src/main.zig

@@ -11,26 +11,76 @@ const sys = @import("./sys.zig");
 /// Entry point.
 ///
 pub fn main() anyerror!void {
-    return sys.runGraphics(anyerror, run);
+    if (ext.SDL_Init(ext.SDL_INIT_EVERYTHING) != 0) {
+        ext.SDL_LogCritical(ext.SDL_LOG_CATEGORY_APPLICATION, "Failed to initialize SDL2 runtime");
+
+        return error.InitFailure;
     }
 
-fn run(event_loop: *sys.EventLoop, graphics: *sys.GraphicalContext) anyerror!void {
-    var gpa = std.heap.GeneralPurposeAllocator(){};
+    defer ext.SDL_Quit();
 
-    {
-        const file = event_loop.open(.readonly, sys.Path.get(.data, &.{"ona.lua"}));
+    const pref_path = create_pref_path: {
+        const path = ext.SDL_GetPrefPath("ona", "ona") orelse {
+            ext.SDL_LogCritical(ext.SDL_LOG_CATEGORY_APPLICATION, "Failed to load user path");
 
-        defer _ = event_loop.closeFile(file);
+            return error.InitFailure;
+        };
 
-        const file_size = try file.size(event_loop);
-        var buffer = try gpa.allocator().alloc(u8, file_size);
+        break: create_pref_path path[0 .. std.mem.len(path)];
+    };
 
-        if (try event_loop.readFile(buffer) != file_size) return error.ScriptLoadError;
+    defer ext.SDL_free(pref_path.ptr);
 
-        sys.log(buffer);
-    }
+    const window = create_window: {
+        const pos = ext.SDL_WINDOWPOS_UNDEFINED;
+        var flags = @as(u32, 0);
 
-    while (graphics.poll()) |_| {
-        graphics.present();
+        break: create_window ext.SDL_CreateWindow("Ona", pos, pos, 640, 480, flags) orelse {
+            ext.SDL_LogCritical(ext.SDL_LOG_CATEGORY_APPLICATION, "Failed to load SDL2 window");
+
+            return error.InitFailure;
+        };
+    };
+
+    defer ext.SDL_DestroyWindow(window);
+
+    const renderer = create_renderer: {
+        var flags = @as(u32, 0);
+
+        break: create_renderer ext.SDL_CreateRenderer(window, -1, flags) orelse {
+            ext.SDL_LogCritical(ext.SDL_LOG_CATEGORY_APPLICATION, "Failed to load SDL2 renderer");
+
+            return error.InitFailure;
+        };
+    };
+
+    defer ext.SDL_DestroyRenderer(renderer);
+
+    var event_loop = sys.EventLoop{};
+    var is_running = true;
+
+    while (is_running) {
+        var event = std.mem.zeroes(ext.SDL_Event);
+
+        while (ext.SDL_PollEvent(&event) != 0) {
+            switch (event.type) {
+                ext.SDL_QUIT => is_running = false,
+                else => {},
+            }
+        }
+
+        if (ext.SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255) != 0) {
+            ext.SDL_LogError(ext.SDL_LOG_CATEGORY_VIDEO, ext.SDL_GetError());
+            ext.SDL_ClearError();
+        }
+
+        if (ext.SDL_RenderClear(renderer) != 0) {
+            ext.SDL_LogError(ext.SDL_LOG_CATEGORY_VIDEO, ext.SDL_GetError());
+            ext.SDL_ClearError();
+        }
+
+        ext.SDL_RenderPresent(renderer);
+        event_loop.tick();
+        ext.SDL_Delay(1);
     }
 }

src/stack.zig

@@ -1,6 +1,17 @@
 const io = @import("./io.zig");
 const std = @import("std");
 
+///
+/// Potential errors that may occur while trying to push one or more elements into a stack of a
+/// known maximum size.
+///
+/// [FinitePushError.Overflow] is returned if the stack does not have sufficient capacity to hold a
+/// given set of elements.
+///
+pub const FixedPushError = error {
+    Overflow,
+};
+
 pub fn Fixed(comptime Element: type) type {
     return struct {
         filled: usize = 0,
@@ -13,7 +24,7 @@ pub fn Fixed(comptime Element: type) type {
         ///
         /// Note that this will raise a compilation error if [Element] is not `u8`.
         ///
-        pub fn writer(self: *Self) io.Writer {
+        pub fn asWriter(self: *Self) io.Writer {
             if (Element != u8) @compileError("Cannot coerce fixed stack of type " ++
                 @typeName(Element) ++ " into a Writer");
 
@@ -80,17 +91,6 @@ pub fn Fixed(comptime Element: type) type {
     };
 }
 
-///
-/// Potential errors that may occur while trying to push one or more elements into a stack of a
-/// known maximum size.
-///
-/// [FinitePushError.Overflow] is returned if the stack does not have sufficient capacity to hold a
-/// given set of elements.
-///
-pub const FixedPushError = error {
-    Overflow,
-};
-
 test "fixed stack" {
     const testing = @import("std").testing;
     const expectError = testing.expectError;
@@ -112,7 +112,7 @@ test "fixed stack" {
 
     try expectEqual(stack.count(), 0);
 
