Implement bindsym --to-code

* `bindsym --to-code` enables keysym to keycode translation.
* If there are no `xkb_layout` commands in the config file, the translation
uses the XKB_DEFAULT_LAYOUT value.
* It there is one or more `xkb_layout` command, the translation uses
the first one.
* If the translation is unsuccessful, a message is logged and the binding
is stored as BINDING_KEYSYM.
* The binding keysyms are stored and re-translated when a change in the input
configuration may affect the translated bindings.

sway/commands/bind.c

@@ -24,6 +24,7 @@ void free_sway_binding(struct sway_binding *binding) {
 	}
 
 	list_free_items_and_destroy(binding->keys);
+	list_free_items_and_destroy(binding->syms);
 	free(binding->input);
 	free(binding->command);
 	free(binding);
@@ -249,31 +250,41 @@ static struct cmd_results *switch_binding_remove(
 			switchcombo);
 }
 
-static struct cmd_results *binding_add(struct sway_binding *binding,
-		list_t *mode_bindings, const char *bindtype,
-		const char *keycombo, bool warn) {
-	// overwrite the binding if it already exists
-	bool overwritten = false;
+/**
+ * Insert or update the binding.
+ * Return the binding which has been replaced or NULL.
+ */
+static struct sway_binding *binding_upsert(struct sway_binding *binding,
+		list_t *mode_bindings) {
 	for (int i = 0; i < mode_bindings->length; ++i) {
 		struct sway_binding *config_binding = mode_bindings->items[i];
 		if (binding_key_compare(binding, config_binding)) {
-			sway_log(SWAY_INFO, "Overwriting binding '%s' for device '%s' "
-					"to `%s` from `%s`", keycombo, binding->input,
-					binding->command, config_binding->command);
-			if (warn) {
-				config_add_swaynag_warning("Overwriting binding"
-						"'%s' for device '%s' to `%s` from `%s`",
-						keycombo, binding->input, binding->command,
-						config_binding->command);
-			}
-			free_sway_binding(config_binding);
 			mode_bindings->items[i] = binding;
-			overwritten = true;
+			return config_binding;
 		}
 	}
 
-	if (!overwritten) {
-		list_add(mode_bindings, binding);
+	list_add(mode_bindings, binding);
+	return NULL;
+}
+
+static struct cmd_results *binding_add(struct sway_binding *binding,
+		list_t *mode_bindings, const char *bindtype,
+		const char *keycombo, bool warn) {
+	struct sway_binding *config_binding = binding_upsert(binding, mode_bindings);
+
+	if (config_binding) {
+		sway_log(SWAY_INFO, "Overwriting binding '%s' for device '%s' "
+				"to `%s` from `%s`", keycombo, binding->input,
+				binding->command, config_binding->command);
+		if (warn) {
+			config_add_swaynag_warning("Overwriting binding"
+					"'%s' for device '%s' to `%s` from `%s`",
+					keycombo, binding->input, binding->command,
+					config_binding->command);
+		}
+		free_sway_binding(config_binding);
+	} else {
 		sway_log(SWAY_DEBUG, "%s - Bound %s to command `%s` for device '%s'",
 				bindtype, keycombo, binding->command, binding->input);
 	}
@@ -329,7 +340,6 @@ static struct cmd_results *cmd_bindsym_or_bindcode(int argc, char **argv,
 	bool exclude_titlebar = false;
 	bool warn = true;
 
-	// Handle --release and --locked
 	while (argc > 0) {
 		if (strcmp("--release", argv[0]) == 0) {
 			binding->flags |= BINDING_RELEASE;
@@ -339,6 +349,10 @@ static struct cmd_results *cmd_bindsym_or_bindcode(int argc, char **argv,
 			binding->flags |= BINDING_BORDER | BINDING_CONTENTS | BINDING_TITLEBAR;
 		} else if (strcmp("--border", argv[0]) == 0) {
 			binding->flags |= BINDING_BORDER;
+		} else if (strcmp("--to-code", argv[0]) == 0) {
+			if (!bindcode) {
+				binding->flags |= BINDING_CODE;
+			}
 		} else if (strcmp("--exclude-titlebar", argv[0]) == 0) {
 			exclude_titlebar = true;
 		} else if (strncmp("--input-device=", argv[0],
@@ -410,6 +424,12 @@ static struct cmd_results *cmd_bindsym_or_bindcode(int argc, char **argv,
 	// sort ascending
 	list_qsort(binding->keys, key_qsort_cmp);
 
