Add spellcheck and word suggestion to the prediction service

third_party/android_prediction/suggest/policyimpl/dictionary/utils/byte_array_utils.h

+/*
+ * 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_BYTE_ARRAY_UTILS_H
+#define LATINIME_BYTE_ARRAY_UTILS_H
+
+#include <cstdint>
+
+#include "third_party/android_prediction/defines.h"
+
+namespace latinime {
+
+/**
+ * Utility methods for reading byte arrays.
+ */
+class ByteArrayUtils {
+ public:
+    /**
+     * Integer writing
+     *
+     * Each method write a corresponding size integer in a big endian manner.
+     */
+    static AK_FORCE_INLINE void writeUintAndAdvancePosition(uint8_t *const buffer,
+            const uint32_t data, const int size, int *const pos) {
+        // size must be in 1 to 4.
+        ASSERT(size >= 1 && size <= 4);
+        switch (size) {
+            case 1:
+                ByteArrayUtils::writeUint8AndAdvancePosition(buffer, data, pos);
+                return;
+            case 2:
+                ByteArrayUtils::writeUint16AndAdvancePosition(buffer, data, pos);
+                return;
+            case 3:
+                ByteArrayUtils::writeUint24AndAdvancePosition(buffer, data, pos);
+                return;
+            case 4:
+                ByteArrayUtils::writeUint32AndAdvancePosition(buffer, data, pos);
+                return;
+            default:
+                break;
+        }
+    }
+
+    /**
+     * Integer reading
+     *
+     * Each method read a corresponding size integer in a big endian manner.
+     */
+    static AK_FORCE_INLINE uint32_t readUint32(const uint8_t *const buffer, const int pos) {
+        return (buffer[pos] << 24) ^ (buffer[pos + 1] << 16)
+                ^ (buffer[pos + 2] << 8) ^ buffer[pos + 3];
+    }
+
+    static AK_FORCE_INLINE uint32_t readUint24(const uint8_t *const buffer, const int pos) {
+        return (buffer[pos] << 16) ^ (buffer[pos + 1] << 8) ^ buffer[pos + 2];
+    }
+
+    static AK_FORCE_INLINE uint16_t readUint16(const uint8_t *const buffer, const int pos) {
+        return (buffer[pos] << 8) ^ buffer[pos + 1];
+    }
+
+    static AK_FORCE_INLINE uint8_t readUint8(const uint8_t *const buffer, const int pos) {
+        return buffer[pos];
+    }
+
+    static AK_FORCE_INLINE uint32_t readUint32AndAdvancePosition(
+            const uint8_t *const buffer, int *const pos) {
+        const uint32_t value = readUint32(buffer, *pos);
+        *pos += 4;
+        return value;
+    }
+
+    static AK_FORCE_INLINE int readSint24AndAdvancePosition(
+            const uint8_t *const buffer, int *const pos) {
+        const uint8_t value = readUint8(buffer, *pos);
+        if (value < 0x80) {
+            return readUint24AndAdvancePosition(buffer, pos);
+        } else {
+            (*pos)++;
+            return -(((value & 0x7F) << 16) ^ readUint16AndAdvancePosition(buffer, pos));
+        }
+    }
+
+    static AK_FORCE_INLINE uint32_t readUint24AndAdvancePosition(
+            const uint8_t *const buffer, int *const pos) {
+        const uint32_t value = readUint24(buffer, *pos);
+        *pos += 3;
+        return value;
+    }
+
+    static AK_FORCE_INLINE uint16_t readUint16AndAdvancePosition(
+            const uint8_t *const buffer, int *const pos) {
+        const uint16_t value = readUint16(buffer, *pos);
+        *pos += 2;
+        return value;
+    }
+
+    static AK_FORCE_INLINE uint8_t readUint8AndAdvancePosition(
+            const uint8_t *const buffer, int *const pos) {
+        return buffer[(*pos)++];
+    }
+
+    static AK_FORCE_INLINE int readUint(const uint8_t *const buffer,
+            const int size, const int pos) {
+        // size must be in 1 to 4.
+        ASSERT(size >= 1 && size <= 4);
+        switch (size) {
+            case 1:
+                return ByteArrayUtils::readUint8(buffer, pos);
+            case 2:
+                return ByteArrayUtils::readUint16(buffer, pos);
+            case 3:
+                return ByteArrayUtils::readUint24(buffer, pos);
+            case 4:
+                return ByteArrayUtils::readUint32(buffer, pos);
+            default:
+                return 0;
+        }
+    }
+
+    /**
+     * Code Point Reading
+     *
+     * 1 byte = bbbbbbbb match
+     * case 000xxxxx: xxxxx << 16 + next byte << 8 + next byte
+     * else: if 00011111 (= 0x1F) : this is the terminator. This is a relevant choice because
+     *       unicode code points range from 0 to 0x10FFFF, so any 3-byte value starting with
+     *       00011111 would be outside unicode.
+     * else: iso-latin-1 code
+     * This allows for the whole unicode range to be encoded, including chars outside of
+     * the BMP. Also everything in the iso-latin-1 charset is only 1 byte, except control
+     * characters which should never happen anyway (and still work, but take 3 bytes).
