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Merge remote-tracking branch 'smol_str/master' into rebuild-master-again

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Laurențiu Nicola 2025-11-15 09:16:33 +02:00
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use std::{
env, fs,
process::{self, Command, ExitStatus, Stdio},
time::Instant,
};
type Error = Box<dyn std::error::Error>;
type Result<T> = std::result::Result<T, Error>;
fn main() {
if let Err(err) = try_main() {
eprintln!("{}", err);
process::exit(1);
}
}
fn try_main() -> Result<()> {
let cwd = env::current_dir()?;
let cargo_toml = cwd.join("Cargo.toml");
assert!(
cargo_toml.exists(),
"Cargo.toml not found, cwd: {}",
cwd.display()
);
{
let _s = Section::new("BUILD_NO_DEFAULT_FEATURES");
shell("cargo test --all-features --workspace --no-run --no-default-features")?;
}
{
let _s = Section::new("BUILD");
shell("cargo test --all-features --workspace --no-run")?;
}
{
let _s = Section::new("TEST");
shell("cargo test --all-features --workspace")?;
shell("cargo test --no-default-features --workspace")?;
}
{
let _s = Section::new("TEST_BENCHES");
shell("cargo test --benches --all-features")?;
}
let current_branch = shell_output("git branch --show-current")?;
if &current_branch == "master" {
let _s = Section::new("PUBLISH");
let manifest = fs::read_to_string(&cargo_toml)?;
let version = get_field(&manifest, "version")?;
let tag = format!("v{}", version);
let tags = shell_output("git tag --list")?;
if !tags.contains(&tag) {
let token = env::var("CRATES_IO_TOKEN").unwrap();
shell(&format!("git tag v{}", version))?;
shell(&format!("cargo publish --token {}", token))?;
shell("git push --tags")?;
}
}
Ok(())
}
fn get_field<'a>(text: &'a str, name: &str) -> Result<&'a str> {
for line in text.lines() {
let words = line.split_ascii_whitespace().collect::<Vec<_>>();
match words.as_slice() {
[n, "=", v, ..] if n.trim() == name => {
assert!(v.starts_with('"') && v.ends_with('"'));
return Ok(&v[1..v.len() - 1]);
}
_ => (),
}
}
Err(format!("can't find `{}` in\n----\n{}\n----\n", name, text))?
}
fn shell(cmd: &str) -> Result<()> {
let status = command(cmd).status()?;
check_status(status)
}
fn shell_output(cmd: &str) -> Result<String> {
let output = command(cmd).stderr(Stdio::inherit()).output()?;
check_status(output.status)?;
let res = String::from_utf8(output.stdout)?;
let res = res.trim().to_string();
println!("{}", res);
Ok(res)
}
fn command(cmd: &str) -> Command {
eprintln!("> {}", cmd);
let words = cmd.split_ascii_whitespace().collect::<Vec<_>>();
let (cmd, args) = words.split_first().unwrap();
let mut res = Command::new(cmd);
res.args(args);
res
}
fn check_status(status: ExitStatus) -> Result<()> {
if !status.success() {
Err(format!("$status: {}", status))?;
}
Ok(())
}
struct Section {
name: &'static str,
start: Instant,
}
impl Section {
fn new(name: &'static str) -> Section {
println!("::group::{}", name);
let start = Instant::now();
Section { name, start }
}
}
impl Drop for Section {
fn drop(&mut self) {
eprintln!("{}: {:.2?}", self.name, self.start.elapsed());
println!("::endgroup::");
}
}

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name: CI
on:
pull_request:
push:
branches:
- master
- staging
- trying
env:
CARGO_INCREMENTAL: 0
CARGO_NET_RETRY: 10
CI: 1
RUST_BACKTRACE: short
RUSTFLAGS: -D warnings
RUSTUP_MAX_RETRIES: 10
jobs:
rust:
name: Rust
runs-on: ubuntu-latest
steps:
- name: Checkout repository
uses: actions/checkout@v2
with:
fetch-depth: 0
- name: Install Rust toolchain
uses: actions-rust-lang/setup-rust-toolchain@v1
with:
cache: false
- run: rustc ./.github/ci.rs && ./ci
env:
CRATES_IO_TOKEN: ${{ secrets.CRATES_IO_TOKEN }}

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/target
/ci
/.vscode
Cargo.lock

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# Changelog
## Unreleased
## 0.3.4 - 2025-10-23
- Added `rust-version` field to `Cargo.toml`
## 0.3.3 - 2025-10-23
- Optimise `StrExt::to_ascii_lowercase_smolstr`, `StrExt::to_ascii_uppercase_smolstr`
~2x speedup inline, ~4-22x for heap.
- Optimise `StrExt::to_lowercase_smolstr`, `StrExt::to_uppercase_smolstr` ~2x speedup inline, ~5-50x for heap.
- Optimise `StrExt::replace_smolstr`, `StrExt::replacen_smolstr` for single ascii replace,
~3x speedup inline & heap.
