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diff --git a/native/jni/src/dictionary/utils/mmapped_buffer.h b/native/jni/src/dictionary/utils/mmapped_buffer.h
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+++ b/native/jni/src/dictionary/utils/mmapped_buffer.h
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+/*
+ * Copyright (C) 2013, The Android Open Source Project
+ *
+ * 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 LATINIME_MMAPPED_BUFFER_H
+#define LATINIME_MMAPPED_BUFFER_H
+
+#include <cstdint>
+#include <memory>
+
+#include "defines.h"
+#include "utils/byte_array_view.h"
+
+namespace latinime {
+
+class MmappedBuffer {
+ public:
+    typedef std::unique_ptr<const MmappedBuffer> MmappedBufferPtr;
+
+    static MmappedBufferPtr openBuffer(const char *const path,
+            const int bufferOffset, const int bufferSize, const bool isUpdatable);
+
+    // Mmap entire file.
+    static MmappedBufferPtr openBuffer(const char *const path, const bool isUpdatable);
+
+    static MmappedBufferPtr openBuffer(const char *const dirPath, const char *const fileName,
+            const bool isUpdatable);
+
+    ~MmappedBuffer();
+
+    ReadWriteByteArrayView getReadWriteByteArrayView() const {
+        return mByteArrayView;
+    }
+
+    ReadOnlyByteArrayView getReadOnlyByteArrayView() const {
+        return mByteArrayView.getReadOnlyView();
+    }
+
+    AK_FORCE_INLINE bool isUpdatable() const {
+        return mIsUpdatable;
+    }
+
+ private:
+    AK_FORCE_INLINE MmappedBuffer(uint8_t *const buffer, const int bufferSize,
+            void *const mmappedBuffer, const int alignedSize, const int mmapFd,
+            const bool isUpdatable)
+            : mByteArrayView(buffer, bufferSize), mMmappedBuffer(mmappedBuffer),
+              mAlignedSize(alignedSize), mMmapFd(mmapFd), mIsUpdatable(isUpdatable) {}
+
+    // Empty file. We have to handle an empty file as a valid part of a dictionary.
+    AK_FORCE_INLINE MmappedBuffer(const bool isUpdatable)
+            : mByteArrayView(), mMmappedBuffer(nullptr), mAlignedSize(0),
+              mMmapFd(0), mIsUpdatable(isUpdatable) {}
+
+    DISALLOW_IMPLICIT_CONSTRUCTORS(MmappedBuffer);
+
+    const ReadWriteByteArrayView mByteArrayView;
+    void *const mMmappedBuffer;
+    const int mAlignedSize;
+    const int mMmapFd;
+    const bool mIsUpdatable;
+};
+}
+#endif /* LATINIME_MMAPPED_BUFFER_H */