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ecrypa
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implement min_element
1 parent 1cd7d07 commit eb057bd

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6 files changed

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6 files changed

+190
-2
lines changed

‎example/src/list.cpp

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@@ -657,6 +657,27 @@ IS_SAME(
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/// [transpose]
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)
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HIDE(
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/// [min_element]
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using vals = metal::list<const char, int, long, char>;
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// strict (i.e., irreflexive) ordering: _first_ minimum
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template<class x, class y>
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using smaller = metal::number<(sizeof(x) < sizeof(y))>;
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IS_SAME(metal::min_element<vals, metal::lambda<smaller>>, const char);
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// reflexive ordering: _last_ minimum
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template<class x, class y>
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using not_larger = metal::number<(sizeof(x) <= sizeof(y))>;
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IS_SAME(metal::min_element<vals, metal::lambda<not_larger>>, char);
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// can be used with Numbers; more customizable than metal::min
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using nums = metal::numbers<4, 42, 17, 3, 20>;
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IS_SAME(metal::min_element<nums, metal::lambda<metal::less>>, metal::number<3>);
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IS_SAME(metal::min_element<nums>, metal::number<3>); // use default ordering
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/// [min_element]
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)
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#if !defined(METAL_WORKAROUND)
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HIDE(
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/// [accumulate]

‎include/metal/list.hpp

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#include "list/iota.hpp"
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#include "list/join.hpp"
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#include "list/list.hpp"
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#include "list/min_element.hpp"
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#include "list/none_of.hpp"
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#include "list/partition.hpp"
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#include "list/powerset.hpp"

‎include/metal/list/min_element.hpp

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#ifndef METAL_LIST_MIN_ELEMENT_HPP
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#define METAL_LIST_MIN_ELEMENT_HPP
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#include "../config.hpp"
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#include "../lambda/apply.hpp"
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#include "../lambda/lambda.hpp"
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#include "../number/if.hpp"
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#include "../number/less.hpp"
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namespace metal {
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/// \cond
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namespace detail {
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template<class lbd = metal::lambda<metal::less>>
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struct _min_folder;
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}
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/// \endcond
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/// \ingroup list
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///
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/// ### Description
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/// Finds a minimum element in a \list according to an ordering relation.
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///
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/// \note{The _first_ minimum element is returned if the ordering relation is [strict].}
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/// [strict]:
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/// https://en.wikipedia.org/wiki/Weak_ordering#Strict_weak_orderings
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///
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/// ### Usage
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/// For any \list `l` and \lambda `lbd`
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/// \code
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/// using result = metal::min_element<l, lbd>;
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/// \endcode
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///
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/// \pre: `l` is not empty, and for any two \values `val_i` and `val_j`
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/// contained in `l` `metal::invoke<lbd, val_i, val_j>` returns a \number
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/// \returns: \value
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/// \semantics:
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/// If `l` contains elements `val_0, ..., val_k, ..., val_m-1`, then
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/// \code
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/// using result = val_k;
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/// \endcode
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/// where `val_k` is an element in `l` such that
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/// * `metal::invoke<lbd, val_k, val_j>{} != false` for all `j` in
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/// `[0, k)` and
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/// * `metal::invoke<lbd, val_i, val_k>{} == false` for all
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/// `i` in `(k, m-1]`.
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///
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/// \tip{`lbd` may be omitted, in which case it defaults to `metal::lambda<metal::less>`.}
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///
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/// ### Example
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/// \snippet list.cpp min_element
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///
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/// ### See Also
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/// \see min, sort
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#if !defined(METAL_WORKAROUND)
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template<class seq, class lbd = metal::lambda<metal::less>>
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using min_element = apply<
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lambda<detail::_min_folder<if_<is_lambda<lbd>, lbd>>::template type>,
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seq>;
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#else
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// MSVC 14 has shabby SFINAE support in case of default alias template args
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template<class seq, class... lbd>
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using min_element = apply<
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lambda<detail::_min_folder<if_<is_lambda<lbd>, lbd>...>::template type>,
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seq>;
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#endif
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}
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#include "../lambda/invoke.hpp"
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#include "../value/fold_left.hpp"
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namespace metal {
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/// \cond
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namespace detail {
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template<class lbd>
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struct _min_folder {
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template<class x, class y>
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using custom_min = if_<invoke<lbd, y, x>, y, x>;
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// Must use `invoke` in order to support SFINAE. It is tempting to
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// pattern-match the `expr` from `lbd` and use `expr<y, x>`, but
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// the latter approach spoils SFINAE guarantees.
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template<class... vals>
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using type = fold_left<lambda<custom_min>, vals...>;
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};
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}
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/// \endcond
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}
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#endif

