From 481287ddbc0d7df99b3f0ad2dee99e0693ba9b42 Mon Sep 17 00:00:00 2001 From: Chih-Hung Hsieh Date: Thu, 16 Apr 2020 10:44:21 -0700 Subject: Import 'peeking_take_while' package vesion 0.1.2 * Add OWNERS Bug: 152884384 Test: make Change-Id: Ib100009609a6c53365606558a54babffda855e40 --- .gitignore | 3 + .travis.yml | 18 +++++ Android.bp | 8 ++ Cargo.toml | 14 ++++ LICENSE | 1 + LICENSE-APACHE | 201 +++++++++++++++++++++++++++++++++++++++++++++++++ LICENSE-MIT | 25 ++++++ METADATA | 19 +++++ MODULE_LICENSE_APACHE2 | 0 OWNERS | 1 + README.md | 58 ++++++++++++++ src/lib.rs | 117 ++++++++++++++++++++++++++++ 12 files changed, 465 insertions(+) create mode 100644 .gitignore create mode 100644 .travis.yml create mode 100644 Android.bp create mode 100644 Cargo.toml create mode 120000 LICENSE create mode 100644 LICENSE-APACHE create mode 100644 LICENSE-MIT create mode 100644 METADATA create mode 100644 MODULE_LICENSE_APACHE2 create mode 100644 OWNERS create mode 100644 README.md create mode 100644 src/lib.rs diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..4308d82 --- /dev/null +++ b/.gitignore @@ -0,0 +1,3 @@ +target/ +**/*.rs.bk +Cargo.lock diff --git a/.travis.yml b/.travis.yml new file mode 100644 index 0000000..76aa37f --- /dev/null +++ b/.travis.yml @@ -0,0 +1,18 @@ +sudo: false +language: rust + +rust: + - stable + - beta + - nightly + +cache: cargo + +env: + matrix: + - PROFILE="" + - PROFILE="--release" + +script: + - cargo build $PROFILE --verbose + - cargo test $PROFILE --verbose diff --git a/Android.bp b/Android.bp new file mode 100644 index 0000000..1fd0cf4 --- /dev/null +++ b/Android.bp @@ -0,0 +1,8 @@ +// This file is generated by cargo2android.py. + +rust_library_host_rlib { + name: "libpeeking_take_while", + crate_name: "peeking_take_while", + srcs: ["src/lib.rs"], + edition: "2015", +} diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..40aeef2 --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,14 @@ +[package] +authors = ["Nick Fitzgerald "] +description = "Like `Iterator::take_while`, but calls the predicate on a peeked value. This allows you to use `Iterator::by_ref` and `Iterator::take_while` together, and still get the first value for which the `take_while` predicate returned false after dropping the `by_ref`." +categories = ["rust-patterns"] +keywords = ["iterator", "take_while", "peek", "by_ref"] +license = "Apache-2.0/MIT" +name = "peeking_take_while" +readme = "./README.md" +repository = "https://github.com/fitzgen/peeking_take_while" +version = "0.1.2" + +[badges] +[badges.travis-ci] +repository = "fitzgen/peeking_take_while" diff --git a/LICENSE b/LICENSE new file mode 120000 index 0000000..6b579aa --- /dev/null +++ b/LICENSE @@ -0,0 +1 @@ +LICENSE-APACHE \ No newline at end of file diff --git a/LICENSE-APACHE b/LICENSE-APACHE new file mode 100644 index 0000000..16fe87b --- /dev/null +++ b/LICENSE-APACHE @@ -0,0 +1,201 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + +TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + +1. 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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/METADATA b/METADATA new file mode 100644 index 0000000..85c6822 --- /dev/null +++ b/METADATA @@ -0,0 +1,19 @@ +name: "peeking_take_while" +description: "Provides the peeking_take_while iterator adaptor method." +third_party { + url { + type: HOMEPAGE + value: "https://crates.io/crates/peeking_take_while" + } + url { + type: GIT + value: "https://github.com/fitzgen/peeking_take_while" + } + version: "0.1.2" + license_type: NOTICE + last_upgrade_date { + year: 2020 + month: 3 + day: 31 + } +} diff --git a/MODULE_LICENSE_APACHE2 b/MODULE_LICENSE_APACHE2 new file mode 100644 index 0000000..e69de29 diff --git a/OWNERS b/OWNERS new file mode 100644 index 0000000..46fc303 --- /dev/null +++ b/OWNERS @@ -0,0 +1 @@ +include platform/prebuilts/rust:/OWNERS diff --git a/README.md b/README.md new file mode 100644 index 0000000..c7486b7 --- /dev/null +++ b/README.md @@ -0,0 +1,58 @@ +# `peeking_take_while` + +[![Build Status](https://travis-ci.org/fitzgen/peeking_take_while.png?branch=master)](https://travis-ci.org/fitzgen/peeking_take_while) + +Provides the `peeking_take_while` iterator adaptor method. + +The `peeking_take_while` method is very similar to `take_while`, but behaves +differently when used with a borrowed iterator (perhaps returned by +`Iterator::by_ref`). + +`peeking_take_while` peeks at the next item in the iterator and runs the +predicate on that peeked item. This avoids consuming the first item yielded by +the underlying iterator for which the predicate returns `false`. On the other +hand, `take_while` will consume that first item for which the predicate returns +`false`, and it will be lost. + +```rust +extern crate peeking_take_while; + +// Bring the `peeking_take_while` method for peekable iterators into +// scope. +use peeking_take_while::PeekableExt; + +// Let's say we have two collections we want to iterate through: `xs` and +// `ys`. We want to perform one operation on all the leading contiguous +// elements that match some predicate, and a different thing with the rest of +// the elements. With the `xs`, we will use the normal `take_while`. With the +// `ys`, we will use `peeking_take_while`. + +let xs: Vec = (0..100).collect(); +let ys = xs.clone(); + +let mut iter_xs = xs.into_iter(); +let mut iter_ys = ys.into_iter().peekable(); + +{ + // Let's do one thing with all the items that are less than 10. + + let xs_less_than_ten = iter_xs.by_ref().take_while(|x| *x < 10); + for x in xs_less_than_ten { + do_things_with(x); + } + + let ys_less_than_ten = iter_ys.by_ref().peeking_take_while(|y| *y < 10); + for y in ys_less_than_ten { + do_things_with(y); + } +} + +// And now we will do some other thing with the items that are greater than +// or equal to 10. + +// ...except, when using plain old `take_while` we lost 10! +assert_eq!(iter_xs.next(), Some(11)); + +// However, when using `peeking_take_while` we did not! Great! +assert_eq!(iter_ys.next(), Some(10)); +``` diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..67f36d8 --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,117 @@ +//! # `peeking_take_while` +//! +//! Provides the `peeking_take_while` iterator adaptor method. +//! +//! The `peeking_take_while` method is very similar to `take_while`, but behaves +//! differently when used with a borrowed iterator (perhaps returned by +//! `Iterator::by_ref`). +//! +//! `peeking_take_while` peeks at the next item in the iterator and runs the +//! predicate on that peeked item. This avoids consuming the first item yielded +//! by the underlying iterator for which the predicate returns `false`. On the +//! other hand, `take_while` will consume that first item for which the +//! predicate returns `false`, and it will be lost. +//! +//! ``` +//! extern crate peeking_take_while; +//! +//! // Bring the `peeking_take_while` method for peekable iterators into +//! // scope. +//! use peeking_take_while::PeekableExt; +//! +//! # fn main() { +//! // Let's say we have two collections we want to iterate through: `xs` and +//! // `ys`. We want to perform one operation on all the leading contiguous +//! // elements that match some predicate, and a different thing with the rest of +//! // the elements. With the `xs`, we will use the normal `take_while`. With the +//! // `ys`, we will use `peeking_take_while`. +//! +//! let xs: Vec = (0..100).collect(); +//! let ys = xs.clone(); +//! +//! let mut iter_xs = xs.into_iter(); +//! let mut iter_ys = ys.into_iter().peekable(); +//! +//! { +//! // Let's do one thing with all the items that are less than 10. +//! # fn do_things_with(_: T) {} +//! +//! let xs_less_than_ten = iter_xs.by_ref().take_while(|x| *x < 10); +//! for x in xs_less_than_ten { +//! do_things_with(x); +//! } +//! +//! let ys_less_than_ten = iter_ys.by_ref().peeking_take_while(|y| *y < 10); +//! for y in ys_less_than_ten { +//! do_things_with(y); +//! } +//! } +//! +//! // And now we will do some other thing with the items that are greater than +//! // or equal to 10. +//! +//! // ...except, when using plain old `take_while` we lost 10! +//! assert_eq!(iter_xs.next(), Some(11)); +//! +//! // However, when using `peeking_take_while` we did not! Great! +//! assert_eq!(iter_ys.next(), Some(10)); +//! # } +//! ``` + +use std::iter::Peekable; + +/// The iterator returned by `peeking_take_while`. +/// +/// See the [module documentation](./index.html) for details. +pub struct PeekingTakeWhile<'a, I, P> + where I: 'a + Iterator +{ + iter: &'a mut Peekable, + predicate: P, +} + +impl<'a, I, P> Iterator for PeekingTakeWhile<'a, I, P> + where I: Iterator, + I::Item: ::std::fmt::Debug, + P: FnMut(&::Item) -> bool +{ + type Item = ::Item; + + fn next(&mut self) -> Option { + let predicate = &mut self.predicate; + if self.iter.peek().map_or(false, |x| !(predicate)(x)) { + None + } else { + self.iter.next() + } + } +} + +/// The `Iterator` extension trait that provides the `peeking_take_while` +/// method. +/// +/// See the [module documentation](./index.html) for details. +pub trait PeekableExt<'a, I>: Iterator + where I: 'a + Iterator +{ + /// The `Iterator` extension trait that provides the `peeking_take_while` + /// method. + /// + /// See the [module documentation](./index.html) for details. + fn peeking_take_while

(&'a mut self, predicate: P) -> PeekingTakeWhile<'a, I, P> + where Self: Sized, + P: FnMut(&::Item) -> bool; +} + +impl<'a, I> PeekableExt<'a, I> for Peekable + where I: 'a + Iterator +{ + fn peeking_take_while

(&'a mut self, predicate: P) -> PeekingTakeWhile + where P: FnMut(&::Item) -> bool + { + PeekingTakeWhile { + iter: self, + predicate: predicate, + } + } +} -- cgit v1.2.3