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