## 0.3.2 - 2024-10-23
- Fix `SmolStrBuilder::push` incorrectly padding null bytes when spilling onto the heap on a
multibyte character push
## 0.3.1 - 2024-09-04
- Fix `SmolStrBuilder` leaking implementation details
## 0.3.0 - 2024-09-04
- Remove deprecated `SmolStr::new_inline_from_ascii` function
- Remove `SmolStr::to_string` in favor of `ToString::to_string`
- Add `impl AsRef<[u8]> for SmolStr` impl
- Add `impl AsRef<OsStr> for SmolStr` impl
- Add `impl AsRef<Path> for SmolStr` impl
- Add `SmolStrBuilder`
## 0.2.2 - 2024-05-14
- Add `StrExt` trait providing `to_lowercase_smolstr`, `replace_smolstr` and similar
- Add `PartialEq` optimization for `ptr_eq`-able representations

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[package]
name = "smol_str"
version = "0.3.4"
description = "small-string optimized string type with O(1) clone"
license = "MIT OR Apache-2.0"
repository = "https://github.com/rust-analyzer/smol_str"
authors = ["Aleksey Kladov <aleksey.kladov@gmail.com>", "Lukas Wirth <lukastw97@gmail.com>"]
edition = "2021"
rust-version = "1.89"
[package.metadata.docs.rs]
rustdoc-args = ["--cfg", "docsrs"]
all-features = true
[dependencies]
serde_core = { version = "1.0.220", optional = true, default-features = false }
borsh = { version = "1.4.0", optional = true, default-features = false }
arbitrary = { version = "1.3", optional = true }
[dev-dependencies]
proptest = "1.5"
serde_json = "1.0"
serde = { version = "1.0", features = ["derive"] }
criterion = "0.7"
rand = "0.9.2"
[features]
default = ["std"]
std = ["serde_core?/std", "borsh?/std"]
serde = ["dep:serde_core"]
[[bench]]
name = "bench"
harness = false
[profile.bench]
lto = "fat"

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# smol_str
[![CI](https://github.com/rust-analyzer/smol_str/workflows/CI/badge.svg)](https://github.com/rust-analyzer/smol_str/actions?query=branch%3Amaster+workflow%3ACI)
[![Crates.io](https://img.shields.io/crates/v/smol_str.svg)](https://crates.io/crates/smol_str)
[![API reference](https://docs.rs/smol_str/badge.svg)](https://docs.rs/smol_str/)
A `SmolStr` is a string type that has the following properties:
* `size_of::<SmolStr>() == 24` (therefore `== size_of::<String>()` on 64 bit platforms)
* `Clone` is `O(1)`
* Strings are stack-allocated if they are:
* Up to 23 bytes long
* Longer than 23 bytes, but substrings of `WS` (see `src/lib.rs`). Such strings consist
solely of consecutive newlines, followed by consecutive spaces
* If a string does not satisfy the aforementioned conditions, it is heap-allocated
* Additionally, a `SmolStr` can be explicitly created from a `&'static str` without allocation
Unlike `String`, however, `SmolStr` is immutable. The primary use case for
`SmolStr` is a good enough default storage for tokens of typical programming
languages. Strings consisting of a series of newlines, followed by a series of
whitespace are a typical pattern in computer programs because of indentation.
Note that a specialized interner might be a better solution for some use cases.
## Benchmarks
Run criterion benches with
```sh
cargo bench --bench \* -- --quick
```
## MSRV Policy
Minimal Supported Rust Version: latest stable.
Bumping MSRV is not considered a semver-breaking change.

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use criterion::{criterion_group, criterion_main, Criterion};
use rand::distr::{Alphanumeric, SampleString};
use smol_str::{format_smolstr, SmolStr, StrExt, ToSmolStr};
use std::hint::black_box;
/// 12: small (inline)
/// 50: medium (heap)
/// 1000: large (heap)
const TEST_LENS: [usize; 3] = [12, 50, 1000];
fn format_bench(c: &mut Criterion) {
for len in TEST_LENS {
let n = rand::random_range(10000..99999);
let str_len = len.checked_sub(n.to_smolstr().len()).unwrap();
let str = Alphanumeric.sample_string(&mut rand::rng(), str_len);
c.bench_function(&format!("format_smolstr! len={len}"), |b| {
let mut v = <_>::default();
b.iter(|| v = format_smolstr!("{str}-{n}"));
assert_eq!(v, format!("{str}-{n}"));
});
}
}
fn from_str_bench(c: &mut Criterion) {
for len in TEST_LENS {
let str = Alphanumeric.sample_string(&mut rand::rng(), len);
c.bench_function(&format!("SmolStr::from len={len}"), |b| {
let mut v = <_>::default();
b.iter(|| v = SmolStr::from(black_box(&str)));
assert_eq!(v, str);
});
}
}
fn clone_bench(c: &mut Criterion) {
for len in TEST_LENS {
let str = Alphanumeric.sample_string(&mut rand::rng(), len);
let smolstr = SmolStr::new(&str);
c.bench_function(&format!("SmolStr::clone len={len}"), |b| {
let mut v = <_>::default();
b.iter(|| v = smolstr.clone());
assert_eq!(v, str);
});
}
}
fn eq_bench(c: &mut Criterion) {
for len in TEST_LENS {
let str = Alphanumeric.sample_string(&mut rand::rng(), len);
let smolstr = SmolStr::new(&str);
c.bench_function(&format!("SmolStr::eq len={len}"), |b| {
let mut v = false;
b.iter(|| v = smolstr == black_box(&str));
assert!(v);
});
}
}
fn to_lowercase_bench(c: &mut Criterion) {
const END_CHAR: char = 'İ';
for len in TEST_LENS {
// mostly ascii seq with some non-ascii at the end
let mut str = Alphanumeric.sample_string(&mut rand::rng(), len - END_CHAR.len_utf8());
str.push(END_CHAR);
let str = str.as_str();
c.bench_function(&format!("to_lowercase_smolstr len={len}"), |b| {
let mut v = <_>::default();
b.iter(|| v = str.to_lowercase_smolstr());
assert_eq!(v, str.to_lowercase());
});
}
}
fn to_ascii_lowercase_bench(c: &mut Criterion) {
for len in TEST_LENS {
let str = Alphanumeric.sample_string(&mut rand::rng(), len);
let str = str.as_str();
c.bench_function(&format!("to_ascii_lowercase_smolstr len={len}"), |b| {
let mut v = <_>::default();
b.iter(|| v = str.to_ascii_lowercase_smolstr());
assert_eq!(v, str.to_ascii_lowercase());
});
}
}
fn replace_bench(c: &mut Criterion) {
for len in TEST_LENS {
let s_dash_s = Alphanumeric.sample_string(&mut rand::rng(), len / 2)
+ "-"
+ &Alphanumeric.sample_string(&mut rand::rng(), len - 1 - len / 2);
let str = s_dash_s.as_str();
c.bench_function(&format!("replace_smolstr len={len}"), |b| {
let mut v = <_>::default();
b.iter(|| v = str.replace_smolstr("-", "_"));
assert_eq!(v, str.replace("-", "_"));
});
}
}
criterion_group!(
benches,
format_bench,
from_str_bench,
clone_bench,
eq_bench,
to_lowercase_bench,
to_ascii_lowercase_bench,
replace_bench,
);
criterion_main!(benches);

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status = [ "Rust" ]
delete_merged_branches = true

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use crate::{Repr, SmolStr, INLINE_CAP};
use alloc::string::{String, ToString};
use borsh::{
io::{Error, ErrorKind, Read, Write},
BorshDeserialize, BorshSerialize,
};
use core::mem::transmute;
impl BorshSerialize for SmolStr {
fn serialize<W: Write>(&self, writer: &mut W) -> borsh::io::Result<()> {
self.as_str().serialize(writer)
}
}
impl BorshDeserialize for SmolStr {
#[inline]
fn deserialize_reader<R: Read>(reader: &mut R) -> borsh::io::Result<Self> {
let len = u32::deserialize_reader(reader)?;
if (len as usize) < INLINE_CAP {
let mut buf = [0u8; INLINE_CAP];
reader.read_exact(&mut buf[..len as usize])?;
_ = core::str::from_utf8(&buf[..len as usize]).map_err(|err| {
let msg = err.to_string();
Error::new(ErrorKind::InvalidData, msg)
})?;
Ok(SmolStr(Repr::Inline {
len: unsafe { transmute::<u8, crate::InlineSize>(len as u8) },
buf,
}))
} else {
// u8::vec_from_reader always returns Some on success in current implementation
let vec = u8::vec_from_reader(len, reader)?
