/*
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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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#ifndef LIBTEXTCLASSIFIER_UTILS_JAVA_STRING_UTILS_H_
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#define LIBTEXTCLASSIFIER_UTILS_JAVA_STRING_UTILS_H_
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#include <jni.h>
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#include <memory>
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#include <string>
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#include "utils/base/logging.h"
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namespace libtextclassifier3 {
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bool JByteArrayToString(JNIEnv* env, const jbyteArray& array,
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std::string* result);
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bool JStringToUtf8String(JNIEnv* env, const jstring& jstr, std::string* result);
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// A deleter to be used with std::unique_ptr to release Java string chars.
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class StringCharsReleaser {
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public:
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StringCharsReleaser() : env_(nullptr) {}
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StringCharsReleaser(JNIEnv* env, jstring jstr) : env_(env), jstr_(jstr) {}
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StringCharsReleaser(const StringCharsReleaser& orig) = default;
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// Copy assignment to allow move semantics in StringCharsReleaser.
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StringCharsReleaser& operator=(const StringCharsReleaser& rhs) {
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// As the releaser and its state are thread-local, it's enough to only
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// ensure the envs are consistent but do nothing.
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TC3_CHECK_EQ(env_, rhs.env_);
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return *this;
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}
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// The delete operator.
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void operator()(const char* chars) const {
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if (env_ != nullptr) {
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env_->ReleaseStringUTFChars(jstr_, chars);
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}
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}
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private:
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// The env_ stashed to use for deletion. Thread-local, don't share!
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JNIEnv* const env_;
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// The referenced jstring.
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jstring jstr_;
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};
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// A smart pointer that releases string chars when it goes out of scope.
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// of scope.
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// Note that this class is not thread-safe since it caches JNIEnv in
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// the deleter. Do not use the same jobject across different threads.
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using ScopedStringChars = std::unique_ptr<const char, StringCharsReleaser>;
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// Returns a scoped pointer to the array of Unicode characters of a string.
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ScopedStringChars GetScopedStringChars(JNIEnv* env, jstring string,
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jboolean* is_copy = nullptr);
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} // namespace libtextclassifier3
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#endif // LIBTEXTCLASSIFIER_UTILS_JAVA_STRING_UTILS_H_
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