Move try_collect into its own trait (#8)

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "fallible_vec"
 description = "Fallible allocation functions for the Rust standard library's `Vec` type."
-version = "0.1.0"
+version = "0.2.0"
 edition = "2021"
 license-file = "LICENSE"
 repository = "https://github.com/microsoft/rust_fallible_vec"

build.ps1

@@ -1,6 +1,13 @@
 Set-StrictMode -Version Latest
 $ErrorActionPreference = 'Stop'
 
+function Invoke-CheckExitCode([scriptblock]$ScriptBlock) {
+    & $ScriptBlock
+    if ($LASTEXITCODE -ne 0) {
+        exit $LASTEXITCODE
+    }
+}
+
 function Invoke-WithEnvironment([System.Collections.IDictionary] $Environment, [scriptblock]$ScriptBlock) {
     try {
         # Set the environment.
@@ -29,18 +36,18 @@ Invoke-WithEnvironment `
         #
         # Run tests
         #
-        cargo test --locked
+        Invoke-CheckExitCode { cargo test --locked }
 
         #
         # Lint and check formatting.
         #
-        cargo clippy --locked -- -D warnings
-        cargo fmt --check
+        Invoke-CheckExitCode { cargo clippy --locked -- -D warnings }
+        Invoke-CheckExitCode { cargo fmt --check }
 
         #
         # Check docs
         #
-        cargo doc --locked
+        Invoke-CheckExitCode { cargo doc --locked }
 
         #
         # Verify that we can build with #[cfg(no_global_oom_handling)] enabled.
@@ -63,10 +70,12 @@ Invoke-WithEnvironment `
                 # in the standard library.
                 'env:RUSTFLAGS' = '--cfg no_global_oom_handling';
             } `
-            -ScriptBlock { cargo build --locked -Z build-std=core,alloc --target $target }
+            -ScriptBlock {
+                Invoke-CheckExitCode { cargo build --locked -Z build-std=core,alloc --target $target }
+            }
 }
 
 # Run tests under miri
-rustup toolchain install nightly --component miri
-cargo +nightly miri setup
-cargo +nightly miri test
+Invoke-CheckExitCode { rustup toolchain install nightly --component miri }
+Invoke-CheckExitCode { cargo +nightly miri setup }
+Invoke-CheckExitCode { cargo +nightly miri test }

src/collect.rs

@@ -0,0 +1,57 @@
+use crate::FallibleVec;
+use alloc::{collections::TryReserveError, vec::Vec};
+use core::alloc::Allocator;
+
+/// Fallible allocations equivalents for [`Iterator::collect`].
+pub trait TryCollect<T> {
+    /// Attempts to collect items from an iterator into a vector with the provided
+    /// allocator.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![feature(allocator_api)]
+    /// # #[macro_use] extern crate fallible_vec;
+    /// use fallible_vec::*;
+    /// use std::alloc::System;
+    ///
+    /// let doubled = [1, 2, 3, 4, 5].map(|i| i * 2);
+    /// let vec = doubled.try_collect_in(System)?;
+    /// assert_eq!(vec, [2, 4, 6, 8, 10]);
+    /// # Ok::<(), std::collections::TryReserveError>(())
+    /// ```
+    fn try_collect_in<A: Allocator>(self, alloc: A) -> Result<Vec<T, A>, TryReserveError>;
+
+    /// Attempts to collect items from an iterator into a vector.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![feature(allocator_api)]
+    /// # #[macro_use] extern crate fallible_vec;
+    /// use fallible_vec::*;
+    ///
+    /// let doubled = [1, 2, 3, 4, 5].map(|i| i * 2);
+    /// let vec = doubled.try_collect()?;
+    /// assert_eq!(vec, [2, 4, 6, 8, 10]);
+    /// # Ok::<(), std::collections::TryReserveError>(())
+    /// ```
+    fn try_collect(self) -> Result<Vec<T>, TryReserveError>;
+}
+
+impl<T, I> TryCollect<T> for I
+where
+    I: IntoIterator<Item = T>,
+{
+    fn try_collect_in<A: Allocator>(self, alloc: A) -> Result<Vec<T, A>, TryReserveError> {
+        let mut vec = Vec::new_in(alloc);
+        vec.try_extend(self.into_iter())?;
+        Ok(vec)
+    }
+
+    fn try_collect(self) -> Result<Vec<T>, TryReserveError> {
+        let mut vec = Vec::new();
+        vec.try_extend(self.into_iter())?;
+        Ok(vec)
+    }
+}

src/lib.rs

@@ -46,20 +46,22 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 
 extern crate alloc;
+mod collect;
 mod set_len_on_drop;
 
+use alloc::{
+    collections::{TryReserveError, TryReserveErrorKind},
+    vec::Vec,
+};
 use core::{
     alloc::Allocator,
     ops::{Range, RangeBounds},
     slice,
 };
-
-use alloc::{
-    collections::{TryReserveError, TryReserveErrorKind},
-    vec::Vec,
-};
 use set_len_on_drop::SetLenOnDrop;
 
+pub use collect::TryCollect;
+
 // These are defined so that the try_vec! and try_vec_in! macros can refer to
 // these types in a consistent way: even if the consuming crate doesn't use
 // `no_std` and `extern crate alloc`.
@@ -68,7 +70,7 @@ pub mod alloc_usings {
     pub use alloc::{alloc::Layout, boxed::Box, collections::TryReserveError, vec::Vec};
 }
 
-/// Methods available for all `Vec` instantiations.
+/// Fallible allocation methods for [`Vec`].
 pub trait FallibleVec<T, A: Allocator>: Sized {
     /// Extends the `Vec` using the items from the given iterator.
     ///
@@ -430,7 +432,7 @@ impl<T, A: Allocator> FallibleVec<T, A> for Vec<T, A> {
         }
 
         // Gather up the remainder and copy those as well.
-        let remainder = try_collect_in(replace_with, alloc)?;
+        let remainder = replace_with.try_collect_in(alloc)?;
         if !remainder.is_empty() {
             move_tail(self, index, remainder.len())?;
             // Don't need to use `SetLenOnDrop` here since we're enumerating
@@ -670,24 +672,6 @@ pub fn try_with_capacity<T>(size: usize) -> Result<Vec<T>, TryReserveError> {
     Ok(vec)
 }
 
-/// Attempts to collect items from an iterator into a vector with the provided
-/// allocator.
-pub fn try_collect_in<T, A: Allocator>(
-    iter: impl Iterator<Item = T>,
-    alloc: A,
-) -> Result<Vec<T, A>, TryReserveError> {
-    let mut vec = Vec::new_in(alloc);
-    vec.try_extend(iter)?;
-    Ok(vec)
-}
-
-/// Attempts to collect items from an iterator into a vector.
-pub fn try_collect<T>(iter: impl Iterator<Item = T>) -> Result<Vec<T>, TryReserveError> {
-    let mut vec = Vec::new();
-    vec.try_extend(iter)?;
-    Ok(vec)
-}
-
 #[doc(hidden)]
 pub fn try_new_repeat_item_in<T: Clone, A: Allocator>(
     item: T,

src/tests.rs

@@ -142,7 +142,7 @@ fn test_collect_after_iterator_clone() {
     let v = try_vec_in![0; 5 => Global].unwrap();
     let mut i = v.into_iter().map(|i| i + 1).peekable();
     i.peek();
-    let v = try_collect_in(i.clone(), Global).unwrap();
+    let v = i.clone().try_collect().unwrap();
     assert_eq!(v, [1, 1, 1, 1, 1]);
     assert!(v.len() <= v.capacity());
 }