.ok_or_else(|| Error::other("u8::vec_from_reader unexpectedly returned None"))?;
Ok(SmolStr::from(String::from_utf8(vec).map_err(|err| {
let msg = err.to_string();
Error::new(ErrorKind::InvalidData, msg)
})?))
}
}
}

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#![cfg_attr(not(feature = "std"), no_std)]
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
extern crate alloc;
use alloc::{borrow::Cow, boxed::Box, string::String, sync::Arc};
use core::{
borrow::Borrow,
cmp::{self, Ordering},
convert::Infallible,
fmt, hash, iter, mem, ops,
str::FromStr,
};
/// A `SmolStr` is a string type that has the following properties:
///
/// * `size_of::<SmolStr>() == 24` (therefor `== size_of::<String>()` on 64 bit platforms)
/// * `Clone` is `O(1)`
/// * Strings are stack-allocated if they are:
/// * Up to 23 bytes long
/// * Longer than 23 bytes, but substrings of `WS` (see below). Such strings consist
/// solely of consecutive newlines, followed by consecutive spaces
/// * If a string does not satisfy the aforementioned conditions, it is heap-allocated
/// * Additionally, a `SmolStr` can be explicitly created from a `&'static str` without allocation
///
/// Unlike `String`, however, `SmolStr` is immutable. The primary use case for
/// `SmolStr` is a good enough default storage for tokens of typical programming
/// languages. Strings consisting of a series of newlines, followed by a series of
/// whitespace are a typical pattern in computer programs because of indentation.
/// Note that a specialized interner might be a better solution for some use cases.
///
/// `WS`: A string of 32 newlines followed by 128 spaces.
pub struct SmolStr(Repr);
impl SmolStr {
/// Constructs an inline variant of `SmolStr`.
///
/// This never allocates.
///
/// # Panics
///
/// Panics if `text.len() > 23`.
#[inline]
pub const fn new_inline(text: &str) -> SmolStr {
assert!(text.len() <= INLINE_CAP); // avoids bounds checks in loop
let text = text.as_bytes();
let mut buf = [0; INLINE_CAP];
let mut i = 0;
while i < text.len() {
buf[i] = text[i];
i += 1
}
SmolStr(Repr::Inline {
// SAFETY: We know that `len` is less than or equal to the maximum value of `InlineSize`
// as we asserted it.
len: unsafe { InlineSize::transmute_from_u8(text.len() as u8) },
buf,
})
}
/// Constructs a `SmolStr` from a statically allocated string.
///
/// This never allocates.
#[inline(always)]
pub const fn new_static(text: &'static str) -> SmolStr {
// NOTE: this never uses the inline storage; if a canonical
// representation is needed, we could check for `len() < INLINE_CAP`
// and call `new_inline`, but this would mean an extra branch.
SmolStr(Repr::Static(text))
}
/// Constructs a `SmolStr` from a `str`, heap-allocating if necessary.
#[inline(always)]
pub fn new(text: impl AsRef<str>) -> SmolStr {
SmolStr(Repr::new(text.as_ref()))
}
/// Returns a `&str` slice of this `SmolStr`.
#[inline(always)]
pub fn as_str(&self) -> &str {
self.0.as_str()
}
/// Returns the length of `self` in bytes.
#[inline(always)]
pub fn len(&self) -> usize {
self.0.len()
}
/// Returns `true` if `self` has a length of zero bytes.
#[inline(always)]
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// Returns `true` if `self` is heap-allocated.
#[inline(always)]
pub const fn is_heap_allocated(&self) -> bool {
matches!(self.0, Repr::Heap(..))
}
}
impl Clone for SmolStr {
#[inline]
fn clone(&self) -> Self {
if !self.is_heap_allocated() {
// SAFETY: We verified that the payload of `Repr` is a POD
return unsafe { core::ptr::read(self as *const SmolStr) };
}
Self(self.0.clone())
}
}
impl Default for SmolStr {
#[inline(always)]
fn default() -> SmolStr {
SmolStr(Repr::Inline {
len: InlineSize::_V0,
buf: [0; INLINE_CAP],
})
}
}
impl ops::Deref for SmolStr {
type Target = str;
#[inline(always)]
fn deref(&self) -> &str {
self.as_str()
}
}
// region: PartialEq implementations
impl Eq for SmolStr {}
impl PartialEq<SmolStr> for SmolStr {
fn eq(&self, other: &SmolStr) -> bool {
self.0.ptr_eq(&other.0) || self.as_str() == other.as_str()
}
}
impl PartialEq<str> for SmolStr {
#[inline(always)]
fn eq(&self, other: &str) -> bool {
self.as_str() == other
}
}
impl PartialEq<SmolStr> for str {
#[inline(always)]
fn eq(&self, other: &SmolStr) -> bool {
other == self
}
}
impl<'a> PartialEq<&'a str> for SmolStr {
#[inline(always)]
fn eq(&self, other: &&'a str) -> bool {
self == *other
}
}
impl PartialEq<SmolStr> for &str {
#[inline(always)]
fn eq(&self, other: &SmolStr) -> bool {
*self == other
}
}
impl PartialEq<String> for SmolStr {
#[inline(always)]
fn eq(&self, other: &String) -> bool {
self.as_str() == other
}
}
impl PartialEq<SmolStr> for String {
#[inline(always)]
fn eq(&self, other: &SmolStr) -> bool {
other == self
}
}
impl<'a> PartialEq<&'a String> for SmolStr {
#[inline(always)]
fn eq(&self, other: &&'a String) -> bool {
self == *other
}
}
impl PartialEq<SmolStr> for &String {
#[inline(always)]
fn eq(&self, other: &SmolStr) -> bool {
*self == other
}
}
// endregion: PartialEq implementations
impl Ord for SmolStr {
fn cmp(&self, other: &SmolStr) -> Ordering {
self.as_str().cmp(other.as_str())
}
}
impl PartialOrd for SmolStr {
fn partial_cmp(&self, other: &SmolStr) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl hash::Hash for SmolStr {
fn hash<H: hash::Hasher>(&self, hasher: &mut H) {
self.as_str().hash(hasher);
}
}
impl fmt::Debug for SmolStr {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(self.as_str(), f)
}
}
impl fmt::Display for SmolStr {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Display::fmt(self.as_str(), f)
}
}
impl iter::FromIterator<char> for SmolStr {
fn from_iter<I: iter::IntoIterator<Item = char>>(iter: I) -> SmolStr {
from_char_iter(iter.into_iter())
}
}
#[inline]
fn from_char_iter(iter: impl Iterator<Item = char>) -> SmolStr {
from_buf_and_chars([0; _], 0, iter)
}
fn from_buf_and_chars(
mut buf: [u8; INLINE_CAP],
buf_len: usize,
mut iter: impl Iterator<Item = char>,
) -> SmolStr {
let min_size = iter.size_hint().0 + buf_len;
if min_size > INLINE_CAP {
let heap: String = core::str::from_utf8(&buf[..buf_len])
.unwrap()
.chars()
.chain(iter)
.collect();
if heap.len() <= INLINE_CAP {
// size hint lied
return SmolStr::new_inline(&heap);
}
return SmolStr(Repr::Heap(heap.into_boxed_str().into()));
}
let mut len = buf_len;
while let Some(ch) = iter.next() {
let size = ch.len_utf8();
if size + len > INLINE_CAP {
let (min_remaining, _) = iter.size_hint();
let mut heap = String::with_capacity(size + len + min_remaining);
heap.push_str(core::str::from_utf8(&buf[..len]).unwrap());
heap.push(ch);
heap.extend(iter);
return SmolStr(Repr::Heap(heap.into_boxed_str().into()));
}
ch.encode_utf8(&mut buf[len..]);
len += size;
}
SmolStr(Repr::Inline {
// SAFETY: We know that `len` is less than or equal to the maximum value of `InlineSize`
// as we otherwise return early.
