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// Copyright (C) 2019 Google LLC
//
// 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.
#ifndef ICING_TOKENIZATION_REVERSE_JNI_REVERSE_JNI_BREAK_ITERATOR_H_
#define ICING_TOKENIZATION_REVERSE_JNI_REVERSE_JNI_BREAK_ITERATOR_H_
#include <jni.h>
#include <queue>
#include <string>
#include "icing/text_classifier/lib3/utils/java/jni-base.h"
#include "icing/jni/jni-cache.h"
namespace icing {
namespace lib {
// A class that handles the cross-JNI interactions with BreakIteratorBatcher and
// hides the batching element to provide an interface akin to
// java.text.BreakIterator.
//
// Example:
// std::string text = "我每天走路去上班。";
// ASSERT_THAT(text, SizeIs(27));
// std::unique_ptr<ReverseJniBreakIterator> itr =
// ReverseJniBreakIterator::Create(jni_cache, text, locale);
// std::vector<int> nexts;
// int next = itr->Next();
// while (next != ReverseJniBreakIterator::kDone) {
// nexts.push_back(next);
// next = itr->Next();
// }
// EXPECT_THAT(nexts, ElementsAre(1, 3, 5, 6, 8));
class ReverseJniBreakIterator {
public:
static constexpr int kDone = -1;
// Creates a ReverseJniBreakiterator with the given text and locale.
//
// Returns:
// A ReverseJniBreakIterator on success
// INVALID_ARGUMENT if jni_cache isn't a valid JniCache pointer
// INTERNAL if unable to create any of the required Java objects
static libtextclassifier3::StatusOr<std::unique_ptr<ReverseJniBreakIterator>>
Create(const JniCache* jni_cache, std::string_view text,
std::string_view locale);
// Returns the UTF-16 boundary following the current boundary. If the current
// boundary is the last text boundary, it returns
// ReverseJniBreakIterator::kDONE.
//
// NOTE: The 'boundary' refers to the UTF-16 boundary - NOT the UTF-8
// boundary. Callers interested in the UTF-8 boundary are required to maintain
// whatever state is necessary to translate from UTF-16 to UTF-8 boundaries.
int Next();
// Returns the first UTF-16 boundary. The iterator's current position is set
// to the first text boundary and any cached data is cleared.
int First();
// Returns the position of the first UTF-16 boundary preceding the UTF-16
// offset. If there is no boundary preceding the specified offset, then
// ReverseJniBreakIterator::kDone is returned.
//
// The iterator's current position is set to the segment whose boundary was
// returned and any cached data is cleared.
int Preceding(int offset);
// Returns the position of the first UTF-16 boundary following the UTF-16
// offset. If there is no boundary following the specified offset, then
// ReverseJniBreakIterator::kDone is returned.
//
// The iterator's current position is set to the segment whose boundary
// was returned and any cached data is cleared.
int Following(int offset);
private:
ReverseJniBreakIterator(
const JniCache* jni_cache,
libtextclassifier3::ScopedGlobalRef<jobject> iterator_batcher);
// Fetches the results of up to kBatchSize next calls and stores them in
// break_indices_cache_. Returns the number of results or kDone if no more
// results could be fetched.
int FetchNextBatch();
// Empties the cache and sets is_done_ and is_almost_done_ to false.
void ClearCache();
// Keeps track of references to Java classes and methods. Does NOT own.
const JniCache* jni_cache_;
// The reference to the actual instance of BreakIteratorBatcher that
// this class interacts with.
libtextclassifier3::ScopedGlobalRef<jobject> iterator_batcher_;
// The cache holding the most recent batch of return values from
// BreakIteratorBatcher#next.
std::queue<int> break_indices_cache_;
bool is_done_;
// The last batch was incomplete (< kBatchSize results were returned). The
// next call to BreakIteratorBatcher#next is guaranteed to return an
// empty array. Once the results from the last batch are evicted from
// break_indices_cache, ReverseJniBreakIterator will transition to is_done_.
bool is_almost_done_;
};
} // namespace lib
} // namespace icing
#endif // ICING_TOKENIZATION_REVERSE_JNI_REVERSE_JNI_BREAK_ITERATOR_H_
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