asio: Make impl() const

src/asio_client_request.cc

@@ -54,7 +54,7 @@ const std::string &request::method() const { return impl_->method(); }
 
 const header_map &request::header() const { return impl_->header(); }
 
-request_impl &request::impl() { return *impl_; }
+request_impl &request::impl() const { return *impl_; }
 
 } // namespace client
 } // namespace asio_http2

src/asio_client_response.cc

@@ -46,7 +46,7 @@ int64_t response::content_length() const { return impl_->content_length(); }
 
 const header_map &response::header() const { return impl_->header(); }
 
-response_impl &response::impl() { return *impl_; }
+response_impl &response::impl() const { return *impl_; }
 
 } // namespace client
 } // namespace asio_http2

src/asio_http2_handler.cc

@@ -66,7 +66,7 @@ void request::on_data(data_cb cb) const {
 
 void request::on_end(void_cb cb) const { return impl_->on_end(std::move(cb)); }
 
-request_impl &request::impl() { return *impl_; }
+request_impl &request::impl() const { return *impl_; }
 
 response::response() : impl_(make_unique<response_impl>()) {}
 
@@ -85,7 +85,7 @@ unsigned int response::status_code() const { return impl_->status_code(); }
 
 bool response::started() const { return impl_->started(); }
 
-response_impl &response::impl() { return *impl_; }
+response_impl &response::impl() const { return *impl_; }
 
 request_impl::request_impl() : stream_(nullptr), pushed_(false) {}
 

src/includes/nghttp2/asio_http2.h

@@ -149,7 +149,7 @@ public:
   bool pushed() const;
 
   // Application must not call this directly.
-  request_impl &impl();
+  request_impl &impl() const;
 
 private:
   std::unique_ptr<request_impl> impl_;
@@ -183,7 +183,7 @@ public:
   bool started() const;
 
   // Application must not call this directly.
-  response_impl &impl();
+  response_impl &impl() const;
 
 private:
   std::unique_ptr<response_impl> impl_;

src/includes/nghttp2/asio_http2_client.h

@@ -50,7 +50,7 @@ public:
 
   const header_map &header() const;
 
-  response_impl &impl();
+  response_impl &impl() const;
 
 private:
   std::unique_ptr<response_impl> impl_;
@@ -82,7 +82,7 @@ public:
 
   const header_map &header() const;
 
-  request_impl &impl();
+  request_impl &impl() const;
 
 private:
   std::unique_ptr<request_impl> impl_;