/*
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* Copyright (C) 2018 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 "annotator/strip-unpaired-brackets.h"
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#include <iterator>
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#include "utils/base/logging.h"
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#include "utils/utf8/unicodetext.h"
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namespace libtextclassifier3 {
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namespace {
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// Returns true if given codepoint is contained in the given span in context.
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bool IsCodepointInSpan(const char32 codepoint,
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const UnicodeText& context_unicode,
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const CodepointSpan span) {
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auto begin_it = context_unicode.begin();
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std::advance(begin_it, span.first);
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auto end_it = context_unicode.begin();
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std::advance(end_it, span.second);
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return std::find(begin_it, end_it, codepoint) != end_it;
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}
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// Returns the first codepoint of the span.
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char32 FirstSpanCodepoint(const UnicodeText& context_unicode,
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const CodepointSpan span) {
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auto it = context_unicode.begin();
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std::advance(it, span.first);
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return *it;
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}
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// Returns the last codepoint of the span.
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char32 LastSpanCodepoint(const UnicodeText& context_unicode,
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const CodepointSpan span) {
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auto it = context_unicode.begin();
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std::advance(it, span.second - 1);
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return *it;
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}
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} // namespace
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CodepointSpan StripUnpairedBrackets(const std::string& context,
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CodepointSpan span, const UniLib& unilib) {
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const UnicodeText context_unicode =
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UTF8ToUnicodeText(context, /*do_copy=*/false);
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return StripUnpairedBrackets(context_unicode, span, unilib);
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}
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// If the first or the last codepoint of the given span is a bracket, the
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// bracket is stripped if the span does not contain its corresponding paired
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// version.
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CodepointSpan StripUnpairedBrackets(const UnicodeText& context_unicode,
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CodepointSpan span, const UniLib& unilib) {
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if (context_unicode.empty() || !ValidNonEmptySpan(span)) {
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return span;
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}
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const char32 begin_char = FirstSpanCodepoint(context_unicode, span);
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const char32 paired_begin_char = unilib.GetPairedBracket(begin_char);
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if (paired_begin_char != begin_char) {
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if (!unilib.IsOpeningBracket(begin_char) ||
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!IsCodepointInSpan(paired_begin_char, context_unicode, span)) {
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++span.first;
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}
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}
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if (span.first == span.second) {
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return span;
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}
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const char32 end_char = LastSpanCodepoint(context_unicode, span);
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const char32 paired_end_char = unilib.GetPairedBracket(end_char);
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if (paired_end_char != end_char) {
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if (!unilib.IsClosingBracket(end_char) ||
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!IsCodepointInSpan(paired_end_char, context_unicode, span)) {
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--span.second;
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}
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}
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// Should not happen, but let's make sure.
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if (span.first > span.second) {
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TC3_LOG(WARNING) << "Inverse indices result: " << span.first << ", "
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<< span.second;
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span.second = span.first;
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}
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return span;
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}
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} // namespace libtextclassifier3
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