1 files changed, 154 insertions, 0 deletions
diff --git a/src/mscorlib/corefx/System/Globalization/TextElementEnumerator.cs b/src/mscorlib/corefx/System/Globalization/TextElementEnumerator.cs
new file mode 100644
index 0000000000..487ef11130
--- /dev/null
+++ b/src/mscorlib/corefx/System/Globalization/TextElementEnumerator.cs
@@ -0,0 +1,154 @@
+// 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.Collections;
+using System.Diagnostics.Contracts;
+using System.Runtime.Serialization;
+
+namespace System.Globalization
+{
+    //
+    // 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");
+            _str = str;
+            _startIndex = startIndex;
+            _strLen = strLen;
+            Reset();
+        }
+
+        // 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;
+        }
+
+        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(SR.InvalidOperation_EnumNotStarted);
+            }
+            if (_index > _strLen)
+            {
+                throw new InvalidOperationException(SR.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(SR.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);
+            }
+        }
+    }
+}