1010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// Copyright 2014 The Chromium Authors. All rights reserved. 2010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// Use of this source code is governed by a BSD-style license that can be 3010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// found in the LICENSE file. 4010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 5010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)#ifndef BASE_ANDROID_JNI_INT_WRAPPER_H_ 6010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)#define BASE_ANDROID_JNI_INT_WRAPPER_H_ 7010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 8010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// Wrapper used to receive int when calling Java from native. 9010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// The wrapper disallows automatic conversion of long to int. 10010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// This is to avoid a common anti-pattern where a Java int is used 11010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// to receive a native pointer. Please use a Java long to receive 12010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// native pointers, so that the code works on both 32-bit and 64-bit 13010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// platforms. Note the wrapper allows other lossy conversions into 14010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// jint that could be consider anti-patterns, such as from size_t. 15010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 16010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// Checking is only done in debugging builds. 17010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 18010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)#ifdef NDEBUG 19010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 20010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)typedef jint JniIntWrapper; 21010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 22010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// This inline is sufficiently trivial that it does not change the 23010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)// final code generated by g++. 24010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)inline jint as_jint(JniIntWrapper wrapper) { 25010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) return wrapper; 26010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)} 27010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 28010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)#else 29010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 30010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)class JniIntWrapper { 31010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) public: 32010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) JniIntWrapper() : i_(0) {} 33010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) JniIntWrapper(int i) : i_(i) {} 34010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) JniIntWrapper(const JniIntWrapper& ji) : i_(ji.i_) {} 35010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) template <class T> JniIntWrapper(const T& t) : i_(t) {} 36010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) jint as_jint() const { return i_; } 37010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) private: 38010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) // If you get an "is private" error at the line below it is because you used 39010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) // an implicit conversion to convert a long to an int when calling Java. 40010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) // We disallow this, as a common anti-pattern allows converting a native 41010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) // pointer (intptr_t) to a Java int. Please use a Java long to represent 42010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) // a native pointer. If you want a lossy conversion, please use an 43010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) // explicit conversion in your C++ code. Note an error is only seen when 44010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) // compiling on a 64-bit platform, as intptr_t is indistinguishable from 45010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) // int on 32-bit platforms. 46010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) JniIntWrapper(long); 47010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) jint i_; 48010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)}; 49010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 50010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)inline jint as_jint(const JniIntWrapper& wrapper) { 51010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) return wrapper.as_jint(); 52010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)} 53010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 54010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)#endif // NDEBUG 55010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles) 56010d83a9304c5a91596085d917d248abff47903aTorne (Richard Coles)#endif // BASE_ANDROID_JNI_INT_WRAPPER_H_ 57