feat(buffers): add tracking of last modified and last used times for buffers

src/buffer/Buffer.zig

@@ -44,6 +44,9 @@ undo_history: ?*UndoNode = null,
 redo_history: ?*UndoNode = null,
 curr_history: ?*UndoNode = null,
 
+mtime: i64,
+utime: i64,
+
 pub const EolMode = enum { lf, crlf };
 pub const EolModeTag = @typeInfo(EolMode).Enum.tag_type;
 
@@ -1052,6 +1055,8 @@ pub fn create(allocator: Allocator) error{OutOfMemory}!*Self {
         .allocator = self.arena.allocator(),
         .external_allocator = allocator,
         .root = try Node.new(self.allocator, &empty_leaf, &empty_leaf),
+        .mtime = std.time.milliTimestamp(),
+        .utime = std.time.milliTimestamp(),
     };
     return self;
 }
@@ -1063,6 +1068,10 @@ pub fn deinit(self: *Self) void {
     self.external_allocator.destroy(self);
 }
 
+pub fn update_last_used_time(self: *Self) void {
+    self.utime = std.time.milliTimestamp();
+}
+
 fn new_file(self: *const Self, file_exists: *bool) error{OutOfMemory}!Root {
     file_exists.* = false;
     return Leaf.new(self.allocator, "", true, false);
@@ -1142,6 +1151,7 @@ pub fn load_from_string_and_update(self: *Self, file_path: []const u8, s: []cons
     self.last_save = self.root;
     self.last_save_eol_mode = self.file_eol_mode;
     self.file_exists = false;
+    self.mtime = std.time.milliTimestamp();
 }
 
 pub const LoadFromFileError = error{
@@ -1213,12 +1223,14 @@ pub fn load_from_file_and_update(self: *Self, file_path: []const u8) LoadFromFil
     self.file_eol_mode = eol_mode;
     self.file_utf8_sanitized = utf8_sanitized;
     self.last_save_eol_mode = eol_mode;
+    self.mtime = std.time.milliTimestamp();
 }
 
 pub fn reset_to_last_saved(self: *Self) void {
     if (self.last_save) |last_save| {
         self.store_undo(&[_]u8{}) catch {};
         self.root = last_save;
+        self.mtime = std.time.milliTimestamp();
     }
 }
 
@@ -1319,6 +1331,7 @@ pub fn version(self: *const Self) usize {
 
 pub fn update(self: *Self, root: Root) void {
     self.root = root;
+    self.mtime = std.time.milliTimestamp();
 }
 
 pub fn store_undo(self: *Self, meta: []const u8) !void {
@@ -1369,6 +1382,7 @@ pub fn undo(self: *Self, meta: []const u8) error{Stop}![]const u8 {
     self.curr_history = h;
     self.root = h.root;
     self.push_redo(r);
+    self.mtime = std.time.milliTimestamp();
     return h.meta;
 }
 
@@ -1380,5 +1394,6 @@ pub fn redo(self: *Self) error{Stop}![]const u8 {
     self.curr_history = h;
     self.root = h.root;
     self.push_undo(u);
+    self.mtime = std.time.milliTimestamp();
     return h.meta;
 }

src/buffer/Manager.zig

@@ -23,39 +23,47 @@ pub fn deinit(self: *Self) void {
 }
 
 pub fn open_file(self: *Self, file_path: []const u8) Buffer.LoadFromFileError!*Buffer {
-    if (self.buffers.get(file_path)) |buffer| {
-        return buffer;
-    } else {
+    const buffer = if (self.buffers.get(file_path)) |buffer| buffer else blk: {
         var buffer = try Buffer.create(self.allocator);
         errdefer buffer.deinit();
         try buffer.load_from_file_and_update(file_path);
         try self.buffers.put(self.allocator, try self.allocator.dupe(u8, file_path), buffer);
+        break :blk buffer;
+    };
+    buffer.update_last_used_time();
     return buffer;
-    }
 }
 
 pub fn open_scratch(self: *Self, file_path: []const u8, content: []const u8) Buffer.LoadFromStringError!*Buffer {
-    if (self.buffers.get(file_path)) |buffer| {
-        return buffer;
-    } else {
+    const buffer = if (self.buffers.get(file_path)) |buffer| buffer else blk: {
         var buffer = try Buffer.create(self.allocator);
         errdefer buffer.deinit();
         try buffer.load_from_string_and_update(file_path, content);
         buffer.file_exists = true;
         try self.buffers.put(self.allocator, try self.allocator.dupe(u8, file_path), buffer);
+        break :blk buffer;
+    };
+    buffer.update_last_used_time();
     return buffer;
+}
+
+pub fn retire(_: *Self, buffer: *Buffer) void {
+    buffer.update_last_used_time();
+}
+
+pub fn list(self: *Self, allocator: std.mem.Allocator) error{OutOfMemory}![]*const Buffer {
+    var buffers: std.ArrayListUnmanaged([]*const Buffer) = .{};
+    var i = self.buffers.iterator();
+    while (i.next()) |kv|
+        (try buffers.addOne()).* = kv.value_ptr.*;
+
+    std.mem.sort(*Buffer, buffers.items, {}, struct {
+        fn less_fn(_: void, lhs: *Buffer, rhs: *Buffer) bool {
+            return lhs.mtime > rhs.mtime;
         }
-}
+    }.less_fn);
 
-pub fn retire(self: *Self, buffer: *Buffer) void {
-    _ = self;
-    _ = buffer;
-}
-
-pub fn list(self: *Self, allocator: std.mem.Allocator) []*const Buffer {
-    _ = self;
-    _ = allocator;
-    unreachable;
+    return buffers.toOwnedSlice(allocator);
 }
 
 pub fn is_dirty(self: *const Self) bool {