From 8bcd1faffcbe17f1879a18b04bab1bbf5a0eadd2 Mon Sep 17 00:00:00 2001
From: fengjiayi <fengjiayi@baidu.com>
Date: Fri, 14 Jul 2017 18:12:14 +0800
Subject: [PATCH] refactor product(DDim ddim)

---
 paddle/framework/ddim.cc      | 15 +++++++++------
 paddle/framework/ddim_test.cc |  3 +++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/paddle/framework/ddim.cc b/paddle/framework/ddim.cc
index 3f949a6595e..a1ae079f4ab 100644
--- a/paddle/framework/ddim.cc
+++ b/paddle/framework/ddim.cc
@@ -178,13 +178,16 @@ std::vector<int> vectorize(const DDim& ddim) {
   return result;
 }
 
-ssize_t product(const DDim& ddim) {
-  ssize_t result = 1;
-  std::vector<int> v = vectorize(ddim);
-  for (auto i : v) {
-    result *= i;
+struct ProductVisitor : public boost::static_visitor<ssize_t> {
+  template <int D>
+  ssize_t operator()(const Dim<D>& dim) {
+    return product(dim);
   }
-  return result;
+};
+
+ssize_t product(const DDim& ddim) {
+  ProductVisitor visitor;
+  return boost::apply_visitor(visitor, ddim);
 }
 
 ///\cond HIDDEN
diff --git a/paddle/framework/ddim_test.cc b/paddle/framework/ddim_test.cc
index 36eef02370e..8ce7886f8ad 100644
--- a/paddle/framework/ddim_test.cc
+++ b/paddle/framework/ddim_test.cc
@@ -52,6 +52,9 @@ TEST(DDim, Equality) {
 
   // product of a DDim
   EXPECT_EQ(paddle::framework::product(vddim), 45);
+  EXPECT_EQ(
+      paddle::framework::product(paddle::framework::make_ddim({3, 2, 5, 3})),
+      90);
 }
 
 TEST(DDim, Print) {
-- 
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