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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_ANDROID_JNI_INT_WRAPPER_H_
#define BASE_ANDROID_JNI_INT_WRAPPER_H_
// Wrapper used to receive int when calling Java from native.
// The wrapper disallows automatic conversion of long to int.
// This is to avoid a common anti-pattern where a Java int is used
// to receive a native pointer. Please use a Java long to receive
// native pointers, so that the code works on both 32-bit and 64-bit
// platforms. Note the wrapper allows other lossy conversions into
// jint that could be consider anti-patterns, such as from size_t.
// Checking is only done in debugging builds.
#ifdef NDEBUG
typedef jint JniIntWrapper;
// This inline is sufficiently trivial that it does not change the
// final code generated by g++.
inline jint as_jint(JniIntWrapper wrapper) {
return wrapper;
}
#else
class JniIntWrapper {
public:
JniIntWrapper() : i_(0) {}
JniIntWrapper(int i) : i_(i) {}
JniIntWrapper(const JniIntWrapper& ji) : i_(ji.i_) {}
template <class T> JniIntWrapper(const T& t) : i_(t) {}
jint as_jint() const { return i_; }
private:
// If you get an "is private" error at the line below it is because you used
// an implicit conversion to convert a long to an int when calling Java.
// We disallow this, as a common anti-pattern allows converting a native
// pointer (intptr_t) to a Java int. Please use a Java long to represent
// a native pointer. If you want a lossy conversion, please use an
// explicit conversion in your C++ code. Note an error is only seen when
// compiling on a 64-bit platform, as intptr_t is indistinguishable from
// int on 32-bit platforms.
JniIntWrapper(long);
jint i_;
};
inline jint as_jint(const JniIntWrapper& wrapper) {
return wrapper.as_jint();
}
#endif // NDEBUG
#endif // BASE_ANDROID_JNI_INT_WRAPPER_H_
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