1// Copyright 2001 - 2003 Google Inc. All Rights Reserved
2
3#ifndef BASE_BASICTYPES_H__
4#define BASE_BASICTYPES_H__
5
6typedef unsigned char  uint8;
7typedef unsigned short uint16;
8typedef unsigned int   uint32;
9
10const uint8  kuint8max  = (( uint8) 0xFF);
11const 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.
27template <typename T, size_t N>
28char (&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
34template <typename T, size_t N>
35char (&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