feat: Implement cartesian_for_index with test

cwahn · Sep 18, 2023 · 07803aa · 07803aa
1 parent 2983160
commit 07803aa
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diff --git a/include/prelude.hpp b/include/prelude.hpp
@@ -606,6 +606,26 @@ namespace efp
         return result;
     }
 
+    // cartesian_for_index
+
+    template <typename F = void (*)(const int &)>
+    void cartesian_for_index(const F &f, const int &i)
+    {
+        for_index(f, i);
+    }
+
+    template <typename... Ints, typename F = void (*)(const int &)>
+    void cartesian_for_index(const F &f, const int &i, const Ints &...is)
+    {
+        for (int i_ = 0; i_ < i; ++i_)
+        {
+            const auto inner = [=](const Ints &...is)
+            { f(i_, is...); };
+
+            cartesian_for_index(inner, is...);
+        }
+    }
+
     // // todo begin
 
     // // todo end

diff --git a/test/prelude_test.hpp b/test/prelude_test.hpp
@@ -408,6 +408,16 @@ TEST_CASE("cartesian_map")
     CHECK(res == Array<int, 4>{1, 3, 2, 6});
 }
 
+TEST_CASE("cartesian_for_index")
+{
+    Vector<int> res;
+    const auto f = [&](int a, int b)
+    { return res.push_back(a * b); };
+
+    cartesian_for_index(f, 2, 3);
+    CHECK(res == Vector<int>{0, 0, 0, 0, 1, 2});
+}
+
 // todo sequence view
 
 TEST_CASE("head")