Move func "helpers_gap_size" to Rust

Makefile

@@ -15,7 +15,7 @@ CONFIGMKS = \
 	config/3-defvars.mk
 
 RUST_SRC = src/*.rs src/**/*.rs
-RUST_APIS = src/constraints.h src/geom.h src/settings.h
+RUST_APIS = src/constraints.h src/geom.h src/helpers.h src/settings.h
 
 MODULES_SRC = \
 	src/atoms.c \

src/api/settings.rs

@@ -184,3 +184,16 @@ unsafe extern "C" fn settings_get_swallow_floatting() -> bool {
 unsafe extern "C" fn settings_set_swallow_floating(value: bool) {
     SETTINGS.unwrap().swallow_floating_set(value);
 }
+
+#[no_mangle]
+unsafe extern "C" fn helpers_gap_size(
+    displayed_clients: c_uint,
+    selected_is_fullscreen: bool,
+    any_is_fullscreen: bool,
+) -> c_int {
+    SETTINGS.unwrap().gap_size_helper(
+        displayed_clients,
+        selected_is_fullscreen,
+        any_is_fullscreen,
+    )
+}

src/helpers.c

@@ -2,31 +2,6 @@
 
 #include "settings.h"
 
-int helpers_gap_size(
-	const unsigned int displayed_clients,
-	const bool selected_is_fullscreen,
-	const bool any_is_fullscreen
-) {
-	const SettingsForSingleWindow gap_for_single_window = settings_get_gap_for_single_window();
-	const int gap_size = settings_get_gap_size();
-
-	if (displayed_clients > 1) return gap_size;
-
-	switch (gap_for_single_window) {
-	case SETTINGS_FOR_SINGLE_WINDOW_NEVER:
-		return 0;
-	case SETTINGS_FOR_SINGLE_WINDOW_ALWAYS:
-		return gap_size;
-	case SETTINGS_FOR_SINGLE_WINDOW_NOT_IN_FULLSCREEN:
-		return selected_is_fullscreen ? 0 : gap_size;
-	case SETTINGS_FOR_SINGLE_WINDOW_NOBODY_IS_FULLSCREEN:
-		return (selected_is_fullscreen || any_is_fullscreen) ? 0 : gap_size;
-	default:
-		// TODO: maybe we should assert here
-		return 0;
-	}
-}
-
 int helpers_border_width(
 	const unsigned int displayed_clients,
 	const bool selected_is_fullscreen,

src/settings.rs

@@ -162,6 +162,36 @@ impl Settings {
         self.gap_size = constraints::gap_size(value);
     }
 
+    pub fn gap_size_helper(
+        &self,
+        displayed_clients: c_uint,
+        selected_is_fullscreen: bool,
+        any_is_fullscreen: bool,
+    ) -> c_int {
+        if displayed_clients > 1 {
+            return self.gap_size;
+        }
+
+        match self.gap_for_single_window {
+            ForSingleWindow::Never => 0,
+            ForSingleWindow::Always => self.gap_size,
+            ForSingleWindow::NotInFullscreen => {
+                if selected_is_fullscreen {
+                    0
+                } else {
+                    self.gap_size
+                }
+            }
+            ForSingleWindow::NobodyIsFullscreen => {
+                if selected_is_fullscreen || any_is_fullscreen {
+                    0
+                } else {
+                    self.gap_size
+                }
+            }
+        }
+    }
+
     pub fn master_area_factor_per_unit(&self) -> unit::Kind {
         self.master_area_factor_per_unit
     }