len: unsafe { InlineSize::transmute_from_u8(len as u8) },
buf,
})
}
fn build_from_str_iter<T>(mut iter: impl Iterator<Item = T>) -> SmolStr
where
T: AsRef<str>,
String: iter::Extend<T>,
{
let mut len = 0;
let mut buf = [0u8; INLINE_CAP];
while let Some(slice) = iter.next() {
let slice = slice.as_ref();
let size = slice.len();
if size + len > INLINE_CAP {
let mut heap = String::with_capacity(size + len);
heap.push_str(core::str::from_utf8(&buf[..len]).unwrap());
heap.push_str(slice);
heap.extend(iter);
return SmolStr(Repr::Heap(heap.into_boxed_str().into()));
}
buf[len..][..size].copy_from_slice(slice.as_bytes());
len += size;
}
SmolStr(Repr::Inline {
// SAFETY: We know that `len` is less than or equal to the maximum value of `InlineSize`
// as we otherwise return early.
len: unsafe { InlineSize::transmute_from_u8(len as u8) },
buf,
})
}
impl iter::FromIterator<String> for SmolStr {
fn from_iter<I: iter::IntoIterator<Item = String>>(iter: I) -> SmolStr {
build_from_str_iter(iter.into_iter())
}
}
impl<'a> iter::FromIterator<&'a String> for SmolStr {
fn from_iter<I: iter::IntoIterator<Item = &'a String>>(iter: I) -> SmolStr {
SmolStr::from_iter(iter.into_iter().map(|x| x.as_str()))
}
}
impl<'a> iter::FromIterator<&'a str> for SmolStr {
fn from_iter<I: iter::IntoIterator<Item = &'a str>>(iter: I) -> SmolStr {
build_from_str_iter(iter.into_iter())
}
}
impl AsRef<str> for SmolStr {
#[inline(always)]
fn as_ref(&self) -> &str {
self.as_str()
}
}
impl AsRef<[u8]> for SmolStr {
#[inline(always)]
fn as_ref(&self) -> &[u8] {
self.as_str().as_bytes()
}
}
#[cfg(feature = "std")]
impl AsRef<std::ffi::OsStr> for SmolStr {
#[inline(always)]
fn as_ref(&self) -> &std::ffi::OsStr {
AsRef::<std::ffi::OsStr>::as_ref(self.as_str())
}
}
#[cfg(feature = "std")]
impl AsRef<std::path::Path> for SmolStr {
#[inline(always)]
fn as_ref(&self) -> &std::path::Path {
AsRef::<std::path::Path>::as_ref(self.as_str())
}
}
impl From<&str> for SmolStr {
#[inline]
fn from(s: &str) -> SmolStr {
SmolStr::new(s)
}
}
impl From<&mut str> for SmolStr {
#[inline]
fn from(s: &mut str) -> SmolStr {
SmolStr::new(s)
}
}
impl From<&String> for SmolStr {
#[inline]
fn from(s: &String) -> SmolStr {
SmolStr::new(s)
}
}
impl From<String> for SmolStr {
#[inline(always)]
fn from(text: String) -> Self {
Self::new(text)
}
}
impl From<Box<str>> for SmolStr {
#[inline]
fn from(s: Box<str>) -> SmolStr {
SmolStr::new(s)
}
}
impl From<Arc<str>> for SmolStr {
#[inline]
fn from(s: Arc<str>) -> SmolStr {
let repr = Repr::new_on_stack(s.as_ref()).unwrap_or(Repr::Heap(s));
Self(repr)
}
}
impl<'a> From<Cow<'a, str>> for SmolStr {
#[inline]
fn from(s: Cow<'a, str>) -> SmolStr {
SmolStr::new(s)
}
}
impl From<SmolStr> for Arc<str> {
#[inline(always)]
fn from(text: SmolStr) -> Self {
match text.0 {
Repr::Heap(data) => data,
_ => text.as_str().into(),
}
}
}
impl From<SmolStr> for String {
#[inline(always)]
fn from(text: SmolStr) -> Self {
text.as_str().into()
}
}
impl Borrow<str> for SmolStr {
#[inline(always)]
fn borrow(&self) -> &str {
self.as_str()
}
}
impl FromStr for SmolStr {
type Err = Infallible;
#[inline]
fn from_str(s: &str) -> Result<SmolStr, Self::Err> {
Ok(SmolStr::from(s))
}
}
const INLINE_CAP: usize = InlineSize::_V23 as usize;
const N_NEWLINES: usize = 32;
const N_SPACES: usize = 128;
const WS: &str =
"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n ";
const _: () = {
assert!(WS.len() == N_NEWLINES + N_SPACES);
assert!(WS.as_bytes()[N_NEWLINES - 1] == b'\n');
assert!(WS.as_bytes()[N_NEWLINES] == b' ');
};
/// A [`u8`] with a bunch of niches.
