adjusted IGameMode trait

src/catch/convert.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use rosu_map::section::{general::GameMode, hit_objects::CurveBuffers};
 
 use crate::{
@@ -28,12 +26,20 @@ const RNG_SEED: i32 = 1337;
 /// A [`Beatmap`] for [`Catch`] calculations.
 pub type CatchBeatmap<'a> = Converted<'a, Catch>;
 
-pub fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
+pub fn check_convert(map: &Beatmap) -> ConvertStatus {
+    match map.mode {
+        GameMode::Osu => ConvertStatus::Conversion,
+        GameMode::Catch => ConvertStatus::Noop,
+        GameMode::Taiko | GameMode::Mania => ConvertStatus::Incompatible,
+    }
+}
+
+pub fn try_convert(map: &mut Beatmap) -> ConvertStatus {
     match map.mode {
         GameMode::Osu => {
-            map.to_mut().mode = GameMode::Catch;
+            map.mode = GameMode::Catch;
 
-            ConvertStatus::Done
+            ConvertStatus::Conversion
         }
         GameMode::Catch => ConvertStatus::Noop,
         GameMode::Taiko | GameMode::Mania => ConvertStatus::Incompatible,

src/catch/mod.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use crate::{
     any::ModeDifficulty,
     model::{
@@ -40,7 +38,11 @@ impl IGameMode for Catch {
     type GradualDifficulty = CatchGradualDifficulty;
     type GradualPerformance = CatchGradualPerformance;
 
-    fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
+    fn check_convert(map: &Beatmap) -> ConvertStatus {
+        convert::check_convert(map)
+    }
+
+    fn try_convert(map: &mut Beatmap) -> ConvertStatus {
         convert::try_convert(map)
     }
 

src/mania/convert/mod.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use rosu_map::{
     section::{general::GameMode, hit_objects::CurveBuffers},
     util::Pos,
@@ -34,12 +32,20 @@ pub type ManiaBeatmap<'a> = Converted<'a, Mania>;
 
 const MAX_NOTES_FOR_DENSITY: usize = 7;
 
-pub fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
+pub fn check_convert(map: &Beatmap) -> ConvertStatus {
+    match map.mode {
+        GameMode::Osu => ConvertStatus::Conversion,
+        GameMode::Mania => ConvertStatus::Noop,
+        GameMode::Taiko | GameMode::Catch => ConvertStatus::Incompatible,
+    }
+}
+
+pub fn try_convert(map: &mut Beatmap) -> ConvertStatus {
     match map.mode {
         GameMode::Osu => {
-            convert(map.to_mut());
+            convert(map);
 
-            ConvertStatus::Done
+            ConvertStatus::Conversion
         }
         GameMode::Mania => ConvertStatus::Noop,
         GameMode::Taiko | GameMode::Catch => ConvertStatus::Incompatible,

src/mania/mod.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use crate::{
     any::ModeDifficulty,
     model::{
@@ -37,7 +35,11 @@ impl IGameMode for Mania {
     type GradualDifficulty = ManiaGradualDifficulty;
     type GradualPerformance = ManiaGradualPerformance;
 
-    fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
+    fn check_convert(map: &Beatmap) -> ConvertStatus {
+        convert::check_convert(map)
+    }
+
+    fn try_convert(map: &mut Beatmap) -> ConvertStatus {
         convert::try_convert(map)
     }
 

src/model/mode.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 pub use rosu_map::section::general::GameMode;
 
 use crate::any::ModeDifficulty;
@@ -31,11 +29,14 @@ pub trait IGameMode: Sized {
     /// The type of a gradual performance calculator.
     type GradualPerformance;
 
+    /// Check whether the map's mode can be converted to the current type.
+    fn check_convert(map: &Beatmap) -> ConvertStatus;
+
     /// Attempt to convert a beatmap.
     ///
-    /// In case [`ConvertStatus::Incompatible`] is returned, the map should
-    /// **not** be modified.
-    fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus;
+    /// In case [`ConvertStatus::Incompatible`] is returned, the map is not
+    /// modified.
+    fn try_convert(map: &mut Beatmap) -> ConvertStatus;
 
