2 files changed, 175 insertions, 0 deletions
diff --git a/native/dicttoolkit/src/utils/utf8_utils.cpp b/native/dicttoolkit/src/utils/utf8_utils.cpp
new file mode 100644
index 000000000..0f349f512
--- /dev/null
+++ b/native/dicttoolkit/src/utils/utf8_utils.cpp
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "utils/utf8_utils.h"
+
+#include "utils/char_utils.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+const size_t Utf8Utils::MAX_SEQUENCE_SIZE_FOR_A_CODE_POINT = 4;
+const uint8_t Utf8Utils::FIRST_BYTE_MARKER_MASKS[] = {0, 0x80, 0xE0, 0xF0, 0xF8};
+const uint8_t Utf8Utils::FIRST_BYTE_MARKERS[] = {0, 0x00, 0xC0, 0xE0, 0xF0};
+const uint8_t Utf8Utils::FIRST_BYTE_CODE_POINT_BITS_MASKS[] = {0, 0x7F, 0x1F, 0x0F, 0x03};
+const int Utf8Utils::MAX_ENCODED_CODE_POINT_VALUES[] = {-1, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};
+
+const uint8_t Utf8Utils::TRAILING_BYTE_CODE_POINT_BITS_MASK = 0x3F;
+const uint8_t Utf8Utils::TRAILING_BYTE_MARKER = 0x80;
+const size_t Utf8Utils::CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE = 6;
+
+/* static */ std::vector<int> Utf8Utils::getCodePoints(const std::string &utf8Str) {
+    std::vector<int> codePoints;
+    int remainingByteCountForCurrentCodePoint = 0;
+    int currentCodePointSequenceSize = 0;
+    int codePoint = 0;
+    for (const char c : utf8Str) {
+        if (remainingByteCountForCurrentCodePoint == 0) {
+            currentCodePointSequenceSize = getSequenceSizeByCheckingFirstByte(c);
+            if (currentCodePointSequenceSize <= 0) {
+                AKLOGE("%x is an invalid utf8 first byte value.", c);
+                return std::vector<int>();
+            }
+            remainingByteCountForCurrentCodePoint = currentCodePointSequenceSize;
+            codePoint = maskFirstByte(c, remainingByteCountForCurrentCodePoint);
+        } else {
+            codePoint <<= CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE;
+            codePoint += maskTrailingByte(c);
+        }
+        remainingByteCountForCurrentCodePoint--;
+        if (remainingByteCountForCurrentCodePoint == 0) {
+            if (codePoint <= MAX_ENCODED_CODE_POINT_VALUES[currentCodePointSequenceSize - 1]) {
+                AKLOGE("%d bytes encode for codePoint(%x) is a redundant UTF-8 sequence.",
+                        currentCodePointSequenceSize,  codePoint);
+                return std::vector<int>();
+            }
+            codePoints.push_back(codePoint);
+        }
+    }
+    return codePoints;
+}
+
+/* static */ int Utf8Utils::getSequenceSizeByCheckingFirstByte(const uint8_t firstByte) {
+    for (size_t i = 1; i <= MAX_SEQUENCE_SIZE_FOR_A_CODE_POINT; ++i) {
+        if ((firstByte & FIRST_BYTE_MARKER_MASKS[i]) == FIRST_BYTE_MARKERS[i]) {
+            return i;
+        }
+    }
+    // Not a valid utf8 char first byte.
+    return -1;
+}
+
+/* static */ AK_FORCE_INLINE int Utf8Utils::maskFirstByte(const uint8_t firstByte,
+        const int sequenceSize) {
+    return firstByte & FIRST_BYTE_CODE_POINT_BITS_MASKS[sequenceSize];
+}
+
+/* static */ AK_FORCE_INLINE int Utf8Utils::maskTrailingByte(const uint8_t secondOrLaterByte) {
+    return secondOrLaterByte & TRAILING_BYTE_CODE_POINT_BITS_MASK;
+}
+
+/* static */ std::string Utf8Utils::getUtf8String(const CodePointArrayView codePoints) {
+    std::string utf8String;
+    for (const int codePoint : codePoints) {
+        const int sequenceSize = getSequenceSizeToEncodeCodePoint(codePoint);
+        if (sequenceSize <= 0) {
+            AKLOGE("Cannot encode code point (%d).", codePoint);
+            return std::string();
+        }
+        const int trailingByteCount = sequenceSize - 1;
+        // Output first byte.
+        const int value = codePoint >> (trailingByteCount * CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE);
+        utf8String.push_back(static_cast<char>(value | FIRST_BYTE_MARKERS[sequenceSize]));
+        // Output second and later bytes.
+        for (int i = 1; i < sequenceSize; ++i) {
+            const int shiftAmount = (trailingByteCount - i) * CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE;
+            const int value = (codePoint >> shiftAmount) & TRAILING_BYTE_CODE_POINT_BITS_MASK;
+            utf8String.push_back(static_cast<char>(value | TRAILING_BYTE_MARKER));
+        }
+    }
+    return utf8String;
+}
+
+/* static */ int Utf8Utils::getSequenceSizeToEncodeCodePoint(const int codePoint) {
+    if (codePoint < 0) {
+        return -1;
+    }
+    for (size_t i = 1; i <= MAX_SEQUENCE_SIZE_FOR_A_CODE_POINT; ++i) {
+        if (codePoint <= MAX_ENCODED_CODE_POINT_VALUES[i]) {
+            return i;
+        }
+    }
+    return -1;
+}
+
+} // namespace dicttoolkit
+} // namespace latinime
diff --git a/native/dicttoolkit/src/utils/utf8_utils.h b/native/dicttoolkit/src/utils/utf8_utils.h
new file mode 100644
index 000000000..35818e56c
--- /dev/null
+++ b/native/dicttoolkit/src/utils/utf8_utils.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2014 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_DICT_TOOLKIT_UTF8_UTILS_H
+#define LATINIME_DICT_TOOLKIT_UTF8_UTILS_H
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "dict_toolkit_defines.h"
+#include "utils/int_array_view.h"
+
+namespace latinime {
+namespace dicttoolkit {
+
+class Utf8Utils {
+public:
+    static std::vector<int> getCodePoints(const std::string &utf8Str);
+    static std::string getUtf8String(const CodePointArrayView codePoints);
+
+private:
+    DISALLOW_IMPLICIT_CONSTRUCTORS(Utf8Utils);
+
+    // Values indexed by sequence size.
+    static const size_t MAX_SEQUENCE_SIZE_FOR_A_CODE_POINT;
+    static const uint8_t FIRST_BYTE_MARKER_MASKS[];
+    static const uint8_t FIRST_BYTE_MARKERS[];
+    static const uint8_t FIRST_BYTE_CODE_POINT_BITS_MASKS[];
+    static const int MAX_ENCODED_CODE_POINT_VALUES[];
+
+    static const uint8_t TRAILING_BYTE_CODE_POINT_BITS_MASK;
+    static const uint8_t TRAILING_BYTE_MARKER;
+    static const size_t CODE_POINT_BIT_COUNT_IN_TRAILING_BYTE;
+
+    static int getSequenceSizeByCheckingFirstByte(const uint8_t firstByte);
+    static int maskFirstByte(const uint8_t firstByte, const int encodeSize);
+    static int maskTrailingByte(const uint8_t secondOrLaterByte);
+    static int getSequenceSizeToEncodeCodePoint(const int codePoint);
+};
+} // namespace dicttoolkit
+} // namespace latinime
+#endif // LATINIME_DICT_TOOLKIT_UTF8_UTILS_H