#[derive(Clone, Copy, Debug, PartialEq)]
#[repr(u8)]
enum InlineSize {
_V0 = 0,
_V1,
_V2,
_V3,
_V4,
_V5,
_V6,
_V7,
_V8,
_V9,
_V10,
_V11,
_V12,
_V13,
_V14,
_V15,
_V16,
_V17,
_V18,
_V19,
_V20,
_V21,
_V22,
_V23,
}
impl InlineSize {
/// SAFETY: `value` must be less than or equal to [`INLINE_CAP`]
#[inline(always)]
const unsafe fn transmute_from_u8(value: u8) -> Self {
debug_assert!(value <= InlineSize::_V23 as u8);
// SAFETY: The caller is responsible to uphold this invariant
unsafe { mem::transmute::<u8, Self>(value) }
}
}
#[derive(Clone, Debug)]
enum Repr {
Inline {
len: InlineSize,
buf: [u8; INLINE_CAP],
},
Static(&'static str),
Heap(Arc<str>),
}
impl Repr {
/// This function tries to create a new Repr::Inline or Repr::Static
/// If it isn't possible, this function returns None
fn new_on_stack<T>(text: T) -> Option<Self>
where
T: AsRef<str>,
{
let text = text.as_ref();
let len = text.len();
if len <= INLINE_CAP {
let mut buf = [0; INLINE_CAP];
buf[..len].copy_from_slice(text.as_bytes());
return Some(Repr::Inline {
// SAFETY: We know that `len` is less than or equal to the maximum value of `InlineSize`
len: unsafe { InlineSize::transmute_from_u8(len as u8) },
buf,
});
}
if len <= N_NEWLINES + N_SPACES {
let bytes = text.as_bytes();
let possible_newline_count = cmp::min(len, N_NEWLINES);
let newlines = bytes[..possible_newline_count]
.iter()
.take_while(|&&b| b == b'\n')
.count();
let possible_space_count = len - newlines;
if possible_space_count <= N_SPACES && bytes[newlines..].iter().all(|&b| b == b' ') {
let spaces = possible_space_count;
let substring = &WS[N_NEWLINES - newlines..N_NEWLINES + spaces];
return Some(Repr::Static(substring));
}
}
None
}
fn new(text: &str) -> Self {
Self::new_on_stack(text).unwrap_or_else(|| Repr::Heap(Arc::from(text)))
}
#[inline(always)]
fn len(&self) -> usize {
match self {
Repr::Heap(data) => data.len(),
Repr::Static(data) => data.len(),
Repr::Inline { len, .. } => *len as usize,
}
}
#[inline(always)]
fn is_empty(&self) -> bool {
match self {
Repr::Heap(data) => data.is_empty(),
Repr::Static(data) => data.is_empty(),
&Repr::Inline { len, .. } => len as u8 == 0,
}
}
#[inline]
fn as_str(&self) -> &str {
match self {
Repr::Heap(data) => data,
Repr::Static(data) => data,
Repr::Inline { len, buf } => {
let len = *len as usize;
// SAFETY: len is guaranteed to be <= INLINE_CAP
let buf = unsafe { buf.get_unchecked(..len) };
// SAFETY: buf is guaranteed to be valid utf8 for ..len bytes
unsafe { ::core::str::from_utf8_unchecked(buf) }
}
}
}
fn ptr_eq(&self, other: &Self) -> bool {
match (self, other) {
(Self::Heap(l0), Self::Heap(r0)) => Arc::ptr_eq(l0, r0),
(Self::Static(l0), Self::Static(r0)) => core::ptr::eq(l0, r0),
(
Self::Inline {
len: l_len,
buf: l_buf,
},
Self::Inline {
len: r_len,
buf: r_buf,
},
) => l_len == r_len && l_buf == r_buf,
_ => false,
}
}
}
/// Convert value to [`SmolStr`] using [`fmt::Display`], potentially without allocating.
///
/// Almost identical to [`ToString`], but converts to `SmolStr` instead.
pub trait ToSmolStr {
fn to_smolstr(&self) -> SmolStr;
}
/// [`str`] methods producing [`SmolStr`]s.
pub trait StrExt: private::Sealed {
/// Returns the lowercase equivalent of this string slice as a new [`SmolStr`],
/// potentially without allocating.
///
/// See [`str::to_lowercase`].
#[must_use = "this returns a new SmolStr without modifying the original"]
fn to_lowercase_smolstr(&self) -> SmolStr;
/// Returns the uppercase equivalent of this string slice as a new [`SmolStr`],
/// potentially without allocating.
///
/// See [`str::to_uppercase`].
#[must_use = "this returns a new SmolStr without modifying the original"]
fn to_uppercase_smolstr(&self) -> SmolStr;
/// Returns the ASCII lowercase equivalent of this string slice as a new [`SmolStr`],
/// potentially without allocating.
///
/// See [`str::to_ascii_lowercase`].
#[must_use = "this returns a new SmolStr without modifying the original"]
fn to_ascii_lowercase_smolstr(&self) -> SmolStr;
/// Returns the ASCII uppercase equivalent of this string slice as a new [`SmolStr`],
/// potentially without allocating.
///
/// See [`str::to_ascii_uppercase`].
#[must_use = "this returns a new SmolStr without modifying the original"]
fn to_ascii_uppercase_smolstr(&self) -> SmolStr;
/// Replaces all matches of a &str with another &str returning a new [`SmolStr`],
/// potentially without allocating.
///
/// See [`str::replace`].
#[must_use = "this returns a new SmolStr without modifying the original"]
fn replace_smolstr(&self, from: &str, to: &str) -> SmolStr;
/// Replaces first N matches of a &str with another &str returning a new [`SmolStr`],
/// potentially without allocating.
///
/// See [`str::replacen`].
