node/convert: support conversion for std::string_view (#1148)

include/yaml-cpp/node/convert.h

@@ -18,6 +18,10 @@
 #include <valarray>
 #include <vector>
 
+#if __cplusplus >= 201703L
+#include <string_view>
+#endif
+
 #include "yaml-cpp/binary.h"
 #include "yaml-cpp/node/impl.h"
 #include "yaml-cpp/node/iterator.h"
@@ -89,6 +93,20 @@ struct convert<char[N]> {
   static Node encode(const char* rhs) { return Node(rhs); }
 };
 
+#if __cplusplus >= 201703L
+template <>
+struct convert<std::string_view> {
+  static Node encode(std::string_view rhs) { return Node(std::string(rhs)); }
+
+  static bool decode(const Node& node, std::string_view& rhs) {
+    if (!node.IsScalar())
+      return false;
+    rhs = node.Scalar();
+    return true;
+  }
+};
+#endif
+
 template <>
 struct convert<_Null> {
   static Node encode(const _Null& /* rhs */) { return Node(); }

test/node/node_test.cpp

@@ -356,6 +356,15 @@ TEST(NodeTest, ConstInteratorOnSequence) {
   EXPECT_EQ(3, count);
 }
 
+#if __cplusplus >= 201703L
+TEST(NodeTest, StdStringViewAsKey) {
+  Node node;
+  std::string_view key = "username";
+  node[key] = "monkey";
+  EXPECT_EQ("monkey", node[key].as<std::string>());
+}
+#endif
+
 TEST(NodeTest, SimpleSubkeys) {
   Node node;
   node["device"]["udid"] = "12345";