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diff --git a/tesseract/unittest/util/utf8/unilib_utf8_utils.h b/tesseract/unittest/util/utf8/unilib_utf8_utils.h
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+/**
+ * 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.
+ */
+
+#ifndef UTIL_UTF8_PUBLIC_UNILIB_UTF8_UTILS_H_
+#define UTIL_UTF8_PUBLIC_UNILIB_UTF8_UTILS_H_
+
+// These definitions are self-contained and have no dependencies.
+// They are also exported from unilib.h for legacy reasons.
+
+#include "syntaxnet/base.h"
+#include "third_party/utf/utf.h"
+
+namespace UniLib {
+
+// Returns true if 'c' is in the range [0, 0xD800) or [0xE000, 0x10FFFF]
+// (i.e., is not a surrogate codepoint). See also
+// IsValidCodepoint(const char* src) in util/utf8/public/unilib.h.
+inline bool IsValidCodepoint(char32 c) {
+  return (static_cast<uint32>(c) < 0xD800)
+    || (c >= 0xE000 && c <= 0x10FFFF);
+}
+
+// Returns true if 'str' is the start of a structurally valid UTF-8
+// sequence and is not a surrogate codepoint. Returns false if str.empty()
+// or if str.length() < UniLib::OneCharLen(str[0]). Otherwise, this function
+// will access 1-4 bytes of src, where n is UniLib::OneCharLen(src[0]).
+inline bool IsUTF8ValidCodepoint(StringPiece str) {
+  char32 c;
+  int consumed;
+  // It's OK if str.length() > consumed.
+  return !str.empty()
+      && isvalidcharntorune(str.data(), str.size(), &c, &consumed)
+      && IsValidCodepoint(c);
+}
+
+// Returns the length (number of bytes) of the Unicode code point
+// starting at src, based on inspecting just that one byte. This
+// requires that src point to a well-formed UTF-8 string; the result
+// is undefined otherwise.
+inline int OneCharLen(const char* src) {
+  return "\1\1\1\1\1\1\1\1\1\1\1\1\2\2\3\4"[(*src & 0xFF) >> 4];
+}
+
+// Returns true if this byte is a trailing UTF-8 byte (10xx xxxx)
+inline bool IsTrailByte(char x) {
+  // return (x & 0xC0) == 0x80;
+  // Since trail bytes are always in [0x80, 0xBF], we can optimize:
+  return static_cast<signed char>(x) < -0x40;
+}
+
+}  // namespace UniLib
+
+#endif  // UTIL_UTF8_PUBLIC_UNILIB_UTF8_UTILS_H_