-    const writer = stack.writer();
+    const writer = stack.asWriter();
 
     try expectEqual(writer.write(&.{0, 0, 0, 0}), 4);
     try expectEqual(writer.writeByte(0), false);

src/sys.zig

@@ -10,31 +10,163 @@ const std = @import("std");
 ///
 ///
 ///
-pub const EventLoop = struct {
+pub const EventLoop = packed struct {
+    current_request: ?*Request = null,
 
+    ///
+    /// [OpenError.NotFound] is used as a catch-all for any hardware or software-specific reason for
+    /// failing to open a given file. This includes file-system restrictions surrounding a specific
+    /// file as well as it simply not existing.
+    ///
+    /// [OpenError.OutOfFiles] occurs when there are no more resources available to open further
+    /// files. As a result, some open files must be closed before more may be opened.
+    ///
+    pub const OpenError = error {
+        NotFound,
+        OutOfFiles,
     };
 
     ///
+    /// Indicates what kind of access the consumer logic has to a file.
+    ///
+    /// [OpenMode.read] is for reading from an existing file from the start.
+    ///
+    /// [OpenMode.overwrite] is for deleting the contents of a file, or creating an empty one if no
+    /// such file exists, and writing to it from the start.
+    ///
+    /// [OpenMode.append] is for writing additional contents to a file, creating an empty one if no
+    /// such file exists, on the end of whatever it already contains.
+    ///
+    pub const OpenMode = enum {
+        readonly,
+        overwrite,
+        append,
+    };
+
+    const Request = struct {
+        next: ?*Request = null,
+        frame: anyframe,
+
+        message: union(enum) {
+            close: struct {
+                file: *FileAccess,
+            },
+
+            open: struct {
+                file_system: FileSystem,
+                path: *const Path,
+                mode: OpenMode,
+                file: OpenError!*FileAccess = error.OutOfFiles,
+            },
+        },
+    };
+
+    const max_files = 512;
+
+    ///
+    /// Asynchronously closes `file_access` via `event_loop`.
+    ///
+    /// *Note* that `file_access` must have been opened by `event_loop` for it to be closed by it,
+    /// otherwise it will cause undefined behavior.
+    ///
+    pub fn close(event_loop: *EventLoop, file_access: *FileAccess) void {
+        var request = Request{
+            .frame = @frame(),
+            .message = .{.close = @ptrCast(*ext.SDL_RWops, file_access)},
+        };
+
+        suspend if (event_loop.current_request) |current_request| {
+            current_request.next = &request;
+        } else {
+            event_loop.current_request = &request;
+        };
+    }
+
     ///
     ///
-pub const FileAccess = opaque {
     ///
-    /// Scans the number of bytes in the file referenced by `file_access` via `event_loop`, returing
-    /// its byte size or a [FileError] if it failed.
+    pub fn open(event_loop: *EventLoop, file_system: FileSystem,
+        path: Path, mode: OpenMode) OpenError!*FileAccess {
+
+        var request = Request{
+            .frame = @frame(),
+
+            .message = .{
+                .open = .{
+                    .file_system = file_system,
+                    .path = &path,
+                    .mode = mode,
+                },
+            },
+        };
+
+        suspend if (event_loop.current_request) |current_request| {
+            current_request.next = &request;
+        } else {
+            event_loop.current_request = &request;
+        };
+
+        return @ptrCast(*FileAccess, try request.message.open.file);
+    }
+
     ///
-    pub fn size(file_access: *FileAccess, event_loop: *EventLoop) FileError!usize {
-        const origin_cursor = try app.tellFile(file_access);
+    ///
+    ///
+    pub fn tick(event_loop: *EventLoop) void {
+        while (event_loop.current_request) |request| {
+            switch (request.message) {
+                .close => |*close| {
+                    // Swallow file close errors.
+                    _ = ext.SDL_RWclose(@ptrCast(*ext.SDL_RWops, @alignCast(@alignOf(ext.SDL_RWops), close.file)));
+                },
 
-        try app.seekFile(file_access, .tail, 0);
+                .open => |*open| {
+                    switch (open.file_system) {
+                        .data => {
+                            var zeroed_path_buffer = std.mem.zeroes([4096]u8);
+                            var zeroed_path = stack.Fixed(u8){.buffer = &zeroed_path_buffer};
 
-        const ending_cursor = try app.tellFile(file_access);
+                            zeroed_path.push('.') catch continue;
 
-        try app.seekFile(file_access, .head, origin_cursor);
+                            _ = open.path.write(zeroed_path.asWriter());
 
