river: Allow floating based on window titles

This extends the `float-filter-add` command to allow matching on window
titles as well, using a `float-filter-add kind pattern` syntax. The
following kinds are supported:

  * `title`, which matches window titles
  * `app-id`, which matches app ids

Only exact matches are considered.

As an example following configuration floats all windows with the title
'asdf with spaces'.

    riverctl float-filter-add title 'asdf with spaces'

doc/riverctl.1.scd

@@ -41,14 +41,14 @@ over the Wayland protocol.
 *exit*
 	Exit the compositor, terminating the Wayland session.
 
-*float-filter-add* _app-id_
-	Add _app-id_ to the float filter list. Views with this _app-id_
-	will start floating. Note that this affects only new views, not already
-	existing ones.
+*float-filter-add* *app-id*|*title* _pattern_
+	Add a pattern to the float filter list. Note that this affects only new
+	views, not already existing ones. Title updates are also not taken into
+	account.
 
-*float-filter-remove* _app-id_
-	Remove an _app-id_ from the float filter list. Note that this affects only
-	new views, not already existing ones.
+*float-filter-remove* *app-id*|*title* _pattern_
+	Remove an app-id or title from the float filter list. Note that this
+	affects only new views, not already existing ones.
 
 *focus-output* *next*|*previous*|*up*|*right*|*down*|*left*
 	Focus the next or previous output or the closest output in any direction.

river/Config.zig

@@ -24,6 +24,7 @@ const util = @import("util.zig");
 const Server = @import("Server.zig");
 const Mode = @import("Mode.zig");
 const AttachMode = @import("view_stack.zig").AttachMode;
+const View = @import("View.zig");
 
 pub const FocusFollowsCursorMode = enum {
     disabled,
@@ -57,8 +58,9 @@ mode_to_id: std.StringHashMap(usize),
 /// All user-defined keymap modes, indexed by mode id
 modes: std.ArrayList(Mode),
 
-/// Set of app_ids which will be started floating
-float_filter: std.StringHashMapUnmanaged(void) = .{},
+/// Sets of app_ids and titles which will be started floating
+float_filter_app_ids: std.StringHashMapUnmanaged(void) = .{},
+float_filter_titles: std.StringHashMapUnmanaged(void) = .{},
 
 /// Set of app_ids which are allowed to use client side decorations
 csd_filter: std.StringHashMapUnmanaged(void) = .{},
@@ -119,9 +121,15 @@ pub fn deinit(self: *Self) void {
     self.modes.deinit();
 
     {
-        var it = self.float_filter.keyIterator();
+        var it = self.float_filter_app_ids.keyIterator();
         while (it.next()) |key| util.gpa.free(key.*);
-        self.float_filter.deinit(util.gpa);
+        self.float_filter_app_ids.deinit(util.gpa);
+    }
+
+    {
+        var it = self.float_filter_titles.keyIterator();
+        while (it.next()) |key| util.gpa.free(key.*);
+        self.float_filter_titles.deinit(util.gpa);
     }
 
     {
@@ -132,3 +140,19 @@ pub fn deinit(self: *Self) void {
 
     util.gpa.free(self.default_layout_namespace);
 }
+
+pub fn shouldFloat(self: Self, view: *View) bool {
+    if (view.getAppId()) |app_id| {
+        if (self.float_filter_app_ids.contains(std.mem.span(app_id))) {
+            return true;
+        }
+    }
+
+    if (view.getTitle()) |title| {
+        if (self.float_filter_titles.contains(std.mem.span(title))) {
+            return true;
+        }
+    }
+
+    return false;
+}

river/XdgToplevel.zig

@@ -212,16 +212,11 @@ fn handleMap(listener: *wl.Listener(*wlr.XdgSurface), xdg_surface: *wlr.XdgSurfa
         view.current.float = true;
         view.pending.float = true;
         view.pending.box = view.float_box;
-    } else {
-        // Make views with app_ids listed in the float filter float
-        if (toplevel.app_id) |app_id| {
-            if (server.config.float_filter.contains(mem.span(app_id))) {
+    } else if (server.config.shouldFloat(view)) {
         view.current.float = true;
         view.pending.float = true;
         view.pending.box = view.float_box;
     }
-        }
-    }
 
     // If the toplevel has an app_id which is not configured to use client side
     // decorations, inform it that it is tiled.

river/XwaylandView.zig

@@ -196,16 +196,11 @@ fn handleMap(listener: *wl.Listener(*wlr.XwaylandSurface), xwayland_surface: *wl
         view.current.float = true;
         view.pending.float = true;
         view.pending.box = view.float_box;
-    } else {
-        // Make views with app_ids listed in the float filter float
-        if (self.xwayland_surface.class) |app_id| {
-            if (server.config.float_filter.contains(std.mem.span(app_id))) {
+    } else if (server.config.shouldFloat(view)) {
         view.current.float = true;
         view.pending.float = true;
         view.pending.box = view.float_box;
     }
-        }
-    }
 
     view.map() catch {
         std.log.crit("out of memory", .{});

river/command/filter.zig

@@ -27,19 +27,31 @@ const ViewStack = @import("view_stack.zig").ViewStack;
 const Error = @import("../command.zig").Error;
 const Seat = @import("../Seat.zig");
 
+const FilterKind = enum {
+    @"app-id",
+    title,
+};
+
 pub fn floatFilterAdd(
     allocator: *mem.Allocator,
     seat: *Seat,
     args: []const [:0]const u8,
     out: *?[]const u8,
 ) Error!void {
-    if (args.len < 2) return Error.NotEnoughArguments;
-    if (args.len > 2) return Error.TooManyArguments;
+    if (args.len < 3) return Error.NotEnoughArguments;
+    if (args.len > 3) return Error.TooManyArguments;
 
-    const gop = try server.config.float_filter.getOrPut(util.gpa, args[1]);
+    const kind = std.meta.stringToEnum(FilterKind, args[1]) orelse return Error.UnknownOption;
+    const map = switch (kind) {
+        .@"app-id" => &server.config.float_filter_app_ids,
+        .title => &server.config.float_filter_titles,
+    };
+
+    const key = args[2];
+    const gop = try map.getOrPut(util.gpa, key);
     if (gop.found_existing) return;
-    errdefer assert(server.config.float_filter.remove(args[1]));
-    gop.key_ptr.* = try std.mem.dupe(util.gpa, u8, args[1]);
+    errdefer assert(map.remove(args[1]));
+    gop.key_ptr.* = try std.mem.dupe(util.gpa, u8, key);
 }
 
 pub fn floatFilterRemove(
@@ -48,10 +60,17 @@ pub fn floatFilterRemove(
     args: []const [:0]const u8,
     out: *?[]const u8,
 ) Error!void {
-    if (args.len < 2) return Error.NotEnoughArguments;
-    if (args.len > 2) return Error.TooManyArguments;
+    if (args.len < 3) return Error.NotEnoughArguments;
+    if (args.len > 3) return Error.TooManyArguments;
 
-    if (server.config.float_filter.fetchRemove(args[1])) |kv| util.gpa.free(kv.key);
+    const kind = std.meta.stringToEnum(FilterKind, args[1]) orelse return Error.UnknownOption;
+    const map = switch (kind) {
+        .@"app-id" => &server.config.float_filter_app_ids,
+        .title => &server.config.float_filter_titles,
+    };
+
+    const key = args[2];
+    if (map.fetchRemove(key)) |kv| util.gpa.free(kv.key);
 }
 
 pub fn csdFilterAdd(