queue: add initial queue and app structure

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>

src/main.zig

@@ -15,13 +15,12 @@ pub fn main() !void {
     var tty = try Tty.init();
     defer tty.deinit();
 
-    const pipe = try std.os.pipe();
     // run our tty read loop in it's own thread
-    const read_thread = try std.Thread.spawn(.{}, Tty.run, .{ &tty, pipe[0] });
+    const read_thread = try std.Thread.spawn(.{}, Tty.run, .{ &tty, Event, eventCallback });
     try read_thread.setName("tty");
 
-    std.time.sleep(100_000_000_0);
-    _ = try std.os.write(pipe[1], "q");
+    std.time.sleep(100_000_000_00);
+    tty.stop();
     read_thread.join();
 
     try stdout.print("Run `zig build test` to run the tests.\n", .{});
@@ -29,9 +28,14 @@ pub fn main() !void {
     try bw.flush(); // don't forget to flush!
 }
 
+const Event = union(enum) {
+    key: u8,
+    mouse: u8,
+};
+
+fn eventCallback(_: Event) void {}
+
 test "simple test" {
-    var list = std.ArrayList(i32).init(std.testing.allocator);
-    defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
-    try list.append(42);
-    try std.testing.expectEqual(@as(i32, 42), list.pop());
+    _ = @import("odditui.zig");
+    _ = @import("queue.zig");
 }

src/odditui.zig

@@ -0,0 +1,47 @@
+const std = @import("std");
+
+const queue = @import("queue.zig");
+
+/// App is the entrypoint for an odditui application. The provided type T should
+/// be a tagged union which contains all of the events the application will
+/// handle. Odditui will look for the following fields on the union and, if
+/// found, emit them via the "nextEvent" method
+pub fn App(comptime T: type) type {
+    return struct {
+        const Self = @This();
+
+        /// the event queue for this App
+        //
+        // TODO: is 512 ok?
+        queue: queue.Queue(T, 512) = .{},
+
+        /// Runtime options
+        const Options = struct {};
+
+        /// Initialize an App with runtime options
+        pub fn init(_: Options) Self {
+            return Self{};
+        }
+
+        /// returns the next available event, blocking until one is available
+        pub fn nextEvent(self: *Self) T {
+            return self.queue.pop();
+        }
+
+        /// posts an event into the event queue. Will block if there is not
+        /// capacity for the event
+        pub fn postEvent(self: *Self, event: T) void {
+            self.queue.push(event);
+        }
+    };
+}
+
+test "App: event queueing" {
+    const Event = union(enum) {
+        key,
+    };
+    var app: App(Event) = App(Event).init(.{});
+    app.postEvent(.key);
+    const event = app.nextEvent();
+    try std.testing.expect(event == .key);
+}

src/queue.zig

@@ -0,0 +1,93 @@
+const std = @import("std");
+const assert = std.debug.assert;
+const atomic = std.atomic;
+const Futex = std.Thread.Futex;
+
+pub fn Queue(
+    comptime T: type,
+    comptime size: usize,
+) type {
+    return struct {
+        buf: [size]T = undefined,
+
+        read_index: usize = 0,
+        write_index: usize = 0,
+
+        mutex: std.Thread.Mutex = .{},
+        // blocks when the buffer is full or empty
+        futex: atomic.Value(u32) = atomic.Value(u32).init(0),
+
+        const Self = @This();
+
+        pub fn pop(self: *Self) T {
+            self.mutex.lock();
+            defer self.mutex.unlock();
+            if (self.isEmpty()) {
+                // If we don't have any items, we unlock and wait
+                self.mutex.unlock();
+                Futex.wait(&self.futex, 0);
+                // regain our lock
+                self.mutex.lock();
+            }
+            if (self.isFull()) {
+                // If we are full, wake up the push
+                defer Futex.wake(&self.futex, 1);
+            }
+            const i = self.read_index;
+            self.read_index += 1;
+            self.read_index = self.read_index % self.buf.len;
+            return self.buf[i];
+        }
+
+        pub fn push(self: *Self, item: T) void {
+            self.mutex.lock();
+            defer self.mutex.unlock();
+            if (self.isFull()) {
+                self.mutex.unlock();
+                Futex.wait(&self.futex, 0);
+                self.mutex.lock();
+            }
+            if (self.isEmpty()) {
+                defer Futex.wake(&self.futex, 1);
+            }
+            const i = self.write_index;
+            self.write_index += 1;
+            self.write_index = self.write_index % self.buf.len;
+            self.buf[i] = item;
+        }
+
+        /// Returns `true` if the ring buffer is empty and `false` otherwise.
+        pub fn isEmpty(self: Self) bool {
+            return self.write_index == self.read_index;
+        }
+
+        /// Returns `true` if the ring buffer is full and `false` otherwise.
+        pub fn isFull(self: Self) bool {
+            return self.mask2(self.write_index + self.buf.len) == self.read_index;
+        }
+
+        /// Returns the length
+        pub fn len(self: Self) usize {
+            const wrap_offset = 2 * self.buf.len * @intFromBool(self.write_index < self.read_index);
+            const adjusted_write_index = self.write_index + wrap_offset;
+            return adjusted_write_index - self.read_index;
+        }
+
+        /// Returns `index` modulo the length of the backing slice.
+        pub fn mask(self: Self, index: usize) usize {
+            return index % self.buf.len;
+        }
+
+        /// Returns `index` modulo twice the length of the backing slice.
+        pub fn mask2(self: Self, index: usize) usize {
+            return index % (2 * self.buf.len);
+        }
+    };
+}
+
+test "Queue: simple push / pop" {
+    var queue: Queue(u8, 16) = .{};
+    queue.push(1);
+    const pop = queue.pop();
+    try std.testing.expectEqual(1, pop);
+}

