1 // Copyright 2001 - 2003 Google Inc. All Rights Reserved 2 3 #ifndef BASE_BASICTYPES_H__ 4 #define BASE_BASICTYPES_H__ 5 6 typedef unsigned char uint8; 7 typedef unsigned short uint16; 8 typedef unsigned int uint32; 9 10 const uint8 kuint8max = (( uint8) 0xFF); 11 const uint32 kuint32max = ((uint32) 0xFFFFFFFF); 12 13 // The arraysize(arr) macro returns the # of elements in an array arr. 14 // The expression is a compile-time constant, and therefore can be 15 // used in defining new arrays, for example. If you use arraysize on 16 // a pointer by mistake, you will get a compile-time error. 17 // 18 // One caveat is that arraysize() doesn't accept any array of an 19 // anonymous type or a type defined inside a function. In these rare 20 // cases, you have to use the unsafe ARRAYSIZE() macro below. This is 21 // due to a limitation in C++'s template system. The limitation might 22 // eventually be removed, but it hasn't happened yet. 23 24 // This template function declaration is used in defining arraysize. 25 // Note that the function doesn't need an implementation, as we only 26 // use its type. 27 template <typename T, size_t N> 28 char (&ArraySizeHelper(T (&array)[N]))[N]; 29 30 // That gcc wants both of these prototypes seems mysterious. VC, for 31 // its part, can't decide which to use (another mystery). Matching of 32 // template overloads: the final frontier. 33 #ifndef _MSC_VER 34 template <typename T, size_t N> 35 char (&ArraySizeHelper(const T (&array)[N]))[N]; 36 #endif 37 38 #define arraysize(array) (sizeof(ArraySizeHelper(array))) 39 40 // ARRAYSIZE performs essentially the same calculation as arraysize, 41 // but can be used on anonymous types or types defined inside 42 // functions. It's less safe than arraysize as it accepts some 43 // (although not all) pointers. Therefore, you should use arraysize 44 // whenever possible. 45 // 46 // The expression ARRAYSIZE(a) is a compile-time constant of type 47 // size_t. 48 // 49 // ARRAYSIZE catches a few type errors. If you see a compiler error 50 // 51 // "warning: division by zero in ..." 52 // 53 // when using ARRAYSIZE, you are (wrongfully) giving it a pointer. 54 // You should only use ARRAYSIZE on statically allocated arrays. 55 // 56 // The following comments are on the implementation details, and can 57 // be ignored by the users. 58 // 59 // ARRAYSIZE(arr) works by inspecting sizeof(arr) (the # of bytes in 60 // the array) and sizeof(*(arr)) (the # of bytes in one array 61 // element). If the former is divisible by the latter, perhaps arr is 62 // indeed an array, in which case the division result is the # of 63 // elements in the array. Otherwise, arr cannot possibly be an array, 64 // and we generate a compiler error to prevent the code from 65 // compiling. 66 // 67 // Since the size of bool is implementation-defined, we need to cast 68 // !(sizeof(a) & sizeof(*(a))) to size_t in order to ensure the final 69 // result has type size_t. 70 // 71 // This macro is not perfect as it wrongfully accepts certain 72 // pointers, namely where the pointer size is divisible by the pointee 73 // size. Since all our code has to go through a 32-bit compiler, 74 // where a pointer is 4 bytes, this means all pointers to a type whose 75 // size is 3 or greater than 4 will be (righteously) rejected. 76 // 77 // Starting with Visual C++ 2005, WinNT.h includes ARRAYSIZE. 78 #define ARRAYSIZE_UNSAFE(a) \ 79 ((sizeof(a) / sizeof(*(a))) / \ 80 static_cast<size_t>(!(sizeof(a) % sizeof(*(a))))) 81 82 // A macro to disallow the evil copy constructor and operator= functions 83 // This should be used in the private: declarations for a class 84 #define DISALLOW_EVIL_CONSTRUCTORS(TypeName) \ 85 TypeName(const TypeName&); \ 86 void operator=(const TypeName&) 87 88 #endif // BASE_BASICTYPES_H__ 89
