1 /*
2 * Copyright (C) 2015 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 <vector>
18 #include <memory>
19 #include <algorithm>
20 #include <string>
21 #include <unicode/uchar.h>
22
23 // HACK: for reading pattern file
24 #include <fcntl.h>
25
26 #define LOG_TAG "Minikin"
27 #include "utils/Log.h"
28
29 #include "minikin/Hyphenator.h"
30
31 using std::vector;
32
33 namespace android {
34
35 static const uint16_t CHAR_SOFT_HYPHEN = 0x00AD;
36
37 // The following are structs that correspond to tables inside the hyb file format
38
39 struct AlphabetTable0 {
40 uint32_t version;
41 uint32_t min_codepoint;
42 uint32_t max_codepoint;
43 uint8_t data[1]; // actually flexible array, size is known at runtime
44 };
45
46 struct AlphabetTable1 {
47 uint32_t version;
48 uint32_t n_entries;
49 uint32_t data[1]; // actually flexible array, size is known at runtime
50
codepointandroid::AlphabetTable151 static uint32_t codepoint(uint32_t entry) { return entry >> 11; }
valueandroid::AlphabetTable152 static uint32_t value(uint32_t entry) { return entry & 0x7ff; }
53 };
54
55 struct Trie {
56 uint32_t version;
57 uint32_t char_mask;
58 uint32_t link_shift;
59 uint32_t link_mask;
60 uint32_t pattern_shift;
61 uint32_t n_entries;
62 uint32_t data[1]; // actually flexible array, size is known at runtime
63 };
64
65 struct Pattern {
66 uint32_t version;
67 uint32_t n_entries;
68 uint32_t pattern_offset;
69 uint32_t pattern_size;
70 uint32_t data[1]; // actually flexible array, size is known at runtime
71
72 // accessors
lenandroid::Pattern73 static uint32_t len(uint32_t entry) { return entry >> 26; }
shiftandroid::Pattern74 static uint32_t shift(uint32_t entry) { return (entry >> 20) & 0x3f; }
bufandroid::Pattern75 const uint8_t* buf(uint32_t entry) const {
76 return reinterpret_cast<const uint8_t*>(this) + pattern_offset + (entry & 0xfffff);
77 }
78 };
79
80 struct Header {
81 uint32_t magic;
82 uint32_t version;
83 uint32_t alphabet_offset;
84 uint32_t trie_offset;
85 uint32_t pattern_offset;
86 uint32_t file_size;
87
88 // accessors
bytesandroid::Header89 const uint8_t* bytes() const { return reinterpret_cast<const uint8_t*>(this); }
alphabetVersionandroid::Header90 uint32_t alphabetVersion() const {
91 return *reinterpret_cast<const uint32_t*>(bytes() + alphabet_offset);
92 }
alphabetTable0android::Header93 const AlphabetTable0* alphabetTable0() const {
94 return reinterpret_cast<const AlphabetTable0*>(bytes() + alphabet_offset);
95 }
alphabetTable1android::Header96 const AlphabetTable1* alphabetTable1() const {
97 return reinterpret_cast<const AlphabetTable1*>(bytes() + alphabet_offset);
98 }
trieTableandroid::Header99 const Trie* trieTable() const {
100 return reinterpret_cast<const Trie*>(bytes() + trie_offset);
101 }
patternTableandroid::Header102 const Pattern* patternTable() const {
103 return reinterpret_cast<const Pattern*>(bytes() + pattern_offset);
104 }
105 };
106
loadBinary(const uint8_t * patternData)107 Hyphenator* Hyphenator::loadBinary(const uint8_t* patternData) {
108 Hyphenator* result = new Hyphenator;
109 result->patternData = patternData;
110 return result;
111 }
112
hyphenate(vector<uint8_t> * result,const uint16_t * word,size_t len)113 void Hyphenator::hyphenate(vector<uint8_t>* result, const uint16_t* word, size_t len) {
114 result->clear();
115 result->resize(len);
116 const size_t paddedLen = len + 2; // start and stop code each count for 1
117 if (patternData != nullptr &&
118 (int)len >= MIN_PREFIX + MIN_SUFFIX && paddedLen <= MAX_HYPHENATED_SIZE) {
119 uint16_t alpha_codes[MAX_HYPHENATED_SIZE];
120 if (alphabetLookup(alpha_codes, word, len)) {
121 hyphenateFromCodes(result->data(), alpha_codes, paddedLen);
122 return;
123 }
124 // TODO: try NFC normalization
125 // TODO: handle non-BMP Unicode (requires remapping of offsets)
126 }
127 hyphenateSoft(result->data(), word, len);
128 }
129
130 // If any soft hyphen is present in the word, use soft hyphens to decide hyphenation,
131 // as recommended in UAX #14 (Use of Soft Hyphen)
