refactor: new tr_variant API in transmission-remote and other cleanup (#6798)

* refactor: remove `Arguments`

* refactor: replace pointer args with lvalue reference

* refactor: use `uint16_t` for port number

* chore: housekeeping

* refactor: replace `char*` with `std::string_view`

* refactor: simplify argument parsing code

* refactor: use new `tr_variant` API in remote

* chore: rename function to snake_case

* chore: move `break` statements in switches outside of compound statements

* chore: use `std::string` literals

* refactor: extract tor start/stop to `MODE_TORRENT_START_STOP`

* refactor: extract tor actions to `MODE_TORRENT_ACTION`

* chore: iwyu

* fix: msvc build failure

* chore: misc cleanup

* fix: dereference optional

* chore: misc cleanup

* ui: fix minor formatting errors

* fix: remove redundant if branches for response string

* code review: remove `o` prefix for optionals

* code review: add condition clause

* code review: check `left_until_done` instead

* fix: unchecked nullptr

* code review: don't reassign method name

* code review: revert accidentally renaming `addIdArg` to `get_id_arg`

* code review: use `TR_ASSERT` instead of `assert`

* refactor: fix static auto constexpr naming

* code review: assert array size

* code review: assert that `arguments` key exists

libtransmission/utils.cc

@@ -552,7 +552,7 @@ std::string tr_strpercent(double x)
     return fmt::format("{:.0Lf}", x);
 }
 
-std::string tr_strratio(double ratio, char const* infinity)
+std::string tr_strratio(double ratio, std::string_view infinity)
 {
     if ((int)ratio == TR_RATIO_NA)
     {
@@ -561,7 +561,7 @@ std::string tr_strratio(double ratio, char const* infinity)
 
     if ((int)ratio == TR_RATIO_INF)
     {
-        return infinity != nullptr ? infinity : "";
+        return std::string{ infinity };
     }
 
     return tr_strpercent(ratio);

libtransmission/utils.h

@@ -256,7 +256,7 @@ template<typename T, std::enable_if_t<std::is_floating_point_v<T>, bool> = true>
 
 /** @param ratio    the ratio to convert to a string
     @param infinity the string representation of "infinity" */
-[[nodiscard]] std::string tr_strratio(double ratio, char const* infinity);
+[[nodiscard]] std::string tr_strratio(double ratio, std::string_view infinity);
 
 // ---
 

libtransmission/variant.cc

@@ -76,8 +76,7 @@ template<typename T>
 
     if (auto* const map = var != nullptr ? var->get_if<tr_variant::MapIndex>() : nullptr; map != nullptr)
     {
-        map->erase(key);
-        return &map->try_emplace(key, std::forward<T>(val)).first;
+        return &map->insert_or_assign(key, std::forward<T>(val)).first;
     }
 
     return {};

libtransmission/variant.h

@@ -148,8 +148,26 @@ public:
             return { vec_.emplace_back(key, tr_variant{ std::forward<Val>(val) }).second, true };
         }
 
+        template<typename Val>
+        std::pair<tr_variant&, bool> insert_or_assign(tr_quark const key, Val&& val)
+        {
+            auto res = try_emplace(key, std::forward<Val>(val));
+            if (!res.second)
+            {
+                res.first = std::forward<Val>(val);
+            }
+            return res;
+        }
+
         // --- custom functions
 
+        template<typename Type>
+        [[nodiscard]] TR_CONSTEXPR20 auto find_if(tr_quark const key) noexcept
+        {
+            auto const iter = find(key);
+            return iter != end() ? iter->second.get_if<Type>() : nullptr;
+        }
+
         template<typename Type>
         [[nodiscard]] TR_CONSTEXPR20 auto find_if(tr_quark const key) const noexcept
         {