refactor!: overhauled gradual calc for catch

src/catch/gradual_difficulty.rs

@@ -153,11 +153,15 @@ impl Iterator for CatchGradualDifficultyAttributes<'_> {
             *last = self.movement.curr_section_peak;
         }
 
-        let mut attributes = self.hit_objects.attributes();
+        let stars =
-        attributes.stars =
             Movement::difficulty_value(&mut self.strain_peak_buf).sqrt() * STAR_SCALING_FACTOR;
 
-        Some(attributes)
+        let attrs = CatchDifficultyAttributes {
+            stars,
+            ..self.hit_objects.attributes()
+        };
+
+        Some(attrs)
     }
 }
 
@@ -196,16 +200,22 @@ impl Iterator for CatchObjectIter<'_> {
     type Item = CatchObject;
 
     fn next(&mut self) -> Option<Self::Item> {
-        if let Some(h) = self.last_object.as_mut().and_then(Iterator::next) {
+        if let opt @ Some(_) = self.last_object.as_mut().and_then(Iterator::next) {
-            return Some(h);
+            return opt;
         }
 
-        for h in &mut self.hit_objects {
+        self.hit_objects
-            if let Some(h) = FruitOrJuice::new(h, &mut self.params) {
+            .find_map(|h| FruitOrJuice::new(h, &mut self.params))
-                return self.last_object.insert(h).next();
+            .and_then(|h| self.last_object.insert(h).next())
-            }
     }
 
-        None
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let min = self
+            .last_object
+            .as_ref()
+            .map(ExactSizeIterator::len)
+            .unwrap_or(0);
+
+        (min, None)
     }
 }

src/catch/gradual_performance.rs

@@ -1,44 +1,14 @@
 use crate::{Beatmap, CatchPP};
 
-use super::{CatchGradualDifficultyAttributes, CatchPerformanceAttributes};
+use super::{CatchGradualDifficultyAttributes, CatchPerformanceAttributes, CatchScoreState};
-
-/// Aggregation for a score's current state i.e. what was the
-/// maximum combo so far and what are the current hitresults.
-///
-/// This struct is used for [`CatchGradualPerformanceAttributes`].
-#[derive(Clone, Debug, Default, Eq, PartialEq)]
-pub struct CatchScoreState {
-    /// Maximum combo that the score has had so far.
-    /// **Not** the maximum possible combo of the map so far.
-    ///
-    /// Note that only fruits and droplets are considered for osu!catch combo.
-    pub max_combo: usize,
-    /// Amount of current fruits (300s).
-    pub n_fruits: usize,
-    /// Amount of current droplets (100s).
-    pub n_droplets: usize,
-    /// Amount of current tiny droplets (50s).
-    pub n_tiny_droplets: usize,
-    /// Amount of current tiny droplet misses (katus).
-    pub n_tiny_droplet_misses: usize,
-    /// Amount of current misses (fruits and droplets).
-    pub n_misses: usize,
-}
-
-impl CatchScoreState {
-    /// Create a new empty score state.
-    pub fn new() -> Self {
-        Self::default()
-    }
-}
 
