From 5ccacafdb14fc0a7d7cc16e3611a2a2f372895e2 Mon Sep 17 00:00:00 2001
From: Jason Rhinelander <jason@imaginary.ca>
Date: Tue, 20 Apr 2021 13:53:35 -0300
Subject: [PATCH] Add support for std::optional<T> send arguments

If the optional is set it gets applied as if you specified the `T` in
the send(...), if unset it works as if you didn't specify the argument
at all.
---
 oxenmq/oxenmq.h         | 11 ++++++++++-
 tests/test_commands.cpp | 10 +++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/oxenmq/oxenmq.h b/oxenmq/oxenmq.h
index 3b122a0..1bde562 100644
--- a/oxenmq/oxenmq.h
+++ b/oxenmq/oxenmq.h
@@ -1094,7 +1094,9 @@ public:
      *                 call connect() first).
      * @param cmd - the first data frame value which is almost always the remote "category.command" name
      * @param opts - any number of std::string (or string_views) and send options.  Each send option
-     *               affects how the send works; each string becomes a message part.
+     *               affects how the send works; each string becomes a message part.  May also
+     *               contain std::optional<T> values: the value will be applied as a string or send
+     *               option if set and skipped if null.
      *
      * Example:
      *
@@ -1462,6 +1464,13 @@ inline void apply_send_option(bt_list& parts, bt_dict&, std::string_view arg) {
     parts.emplace_back(arg);
 }
 
+/// std::optional<T>: if the optional is set, we unwrap it and apply as a send_option, otherwise we
+/// ignore it.
+template <typename T>
+inline void apply_send_option(bt_list& parts, bt_dict& control_data, const std::optional<T>& opt) {
+    if (opt) apply_send_option(parts, control_data, *opt);
+}
+
 /// `data_parts` specialization: appends a range of serialized data parts to the parts to send
 template <typename InputIt>
 void apply_send_option(bt_list& parts, bt_dict&, const send_option::data_parts_impl<InputIt> data) {
diff --git a/tests/test_commands.cpp b/tests/test_commands.cpp
index f750ecc..b0c4e24 100644
--- a/tests/test_commands.cpp
+++ b/tests/test_commands.cpp
@@ -415,13 +415,19 @@ TEST_CASE("data parts", "[send][data_parts]") {
         r.clear();
     }
 
+    std::optional<std::string_view> opt1, opt2;
+    std::optional<std::string> opt3, opt4;
+    opt1 = "o1"sv;
+    opt4 = "o4"s;
     std::vector some_data2{{"a"sv, "b"sv, "\0"sv}};
     client.send(c, "public.hello",
             "hi",
             oxenmq::send_option::data_parts(some_data2.begin(), some_data2.end()),
             "another",
             "string"sv,
-            oxenmq::send_option::data_parts(some_data.begin(), some_data.end()));
+            oxenmq::send_option::data_parts(some_data.begin(), some_data.end()),
+            opt1, opt2, opt3, opt4
+            );
 
     std::vector<std::string> expected;
     expected.push_back("hi");
@@ -429,6 +435,8 @@ TEST_CASE("data parts", "[send][data_parts]") {
     expected.push_back("another");
     expected.push_back("string");
     expected.insert(expected.end(), some_data.begin(), some_data.end());
+    expected.push_back("o1");
+    expected.push_back("o4");
 
     reply_sleep();
     {