+     */
+    static AK_FORCE_INLINE int readCodePoint(const uint8_t *const buffer, const int pos) {
+        int p = pos;
+        return readCodePointAndAdvancePosition(buffer, &p);
+    }
+
+    static AK_FORCE_INLINE int readCodePointAndAdvancePosition(
+            const uint8_t *const buffer, int *const pos) {
+        const uint8_t firstByte = readUint8(buffer, *pos);
+        if (firstByte < MINIMUM_ONE_BYTE_CHARACTER_VALUE) {
+            if (firstByte == CHARACTER_ARRAY_TERMINATOR) {
+                *pos += 1;
+                return NOT_A_CODE_POINT;
+            } else {
+                return readUint24AndAdvancePosition(buffer, pos);
+            }
+        } else {
+            *pos += 1;
+            return firstByte;
+        }
+    }
+
+    /**
+     * String (array of code points) Reading
+     *
+     * Reads code points until the terminator is found.
+     */
+    // Returns the length of the string.
+    static int readStringAndAdvancePosition(const uint8_t *const buffer,
+            const int maxLength, int *const outBuffer, int *const pos) {
+        int length = 0;
+        int codePoint = readCodePointAndAdvancePosition(buffer, pos);
+        while (NOT_A_CODE_POINT != codePoint && length < maxLength) {
+            outBuffer[length++] = codePoint;
+            codePoint = readCodePointAndAdvancePosition(buffer, pos);
+        }
+        return length;
+    }
+
+    // Advances the position and returns the length of the string.
+    static int advancePositionToBehindString(
+            const uint8_t *const buffer, const int maxLength, int *const pos) {
+        int length = 0;
+        int codePoint = readCodePointAndAdvancePosition(buffer, pos);
+        while (NOT_A_CODE_POINT != codePoint && length < maxLength) {
+            codePoint = readCodePointAndAdvancePosition(buffer, pos);
+            length++;
+        }
+        return length;
+    }
+
+    /**
+     * String (array of code points) Writing
+     */
+    static void writeCodePointsAndAdvancePosition(uint8_t *const buffer,
+            const int *const codePoints, const int codePointCount, const bool writesTerminator,
+            int *const pos) {
+        for (int i = 0; i < codePointCount; ++i) {
+            const int codePoint = codePoints[i];
+            if (codePoint == NOT_A_CODE_POINT || codePoint == CHARACTER_ARRAY_TERMINATOR) {
+                break;
+            } else if (codePoint < MINIMUM_ONE_BYTE_CHARACTER_VALUE
+                    || codePoint > MAXIMUM_ONE_BYTE_CHARACTER_VALUE) {
+                // three bytes character.
+                writeUint24AndAdvancePosition(buffer, codePoint, pos);
+            } else {
+                // one byte character.
+                writeUint8AndAdvancePosition(buffer, codePoint, pos);
+            }
+        }
+        if (writesTerminator) {
+            writeUint8AndAdvancePosition(buffer, CHARACTER_ARRAY_TERMINATOR, pos);
+        }
+    }
+
+    static int calculateRequiredByteCountToStoreCodePoints(const int *const codePoints,
+            const int codePointCount, const bool writesTerminator) {
+        int byteCount = 0;
+        for (int i = 0; i < codePointCount; ++i) {
+            const int codePoint = codePoints[i];
+            if (codePoint == NOT_A_CODE_POINT || codePoint == CHARACTER_ARRAY_TERMINATOR) {
+                break;
+            } else if (codePoint < MINIMUM_ONE_BYTE_CHARACTER_VALUE
+                    || codePoint > MAXIMUM_ONE_BYTE_CHARACTER_VALUE) {
+                // three bytes character.
+                byteCount += 3;
+            } else {
+                // one byte character.
+                byteCount += 1;
+            }
+        }
+        if (writesTerminator) {
+            // The terminator is one byte.
+            byteCount += 1;
+        }
+        return byteCount;
+    }
+
+ private:
+    DISALLOW_IMPLICIT_CONSTRUCTORS(ByteArrayUtils);
+
+    static const uint8_t MINIMUM_ONE_BYTE_CHARACTER_VALUE;
+    static const uint8_t MAXIMUM_ONE_BYTE_CHARACTER_VALUE;
+    static const uint8_t CHARACTER_ARRAY_TERMINATOR;
+
+    static AK_FORCE_INLINE void writeUint32AndAdvancePosition(uint8_t *const buffer,
+            const uint32_t data, int *const pos) {
+        buffer[(*pos)++] = (data >> 24) & 0xFF;
+        buffer[(*pos)++] = (data >> 16) & 0xFF;
+        buffer[(*pos)++] = (data >> 8) & 0xFF;
+        buffer[(*pos)++] = data & 0xFF;
+    }
+
+    static AK_FORCE_INLINE void writeUint24AndAdvancePosition(uint8_t *const buffer,
+            const uint32_t data, int *const pos) {
+        buffer[(*pos)++] = (data >> 16) & 0xFF;
+        buffer[(*pos)++] = (data >> 8) & 0xFF;
+        buffer[(*pos)++] = data & 0xFF;
+    }
+
+    static AK_FORCE_INLINE void writeUint16AndAdvancePosition(uint8_t *const buffer,
+            const uint16_t data, int *const pos) {
+        buffer[(*pos)++] = (data >> 8) & 0xFF;
+        buffer[(*pos)++] = data & 0xFF;
+    }
+
+    static AK_FORCE_INLINE void writeUint8AndAdvancePosition(uint8_t *const buffer,
+            const uint8_t data, int *const pos) {
+        buffer[(*pos)++] = data & 0xFF;
+    }
+};
+} // namespace latinime
+#endif /* LATINIME_BYTE_ARRAY_UTILS_H */