--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Implab/Formats/Json/JsonStringScanner.cs	Thu Sep 21 01:14:27 2017 +0300
@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Implab.Formats.Json {
+    public class JsonStringScanner : JsonScanner {
+        const int _defaultBuffer = 64;
+
+        readonly string m_data;
+        int m_offset;
+
+        JsonStringScanner(string data, char[] buffer, int pos, int length, int offset) : base(buffer, pos, length) {
+            m_data = data;
+            m_offset = offset;
+        }
+
+        protected override int Read(char[] buffer, int offset, int size) {
+            if (m_data == null)
+                return 0;
+            if (m_offset >= m_data.Length)
+                return 0;
+
+            var count = Math.Min(size, m_data.Length - m_offset);
+
+            m_data.CopyTo(m_offset, buffer, offset, count);
+            m_offset += count;
+
+            return count;
+        }
+
+        public static JsonStringScanner Create(string data) {
+            Safe.ArgumentNotNull(data, nameof(data));
+
+            if (data.Length <= _defaultBuffer)
+                return new JsonStringScanner(null, data.ToCharArray(), 0, data.Length, data.Length);
+
+            var buffer = new char[_defaultBuffer];
+            data.CopyTo(0, buffer, 0, _defaultBuffer);
+            return new JsonStringScanner(data, buffer, 0, _defaultBuffer, _defaultBuffer);
+        }
+
+        public static JsonStringScanner Create(string data, int offset, int length) {
+            Safe.ArgumentNotNull(data, nameof(data));
+            Safe.ArgumentGreaterThan(offset, 0, nameof(offset));
+            Safe.ArgumentGreaterThan(length, 0, nameof(length));
+
+            if (offset + length > data.Length)
+                throw new ArgumentOutOfRangeException("Specified offset and length are out of the string bounds");
+
+            if (length <= _defaultBuffer) {
+                var buffer = new char[length];
+                data.CopyTo(offset, buffer, 0, length);
+
+                return new JsonStringScanner(null, buffer, 0, length, length);
+            } else {
+                var buffer = new char[_defaultBuffer];
+                data.CopyTo(offset, buffer, 0, _defaultBuffer);
+                return new JsonStringScanner(data, buffer, 0, _defaultBuffer, offset + _defaultBuffer);
+            }
+        }
+
+        public static JsonStringScanner Create(char[] data, int offset, int length) {
+            Safe.ArgumentNotNull(data, nameof(data));
+            Safe.ArgumentGreaterThan(offset, 0, nameof(offset));
+            Safe.ArgumentGreaterThan(length, 0, nameof(length));
+
+            if (offset + length > data.Length)
+                throw new ArgumentOutOfRangeException("Specified offset and length are out of the array bounds");
+
+            return new JsonStringScanner(null, data, offset, offset + length, offset + length);
+
+        }
+    }
+}