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slightlyoutofphase · Apr 2, 2021 · 8a9668c · 8a9668c
1 parent 413c5dc
commit 8a9668c
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Showing 4 changed files with 86 additions and 43 deletions.
diff --git a/Cargo.toml b/Cargo.toml
@@ -5,7 +5,7 @@ repository = "https://github.com/slightlyoutofphase/staticstep"
 documentation = "https://docs.rs/staticstep/"
 license = "MIT OR Apache-2.0"
 readme = "README.md"
-version = "0.2.0"
+version = "0.2.1"
 keywords = ["iterator", "iterators", "step", "range", "ranges"]
 categories = ["data-structures", "algorithms"]
 edition = "2018"

diff --git a/benches/step_by_comparison.rs b/benches/step_by_comparison.rs
@@ -8,79 +8,79 @@ use staticstep::*;
 
 #[bench]
 fn inc_by_exclusive(b: &mut Bencher) {
-  let mut j = 0;
+  let mut j = 0usize;
   b.iter(|| {
-    for i in (0..32768).inc_by::<16>() {
+    for i in (0usize..32768usize).inc_by::<16usize>() {
       j += black_box(i);
     }
   });
 }
 
 #[bench]
 fn inc_by_inclusive(b: &mut Bencher) {
-  let mut j = 0;
+  let mut j = 0usize;
   b.iter(|| {
-    for i in (0..=32768).inc_by::<16>() {
+    for i in (0usize..=32768usize).inc_by::<16usize>() {
       j += black_box(i);
     }
   });
 }
 
 #[bench]
 fn dec_by_exclusive(b: &mut Bencher) {
-  let mut j = 0;
+  let mut j = 0usize;
   b.iter(|| {
-    for i in (32768..0).dec_by::<16>() {
+    for i in (32768usize..0usize).dec_by::<16usize>() {
       j += black_box(i);
     }
   });
 }
 
 #[bench]
 fn dec_by_inclusive(b: &mut Bencher) {
-  let mut j = 0;
+  let mut j = 0usize;
   b.iter(|| {
-    for i in (32768..=0).dec_by::<16>() {
+    for i in (32768usize..=0usize).dec_by::<16usize>() {
       j += black_box(i);
     }
   });
 }
 
 #[bench]
 fn step_by_inc_exclusive(b: &mut Bencher) {
-  let mut j = 0;
+  let mut j = 0usize;
   b.iter(|| {
-    for i in (0..32768).step_by(16) {
+    for i in (0usize..32768usize).step_by(16usize) {
       j += black_box(i);
     }
   });
 }
 
 #[bench]
 fn step_by_inc_inclusive(b: &mut Bencher) {
-  let mut j = 0;
+  let mut j = 0usize;
   b.iter(|| {
-    for i in (0..=32768).step_by(16) {
+    for i in (0usize..=32768usize).step_by(16usize) {
       j += black_box(i);
     }
   });
 }
 
 #[bench]
 fn step_by_dec_exclusive(b: &mut Bencher) {
-  let mut j = 0;
+  let mut j = 0usize;
   b.iter(|| {
-    for i in (16..32784).step_by(16).rev() {
+    for i in (16usize..32784usize).step_by(16usize).rev() {
       j += black_box(i);
     }
   });
 }
 
 #[bench]
 fn step_by_dec_inclusive(b: &mut Bencher) {
-  let mut j = 0;
+  let mut j = 0usize;
   b.iter(|| {
-    for i in (0..=32768).rev().step_by(16) {
+    for i in (0usize..=32768usize).rev().step_by(16usize) {
       j += black_box(i);
     }
   });

diff --git a/src/lib.rs b/src/lib.rs
@@ -41,14 +41,14 @@ impl<T: Copy + Default + Step, const STEP: usize> IncBy<T, STEP> {
 impl<T: Copy + Default + Step, const STEP: usize> DecBy<T, STEP> {
   #[inline(always)]
   fn new<R: RangeBounds<T>>(bounds: R) -> DecBy<T, STEP> {
-    let start = match bounds.start_bound() {
-      Included(&idx) => idx,
-      Excluded(&idx) => idx,
-      Unbounded => Default::default(),
-    };
-    let end = match bounds.end_bound() {
+    let start = match bounds.end_bound() {
       Included(&idx) => idx,
       Excluded(&idx) => Step::forward(idx, 1),
+      Unbounded => Step::forward(Default::default(), 1),
+    };
+    let end = match bounds.start_bound() {
+      Included(&idx) => Step::forward(idx, STEP),
+      Excluded(&idx) => Step::forward(idx, STEP + 1),
       Unbounded => Default::default(),
     };
     DecBy { start, end }
@@ -60,14 +60,10 @@ impl<T: Copy + Default + Step, const STEP: usize> Iterator for IncBy<T, STEP> {
 
