iterator sizing lib
init
| -rw-r--r-- | .gitignore | 1 | ||||
| -rw-r--r-- | Cargo.toml | 9 | ||||
| -rw-r--r-- | LICENSE | 21 | ||||
| -rw-r--r-- | README.md | 3 | ||||
| -rw-r--r-- | src/lib.rs | 35 |
5 files changed, 69 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..ffa3bbd --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +Cargo.lock
\ No newline at end of file diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..d176b56 --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,9 @@ +[package] +name = "hinted" +version = "0.0.0" +edition = "2021" +authors = ["bend-n <[email protected]>"] +license = "MIT" +repository = "https://github.com/bend-n/hinted" +exclude = [".gitignore"] +description = "small crate for providing a size hint on an iterator" @@ -0,0 +1,21 @@ +MIT License + +Copyright (c) 2024 bendn + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. diff --git a/README.md b/README.md new file mode 100644 index 0000000..9bdde41 --- /dev/null +++ b/README.md @@ -0,0 +1,3 @@ +# hinted + +small library providing a `hinted` function to set the lower bound size hint of any iterator.
\ No newline at end of file diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..86bb130 --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,35 @@ +/// Provides a hint for an iterator. +pub struct Hinted<I: Iterator> { + /// Wrapped iterator. + pub iter: I, + /// Size hint, decreased on every call to [`next()`](Iterator::next). + pub hint: usize, +} + +/// Set the size hint for an iterator. +pub trait HintExt: Iterator +where + Self: Sized, +{ + fn hinted(self, hint: usize) -> Hinted<Self> { + Hinted { iter: self, hint } + } +} + +impl<I: Iterator> HintExt for I {} + +impl<I> Iterator for Hinted<I> +where + I: Iterator + Sized, +{ + type Item = <I as Iterator>::Item; + + fn next(&mut self) -> Option<Self::Item> { + self.hint = self.hint.saturating_sub(1); + self.iter.next() + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (self.hint, self.iter.size_hint().1) + } +} |