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/*
* Copyright (C) 2015 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.
*/
/**
* An implementation of Liang's hyphenation algorithm.
*/
#include <memory>
#include <unordered_map>
#ifndef MINIKIN_HYPHENATOR_H
#define MINIKIN_HYPHENATOR_H
namespace android {
// hyb file header; implementation details are in the .cpp file
struct Header;
class Hyphenator {
public:
// Note: this will also require a locale, for proper case folding behavior
static Hyphenator* load(const uint16_t* patternData, size_t size);
// Compute the hyphenation of a word, storing the hyphenation in result vector. Each
// entry in the vector is a "hyphen edit" to be applied at the corresponding code unit
// offset in the word. Currently 0 means no hyphen and 1 means insert hyphen and break,
// but this will be expanded to other edits for nonstandard hyphenation.
// Example: word is "hyphen", result is [0 0 1 0 0 0], corresponding to "hy-phen".
void hyphenate(std::vector<uint8_t>* result, const uint16_t* word, size_t len);
// pattern data is in binary format, as described in doc/hyb_file_format.md. Note:
// the caller is responsible for ensuring that the lifetime of the pattern data is
// at least as long as the Hyphenator object.
// Note: nullptr is valid input, in which case the hyphenator only processes soft hyphens
static Hyphenator* loadBinary(const uint8_t* patternData);
private:
// apply soft hyphens only, ignoring patterns
void hyphenateSoft(uint8_t* result, const uint16_t* word, size_t len);
// try looking up word in alphabet table, return false if any code units fail to map
// Note that this methor writes len+2 entries into alpha_codes (including start and stop)
bool alphabetLookup(uint16_t* alpha_codes, const uint16_t* word, size_t len);
// calculate hyphenation from patterns, assuming alphabet lookup has already been done
void hyphenateFromCodes(uint8_t* result, const uint16_t* codes, size_t len);
// TODO: these should become parameters, as they might vary by locale, screen size, and
// possibly explicit user control.
static const int MIN_PREFIX = 2;
static const int MIN_SUFFIX = 3;
// See also LONGEST_HYPHENATED_WORD in LineBreaker.cpp. Here the constant is used so
// that temporary buffers can be stack-allocated without waste, which is a slightly
// different use case. It measures UTF-16 code units.
static const size_t MAX_HYPHENATED_SIZE = 64;
const uint8_t* patternData;
// accessors for binary data
const Header* getHeader() const {
return reinterpret_cast<const Header*>(patternData);
}
};
} // namespace android
#endif // MINIKIN_HYPHENATOR_H
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