C++ 概念： BitmaskType

 

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定义了一种类型，它可以被用来表示一组常数值或这些值的任何组合。这种特质的典型实现是整数类型，std::bitset，或枚举（范围和无作用域）额外的运算符重载.

Original:

Defines a type that can be used to represent a set of constant values or any combination of those values. This trait is typically implemented by integer types, std::bitset, or enumerations (scoped and unscoped) with additional operator overloads.

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要求

的位掩码类型支持有限数量的位掩码的元素，这是不同的值的位掩码类型，例如，对于任何一对Ci和Cj，Ci & Ci != 0和Ci & Cj == 0.

Original:

The bitmask type supports a finite number of bitmask elements, which are distinct values of the bitmask type, such that, for any pair Ci and Cj, Ci & Ci != 0 and Ci & Cj == 0.

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按位运算符operator&，operator|，operator^，operator~，operator&=，operator|=，并operator^=定义的位掩码类型的值，并有相应的内置运营商无符号整数相同的语义，如果是不同的整数位掩码元素两个权力.

Original:

The bitwise operators operator&, operator|, operator^, operator~, operator&=, operator|=, and operator^= are defined for values of the bitmask type and have the same semantics as the corresponding built-in operators on unsigned integers would have if the bitmask elements were the distinct integer powers of two.

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下面的表达式是良好的，任何BitsetType十

Original:

The following expressions are well-formed and have the following meaning for any BitsetType X

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X |= Y	设置对象的X值Y Original: sets the value Y in the object X The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
X &= ~Y	清除对象的X值Y Original: clears the value Y in the object X The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
X&Y != 0	表示的值Y被设置在对象的X Original: indicates that the value Y is set in the object X The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

具有以下涵义。 的每个representible位掩码元素被定义作为constexpr位掩码类型值.

Original:

Each representible bitmask element is defined as a constexpr value of the bitmask type.

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用法

以下的标准库，能满足不同BitmaskType

Original:

The following standard library types satisfy BitmaskType:

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• std::ctype_base::mask
• std::ios_base::fmtflags
• std::ios_base::iostate
• std::ios_base::openmode
• std::regex_traits::char_class_type
• std::regex_constants::syntax_option_type
• std::regex_constants::match_flag_type
• std::launch,

依赖于一些特定的实施方案（例如int n = std::ios_base::hex），代码是不可移植的，因为std::ios_base::fmtflags不一定是隐式转换为int.

Original:

Code that relies on some particular implementation option (e.g. int n = std::ios_base::hex), is nonportable because std::ios_base::fmtflags is not necessarily implicitly convertible to int.

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