 /// Gradually calculate the performance attributes of an osu!catch map.
 ///
 /// After each hit object you can call
-/// [`process_next_object`](`CatchGradualPerformanceAttributes::process_next_object`)
+/// [`next`](`CatchGradualPerformanceAttributes::next`)
 /// and it will return the resulting current [`CatchPerformanceAttributes`].
 /// To process multiple objects at once, use
-/// [`process_next_n_objects`](`CatchGradualPerformanceAttributes::process_next_n_objects`) instead.
+/// [`nth`](`CatchGradualPerformanceAttributes::nth`) instead.
 ///
 /// Both methods require a [`CatchScoreState`] that contains the current
 /// hitresults as well as the maximum combo so far.
@@ -69,10 +39,10 @@ impl CatchScoreState {
 ///     state.max_combo += 1;
 ///
 ///     # /*
-///     let performance = gradual_perf.process_next_object(state.clone()).unwrap();
+///     let performance = gradual_perf.next(state.clone()).unwrap();
 ///     println!("PP: {}", performance.pp);
 ///     # */
-///     # let _ = gradual_perf.process_next_object(state.clone());
+///     # let _ = gradual_perf.next(state.clone());
 /// }
 ///
 /// // Then comes a miss.
@@ -80,10 +50,10 @@ impl CatchScoreState {
 /// // the next few objects because the combo is reset.
 /// state.n_misses += 1;
 /// # /*
-/// let performance = gradual_perf.process_next_object(state.clone()).unwrap();
+/// let performance = gradual_perf.next(state.clone()).unwrap();
 /// println!("PP: {}", performance.pp);
 /// # */
-/// # let _ = gradual_perf.process_next_object(state.clone());
+/// # let _ = gradual_perf.next(state.clone());
 ///
 /// // The next 10 objects will be a mixture of fruits and droplets.
 /// // Notice how tiny droplets from sliders do not count as hit objects
@@ -92,20 +62,21 @@ impl CatchScoreState {
 /// state.n_fruits += 4;
 /// state.n_droplets += 6;
 /// state.n_tiny_droplets += 12;
+/// // The `nth` method takes a zero-based value.
 /// # /*
-/// let performance = gradual_perf.process_next_n_objects(state.clone(), 10).unwrap();
+/// let performance = gradual_perf.nth(state.clone(), 9).unwrap();
 /// println!("PP: {}", performance.pp);
 /// # */
-/// # let _ = gradual_perf.process_next_n_objects(state.clone(), 10);
+/// # let _ = gradual_perf.nth(state.clone(), 9);
 ///
 /// // Now comes another fruit. Note that the max combo gets incremented again.
 /// state.n_fruits += 1;
 /// state.max_combo += 1;
 /// # /*
-/// let performance = gradual_perf.process_next_object(state.clone()).unwrap();
+/// let performance = gradual_perf.next(state.clone()).unwrap();
 /// println!("PP: {}", performance.pp);
 /// # */
-/// # let _ = gradual_perf.process_next_object(state.clone());
+/// # let _ = gradual_perf.next(state.clone());
 ///
 /// // Skip to the end
 /// # /*
@@ -115,14 +86,14 @@ impl CatchScoreState {
 /// state.n_tiny_droplets = ...
 /// state.n_tiny_droplet_misses = ...
 /// state.n_misses = ...
-/// let final_performance = gradual_perf.process_next_n_objects(state.clone(), usize::MAX).unwrap();
+/// let final_performance = gradual_perf.nth(state.clone(), usize::MAX).unwrap();
 /// println!("PP: {}", performance.pp);
 /// # */
-/// # let _ = gradual_perf.process_next_n_objects(state.clone(), usize::MAX);
+/// # let _ = gradual_perf.nth(state.clone(), usize::MAX);
 ///
 /// // Once the final performance was calculated,
 /// // attempting to process further objects will return `None`.
-/// assert!(gradual_perf.process_next_object(state).is_none());
+/// assert!(gradual_perf.next(state).is_none());
 /// ```
 #[derive(Clone, Debug)]
 pub struct CatchGradualPerformanceAttributes<'map> {
@@ -147,34 +118,17 @@ impl<'map> CatchGradualPerformanceAttributes<'map> {
     ///
     /// Note that neither hits nor misses of tiny droplets require
     /// to be processed. Only fruits and droplets do.
-    pub fn process_next_object(
+    pub fn next(&mut self, state: CatchScoreState) -> Option<CatchPerformanceAttributes> {
-        &mut self,
+        self.nth(state, 0)
-        state: CatchScoreState,
-    ) -> Option<CatchPerformanceAttributes> {
-        self.process_next_n_objects(state, 1)
     }
 
-    /// Same as [`process_next_object`](`CatchGradualPerformanceAttributes::process_next_object`)
+    /// Process everything up the the next `n`th hit object and calculate the performance
-    /// but instead of processing only one object it process `n` many.
+    /// attributes for the resulting score state.
     ///
-    /// If `n` is 0 it will be considered as 1.
+    /// Note that the count is zero-indexed, so `n=0` will process 1 object, `n=1` will process 2,
-    /// If there are still objects to be processed but `n` is larger than the amount
+    /// and so on.
-    /// of remaining objects, `n` will be considered as the amount of remaining objects.
+    pub fn nth(&mut self, state: CatchScoreState, n: usize) -> Option<CatchPerformanceAttributes> {
-    pub fn process_next_n_objects(
+        let difficulty = self.difficulty.by_ref().take(n.saturating_add(1)).last()?;
-        &mut self,
-        state: CatchScoreState,
-        n: usize,
-    ) -> Option<CatchPerformanceAttributes> {
-        let mut difficulty = None;
-
-        for _ in 0..n.max(1) {
-            match self.difficulty.next() {
-                Some(attrs) => difficulty = Some(attrs),
-                None => break,
-            }
-        }
-
-        let difficulty = difficulty?;
 
         let performance = self
             .performance

src/catch/mod.rs

@@ -1,15 +1,25 @@
 mod catch_object;
 mod difficulty_object;
 mod fruit_or_juice;
-mod gradual_difficulty;
-mod gradual_performance;
 mod movement;
 mod pp;
+mod score_state;
+
+#[cfg(feature = "gradual")]
+mod gradual_difficulty;
+#[cfg(feature = "gradual")]
+mod gradual_performance;
 
 use difficulty_object::DifficultyObject;
 use movement::Movement;
 