src/tty/Tty.zig

@@ -1,6 +1,5 @@
 const std = @import("std");
 const os = std.os;
-const xev = @import("xev");
 
 const log = std.log.scoped(.tty);
 
@@ -12,6 +11,9 @@ termios: os.termios,
 /// The file descriptor we are using for I/O
 fd: os.fd_t,
 
+/// the write end of a pipe to signal the tty should exit it's run loop
+quit_fd: ?os.fd_t = null,
+
 /// initializes a Tty instance by opening /dev/tty and "making it raw"
 pub fn init() !Tty {
     // Open our tty
@@ -34,23 +36,38 @@ pub fn deinit(self: *Tty) void {
     os.close(self.fd);
 }
 
+/// stops the run loop
+pub fn stop(self: *Tty) void {
+    if (self.quit_fd) |fd| {
+        _ = std.os.write(fd, "q") catch {};
+    }
+}
+
 /// read input from the tty
-pub fn run(self: *Tty, quit: os.fd_t) !void {
-    defer os.close(quit);
+pub fn run(self: *Tty, comptime T: type, comptime _: fn (ev: T) void) !void {
+    // create a pipe so we can signal to exit the run loop
+    const pipe = try os.pipe();
+    defer os.close(pipe[0]);
+    defer os.close(pipe[1]);
+
+    self.quit_fd = pipe[1];
+
+    var parser: Parser = .{};
+
     var buf: [1024]u8 = undefined;
     var pollfds: [2]std.os.pollfd = .{
         .{ .fd = self.fd, .events = std.os.POLL.IN, .revents = undefined },
-        .{ .fd = quit, .events = std.os.POLL.IN, .revents = undefined },
+        .{ .fd = pipe[0], .events = std.os.POLL.IN, .revents = undefined },
     };
     while (true) {
         _ = try std.os.poll(&pollfds, -1);
         if (pollfds[1].revents & std.os.POLL.IN != 0) {
-            log.info("read thread got quit signal", .{});
+            log.info("quitting read thread", .{});
             return;
         }
 
         const n = try os.read(self.fd, &buf);
-        log.err("{s}", .{buf[0..n]});
+        parser.parse(self, buf[0..n]);
     }
 }
 
@@ -93,3 +110,38 @@ pub fn makeRaw(fd: os.fd_t) !os.termios {
     try os.tcsetattr(fd, .FLUSH, raw);
     return state;
 }
+
+/// parses vt input. Retains some state so we need an object for it
+const Parser = struct {
+    const log = std.log.scoped(.parser);
+
+    // the state of the parser
+    const State = enum {
+        ground,
+        escape,
+        csi,
+        osc,
+        dcs,
+        sos,
+        pm,
+        apc,
+        ss2,
+        ss3,
+    };
+
+    state: State = .ground,
+
+    fn parse(self: *Parser, tty: *Tty, input: []u8) void {
+        _ = tty; // autofix
+        var i: usize = 0;
+        const start: usize = 0;
+        _ = start; // autofix
+        while (i < input.len) : (i += 1) {
+            const b = input[i];
+            switch (self.state) {
+                .ground => Parser.log.err("0x{x}\r", .{b}),
+                else => {},
+            }
+        }
+    }
+};