tmp/tmpr762_l2a/{from.md → to.md}
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| 1 |
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#### Class template `scaled_accessor` <a id="linalg.scaled.scaledaccessor">[[linalg.scaled.scaledaccessor]]</a>
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The class template `scaled_accessor` is an `mdspan` accessor policy
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which upon access produces scaled elements. It is part of the
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implementation of `scaled` [[linalg.scaled.scaled]].
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``` cpp
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namespace std::linalg {
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template<class ScalingFactor, class NestedAccessor>
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class scaled_accessor {
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public:
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using element_type =
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const decltype(declval<ScalingFactor>() * declval<NestedAccessor::element_type>());
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using reference = remove_const_t<element_type>;
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using data_handle_type = NestedAccessor::data_handle_type;
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using offset_policy = scaled_accessor<ScalingFactor, NestedAccessor::offset_policy>;
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constexpr scaled_accessor() = default;
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template<class OtherNestedAccessor>
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explicit(!is_convertible_v<OtherNestedAccessor, NestedAccessor>)
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constexpr scaled_accessor(const scaled_accessor<ScalingFactor,
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OtherNestedAccessor>& other);
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constexpr scaled_accessor(const ScalingFactor& s, const NestedAccessor& a);
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constexpr reference access(data_handle_type p, size_t i) const;
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constexpr offset_policy::data_handle_type offset(data_handle_type p, size_t i) const;
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constexpr const ScalingFactor& scaling_factor() const noexcept { return scaling-factor; }
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constexpr const NestedAccessor& nested_accessor() const noexcept { return nested-accessor; }
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private:
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ScalingFactor scaling-factor{}; // exposition only
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NestedAccessor nested-accessor{}; // exposition only
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};
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}
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```
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*Mandates:*
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- `element_type` is valid and denotes a type,
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- `is_copy_constructible_v<reference>` is `true`,
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- `is_reference_v<element_type>` is `false`,
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- `ScalingFactor` models `semiregular`, and
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- `NestedAccessor` meets the accessor policy requirements
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[[mdspan.accessor.reqmts]].
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``` cpp
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template<class OtherNestedAccessor>
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explicit(!is_convertible_v<OtherNestedAccessor, NestedAccessor>)
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constexpr scaled_accessor(const scaled_accessor<ScalingFactor, OtherNestedAccessor>& other);
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```
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*Constraints:*
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`is_constructible_v<NestedAccessor, const OtherNestedAccessor&>` is
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`true`.
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*Effects:*
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- Direct-non-list-initializes *scaling-factor* with
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`other.scaling_factor()`, and
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- direct-non-list-initializes *nested-accessor* with
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`other.nested_accessor()`.
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``` cpp
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constexpr scaled_accessor(const ScalingFactor& s, const NestedAccessor& a);
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```
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*Effects:*
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- Direct-non-list-initializes *scaling-factor* with `s`, and
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- direct-non-list-initializes *nested-accessor* with `a`.
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``` cpp
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constexpr reference access(data_handle_type p, size_t i) const;
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```
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*Returns:*
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``` cpp
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scaling_factor() * NestedAccessor::element_type(nested-accessor.access(p, i))
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```
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``` cpp
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constexpr offset_policy::data_handle_type offset(data_handle_type p, size_t i) const;
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```
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*Returns:* *`nested-accessor`*`.offset(p, i)`
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