/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "LineBreakerUtil.h"
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namespace minikin {
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// Very long words trigger O(n^2) behavior in hyphenation, so we disable hyphenation for
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// unreasonably long words. This is somewhat of a heuristic because extremely long words are
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// possible in some languages. This does mean that very long real words can get broken by
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// desperate breaks, with no hyphens.
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constexpr size_t LONGEST_HYPHENATED_WORD = 45;
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// Hyphenates a string potentially containing non-breaking spaces.
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std::vector<HyphenationType> hyphenate(const U16StringPiece& str, const Hyphenator& hyphenator) {
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std::vector<HyphenationType> out;
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const size_t len = str.size();
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out.resize(len);
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// A word here is any consecutive string of non-NBSP characters.
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bool inWord = false;
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size_t wordStart = 0; // The initial value will never be accessed, but just in case.
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for (size_t i = 0; i <= len; i++) {
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if (i == len || str[i] == CHAR_NBSP) {
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if (inWord) {
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// A word just ended. Hyphenate it.
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const U16StringPiece word = str.substr(Range(wordStart, i));
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if (word.size() <= LONGEST_HYPHENATED_WORD) {
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hyphenator.hyphenate(word, out.data() + wordStart);
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} else { // Word is too long. Inefficient to hyphenate.
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out.insert(out.end(), word.size(), HyphenationType::DONT_BREAK);
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}
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inWord = false;
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}
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if (i < len) {
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// Insert one DONT_BREAK for the NBSP.
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out.push_back(HyphenationType::DONT_BREAK);
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}
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} else if (!inWord) {
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inWord = true;
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wordStart = i;
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}
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}
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return out;
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}
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} // namespace minikin
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