‎include/metal/list/sort.hpp

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@@ -49,7 +49,7 @@ namespace metal {
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/// \snippet list.cpp sort
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///
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/// ### See Also
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/// \see list, reverse, rotate
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/// \see list, min_element, reverse, rotate
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#if !defined(METAL_WORKAROUND)
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template<class seq, class lbd = metal::lambda<metal::less>>
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using sort = detail::call<

‎include/metal/number/min.hpp

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@@ -39,7 +39,7 @@ namespace metal {
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/// \snippet number.cpp min
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///
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/// ### See Also
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/// \see number, greater, less, max
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/// \see number, greater, less, max, min_element
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template<class... nums>
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using min = fold_left<lambda<detail::min>, if_<is_number<nums>, nums>...>;
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}

‎test/unit/src/metal/list/min_element.cpp

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#include <metal.hpp>
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#include "test.hpp"
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#define MATRIX(M, N) \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, VALUE(M)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, VALUE(M), VALUE(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, VALUE(M), NUMBER(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, VALUE(M), PAIR(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, VALUE(M), LIST(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, VALUE(M), MAP(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, VALUE(M), LAMBDA(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, NUMBER(M)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, NUMBER(M), VALUE(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, NUMBER(M), NUMBER(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, NUMBER(M), PAIR(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, NUMBER(M), LIST(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, NUMBER(M), MAP(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, NUMBER(M), LAMBDA(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, NUMBER(M), LAMBDA(_)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, PAIR(M)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, PAIR(M), VALUE(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, PAIR(M), NUMBER(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, PAIR(M), PAIR(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, PAIR(M), LIST(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, PAIR(M), MAP(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, PAIR(M), LAMBDA(N)>), (BOOL(N == 2))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, PAIR(M), LAMBDA(_)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LIST(M)>), (BOOL(M == 1))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LIST(M), VALUE(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LIST(M), NUMBER(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LIST(M), PAIR(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LIST(M), LIST(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LIST(M), MAP(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LIST(M), LAMBDA(N)>), (BOOL((N == 2 && M > 0) || M == 1))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LIST(M), LAMBDA(_)>), (BOOL(M == 1))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, MAP(M)>), (BOOL(M == 1))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, MAP(M), VALUE(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, MAP(M), NUMBER(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, MAP(M), PAIR(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, MAP(M), LIST(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, MAP(M), MAP(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, MAP(M), LAMBDA(N)>), (BOOL((N == 2 && M > 0) || M == 1))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, MAP(M), LAMBDA(_)>), (BOOL(M == 1))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>>), (BOOL(M > 0))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>, VALUE(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>, NUMBER(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>, PAIR(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>, LIST(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>, MAP(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>, metal::list<NUMBERS(N)>>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>, LAMBDA(N)>), (BOOL((N == 2 && M > 0) || M == 1))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, metal::list<NUMBERS(M)>, LAMBDA(_)>), (BOOL(M == 1))); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(M)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(M), VALUE(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(M), NUMBER(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(M), PAIR(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(M), LIST(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(M), MAP(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(M), LAMBDA(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(M), LAMBDA(_)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(_)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(_), VALUE(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(_), NUMBER(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(_), PAIR(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(_), LIST(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(_), MAP(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(_), LAMBDA(N)>), (FALSE)); \
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CHECK((metal::is_invocable<metal::lambda<metal::min_element>, LAMBDA(_), LAMBDA(_)>), (FALSE)); \
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CHECK((metal::min_element<metal::list<NUMBERSX20(INC(M))>, metal::lambda<metal::greater>>), (metal::number<M>)); \
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CHECK((metal::min_element<metal::list<NUMBERSX20(INC(M))>, metal::lambda<metal::less>>), (metal::number<0>)); \
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CHECK((metal::min_element<metal::list<NUMBERSX20(INC(M))>>), (metal::number<0>)); \
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CHECK((metal::min_element<metal::list<ENUM(INC(N), NUMBERS FIX(INC(M)))>, metal::lambda<metal::less>>), (metal::number<0>)); \
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CHECK((metal::min_element<metal::list<ENUM(INC(N), NUMBERS FIX(INC(M)))>>), (metal::number<0>)); \
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/**/
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GEN(MATRIX)

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