improve the performance of copy_if<> and replace_if<>

squash copy_if
brunocodutra · Aug 18, 2016 · f67e991 · f67e991
1 parent 70a8e1c
commit f67e991
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Showing 2 changed files with 68 additions and 25 deletions.
diff --git a/include/metal/list/copy_if.hpp b/include/metal/list/copy_if.hpp
@@ -5,24 +5,47 @@
 #ifndef METAL_LIST_COPY_IF_HPP
 #define METAL_LIST_COPY_IF_HPP
 
-#include <metal/list/list.hpp>
-#include <metal/list/join.hpp>
 #include <metal/list/transform.hpp>
-#include <metal/lambda/apply.hpp>
-#include <metal/lambda/quote.hpp>
-#include <metal/lambda/lambda.hpp>
-#include <metal/lambda/partial.hpp>
-#include <metal/number/if.hpp>
 
 namespace metal
 {
+    namespace detail
+    {
+        template<typename, typename>
+        struct _copy_if_impl;
+    }
+
     /// \ingroup list
     /// ...
     template<typename seq, typename lbd>
-    using copy_if = apply<
-        partial<lambda<join>, list<>>,
-        transform<bind<lambda<if_>, lbd, lambda<list>, quote<list<>>>, seq>
-    >;
+    using copy_if =
+        typename detail::_copy_if_impl<seq, transform<lbd, seq>>::type;
+}
+
+#include <metal/list/list.hpp>
+#include <metal/list/join.hpp>
+#include <metal/number/if.hpp>
+#include <metal/number/number.hpp>
+
+namespace metal
+{
+    namespace detail
+    {
+        template<typename, typename>
+        struct _copy_if_impl
+        {};
+
+        template<>
+        struct _copy_if_impl<list<>, list<>>
+        {
+            using type = list<>;
+        };
+
+        template<typename... vals, int_... vs>
+        struct _copy_if_impl<list<vals...>, list<number<vs>...>> :
+            _join<if_<number<vs>, list<vals>, list<>>...>
+        {};
+    }
 }
 
 #endif
diff --git a/include/metal/list/replace_if.hpp b/include/metal/list/replace_if.hpp
@@ -6,26 +6,46 @@
 #define METAL_LIST_REPLACE_IF_HPP
 
 #include <metal/list/transform.hpp>
-#include <metal/lambda/arg.hpp>
-#include <metal/lambda/bind.hpp>
-#include <metal/lambda/quote.hpp>
-#include <metal/lambda/lambda.hpp>
-#include <metal/number/if.hpp>
 
 namespace metal
 {
+    namespace detail
+    {
+        template<typename, typename, typename>
+        struct _replace_if_impl;
+    }
+
     /// \ingroup list
     /// ...
     template<typename seq, typename lbd, typename val>
-    using replace_if = metal::transform<
-        metal::bind<
-            metal::lambda<metal::if_>,
-            lbd,
-            metal::quote<val>,
-            metal::_1
-        >,
-        seq
-    >;
+    using replace_if =
+        typename detail::_replace_if_impl<seq, transform<lbd, seq>, val>::type;
+}
+
+#include <metal/list/list.hpp>
+#include <metal/number/if.hpp>
+#include <metal/number/number.hpp>
+
+namespace metal
+{
+    namespace detail
+    {
+        template<typename, typename, typename>
+        struct _replace_if_impl
+        {};
+
+        template<typename val>
+        struct _replace_if_impl<list<>, list<>, val>
+        {
+            using type = list<>;
+        };
+
+        template<typename... vals, int_... vs, typename val>
+        struct _replace_if_impl<list<vals...>, list<number<vs>...>, val>
+        {
+            using type = list<if_<number<vs>, val, vals>...>;
+        };
+    }
 }
 
 #endif