-        return ending_cursor;
+                            zeroed_path.push(0) catch continue;
+
+                            // TODO: Access TAR file.
+                        },
+
+                        .user => {
+                            var zeroed_path_buffer = std.mem.zeroes([4096]u8);
+                            var zeroed_path = stack.Fixed(u8){.buffer = &zeroed_path_buffer};
+
+                            zeroed_path.pushAll("/home/kayomn/.local/share") catch continue;
+
+                            _ = open.path.write(zeroed_path.asWriter());
+
+                            zeroed_path.push(0) catch continue;
+
+                            open.file = @ptrCast(?*FileAccess, ext.SDL_RWFromFile(&zeroed_path_buffer, switch (open.mode) {
+                                .readonly => "rb",
+                                .overwrite => "wb",
+                                .append => "ab",
+                            })) orelse error.NotFound;
+                        },
+                    }
+                },
+            }
+
+            resume request.frame;
+
+            event_loop.current_request = request.next;
+        }
     }
 };
 
+///
+///
+///
+pub const FileAccess = opaque {};
+
 ///
 /// With files typically being backed by a block device, they can produce a variety of errors -
 /// from physical to virtual errors - these are all encapsulated by the API as general
@@ -44,6 +176,14 @@ pub const FileError = error {
     Inaccessible,
 };
 
+///
+///
+///
+pub const FileSystem = enum {
+    data,
+    user,
+};
+
 ///
 /// Platform-agnostic mechanism for accessing files on any of the virtual file-systems supported by
 /// Ona.
@@ -59,13 +199,6 @@ pub const Path = struct {
         TooLong,
     };
 
-    ///
-    ///
-    ///
-    pub fn isComplete(path: Path) bool {
-        return (path.length != 0) and (path.buffer[0] == '/');
-    }
-
     ///
     /// Returns `true` if the length of `path` is empty, otherwise `false`.
     ///
@@ -80,80 +213,6 @@ pub const Path = struct {
         return std.mem.eql(u8, this.buffer[0 .. this.length], that.buffer[0 .. that.length]);
     }
 
-    ///
-    /// Creates and returns a [Path] value in the file system indicated by `file_system` from the
-    /// path components in `component_groups`.
-    ///
-    pub fn from(file_system: FileSystem, component_groups: []const []const u8) Error!Path {
-        var path = Path{
-            .file_system = file_system,
-            .buffer = std.mem.zeroes([max]u8),
-            .length = 0,
-        };
-
-        for (component_groups) |first_component_group,
-            first_component_group_index| if (first_component_group.len != 0) {
-
-            var first_component_root_offset = @as(usize, 0);
-
-            if (component_group[0] == '/') {
-                comptime if (max < 1) unreachable;
-
-                path.buffer[path.length] = '/';
-                path.length += 1;
-                first_component_root_offset = 1;
-            }
-
-            var first_components = mem.Spliterator(u8){
-                .source = first_component_group[first_component_root_offset ..
-                    (first_component_group.len - first_component_root_offset)],
-
-                .delimiter = "/",
-            };
-
-            while (first_components.next()) |component| if (component.len != 0) {
-                for (component) |byte| {
-                    if (path.length == max) return error.TooLong;
-
-                    path.buffer[path.length] = byte;
-                    path.length += 1;
-                }
-
-                if (path.length == max) return error.TooLong;
-
-                path.buffer[path.length] = '/';
-                path.length += 1;
-            };
-
-            const second_component_group_index = (first_component_group_index + 1);
-
-            for (component_groups[second_component_group_index .. (component_groups.len -
-                second_component_group_index)]) |component_group| if (component_group.len != 0) {
-
-                var components = mem.Spliterator(u8){
-                    .source = component_group,
-                    .delimiter = "/",
-                };
-
-                while (components.next()) |component| if (component.len != 0) {
-                    for (component) |byte| {
-                        if (path.length == max) return error.TooLong;
-
-                        path.buffer[path.length] = byte;
-                        path.length += 1;
-                    }
-
-                    if (path.length == max) return error.TooLong;
-
-                    path.buffer[path.length] = '/';
-                    path.length += 1;
-                };
-            };
-        };
-
-        return path;
-    }
-
     ///
     /// The maximum possible byte-length of a [Path].
     ///
@@ -163,17 +222,31 @@ pub const Path = struct {
     ///
     pub const max = 1000;
 
+    ///
+    ///
+    ///
+    pub fn parseJoins(path: Path, joins: []const []const u8) Error!Path {
+        _ = path;
+        _ = joins;
+
+        return Path{
+            .buffer = std.mem.zeroes([max]u8),
+            .length = 0
+        };
+    }
+
     ///
     ///
     ///
     pub fn write(path: Path, writer: io.Writer) bool {
         return (writer.write(path.buffer[0 .. path.length]) == path.length);
     }
+
+    ///
+    ///
+    ///
+    pub const root = Path{
+        .buffer = [_]u8{'/'} ** max,
+        .length = 1,
+    };
 };
-
-///
-///
-///
-pub fn runGraphics(comptime ErrorUnion: anytype, run: fn (*App) ErrorUnion!void) void {
-
-}