#[must_use = "this returns a new SmolStr without modifying the original"]
fn replacen_smolstr(&self, from: &str, to: &str, count: usize) -> SmolStr;
}
impl StrExt for str {
#[inline]
fn to_lowercase_smolstr(&self) -> SmolStr {
let len = self.len();
if len <= INLINE_CAP {
let (buf, rest) = inline_convert_while_ascii(self, u8::to_ascii_lowercase);
from_buf_and_chars(
buf,
len - rest.len(),
rest.chars().flat_map(|c| c.to_lowercase()),
)
} else {
self.to_lowercase().into()
}
}
#[inline]
fn to_uppercase_smolstr(&self) -> SmolStr {
let len = self.len();
if len <= INLINE_CAP {
let (buf, rest) = inline_convert_while_ascii(self, u8::to_ascii_uppercase);
from_buf_and_chars(
buf,
len - rest.len(),
rest.chars().flat_map(|c| c.to_uppercase()),
)
} else {
self.to_uppercase().into()
}
}
#[inline]
fn to_ascii_lowercase_smolstr(&self) -> SmolStr {
let len = self.len();
if len <= INLINE_CAP {
let mut buf = [0u8; INLINE_CAP];
buf[..len].copy_from_slice(self.as_bytes());
buf[..len].make_ascii_lowercase();
SmolStr(Repr::Inline {
// SAFETY: `len` is in bounds
len: unsafe { InlineSize::transmute_from_u8(len as u8) },
buf,
})
} else {
self.to_ascii_lowercase().into()
}
}
#[inline]
fn to_ascii_uppercase_smolstr(&self) -> SmolStr {
let len = self.len();
if len <= INLINE_CAP {
let mut buf = [0u8; INLINE_CAP];
buf[..len].copy_from_slice(self.as_bytes());
buf[..len].make_ascii_uppercase();
SmolStr(Repr::Inline {
// SAFETY: `len` is in bounds
len: unsafe { InlineSize::transmute_from_u8(len as u8) },
buf,
})
} else {
self.to_ascii_uppercase().into()
}
}
#[inline]
fn replace_smolstr(&self, from: &str, to: &str) -> SmolStr {
self.replacen_smolstr(from, to, usize::MAX)
}
#[inline]
fn replacen_smolstr(&self, from: &str, to: &str, mut count: usize) -> SmolStr {
// Fast path for replacing a single ASCII character with another inline.
if let [from_u8] = from.as_bytes() {
if let [to_u8] = to.as_bytes() {
return if self.len() <= count {
// SAFETY: `from_u8` & `to_u8` are ascii
unsafe { replacen_1_ascii(self, |b| if b == from_u8 { *to_u8 } else { *b }) }
} else {
unsafe {
replacen_1_ascii(self, |b| {
if b == from_u8 && count != 0 {
count -= 1;
*to_u8
} else {
*b
}
})
}
};
}
}
let mut result = SmolStrBuilder::new();
let mut last_end = 0;
for (start, part) in self.match_indices(from).take(count) {
// SAFETY: `start` is guaranteed to be within the bounds of `self` as per
// `match_indices` and last_end is always less than or equal to `start`
result.push_str(unsafe { self.get_unchecked(last_end..start) });
result.push_str(to);
last_end = start + part.len();
}
// SAFETY: `self.len()` is guaranteed to be within the bounds of `self` and last_end is
// always less than or equal to `self.len()`
result.push_str(unsafe { self.get_unchecked(last_end..self.len()) });
SmolStr::from(result)
}
}
/// SAFETY: `map` fn must only replace ascii with ascii or return unchanged bytes.
#[inline]
unsafe fn replacen_1_ascii(src: &str, mut map: impl FnMut(&u8) -> u8) -> SmolStr {
if src.len() <= INLINE_CAP {
let mut buf = [0u8; INLINE_CAP];
for (idx, b) in src.as_bytes().iter().enumerate() {
buf[idx] = map(b);
}
SmolStr(Repr::Inline {
// SAFETY: `len` is in bounds
len: unsafe { InlineSize::transmute_from_u8(src.len() as u8) },
buf,
})
} else {
let out = src.as_bytes().iter().map(map).collect();
// SAFETY: We replaced ascii with ascii on valid utf8 strings.
unsafe { String::from_utf8_unchecked(out).into() }
}
}
/// Inline version of std fn `convert_while_ascii`. `s` must have len <= 23.
#[inline]
fn inline_convert_while_ascii(s: &str, convert: fn(&u8) -> u8) -> ([u8; INLINE_CAP], &str) {
// Process the input in chunks of 16 bytes to enable auto-vectorization.
// Previously the chunk size depended on the size of `usize`,
// but on 32-bit platforms with sse or neon is also the better choice.
// The only downside on other platforms would be a bit more loop-unrolling.
const N: usize = 16;
debug_assert!(s.len() <= INLINE_CAP, "only for inline-able strings");
let mut slice = s.as_bytes();
let mut out = [0u8; INLINE_CAP];
let mut out_slice = &mut out[..slice.len()];
let mut is_ascii = [false; N];
while slice.len() >= N {
// SAFETY: checked in loop condition
let chunk = unsafe { slice.get_unchecked(..N) };
// SAFETY: out_slice has at least same length as input slice and gets sliced with the same offsets
let out_chunk = unsafe { out_slice.get_unchecked_mut(..N) };
for j in 0..N {
is_ascii[j] = chunk[j] <= 127;
}
// Auto-vectorization for this check is a bit fragile, sum and comparing against the chunk
// size gives the best result, specifically a pmovmsk instruction on x86.
// See https://github.com/llvm/llvm-project/issues/96395 for why llvm currently does not
// currently recognize other similar idioms.
if is_ascii.iter().map(|x| *x as u8).sum::<u8>() as usize != N {
break;
}
for j in 0..N {
out_chunk[j] = convert(&chunk[j]);
}
slice = unsafe { slice.get_unchecked(N..) };
out_slice = unsafe { out_slice.get_unchecked_mut(N..) };
}
// handle the remainder as individual bytes
while !slice.is_empty() {
let byte = slice[0];
if byte > 127 {
break;
}
// SAFETY: out_slice has at least same length as input slice
unsafe {
*out_slice.get_unchecked_mut(0) = convert(&byte);
}
slice = unsafe { slice.get_unchecked(1..) };
out_slice = unsafe { out_slice.get_unchecked_mut(1..) };
}
unsafe {
// SAFETY: we know this is a valid char boundary
// since we only skipped over leading ascii bytes
let rest = core::str::from_utf8_unchecked(slice);
(out, rest)
}
}
impl<T> ToSmolStr for T
where
T: fmt::Display + ?Sized,
{
fn to_smolstr(&self) -> SmolStr {
format_smolstr!("{}", self)
}
}
mod private {
/// No downstream impls allowed.
pub trait Sealed {}
impl Sealed for str {}
}
/// Formats arguments to a [`SmolStr`], potentially without allocating.
///
/// See [`alloc::format!`] or [`format_args!`] for syntax documentation.
