1 files changed, 155 insertions, 0 deletions
diff --git a/src/mscorlib/src/System/Globalization/TextElementEnumerator.cs b/src/mscorlib/src/System/Globalization/TextElementEnumerator.cs
new file mode 100644
index 0000000000..5f47f5fbd4
--- /dev/null
+++ b/src/mscorlib/src/System/Globalization/TextElementEnumerator.cs
@@ -0,0 +1,155 @@
+// 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:  
+//
+//
+////////////////////////////////////////////////////////////////////////////
+
+using System.Runtime.Serialization;
+
+
+namespace System.Globalization {
+    using System.Collections;
+    using System.Diagnostics.Contracts;
+
+    //
+    // This is public because GetTextElement() is public.
+    //
+
+    [Serializable]
+    [System.Runtime.InteropServices.ComVisible(true)]
+    public class TextElementEnumerator: IEnumerator
+    {
+        private String str;
+        private int index;
+        private int startIndex;
+        
+        [NonSerialized] 
+        private int strLen;                // This is the length of the total string, counting from the beginning of string.
+        
+        [NonSerialized]
+        private int currTextElementLen; // The current text element lenght after MoveNext() is called.
+        
+        [OptionalField(VersionAdded = 2)] 
+        private UnicodeCategory uc;
+        
+        [OptionalField(VersionAdded = 2)] 
+        private int charLen;            // The next abstract char to look at after MoveNext() is called.  It could be 1 or 2, depending on if it is a surrogate or not.
+
+        internal TextElementEnumerator(String str, int startIndex, int strLen)
+        {
+            Contract.Assert(str != null, "TextElementEnumerator(): str != null");
+            Contract.Assert(startIndex >= 0 && strLen >= 0, "TextElementEnumerator(): startIndex >= 0 && strLen >= 0");
+            Contract.Assert(strLen >= startIndex, "TextElementEnumerator(): strLen >= startIndex");
+            this.str = str;
+            this.startIndex = startIndex;
+            this.strLen = strLen;
+            Reset();
+        }
+
+#region Serialization 
+        // the following fields is defined to keep the compatibility with Everett.
+        // don't change/remove the names/types of these fields.
+        private int endIndex;
+        private int nextTextElementLen;
+
+        [OnDeserializing] 
+        private void OnDeserializing(StreamingContext ctx) 
+        { 
+            charLen = -1;    
+        }   
+        
+        [OnDeserialized]
+        private void OnDeserialized(StreamingContext ctx)
+        {
+            strLen              = endIndex + 1;
+            currTextElementLen  = nextTextElementLen;
+
+            if (charLen == -1)
+            {
+                uc = CharUnicodeInfo.InternalGetUnicodeCategory(str, index, out charLen);
+            }
+        }   
+        
+        [OnSerializing] 
+        private void OnSerializing(StreamingContext ctx) 
+        { 
+            endIndex            = strLen - 1;
+            nextTextElementLen  = currTextElementLen;
+        }   
+
+#endregion Serialization
+
+
+
+        public bool MoveNext()
+        {
+            if (index >= strLen)
+            {
+                // Make the index to be greater than strLen so that we can throw exception if GetTextElement() is called.
+                index = strLen + 1;
+                return (false);
+            }
+            currTextElementLen = StringInfo.GetCurrentTextElementLen(str, index, strLen, ref uc, ref charLen);
+            index += currTextElementLen;
+            return (true);
+        }
+
+        //
+        // Get the current text element.
+        //
+
+        public Object Current {
+            get {
+                return (GetTextElement());
+            }
+        }
+
+        //
+        // Get the current text element.
+        //
+
+        public String GetTextElement()
+        {
+            if (index == startIndex) {
+                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_EnumNotStarted"));
+            }
+            if (index > strLen) {
+                throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_EnumEnded"));                        
+            }                
+            
+            return (str.Substring(index - currTextElementLen, currTextElementLen));
+        }
+        
+        //
+        // Get the starting index of the current text element.
+        //
+
+        public int ElementIndex
+        {
+            get
+            {
+                if (index == startIndex) 
+                {
+                    throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_EnumNotStarted"));
+                }
+                return (index - currTextElementLen);
+            }
+        }
+
+
+        public void Reset()
+        {
+            index = startIndex;
+            if (index < strLen) {
+                // If we have more than 1 character, get the category of the current char.
+                uc = CharUnicodeInfo.InternalGetUnicodeCategory(str, index, out charLen);
+            }            
+        }
+    }
+}