+	// translate keysyms into keycodes
+	if (!translate_binding(binding)) {
+		sway_log(SWAY_INFO,
+				"Unable to translate bindsym into bindcode: %s", argv[0]);
+	}
+
 	list_t *mode_bindings;
 	if (binding->type == BINDING_KEYCODE) {
 		mode_bindings = config->current_mode->keycode_bindings;
@@ -566,3 +586,114 @@ void seat_execute_command(struct sway_seat *seat, struct sway_binding *binding)
 		ipc_event_binding(binding);
 	}
 }
+
+/**
+ * The last found keycode associated with the keysym
+ * and the total count of matches.
+ */
+struct keycode_matches {
+	xkb_keysym_t keysym;
+	xkb_keycode_t keycode;
+	int count;
+};
+
+/**
+ * Iterate through keycodes in the keymap to find ones matching
+ * the specified keysym.
+ */
+static void find_keycode(struct xkb_keymap *keymap,
+		xkb_keycode_t keycode, void *data) {
+	xkb_keysym_t keysym = xkb_state_key_get_one_sym(
+			config->keysym_translation.xkb_state, keycode);
+
+	if (keysym == XKB_KEY_NoSymbol) {
+		return;
+	}
+
+	struct keycode_matches *matches = data;
+	if (matches->keysym == keysym) {
+		matches->keycode = keycode;
+		matches->count++;
+	}
+}
+
+/**
+ * Return the keycode for the specified keysym.
+ */
+static struct keycode_matches get_keycode_for_keysym(xkb_keysym_t keysym) {
+	struct keycode_matches matches = {
+		.keysym = keysym,
+		.keycode = XKB_KEYCODE_INVALID,
+		.count = 0,
+	};
+
+	xkb_keymap_key_for_each(config->keysym_translation.xkb_keymap,
+			find_keycode, &matches);
+	return matches;
+}
+
+bool translate_binding(struct sway_binding *binding) {
+	if ((binding->flags & BINDING_CODE) == 0) {
+		return true;
+	}
+
+	switch (binding->type) {
+	// a bindsym to translate
+	case BINDING_KEYSYM:
+		binding->syms = binding->keys;
+		binding->keys = create_list();
+		break;
+	// a bindsym to re-translate
+	case BINDING_KEYCODE:
+		list_free_items_and_destroy(binding->keys);
+		binding->keys = create_list();
+		break;
+	default:
+		return true;
+	}
+
+	for (int i = 0; i < binding->syms->length; ++i) {
+		xkb_keysym_t *keysym = binding->syms->items[i];
+		struct keycode_matches matches = get_keycode_for_keysym(*keysym);
+
+		if (matches.count != 1) {
+			sway_log(SWAY_INFO, "Unable to convert keysym %d into"
+					" a single keycode (found %d matches)",
+					*keysym, matches.count);
+			goto error;
+		}
+
+		xkb_keycode_t *keycode = malloc(sizeof(xkb_keycode_t));
+		if (!keycode) {
+			sway_log(SWAY_ERROR, "Unable to allocate memory for a keycode");
+			goto error;
+		}
+
+		*keycode = matches.keycode;
+		list_add(binding->keys, keycode);
+	}
+
+	list_qsort(binding->keys, key_qsort_cmp);
+	binding->type = BINDING_KEYCODE;
+	return true;
+
+error:
+	list_free_items_and_destroy(binding->keys);
+	binding->type = BINDING_KEYSYM;
+	binding->keys = binding->syms;
+	binding->syms = NULL;
+	return false;
+}
+
+void binding_add_translated(struct sway_binding *binding,
+		list_t *mode_bindings) {
+	struct sway_binding *config_binding =
+		binding_upsert(binding, mode_bindings);
+
+	if (config_binding) {
+		sway_log(SWAY_INFO, "Overwriting binding for device '%s' "
+				"to `%s` from `%s`", binding->input,
+				binding->command, config_binding->command);
+		free_sway_binding(config_binding);
+	}
+}

sway/commands/input.c

@@ -39,6 +39,30 @@ static struct cmd_handler input_config_handlers[] = {
 	{ "xkb_numlock", input_cmd_xkb_numlock },
 };
 
+/**
+ * Re-translate keysyms if a change in the input config could affect them.
+ */
+static void retranslate_keysyms(struct input_config *input_config) {
+	bool matched = false;
+	for (int i = 0; i < config->input_configs->length; ++i) {
+		struct input_config *ic = config->input_configs->items[i];
+		matched |= ic->identifier == input_config->identifier;
+
+		// the first configured xkb_layout
+		if (ic->xkb_layout) {
+			if (matched) {
+				translate_keysyms(ic->xkb_layout);
+			}
+
+			// nothing has changed
+			return;
+		}
+	}
+
+	// no xkb_layout has been set, restore the default
+	translate_keysyms(getenv("XKB_DEFAULT_LAYOUT"));
+}
+
 struct cmd_results *cmd_input(int argc, char **argv) {
 	struct cmd_results *error = NULL;
 	if ((error = checkarg(argc, "input", EXPECTED_AT_LEAST, 2))) {
@@ -73,6 +97,7 @@ struct cmd_results *cmd_input(int argc, char **argv) {
 			store_input_config(config->handler_context.input_config);
 
 		input_manager_apply_input_config(ic);
+		retranslate_keysyms(ic);
 	} else {
 		free_input_config(config->handler_context.input_config);
 	}