   #[inline(always)]
   fn next(&mut self) -> Option<T> {
-    if let Some(remaining) = Step::backward_checked(self.end, STEP) {
-      if remaining >= self.start {
-        let res = Some(self.start);
-        self.start = Step::forward(self.start, STEP);
-        res
-      } else {
-        None
-      }
+    if self.start <= Step::backward(self.end, STEP) {
+      let res = Some(self.start);
+      self.start = Step::forward(self.start, STEP);
+      res
     } else {
       None
     }
@@ -79,14 +75,9 @@ impl<T: Copy + Default + Step, const STEP: usize> Iterator for DecBy<T, STEP> {
 
   #[inline(always)]
   fn next(&mut self) -> Option<T> {
-    if let Some(remaining) = Step::backward_checked(self.start, STEP) {
-      if self.start >= self.end {
-        let res = Some(self.start);
-        self.start = remaining;
-        res
-      } else {
-        None
-      }
+    if Step::forward(self.start, STEP) <= self.end {
+      self.end = Step::backward(self.end, STEP);
+      Some(self.end)
     } else {
       None
     }

diff --git a/tests/test_staticstep.rs b/tests/test_staticstep.rs
@@ -10,6 +10,16 @@ fn inc_by_exclusive() {
   assert_eq!(r.next(), None);
 }
 
+#[test]
+fn inc_by_exclusive_unbound_start() {
+  let mut r = (..64).inc_by::<16>();
+  assert_eq!(r.next(), Some(0));
+  assert_eq!(r.next(), Some(16));
+  assert_eq!(r.next(), Some(32));
+  assert_eq!(r.next(), Some(48));
+  assert_eq!(r.next(), None);
+}
+
 #[test]
 fn inc_by_inclusive() {
   let mut r = (0..=64).inc_by::<16>();
@@ -22,8 +32,40 @@ fn inc_by_inclusive() {
 }
 
 #[test]
-fn dec_by_exclusive() {
-  let mut r = (64usize..0usize).dec_by::<16usize>();
+fn inc_by_inclusive_unbound_start() {
+  let mut r = (..=64).inc_by::<16>();
+  assert_eq!(r.next(), Some(0));
+  assert_eq!(r.next(), Some(16));
+  assert_eq!(r.next(), Some(32));
+  assert_eq!(r.next(), Some(48));
+  assert_eq!(r.next(), Some(64));
+  assert_eq!(r.next(), None);
+}
+
+#[test]
+fn dec_by_exclusive_usize() {
+  let mut r = (64usize..0usize).dec_by::<16>();
+  assert_eq!(r.next(), Some(64));
+  assert_eq!(r.next(), Some(48));
+  assert_eq!(r.next(), Some(32));
+  assert_eq!(r.next(), Some(16));
+  assert_eq!(r.next(), None);
+}
+
+#[test]
+fn dec_by_inclusive_usize() {
+  let mut r = (64usize..=0usize).dec_by::<16>();
+  assert_eq!(r.next(), Some(64));
+  assert_eq!(r.next(), Some(48));
+  assert_eq!(r.next(), Some(32));
+  assert_eq!(r.next(), Some(16));
+  assert_eq!(r.next(), Some(0));
+  assert_eq!(r.next(), None);
+}
+
+#[test]
+fn dec_by_exclusive_isize() {
+  let mut r = (64isize..0isize).dec_by::<16>();
   assert_eq!(r.next(), Some(64));
   assert_eq!(r.next(), Some(48));
   assert_eq!(r.next(), Some(32));
@@ -32,8 +74,8 @@ fn dec_by_exclusive() {
 }
 
 #[test]
-fn dec_by_inclusive() {
-  let mut r = (64..=0).dec_by::<16>();
+fn dec_by_inclusive_isize() {
+  let mut r = (64isize..=0isize).dec_by::<16>();
   assert_eq!(r.next(), Some(64));
   assert_eq!(r.next(), Some(48));
   assert_eq!(r.next(), Some(32));
@@ -42,6 +84,16 @@ fn dec_by_inclusive() {
   assert_eq!(r.next(), None);
 }
 
+#[test]
+fn dec_by_exclusive_unbound_end() {
+  let mut r = (64isize..).dec_by::<16>();
+  assert_eq!(r.next(), Some(64));
+  assert_eq!(r.next(), Some(48));
+  assert_eq!(r.next(), Some(32));
+  assert_eq!(r.next(), Some(16));
+  assert_eq!(r.next(), None);
+}
+
 #[test]
 fn inc_by_exclusive_wrong() {
   let mut r = (64..0).inc_by::<16>();