#[macro_export]
macro_rules! format_smolstr {
($($tt:tt)*) => {{
let mut w = $crate::SmolStrBuilder::new();
::core::fmt::Write::write_fmt(&mut w, format_args!($($tt)*)).expect("a formatting trait implementation returned an error");
w.finish()
}};
}
/// A builder that can be used to efficiently build a [`SmolStr`].
///
/// This won't allocate if the final string fits into the inline buffer.
#[derive(Clone, Default, Debug, PartialEq, Eq)]
pub struct SmolStrBuilder(SmolStrBuilderRepr);
#[derive(Clone, Debug, PartialEq, Eq)]
enum SmolStrBuilderRepr {
Inline { len: usize, buf: [u8; INLINE_CAP] },
Heap(String),
}
impl Default for SmolStrBuilderRepr {
#[inline]
fn default() -> Self {
SmolStrBuilderRepr::Inline {
buf: [0; INLINE_CAP],
len: 0,
}
}
}
impl SmolStrBuilder {
/// Creates a new empty [`SmolStrBuilder`].
#[must_use]
pub const fn new() -> Self {
Self(SmolStrBuilderRepr::Inline {
buf: [0; INLINE_CAP],
len: 0,
})
}
/// Builds a [`SmolStr`] from `self`.
#[must_use]
pub fn finish(&self) -> SmolStr {
SmolStr(match &self.0 {
&SmolStrBuilderRepr::Inline { len, buf } => {
debug_assert!(len <= INLINE_CAP);
Repr::Inline {
// SAFETY: We know that `value.len` is less than or equal to the maximum value of `InlineSize`
len: unsafe { InlineSize::transmute_from_u8(len as u8) },
buf,
}
}
SmolStrBuilderRepr::Heap(heap) => Repr::new(heap),
})
}
/// Appends the given [`char`] to the end of `self`'s buffer.
pub fn push(&mut self, c: char) {
match &mut self.0 {
SmolStrBuilderRepr::Inline { len, buf } => {
let char_len = c.len_utf8();
let new_len = *len + char_len;
if new_len <= INLINE_CAP {
c.encode_utf8(&mut buf[*len..]);
*len += char_len;
} else {
let mut heap = String::with_capacity(new_len);
// copy existing inline bytes over to the heap
// SAFETY: inline data is guaranteed to be valid utf8 for `old_len` bytes
unsafe { heap.as_mut_vec().extend_from_slice(&buf[..*len]) };
heap.push(c);
self.0 = SmolStrBuilderRepr::Heap(heap);
}
}
SmolStrBuilderRepr::Heap(h) => h.push(c),
}
}
/// Appends a given string slice onto the end of `self`'s buffer.
pub fn push_str(&mut self, s: &str) {
match &mut self.0 {
SmolStrBuilderRepr::Inline { len, buf } => {
let old_len = *len;
*len += s.len();
// if the new length will fit on the stack (even if it fills it entirely)
if *len <= INLINE_CAP {
buf[old_len..*len].copy_from_slice(s.as_bytes());
return; // skip the heap push below
}
let mut heap = String::with_capacity(*len);
// copy existing inline bytes over to the heap
// SAFETY: inline data is guaranteed to be valid utf8 for `old_len` bytes
unsafe { heap.as_mut_vec().extend_from_slice(&buf[..old_len]) };
heap.push_str(s);
self.0 = SmolStrBuilderRepr::Heap(heap);
}
SmolStrBuilderRepr::Heap(heap) => heap.push_str(s),
}
}
}
impl fmt::Write for SmolStrBuilder {
#[inline]
fn write_str(&mut self, s: &str) -> fmt::Result {
self.push_str(s);
Ok(())
}
}
impl From<SmolStrBuilder> for SmolStr {
fn from(value: SmolStrBuilder) -> Self {
value.finish()
}
}
#[cfg(feature = "arbitrary")]
impl<'a> arbitrary::Arbitrary<'a> for SmolStr {
fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> Result<Self, arbitrary::Error> {
let s = <&str>::arbitrary(u)?;
Ok(SmolStr::new(s))
}
}
#[cfg(feature = "borsh")]
mod borsh;
#[cfg(feature = "serde")]
mod serde;
#[test]
fn from_buf_and_chars_size_hinted_heap() {
let str = from_buf_and_chars(
*b"abcdefghijklmnopqr00000",
18,
"_0x1x2x3x4x5x6x7x8x9x10x11x12x13".chars(),
);
assert_eq!(str, "abcdefghijklmnopqr_0x1x2x3x4x5x6x7x8x9x10x11x12x13");
}

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use alloc::{string::String, vec::Vec};
use core::fmt;
use serde::de::{Deserializer, Error, Unexpected, Visitor};
use serde_core as serde;
use crate::SmolStr;
// https://github.com/serde-rs/serde/blob/629802f2abfd1a54a6072992888fea7ca5bc209f/serde/src/private/de.rs#L56-L125
fn smol_str<'de: 'a, 'a, D>(deserializer: D) -> Result<SmolStr, D::Error>
where
D: Deserializer<'de>,
{
struct SmolStrVisitor;
impl<'a> Visitor<'a> for SmolStrVisitor {
type Value = SmolStr;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a string")
}
fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
where
E: Error,
{
Ok(SmolStr::from(v))
}
fn visit_borrowed_str<E>(self, v: &'a str) -> Result<Self::Value, E>
where
E: Error,
{
Ok(SmolStr::from(v))
}
fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
where
E: Error,
{
Ok(SmolStr::from(v))
}
fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
where
E: Error,
{
match core::str::from_utf8(v) {
Ok(s) => Ok(SmolStr::from(s)),
Err(_) => Err(Error::invalid_value(Unexpected::Bytes(v), &self)),
}
}
fn visit_borrowed_bytes<E>(self, v: &'a [u8]) -> Result<Self::Value, E>
where
E: Error,
{
match core::str::from_utf8(v) {
Ok(s) => Ok(SmolStr::from(s)),
Err(_) => Err(Error::invalid_value(Unexpected::Bytes(v), &self)),
}
}
fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
where
E: Error,
{
match String::from_utf8(v) {
Ok(s) => Ok(SmolStr::from(s)),
Err(e) => Err(Error::invalid_value(
Unexpected::Bytes(&e.into_bytes()),
&self,
)),
}
}
}
deserializer.deserialize_str(SmolStrVisitor)
}
impl serde::Serialize for SmolStr {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: serde::Serializer,
