Refactor layer selection logic for more flexibility

Updated the layer selection logic to utilize an enum, LayersSelector, which supports selecting no layers, specific layers, or all available layers. This refactor enhances code clarity and allows for more flexible layer management.

src/vulkan/utils/layers.rs

@@ -1,17 +1,29 @@
 use std::ffi::CString;
 
+pub enum LayersSelector<'a> {
+    Nothing,
+    SpecificLayers(Vec<&'a str>),
+    All
+}
+
 pub fn use_layers(
     entry: &ash::Entry,
-    layers_to_select: Vec<&str>,
+    selector: LayersSelector,
 ) -> Vec<CString> {
-    let layers_available = get_layers_available(entry);
-
-    let selected_layers = select_layers(&layers_available, &layers_to_select);
-
-    selected_layers
+    let layers_available = get_layers_available(entry)
         .iter()
-        .map(|sl| CString::new(sl.clone().as_bytes()).unwrap())
-        .collect::<Vec<_>>()
+        .filter_map(|layer| {
+            layer.layer_name_as_c_str()
+                .and_then(|layer_name| Ok(CString::from(layer_name)))
+                .ok()
+        })
+        .collect::<Vec<_>>();
+
+    match selector {
+        LayersSelector::Nothing => Vec::new(),
+        LayersSelector::SpecificLayers(layers) => select_layers(&layers_available, &layers),
+        LayersSelector::All => layers_available,
+    }
 }
 
 fn get_layers_available(entry: &ash::Entry) -> Vec<ash::vk::LayerProperties> {
@@ -19,20 +31,21 @@ fn get_layers_available(entry: &ash::Entry) -> Vec<ash::vk::LayerProperties> {
 }
 
 fn select_layers(
-    layers_available: &[ash::vk::LayerProperties],
+    layers_available: &Vec<CString>,
     layers_to_select: &[&str],
-) -> Vec<String> {
-    layers_available
+) -> Vec<CString> {
+    layers_to_select
         .iter()
-        .filter_map(|l| {
-            let layer_name = l
-                .layer_name_as_c_str()
-                .unwrap_or_default()
-                .to_string_lossy();
-            layers_to_select
-                .iter()
-                .find(|&&ln| ln == layer_name)
-                .map(|_| layer_name.into_owned())
+        .filter_map(|layer_name| {
+            if layers_available.iter().any(|layer_available| {
+                layer_available.to_str()
+                    .and_then(|layer_available| Ok(layer_available.eq(*layer_name)))
+                    .unwrap_or(false)
+            }) {
+                CString::new(*layer_name).ok()
+            } else {
+                None
+            }
         })
-        .collect()
+        .collect::<Vec<_>>()
 }