-pub use self::{catch_object::CatchObject, gradual_difficulty::*, gradual_performance::*, pp::*};
+pub use self::{catch_object::CatchObject, pp::*, score_state::CatchScoreState};
+
+#[cfg(feature = "gradual")]
+pub use self::{
+    gradual_difficulty::CatchGradualDifficultyAttributes,
+    gradual_performance::CatchGradualPerformanceAttributes,
+};
 
 pub(crate) use self::fruit_or_juice::{FruitOrJuice, FruitParams};
 

src/catch/score_state.rs

@@ -0,0 +1,29 @@
+/// Aggregation for a score's current state i.e. what was the
+/// maximum combo so far and what are the current hitresults.
+///
+/// This struct is used for [`CatchGradualPerformanceAttributes`].
+#[derive(Clone, Debug, Default, Eq, PartialEq)]
+pub struct CatchScoreState {
+    /// Maximum combo that the score has had so far.
+    /// **Not** the maximum possible combo of the map so far.
+    ///
+    /// Note that only fruits and droplets are considered for osu!catch combo.
+    pub max_combo: usize,
+    /// Amount of current fruits (300s).
+    pub n_fruits: usize,
+    /// Amount of current droplets (100s).
+    pub n_droplets: usize,
+    /// Amount of current tiny droplets (50s).
+    pub n_tiny_droplets: usize,
+    /// Amount of current tiny droplet misses (katus).
+    pub n_tiny_droplet_misses: usize,
+    /// Amount of current misses (fruits and droplets).
+    pub n_misses: usize,
+}
+
+impl CatchScoreState {
+    /// Create a new empty score state.
+    pub fn new() -> Self {
+        Self::default()
+    }
+}

src/gradual.rs

@@ -231,7 +231,7 @@ impl<'map> GradualPerformanceAttributes<'map> {
                 .nth(state.into(), n)
                 .map(PerformanceAttributes::Taiko),
             GradualPerformanceAttributes::Catch(f) => f
-                .process_next_n_objects(state.into(), n)
+                .nth(state.into(), n)
                 .map(PerformanceAttributes::Catch),
             GradualPerformanceAttributes::Mania(m) => m
                 .nth(state.into(), n)

tests/gradual_catch.rs

@@ -35,10 +35,10 @@ fn correct_empty() {
     let mut gradual = CatchGradualPerformanceAttributes::new(&map, 0);
     let state = CatchScoreState::default();
 
-    let first_attrs = gradual.process_next_n_objects(state.clone(), usize::MAX);
+    let first_attrs = gradual.nth(state.clone(), usize::MAX);
 
     assert!(first_attrs.is_some());
-    assert!(gradual.process_next_object(state).is_none());
+    assert!(gradual.next(state).is_none());
 }
 
 #[test]
@@ -50,14 +50,14 @@ fn next_and_next_n() {
     let mut gradual2 = CatchGradualPerformanceAttributes::new(&map, 0);
 
     for _ in 0..20 {
-        let _ = gradual1.process_next_object(state.clone());
+        let _ = gradual1.next(state.clone());
-        let _ = gradual2.process_next_object(state.clone());
+        let _ = gradual2.next(state.clone());
     }
 
     let n = 80;
 
     for _ in 1..n {
-        let _ = gradual1.process_next_object(state.clone());
+        let _ = gradual1.next(state.clone());
     }
 
     let state = CatchScoreState {
@@ -69,8 +69,8 @@ fn next_and_next_n() {
         n_misses: 0,
     };
 
-    let next = gradual1.process_next_object(state.clone());
+    let next = gradual1.next(state.clone());
-    let next_n = gradual2.process_next_n_objects(state, n);
+    let next_n = gradual2.nth(state, n - 1);
 
     assert_eq!(next_n, next);
 }
@@ -91,7 +91,7 @@ fn gradual_end_eq_regular() {
         n_misses: 0,
     };
 
-    let gradual_end = gradual.process_next_n_objects(state, usize::MAX).unwrap();
+    let gradual_end = gradual.nth(state, usize::MAX).unwrap();
 
     assert_eq!(regular, gradual_end);
 }
@@ -113,7 +113,7 @@ fn gradual_eq_regular_passed() {
         n_misses: 0,
     };
 
-    let gradual = gradual.process_next_n_objects(state, n).unwrap();
+    let gradual = gradual.nth(state, n - 1).unwrap();
 
     assert_eq!(regular, gradual);
 }