hyphenateSoft(uint8_t * result,const uint16_t * word,size_t len)132 void Hyphenator::hyphenateSoft(uint8_t* result, const uint16_t* word, size_t len) {
133 result[0] = 0;
134 for (size_t i = 1; i < len; i++) {
135 result[i] = word[i - 1] == CHAR_SOFT_HYPHEN;
136 }
137 }
138
alphabetLookup(uint16_t * alpha_codes,const uint16_t * word,size_t len)139 bool Hyphenator::alphabetLookup(uint16_t* alpha_codes, const uint16_t* word, size_t len) {
140 const Header* header = getHeader();
141 // TODO: check header magic
142 uint32_t alphabetVersion = header->alphabetVersion();
143 if (alphabetVersion == 0) {
144 const AlphabetTable0* alphabet = header->alphabetTable0();
145 uint32_t min_codepoint = alphabet->min_codepoint;
146 uint32_t max_codepoint = alphabet->max_codepoint;
147 alpha_codes[0] = 0; // word start
148 for (size_t i = 0; i < len; i++) {
149 uint16_t c = word[i];
150 if (c < min_codepoint || c >= max_codepoint) {
151 return false;
152 }
153 uint8_t code = alphabet->data[c - min_codepoint];
154 if (code == 0) {
155 return false;
156 }
157 alpha_codes[i + 1] = code;
158 }
159 alpha_codes[len + 1] = 0; // word termination
160 return true;
161 } else if (alphabetVersion == 1) {
162 const AlphabetTable1* alphabet = header->alphabetTable1();
163 size_t n_entries = alphabet->n_entries;
164 const uint32_t* begin = alphabet->data;
165 const uint32_t* end = begin + n_entries;
166 alpha_codes[0] = 0;
167 for (size_t i = 0; i < len; i++) {
168 uint16_t c = word[i];
169 auto p = std::lower_bound(begin, end, c << 11);
170 if (p == end) {
171 return false;
172 }
173 uint32_t entry = *p;
174 if (AlphabetTable1::codepoint(entry) != c) {
175 return false;
176 }
177 alpha_codes[i + 1] = AlphabetTable1::value(entry);
178 }
179 alpha_codes[len + 1] = 0;
180 return true;
181 }
182 return false;
183 }
184
185 /**
186 * Internal implementation, after conversion to codes. All case folding and normalization
187 * has been done by now, and all characters have been found in the alphabet.
188 * Note: len here is the padded length including 0 codes at start and end.
189 **/
hyphenateFromCodes(uint8_t * result,const uint16_t * codes,size_t len)190 void Hyphenator::hyphenateFromCodes(uint8_t* result, const uint16_t* codes, size_t len) {
191 const Header* header = getHeader();
192 const Trie* trie = header->trieTable();
193 const Pattern* pattern = header->patternTable();
194 uint32_t char_mask = trie->char_mask;
195 uint32_t link_shift = trie->link_shift;
196 uint32_t link_mask = trie->link_mask;
197 uint32_t pattern_shift = trie->pattern_shift;
198 size_t maxOffset = len - MIN_SUFFIX - 1;
199 for (size_t i = 0; i < len - 1; i++) {
200 uint32_t node = 0; // index into Trie table
201 for (size_t j = i; j < len; j++) {
202 uint16_t c = codes[j];
203 uint32_t entry = trie->data[node + c];
204 if ((entry & char_mask) == c) {
205 node = (entry & link_mask) >> link_shift;
206 } else {
207 break;
208 }
209 uint32_t pat_ix = trie->data[node] >> pattern_shift;
210 // pat_ix contains a 3-tuple of length, shift (number of trailing zeros), and an offset
211 // into the buf pool. This is the pattern for the substring (i..j) we just matched,
212 // which we combine (via point-wise max) into the result vector.
213 if (pat_ix != 0) {
214 uint32_t pat_entry = pattern->data[pat_ix];
215 int pat_len = Pattern::len(pat_entry);
216 int pat_shift = Pattern::shift(pat_entry);
217 const uint8_t* pat_buf = pattern->buf(pat_entry);
218 int offset = j + 1 - (pat_len + pat_shift);
219 // offset is the index within result that lines up with the start of pat_buf
220 int start = std::max(MIN_PREFIX - offset, 0);
221 int end = std::min(pat_len, (int)maxOffset - offset);
222 for (int k = start; k < end; k++) {
223 result[offset + k] = std::max(result[offset + k], pat_buf[k]);
224 }
225 }
226 }
227 }
228 // Since the above calculation does not modify values outside
229 // [MIN_PREFIX, len - MIN_SUFFIX], they are left as 0.
230 for (size_t i = MIN_PREFIX; i < maxOffset; i++) {
231 result[i] &= 1;
232 }
233 }
234
235 } // namespace android
236