ConcreteFormattableString : FormattableString
+        {
+            private readonly string _format;
+            private readonly object[] _arguments;
+
+            internal ConcreteFormattableString(string format, object[] arguments)
+            {
+                _format = format;
+                _arguments = arguments;
+            }
+
+            public override string Format { get { return _format; } }
+            public override object[] GetArguments() { return _arguments; }
+            public override int ArgumentCount { get { return _arguments.Length; } }
+            public override object GetArgument(int index) { return _arguments[index]; }
+            public override string ToString(IFormatProvider formatProvider) { return string.Format(formatProvider, _format, _arguments); }
+        }
+    }
+}