audio_core: Make g_sink_details internally linked

We can hide the direct array from external view and instead provide
functions to retrieve the necessary info. This has the benefit of
completely hiding the makeup of the SinkDetails structure from the rest
of the code.

Given that this makes the array hidden, we can also make the array
constexpr by altering the members slightly. This gets rid of several
static constructor calls related to std::vector and std::function.

Now we don't have heap allocations here that need to occur before the
program can even enter main(). It also has the benefit of saving a
little bit of heap space, but this doesn't matter too much, since the
savings in that regard are pretty tiny.

7 files changed, 58 insertions, 36 deletions

diff --git a/src/audio_core/audio_out.cpp b/src/audio_core/audio_out.cpp
index 0c8f5b18e..cbba17632 100644
--- a/src/audio_core/audio_out.cpp
+++ b/src/audio_core/audio_out.cpp
@@ -30,8 +30,7 @@ static Stream::Format ChannelsToStreamFormat(u32 num_channels) {
 StreamPtr AudioOut::OpenStream(u32 sample_rate, u32 num_channels, std::string&& name,
                                Stream::ReleaseCallback&& release_callback) {
     if (!sink) {
-        const SinkDetails& sink_details = GetSinkDetails(Settings::values.sink_id);
-        sink = sink_details.factory(Settings::values.audio_device_id);
+        sink = CreateSinkFromID(Settings::values.sink_id, Settings::values.audio_device_id);
     }
 
     return std::make_shared<Stream>(
diff --git a/src/audio_core/cubeb_sink.cpp b/src/audio_core/cubeb_sink.cpp
index d31a1c844..097328901 100644
--- a/src/audio_core/cubeb_sink.cpp
+++ b/src/audio_core/cubeb_sink.cpp
@@ -107,7 +107,7 @@ private:
     static void StateCallback(cubeb_stream* stream, void* user_data, cubeb_state state);
 };
 
-CubebSink::CubebSink(std::string target_device_name) {
+CubebSink::CubebSink(std::string_view target_device_name) {
     if (cubeb_init(&ctx, "yuzu", nullptr) != CUBEB_OK) {
         LOG_CRITICAL(Audio_Sink, "cubeb_init failed");
         return;
diff --git a/src/audio_core/cubeb_sink.h b/src/audio_core/cubeb_sink.h
index 59cbf05e9..efb9d1634 100644
--- a/src/audio_core/cubeb_sink.h
+++ b/src/audio_core/cubeb_sink.h
@@ -15,7 +15,7 @@ namespace AudioCore {
 
 class CubebSink final : public Sink {
 public:
-    explicit CubebSink(std::string device_id);
+    explicit CubebSink(std::string_view device_id);
     ~CubebSink() override;
 
     SinkStream& AcquireSinkStream(u32 sample_rate, u32 num_channels,
diff --git a/src/audio_core/null_sink.h b/src/audio_core/null_sink.h
index a78d78893..61a28d542 100644
--- a/src/audio_core/null_sink.h
+++ b/src/audio_core/null_sink.h
@@ -10,7 +10,7 @@ namespace AudioCore {
 
 class NullSink final : public Sink {
 public:
-    explicit NullSink(std::string){};
+    explicit NullSink(std::string_view) {}
     ~NullSink() override = default;
 
     SinkStream& AcquireSinkStream(u32 /*sample_rate*/, u32 /*num_channels*/,
diff --git a/src/audio_core/sink_details.cpp b/src/audio_core/sink_details.cpp
index 67cf1f3b2..a848eb1c9 100644
--- a/src/audio_core/sink_details.cpp
+++ b/src/audio_core/sink_details.cpp
@@ -14,31 +14,68 @@
 #include "common/logging/log.h"
 
 namespace AudioCore {
+namespace {
+struct SinkDetails {
+    using FactoryFn = std::unique_ptr<Sink> (*)(std::string_view);
+    using ListDevicesFn = std::vector<std::string> (*)();
 
-// g_sink_details is ordered in terms of desirability, with the best choice at the top.
-const std::vector<SinkDetails> g_sink_details = {
+    /// Name for this sink.
+    const char* id;
+    /// A method to call to construct an instance of this type of sink.
+    FactoryFn factory;
+    /// A method to call to list available devices.
+    ListDevicesFn list_devices;
+};
+
+// sink_details is ordered in terms of desirability, with the best choice at the top.
+constexpr SinkDetails sink_details[] = {
 #ifdef HAVE_CUBEB
-    SinkDetails{"cubeb", &std::make_unique<CubebSink, std::string>, &ListCubebSinkDevices},
+    SinkDetails{"cubeb",
+                [](std::string_view device_id) -> std::unique_ptr<Sink> {
+                    return std::make_unique<CubebSink>(device_id);
+                },
+                &ListCubebSinkDevices},
 #endif
-    SinkDetails{"null", &std::make_unique<NullSink, std::string>,
+    SinkDetails{"null",
+                [](std::string_view device_id) -> std::unique_ptr<Sink> {
+                    return std::make_unique<NullSink>(device_id);
+                },
                 [] { return std::vector<std::string>{"null"}; }},
 };
 
 const SinkDetails& GetSinkDetails(std::string_view sink_id) {
     auto iter =
-        std::find_if(g_sink_details.begin(), g_sink_details.end(),
+        std::find_if(std::begin(sink_details), std::end(sink_details),
                      [sink_id](const auto& sink_detail) { return sink_detail.id == sink_id; });
 
