Use limit to limit the number of paramters for lazy or any function

boostorg · Mar 23, 2016 · 40f68b7 · 40f68b7
1 parent 439148f
commit 40f68b7
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Showing 2 changed files with 29 additions and 1 deletion.
diff --git a/include/fit/limit.hpp b/include/fit/limit.hpp
@@ -74,17 +74,35 @@
 #include <fit/detail/delegate.hpp>
 #include <fit/detail/move.hpp>
 #include <fit/detail/static_const_var.hpp>
+#include <fit/always.hpp>
 #include <cstdint>
 
 namespace fit {
 
 namespace detail {
-
+// TODO: Make this work with fit_rewritable1_tag
 template<std::size_t N, class F>
 struct limit_adaptor : detail::callable_base<F>
 {
     typedef std::integral_constant<std::size_t, N> fit_function_param_limit;
     FIT_INHERIT_CONSTRUCTOR(limit_adaptor, detail::callable_base<F>)
+
+    template<class... Ts>
+    constexpr const detail::callable_base<F>& base_function(Ts&&... xs) const
+    {
+        return always_ref(*this)(xs...);
+    }
+
+    FIT_RETURNS_CLASS(limit_adaptor);
+
+    template<class... Ts, class=typename std::enable_if<(sizeof...(Ts) <= N)>::type>
+    constexpr FIT_SFINAE_RESULT(const detail::callable_base<F>&, id_<Ts>...) 
+    operator()(Ts&&... xs) const FIT_SFINAE_RETURNS
+    (
+        (FIT_MANGLE_CAST(const detail::callable_base<F>&)(FIT_CONST_THIS->base_function(xs...)))
+            (FIT_FORWARD(Ts)(xs)...)
+    );
+
 };
 
 template<std::size_t N>

diff --git a/test/match.cpp b/test/match.cpp
@@ -2,6 +2,7 @@
 #include <fit/static.hpp>
 #include <fit/lambda.hpp>
 #include <fit/placeholders.hpp>
+#include <fit/limit.hpp>
 #include "test.hpp"
 
 #include <memory>
@@ -169,3 +170,12 @@ FIT_TEST_CASE()
     // FIT_TEST_CHECK(fit::match(negate, sub)(0, 1) == sub(0, 1));
 }
 
+FIT_TEST_CASE()
+{
+    const auto negate = fit::limit_c<1>(!fit::_1);
+    const auto sub = fit::limit_c<2>(fit::_1 - fit::_2);
+    FIT_TEST_CHECK(fit::match(negate, sub)(0) == negate(0));
+    // This test will pass because we have limited the number of parameters.
+    FIT_TEST_CHECK(fit::match(negate, sub)(0, 1) == sub(0, 1));
+}
+