Provide an integral-constant-to-type conversion.
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Detailed Description
- Outline
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- Purpose:
- Provide an integral-constant-to-type conversion.
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- Classes:
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- Macros:
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- Description:
- This component defines a simple template structure used to map an integral constant to a C++ type.
bslmf::Tag<unsigned> defines a different type for each distinct compile-time constant integral parameter. That is, instantiations with different integer values form distinct types, so that bslmf::Tag<0> is a distinct type from bslmf::Tag<1>, which, in turn, is also distinct from bslmf::Tag<2>, and so on.
- This component also provides two macros for mapping a
bslmf::Tag<t_N> instance to the integral value t_N (BSLMF_TAG_TO_INT), and to the boolean value t_N != 0 (BSLMF_TAG_TO_BOOL).
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- Macro Summary:
- This section provides a brief description of the macros defined in this component.
BSLMF_TAG_TO_INT(EXPR) Given an integral value,
V, and an expression,
EXPR, of type
bslmf::Tag<V>, this macro returns a compile-time constant with the value
V.
EXPR is not evaluated at run-time.
BSLMF_TAG_TO_BOOL(EXPR) Given an integral value,
V, and an expression,
EXPR, of type
bslmf::Tag<V>, this macro returns a compile-time constant with the value
true or
false, depending on the boolean value of
V.
EXPR is not evaluated at run-time.
Define Documentation
| #define BSLMF_TAG_TO_UINT |
( |
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BSLMF_EXPR |
) |
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Value:(((sizeof(BSLMF_EXPR.d_upperSizeArray) - 1) << 16) \
| (sizeof(BSLMF_EXPR.d_lowerSizeArray) - 1))
| #define BSLMF_TAG_TO_INT |
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BSLMF_EXPR |
) |
((int)BSLMF_TAG_TO_UINT(BSLMF_EXPR)) |
| #define BSLMF_TAG_TO_BOOL |
( |
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BSLMF_EXPR |
) |
(BSLMF_TAG_TO_INT(BSLMF_EXPR) != 0) |