-    if (sink_id == "auto" || iter == g_sink_details.end()) {
+    if (sink_id == "auto" || iter == std::end(sink_details)) {
         if (sink_id != "auto") {
             LOG_ERROR(Audio, "AudioCore::SelectSink given invalid sink_id {}", sink_id);
         }
         // Auto-select.
-        // g_sink_details is ordered in terms of desirability, with the best choice at the front.
-        iter = g_sink_details.begin();
+        // sink_details is ordered in terms of desirability, with the best choice at the front.
+        iter = std::begin(sink_details);
     }
 
     return *iter;
 }
+} // Anonymous namespace
+
+std::vector<const char*> GetSinkIDs() {
+    std::vector<const char*> sink_ids(std::size(sink_details));
+
+    std::transform(std::begin(sink_details), std::end(sink_details), std::begin(sink_ids),
+                   [](const auto& sink) { return sink.id; });
+
+    return sink_ids;
+}
+
+std::vector<std::string> GetDeviceListForSink(std::string_view sink_id) {
+    return GetSinkDetails(sink_id).list_devices();
+}
+
+std::unique_ptr<Sink> CreateSinkFromID(std::string_view sink_id, std::string_view device_id) {
+    return GetSinkDetails(sink_id).factory(device_id);
+}
 
 } // namespace AudioCore
diff --git a/src/audio_core/sink_details.h b/src/audio_core/sink_details.h
index 03534b187..bc8786270 100644
--- a/src/audio_core/sink_details.h
+++ b/src/audio_core/sink_details.h
@@ -4,34 +4,21 @@
 
 #pragma once
 
-#include <functional>
-#include <memory>
 #include <string>
 #include <string_view>
-#include <utility>
 #include <vector>
 
 namespace AudioCore {
 
 class Sink;
 
-struct SinkDetails {
-    using FactoryFn = std::function<std::unique_ptr<Sink>(std::string)>;
-    using ListDevicesFn = std::function<std::vector<std::string>()>;
+/// Retrieves the IDs for all available audio sinks.
+std::vector<const char*> GetSinkIDs();
 
-    SinkDetails(const char* id_, FactoryFn factory_, ListDevicesFn list_devices_)
-        : id(id_), factory(std::move(factory_)), list_devices(std::move(list_devices_)) {}
+/// Gets the list of devices for a particular sink identified by the given ID.
+std::vector<std::string> GetDeviceListForSink(std::string_view sink_id);
 
-    /// Name for this sink.
-    const char* id;
-    /// A method to call to construct an instance of this type of sink.
-    FactoryFn factory;
-    /// A method to call to list available devices.
-    ListDevicesFn list_devices;
-};
-
-extern const std::vector<SinkDetails> g_sink_details;
-
-const SinkDetails& GetSinkDetails(std::string_view sink_id);
+/// Creates an audio sink identified by the given device ID.
+std::unique_ptr<Sink> CreateSinkFromID(std::string_view sink_id, std::string_view device_id);
 
 } // namespace AudioCore
diff --git a/src/yuzu/configuration/configure_audio.cpp b/src/yuzu/configuration/configure_audio.cpp
index eb1da0f9e..5d9ccc6e8 100644
--- a/src/yuzu/configuration/configure_audio.cpp
+++ b/src/yuzu/configuration/configure_audio.cpp
@@ -17,8 +17,8 @@ ConfigureAudio::ConfigureAudio(QWidget* parent)
 
     ui->output_sink_combo_box->clear();
     ui->output_sink_combo_box->addItem("auto");
-    for (const auto& sink_detail : AudioCore::g_sink_details) {
-        ui->output_sink_combo_box->addItem(sink_detail.id);
+    for (const char* id : AudioCore::GetSinkIDs()) {
+        ui->output_sink_combo_box->addItem(id);
     }
 
     connect(ui->volume_slider, &QSlider::valueChanged, this,
@@ -97,8 +97,7 @@ void ConfigureAudio::updateAudioDevices(int sink_index) {
     ui->audio_device_combo_box->addItem(AudioCore::auto_device_name);
 
     const std::string sink_id = ui->output_sink_combo_box->itemText(sink_index).toStdString();
-    const std::vector<std::string> device_list = AudioCore::GetSinkDetails(sink_id).list_devices();
-    for (const auto& device : device_list) {
+    for (const auto& device : AudioCore::GetDeviceListForSink(sink_id)) {
         ui->audio_device_combo_box->addItem(QString::fromStdString(device));
     }
 }