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Diffstat (limited to 'googleurl/base/basictypes.h')
-rw-r--r-- | googleurl/base/basictypes.h | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/googleurl/base/basictypes.h b/googleurl/base/basictypes.h new file mode 100644 index 0000000..b0c404d --- /dev/null +++ b/googleurl/base/basictypes.h @@ -0,0 +1,88 @@ +// Copyright 2001 - 2003 Google Inc. All Rights Reserved + +#ifndef BASE_BASICTYPES_H__ +#define BASE_BASICTYPES_H__ + +typedef unsigned char uint8; +typedef unsigned short uint16; +typedef unsigned int uint32; + +const uint8 kuint8max = (( uint8) 0xFF); +const uint32 kuint32max = ((uint32) 0xFFFFFFFF); + +// The arraysize(arr) macro returns the # of elements in an array arr. +// The expression is a compile-time constant, and therefore can be +// used in defining new arrays, for example. If you use arraysize on +// a pointer by mistake, you will get a compile-time error. +// +// One caveat is that arraysize() doesn't accept any array of an +// anonymous type or a type defined inside a function. In these rare +// cases, you have to use the unsafe ARRAYSIZE() macro below. This is +// due to a limitation in C++'s template system. The limitation might +// eventually be removed, but it hasn't happened yet. + +// This template function declaration is used in defining arraysize. +// Note that the function doesn't need an implementation, as we only +// use its type. +template <typename T, size_t N> +char (&ArraySizeHelper(T (&array)[N]))[N]; + +// That gcc wants both of these prototypes seems mysterious. VC, for +// its part, can't decide which to use (another mystery). Matching of +// template overloads: the final frontier. +#ifndef _MSC_VER +template <typename T, size_t N> +char (&ArraySizeHelper(const T (&array)[N]))[N]; +#endif + +#define arraysize(array) (sizeof(ArraySizeHelper(array))) + +// ARRAYSIZE performs essentially the same calculation as arraysize, +// but can be used on anonymous types or types defined inside +// functions. It's less safe than arraysize as it accepts some +// (although not all) pointers. Therefore, you should use arraysize +// whenever possible. +// +// The expression ARRAYSIZE(a) is a compile-time constant of type +// size_t. +// +// ARRAYSIZE catches a few type errors. If you see a compiler error +// +// "warning: division by zero in ..." +// +// when using ARRAYSIZE, you are (wrongfully) giving it a pointer. +// You should only use ARRAYSIZE on statically allocated arrays. +// +// The following comments are on the implementation details, and can +// be ignored by the users. +// +// ARRAYSIZE(arr) works by inspecting sizeof(arr) (the # of bytes in +// the array) and sizeof(*(arr)) (the # of bytes in one array +// element). If the former is divisible by the latter, perhaps arr is +// indeed an array, in which case the division result is the # of +// elements in the array. Otherwise, arr cannot possibly be an array, +// and we generate a compiler error to prevent the code from +// compiling. +// +// Since the size of bool is implementation-defined, we need to cast +// !(sizeof(a) & sizeof(*(a))) to size_t in order to ensure the final +// result has type size_t. +// +// This macro is not perfect as it wrongfully accepts certain +// pointers, namely where the pointer size is divisible by the pointee +// size. Since all our code has to go through a 32-bit compiler, +// where a pointer is 4 bytes, this means all pointers to a type whose +// size is 3 or greater than 4 will be (righteously) rejected. +// +// Starting with Visual C++ 2005, WinNT.h includes ARRAYSIZE. +#define ARRAYSIZE_UNSAFE(a) \ + ((sizeof(a) / sizeof(*(a))) / \ + static_cast<size_t>(!(sizeof(a) % sizeof(*(a))))) + +// A macro to disallow the evil copy constructor and operator= functions +// This should be used in the private: declarations for a class +#define DISALLOW_EVIL_CONSTRUCTORS(TypeName) \ + TypeName(const TypeName&); \ + void operator=(const TypeName&) + +#endif // BASE_BASICTYPES_H__ |