core: Add start_application() to replace the vull::main target

It is better for the application to define int main(). Also switch
to the new ArgsParser class.

engine/CMakeLists.txt

@@ -1,7 +1,6 @@
 vull_module(core xxHash::xxHash Zstd::Zstd)
 vull_module(graphics vull::core vull::vulkan)
 vull_module(json vull::core)
-vull_module(main vull::core)
 vull_module(physics vull::core)
 vull_module(script vull::core)
 vull_module(shaderc vull::core)

engine/include/vull/core/application.hh

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <vull/support/function.hh>
+
+namespace vull {
+
+class ArgsParser;
+
+int start_application(int argc, char **argv, ArgsParser &args_parser, Function<void()> start_fn);
+
+} // namespace vull

engine/sources/CMakeLists.txt

@@ -1,4 +1,5 @@
 target_sources(vull-core PRIVATE
+    core/application.cc
     core/log.cc
     ecs/entity.cc
     ecs/world.cc
@@ -40,8 +41,6 @@ target_sources(vull-json PRIVATE
     json/parser.cc
     json/tree.cc)
 
-target_sources(vull-main PRIVATE core/main.cc)
-
 target_sources(vull-physics PRIVATE
     physics/mpr.cc
     physics/physics_engine.cc

engine/sources/core/application.cc

@@ -0,0 +1,83 @@
+#include <vull/core/application.hh>
+
+#include <vull/core/log.hh>
+#include <vull/platform/file.hh>
+#include <vull/support/args_parser.hh>
+#include <vull/tasklet/scheduler.hh>
+#include <vull/vpak/file_system.hh>
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+namespace vull {
+
+static int vpak_select(const struct dirent *entry) {
+    return StringView(static_cast<const char *>(entry->d_name)).ends_with(".vpak") ? 1 : 0;
+}
+
+int start_application(int argc, char **argv, ArgsParser &args_parser, Function<void()> start_fn) {
+    String vpak_directory_path;
+    args_parser.add_option(vpak_directory_path, "Vpak directory path", "vpak-dir");
+    if (auto result = args_parser.parse_args(argc, argv); result != ArgsParseResult::Continue) {
+        return result == ArgsParseResult::ExitSuccess ? EXIT_SUCCESS : EXIT_FAILURE;
+    }
+
+    // Default to directory containing the executable.
+    if (vpak_directory_path.empty()) {
+        char *last_slash = argv[0];
+        for (char *path = argv[0]; *path != '\0'; path++) {
+            if (*path == '/') {
+                last_slash = path;
+            }
+        }
+        vpak_directory_path = String::copy_raw(argv[0], static_cast<size_t>(last_slash - argv[0]));
+    }
+
+    vull::open_log();
+    vull::set_log_colours_enabled(isatty(STDOUT_FILENO) == 1);
+
+    struct dirent **entry_list;
+    int entry_count = scandir(vpak_directory_path.data(), &entry_list, &vpak_select, &alphasort);
+    if (entry_count < 0) {
+        vull::error("[main] Failed to scan vpak directory '{}': {}", vpak_directory_path, strerror(errno));
+        return EXIT_FAILURE;
+    }
+
+    int dir_fd = open(vpak_directory_path.data(), O_DIRECTORY);
+    if (dir_fd < 0) {
+        vull::error("[main] Failed to open vpak directory '{}': {}", vpak_directory_path, strerror(errno));
+        return EXIT_FAILURE;
+    }
+
+    for (int i = 0; i < entry_count; i++) {
+        const dirent *entry = entry_list[i];
+
+        String name(static_cast<const char *>(entry->d_name));
+        vull::info("[main] Found vpak {}", name);
+
+        int fd = openat(dir_fd, name.data(), 0);
+        if (fd < 0) {
+            vull::error("[main] Failed to open vpak '{}': {}", name, strerror(errno));
+            return EXIT_FAILURE;
+        }
+
+        vpak::load_vpak(File::from_fd(fd));
+        free(entry_list[i]);
+    }
+    free(entry_list);
+    close(dir_fd);
+
+    Scheduler scheduler;
+    scheduler.start([start_fn = vull::move(start_fn)] {
+        start_fn();
+        Scheduler::current().stop();
+        vull::close_log();
+    });
+    return EXIT_SUCCESS;
+}
+
+} // namespace vull

sandbox/CMakeLists.txt

@@ -1,3 +1,3 @@
-vull_executable(vull-sandbox vull::core vull::graphics vull::main vull::physics vull::ui vull::x11-window)
+vull_executable(vull-sandbox vull::core vull::graphics vull::physics vull::ui vull::x11-window)
 target_sources(vull-sandbox PRIVATE free_camera.cc main.cc orbit_camera.cc)
 vull_depend_builtin(vull-sandbox)

sandbox/main.cc

@@ -3,9 +3,9 @@
 #include <vull/container/array.hh>
 #include <vull/container/hash_map.hh>
 #include <vull/container/vector.hh>
+#include <vull/core/application.hh>
 #include <vull/core/input.hh>
 #include <vull/core/log.hh>
-#include <vull/core/main.hh>
 #include <vull/core/window.hh>
 #include <vull/ecs/world.hh>
 #include <vull/graphics/default_renderer.hh>
@@ -23,6 +23,7 @@
 #include <vull/platform/timer.hh>
 #include <vull/scene/scene.hh>
 #include <vull/support/algorithm.hh>
+#include <vull/support/args_parser.hh>
 #include <vull/support/function.hh>
 #include <vull/support/optional.hh>
 #include <vull/support/result.hh>
@@ -61,28 +62,7 @@
 
 using namespace vull;
 
-void vull_main(Vector<StringView> &&args) {
-    if (args.size() < 2) {
-        vull::println("usage: {} [--enable-vvl] <scene-name>", args[0]);
-        return;
-    }
-
-    StringView scene_name;
-    bool enable_validation = false;
-    for (const auto &arg : vull::slice(args, 1u)) {
-        if (arg == "--enable-vvl") {
-            enable_validation = true;
-        } else if (arg[0] == '-') {
-            vull::println("fatal: unknown option {}", arg);
-            return;
-        } else if (scene_name.empty()) {
-            scene_name = arg;
-        } else {
-            vull::println("fatal: unexpected argument {}", arg);
-            return;
-        }
-    }
-
+void sandbox_main(bool enable_validation, StringView scene_name) {
     Window window({}, {}, true);
     vk::Context context(enable_validation);
     auto swapchain = window.create_swapchain(context, vk::SwapchainMode::LowPower);
@@ -277,3 +257,15 @@ void vull_main(Vector<StringView> &&args) {
     }
     context.vkDeviceWaitIdle();
 }
+
+int main(int argc, char **argv) {
+    bool enable_validation = false;
+    String scene_name;
+
+    ArgsParser args_parser("vull-sandbox", "Vull Sandbox", "0.1.0");
+    args_parser.add_flag(enable_validation, "Enable vulkan validation layer", "enable-vvl");
+    args_parser.add_argument(scene_name, "scene-name", true);
+    return vull::start_application(argc, argv, args_parser, [&] {
+        sandbox_main(enable_validation, scene_name);
+    });
+}