1 files changed, 99 insertions, 0 deletions
diff --git a/src/boost/libs/yap/perf/code_gen_samples.cpp b/src/boost/libs/yap/perf/code_gen_samples.cpp
new file mode 100644
index 000000000..3df71b1cb
--- /dev/null
+++ b/src/boost/libs/yap/perf/code_gen_samples.cpp
@@ -0,0 +1,99 @@
+// Copyright (C) 2016-2018 T. Zachary Laine
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+#include <boost/yap/expression.hpp>
+
+
+template<typename T>
+using term = boost::yap::terminal<boost::yap::expression, T>;
+
+namespace yap = boost::yap;
+namespace bh = boost::hana;
+
+
+namespace user {
+
+    struct number
+    {
+        double value;
+
+        friend number operator+(number lhs, number rhs)
+        {
+            return number{lhs.value + rhs.value};
+        }
+
+        friend number operator*(number lhs, number rhs)
+        {
+            return number{lhs.value * rhs.value};
+        }
+    };
+
+    // A more efficient fused multiply-add operation would normally go here.
+    number naxpy(number a, number x, number y)
+    {
+        return number{a.value * x.value + y.value};
+    }
+
+    // Transforms expressions of the form "a * x + y" to "naxpy(a, x, y)" via
+    // the implicit transform customiztion point.
+    template<typename Expr1, typename Expr2, typename Expr3>
+    decltype(auto) transform_expression(yap::expression<
+                                        yap::expr_kind::plus,
+                                        bh::tuple<
+                                            yap::expression<
+                                                yap::expr_kind::multiplies,
+                                                bh::tuple<Expr1, Expr2>>,
+                                            Expr3>> const & expr)
+    {
+        return naxpy(
+            evaluate(expr.left().left()),
+            evaluate(expr.left().right()),
+            evaluate(expr.right()));
+    }
+}
+
+term<user::number> a{{1.0}};
+term<user::number> x{{42.0}};
+term<user::number> y{{3.0}};
+
+user::number
+eval_as_yap_expr(decltype((a * x + y) * (a * x + y) + (a * x + y)) & expr)
+{
+    return yap::evaluate(expr);
+}
+
+user::number eval_as_yap_expr_4x(decltype(
+    (a * x + y) * (a * x + y) + (a * x + y) + (a * x + y) * (a * x + y) +
+    (a * x + y) + (a * x + y) * (a * x + y) + (a * x + y) +
+    (a * x + y) * (a * x + y) + (a * x + y)) & expr)
+{
+    return yap::evaluate(expr);
+}
+
+user::number eval_as_cpp_expr(user::number a, user::number x, user::number y)
+{
+    return (a * x + y) * (a * x + y) + (a * x + y);
+}
+
+user::number eval_as_cpp_expr_4x(user::number a, user::number x, user::number y)
+{
+    return (a * x + y) * (a * x + y) + (a * x + y) + (a * x + y) * (a * x + y) +
+           (a * x + y) + (a * x + y) * (a * x + y) + (a * x + y) +
+           (a * x + y) * (a * x + y) + (a * x + y);
+}
+
+
+int main()
+{
+    auto expr = (a * x + y) * (a * x + y) + (a * x + y);
+    user::number result_1 = eval_as_yap_expr(expr);
+    user::number result_2 =
+        eval_as_cpp_expr(yap::value(a), yap::value(x), yap::value(y));
+
+    (void)result_1;
+    (void)result_2;
+
+    return 0;
+}