Remove redundant copy in Request API getter (#738)

include/pistache/http.h

@@ -160,7 +160,7 @@ public:
   Request &operator=(Request &&other) = default;
 
   Method method() const;
-  std::string resource() const;
+  const std::string &resource() const;
 
   const Uri::Query &query() const;
 

src/common/http.cc

@@ -549,7 +549,7 @@ CookieJar &Message::cookies() { return cookies_; }
 
 Method Request::method() const { return method_; }
 
-std::string Request::resource() const { return resource_; }
+const std::string &Request::resource() const { return resource_; }
 
 const Uri::Query &Request::query() const { return query_; }
 

tests/http_client_test.cc

@@ -33,7 +33,8 @@ struct FastEvenPagesHandler : public Http::Handler {
 
   void onRequest(const Http::Request &request,
                  Http::ResponseWriter writer) override {
-    std::string page = request.resource().erase(0, 1);
+    std::string page = request.resource();
+    page.erase(0, 1);
     int num = std::stoi(page);
     if (num % 2 != 0) {
       std::this_thread::sleep_for(std::chrono::milliseconds(2500));