icu/src/main/native/ScopedJavaUnicodeString.h

/*
 * Copyright (C) 2010 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.
 */

#ifndef SCOPED_JAVA_UNICODE_STRING_H_included
#define SCOPED_JAVA_UNICODE_STRING_H_included

#include "JNIHelp.h"
#include "unicode/unistr.h"

// A smart pointer that provides access to an ICU UnicodeString given a JNI
// jstring. We give ICU a direct pointer to the characters on the Java heap.
// It's clever enough to copy-on-write if necessary, but we only provide
// const UnicodeString access anyway because attempted write access seems
// likely to be an error.
class ScopedJavaUnicodeString {
public:
    ScopedJavaUnicodeString(JNIEnv* env, jstring s) : mEnv(env), mString(s) {
        mChars = env->GetStringChars(mString, NULL);
        const int32_t charCount = env->GetStringLength(mString);
        mUnicodeString.setTo(false, mChars, charCount);
    }

    ~ScopedJavaUnicodeString() {
        mEnv->ReleaseStringChars(mString, mChars);
    }

    const UnicodeString& unicodeString() {
        return mUnicodeString;
    }

private:
    JNIEnv* mEnv;
    jstring mString;
    const UChar* mChars;
    UnicodeString mUnicodeString;
};

#endif  // SCOPED_JAVA_UNICODE_STRING_H_included