1/*
2 * Copyright (C) 2013, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "suggest/policyimpl/dictionary/patricia_trie_reading_utils.h"
18
19#include "defines.h"
20#include "suggest/policyimpl/dictionary/utils/byte_array_utils.h"
21
22namespace latinime {
23
24typedef PatriciaTrieReadingUtils PtReadingUtils;
25
26const PtReadingUtils::NodeFlags PtReadingUtils::MASK_CHILDREN_POSITION_TYPE = 0xC0;
27const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_CHILDREN_POSITION_TYPE_NOPOSITION = 0x00;
28const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_CHILDREN_POSITION_TYPE_ONEBYTE = 0x40;
29const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_CHILDREN_POSITION_TYPE_TWOBYTES = 0x80;
30const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_CHILDREN_POSITION_TYPE_THREEBYTES = 0xC0;
31
32// Flag for single/multiple char group
33const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_HAS_MULTIPLE_CHARS = 0x20;
34// Flag for terminal PtNodes
35const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_IS_TERMINAL = 0x10;
36// Flag for shortcut targets presence
37const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_HAS_SHORTCUT_TARGETS = 0x08;
38// Flag for bigram presence
39const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_HAS_BIGRAMS = 0x04;
40// Flag for non-words (typically, shortcut only entries)
41const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_IS_NOT_A_WORD = 0x02;
42// Flag for blacklist
43const PtReadingUtils::NodeFlags PtReadingUtils::FLAG_IS_BLACKLISTED = 0x01;
44
45/* static */ int PtReadingUtils::getPtNodeArraySizeAndAdvancePosition(
46        const uint8_t *const buffer, int *const pos) {
47    const uint8_t firstByte = ByteArrayUtils::readUint8AndAdvancePosition(buffer, pos);
48    if (firstByte < 0x80) {
49        return firstByte;
50    } else {
51        return ((firstByte & 0x7F) << 8) ^ ByteArrayUtils::readUint8AndAdvancePosition(
52                buffer, pos);
53    }
54}
55
56/* static */ PtReadingUtils::NodeFlags PtReadingUtils::getFlagsAndAdvancePosition(
57        const uint8_t *const buffer, int *const pos) {
58    return ByteArrayUtils::readUint8AndAdvancePosition(buffer, pos);
59}
60
61/* static */ int PtReadingUtils::getCodePointAndAdvancePosition(const uint8_t *const buffer,
62        int *const pos) {
63    return ByteArrayUtils::readCodePointAndAdvancePosition(buffer, pos);
64}
65
66// Returns the number of read characters.
67/* static */ int PtReadingUtils::getCharsAndAdvancePosition(const uint8_t *const buffer,
68        const NodeFlags flags, const int maxLength, int *const outBuffer, int *const pos) {
69    int length = 0;
70    if (hasMultipleChars(flags)) {
71        length = ByteArrayUtils::readStringAndAdvancePosition(buffer, maxLength, outBuffer,
72                pos);
73    } else {
74        const int codePoint = getCodePointAndAdvancePosition(buffer, pos);
75        if (codePoint == NOT_A_CODE_POINT) {
76            // CAVEAT: codePoint == NOT_A_CODE_POINT means the code point is
77            // CHARACTER_ARRAY_TERMINATOR. The code point must not be CHARACTER_ARRAY_TERMINATOR
78            // when the PtNode has a single code point.
79            length = 0;
80            AKLOGE("codePoint is NOT_A_CODE_POINT. pos: %d, codePoint: 0x%x, buffer[pos - 1]: 0x%x",
81                    *pos - 1, codePoint, buffer[*pos - 1]);
82            ASSERT(false);
83        } else if (maxLength > 0) {
84            outBuffer[0] = codePoint;
85            length = 1;
86        }
87    }
88    return length;
89}
90
91// Returns the number of skipped characters.
92/* static */ int PtReadingUtils::skipCharacters(const uint8_t *const buffer, const NodeFlags flags,
93        const int maxLength, int *const pos) {
94    if (hasMultipleChars(flags)) {
95        return ByteArrayUtils::advancePositionToBehindString(buffer, maxLength, pos);
96    } else {
97        if (maxLength > 0) {
98            getCodePointAndAdvancePosition(buffer, pos);
99            return 1;
100        } else {
101            return 0;
102        }
103    }
104}
105
106/* static */ int PtReadingUtils::readProbabilityAndAdvancePosition(const uint8_t *const buffer,
107        int *const pos) {
108    return ByteArrayUtils::readUint8AndAdvancePosition(buffer, pos);
109}
110
111/* static */ int PtReadingUtils::readChildrenPositionAndAdvancePosition(
112        const uint8_t *const buffer, const NodeFlags flags, int *const pos) {
113    const int base = *pos;
114    int offset = 0;
115    switch (MASK_CHILDREN_POSITION_TYPE & flags) {
116        case FLAG_CHILDREN_POSITION_TYPE_ONEBYTE:
117            offset = ByteArrayUtils::readUint8AndAdvancePosition(buffer, pos);
118            break;
119        case FLAG_CHILDREN_POSITION_TYPE_TWOBYTES:
120            offset = ByteArrayUtils::readUint16AndAdvancePosition(buffer, pos);
121            break;
122        case FLAG_CHILDREN_POSITION_TYPE_THREEBYTES:
123            offset = ByteArrayUtils::readUint24AndAdvancePosition(buffer, pos);
124            break;
125        default:
126            // If we come here, it means we asked for the children of a word with
127            // no children.
128            return NOT_A_DICT_POS;
129    }
130    return base + offset;
131}
132
133} // namespace latinime
134