     /// Perform a difficulty calculation for a [`Converted`] beatmap and
     /// process the final skill values.
@@ -67,10 +68,10 @@ pub trait IGameMode: Sized {
 /// The status of a conversion through [`IGameMode::try_convert`].
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum ConvertStatus {
-    /// Conversion was not necessary.
+    /// Conversion not necessary.
     Noop,
-    /// Conversion was successful.
-    Done,
-    /// Conversion was not possible.
+    /// Conversion possible.
+    Conversion,
+    /// Conversion not possible.
     Incompatible,
 }

src/osu/convert.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use rosu_map::section::{general::GameMode, hit_objects::CurveBuffers};
 
 use crate::model::{
@@ -17,7 +15,7 @@ use super::{
 /// A [`Beatmap`] for [`Osu`] calculations.
 pub type OsuBeatmap<'a> = Converted<'a, Osu>;
 
-pub fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
+pub fn check_convert(map: &Beatmap) -> ConvertStatus {
     if map.mode == GameMode::Osu {
         ConvertStatus::Noop
     } else {
@@ -25,6 +23,10 @@ pub fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
     }
 }
 
+pub fn try_convert(map: &mut Beatmap) -> ConvertStatus {
+    check_convert(map)
+}
+
 pub fn convert_objects(
     converted: &OsuBeatmap<'_>,
     scaling_factor: &ScalingFactor,

src/osu/mod.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use rosu_map::util::Pos;
 
 use crate::{
@@ -41,7 +39,11 @@ impl IGameMode for Osu {
     type GradualDifficulty = OsuGradualDifficulty;
     type GradualPerformance = OsuGradualPerformance;
 
-    fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
+    fn check_convert(map: &Beatmap) -> ConvertStatus {
+        convert::check_convert(map)
+    }
+
+    fn try_convert(map: &mut Beatmap) -> ConvertStatus {
         convert::try_convert(map)
     }
 

src/taiko/convert.rs

@@ -1,4 +1,4 @@
-use std::{borrow::Cow, cmp};
+use std::cmp;
 
 use rosu_map::{
     section::{general::GameMode, hit_objects::CurveBuffers},
@@ -23,12 +23,20 @@ pub type TaikoBeatmap<'a> = Converted<'a, Taiko>;
 const LEGACY_TAIKO_VELOCITY_MULTIPLIER: f32 = 1.4;
 const OSU_BASE_SCORING_DIST: f32 = 100.0;
 
-pub fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
+pub fn check_convert(map: &Beatmap) -> ConvertStatus {
+    match map.mode {
+        GameMode::Osu => ConvertStatus::Conversion,
+        GameMode::Taiko => ConvertStatus::Noop,
+        GameMode::Catch | GameMode::Mania => ConvertStatus::Incompatible,
+    }
+}
+
+pub fn try_convert(map: &mut Beatmap) -> ConvertStatus {
     match map.mode {
         GameMode::Osu => {
-            convert(map.to_mut());
+            convert(map);
 
-            ConvertStatus::Done
+            ConvertStatus::Conversion
         }
         GameMode::Taiko => ConvertStatus::Noop,
         GameMode::Catch | GameMode::Mania => ConvertStatus::Incompatible,

src/taiko/mod.rs

@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use crate::{
     any::ModeDifficulty,
     model::{
@@ -37,7 +35,11 @@ impl IGameMode for Taiko {
     type GradualDifficulty = TaikoGradualDifficulty;
     type GradualPerformance = TaikoGradualPerformance;
 
-    fn try_convert(map: &mut Cow<'_, Beatmap>) -> ConvertStatus {
+    fn check_convert(map: &Beatmap) -> ConvertStatus {
+        convert::check_convert(map)
+    }
+
+    fn try_convert(map: &mut Beatmap) -> ConvertStatus {
         convert::try_convert(map)
     }