{
self.as_str().serialize(serializer)
}
}
impl<'de> serde::Deserialize<'de> for SmolStr {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: serde::Deserializer<'de>,
{
smol_str(deserializer)
}
}

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use std::sync::Arc;
#[cfg(not(miri))]
use proptest::{prop_assert, prop_assert_eq, proptest};
use smol_str::{SmolStr, SmolStrBuilder};
#[test]
#[cfg(target_pointer_width = "64")]
fn smol_str_is_smol() {
assert_eq!(
::std::mem::size_of::<SmolStr>(),
::std::mem::size_of::<String>(),
);
}
#[test]
fn assert_traits() {
fn f<T: Send + Sync + ::std::fmt::Debug + Clone>() {}
f::<SmolStr>();
}
#[test]
fn conversions() {
let s: SmolStr = "Hello, World!".into();
let s: String = s.into();
assert_eq!(s, "Hello, World!");
let s: SmolStr = Arc::<str>::from("Hello, World!").into();
let s: Arc<str> = s.into();
assert_eq!(s.as_ref(), "Hello, World!");
}
#[test]
fn const_fn_ctor() {
const EMPTY: SmolStr = SmolStr::new_inline("");
const A: SmolStr = SmolStr::new_inline("A");
const HELLO: SmolStr = SmolStr::new_inline("HELLO");
const LONG: SmolStr = SmolStr::new_inline("ABCDEFGHIZKLMNOPQRSTUVW");
assert_eq!(EMPTY, SmolStr::from(""));
assert_eq!(A, SmolStr::from("A"));
assert_eq!(HELLO, SmolStr::from("HELLO"));
assert_eq!(LONG, SmolStr::from("ABCDEFGHIZKLMNOPQRSTUVW"));
}
#[cfg(not(miri))]
fn check_props(std_str: &str, smol: SmolStr) -> Result<(), proptest::test_runner::TestCaseError> {
prop_assert_eq!(smol.as_str(), std_str);
prop_assert_eq!(smol.len(), std_str.len());
prop_assert_eq!(smol.is_empty(), std_str.is_empty());
if smol.len() <= 23 {
prop_assert!(!smol.is_heap_allocated());
}
Ok(())
}
#[cfg(not(miri))]
proptest! {
#[test]
fn roundtrip(s: String) {
check_props(s.as_str(), SmolStr::new(s.clone()))?;
}
#[test]
fn roundtrip_spaces(s in r"( )*") {
check_props(s.as_str(), SmolStr::new(s.clone()))?;
}
#[test]
fn roundtrip_newlines(s in r"\n*") {
check_props(s.as_str(), SmolStr::new(s.clone()))?;
}
#[test]
fn roundtrip_ws(s in r"( |\n)*") {
check_props(s.as_str(), SmolStr::new(s.clone()))?;
}
#[test]
fn from_string_iter(slices in proptest::collection::vec(".*", 1..100)) {
let string: String = slices.iter().map(|x| x.as_str()).collect();
let smol: SmolStr = slices.into_iter().collect();
check_props(string.as_str(), smol)?;
}
#[test]
fn from_str_iter(slices in proptest::collection::vec(".*", 1..100)) {
let string: String = slices.iter().map(|x| x.as_str()).collect();
let smol: SmolStr = slices.iter().collect();
check_props(string.as_str(), smol)?;
}
}
#[cfg(feature = "serde")]
mod serde_tests {
use super::*;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
#[derive(Serialize, Deserialize)]
struct SmolStrStruct {
pub(crate) s: SmolStr,
pub(crate) vec: Vec<SmolStr>,
pub(crate) map: HashMap<SmolStr, SmolStr>,
}
#[test]
fn test_serde() {
let s = SmolStr::new("Hello, World");
let s = serde_json::to_string(&s).unwrap();
assert_eq!(s, "\"Hello, World\"");
let s: SmolStr = serde_json::from_str(&s).unwrap();
assert_eq!(s, "Hello, World");
}
#[test]
fn test_serde_reader() {
let s = SmolStr::new("Hello, World");
let s = serde_json::to_string(&s).unwrap();
assert_eq!(s, "\"Hello, World\"");
let s: SmolStr = serde_json::from_reader(std::io::Cursor::new(s)).unwrap();
assert_eq!(s, "Hello, World");
}
#[test]
fn test_serde_struct() {
let mut map = HashMap::new();
map.insert(SmolStr::new("a"), SmolStr::new("ohno"));
let struct_ = SmolStrStruct {
s: SmolStr::new("Hello, World"),
vec: vec![SmolStr::new("Hello, World"), SmolStr::new("Hello, World")],
map,
};
let s = serde_json::to_string(&struct_).unwrap();
let _new_struct: SmolStrStruct = serde_json::from_str(&s).unwrap();
}
#[test]
fn test_serde_struct_reader() {
let mut map = HashMap::new();
map.insert(SmolStr::new("a"), SmolStr::new("ohno"));
let struct_ = SmolStrStruct {
s: SmolStr::new("Hello, World"),
vec: vec![SmolStr::new("Hello, World"), SmolStr::new("Hello, World")],
map,
};
let s = serde_json::to_string(&struct_).unwrap();
let _new_struct: SmolStrStruct = serde_json::from_reader(std::io::Cursor::new(s)).unwrap();
}
#[test]
fn test_serde_hashmap() {
let mut map = HashMap::new();
map.insert(SmolStr::new("a"), SmolStr::new("ohno"));
let s = serde_json::to_string(&map).unwrap();
let _s: HashMap<SmolStr, SmolStr> = serde_json::from_str(&s).unwrap();
}
#[test]
fn test_serde_hashmap_reader() {
let mut map = HashMap::new();
map.insert(SmolStr::new("a"), SmolStr::new("ohno"));
let s = serde_json::to_string(&map).unwrap();
let _s: HashMap<SmolStr, SmolStr> =
serde_json::from_reader(std::io::Cursor::new(s)).unwrap();
}
#[test]
fn test_serde_vec() {
let vec = vec![SmolStr::new(""), SmolStr::new("b")];
let s = serde_json::to_string(&vec).unwrap();
let _s: Vec<SmolStr> = serde_json::from_str(&s).unwrap();
}
#[test]
fn test_serde_vec_reader() {
let vec = vec![SmolStr::new(""), SmolStr::new("b")];
let s = serde_json::to_string(&vec).unwrap();
let _s: Vec<SmolStr> = serde_json::from_reader(std::io::Cursor::new(s)).unwrap();
}
}
#[test]
fn test_search_in_hashmap() {
let mut m = ::std::collections::HashMap::<SmolStr, i32>::new();
m.insert("aaa".into(), 17);
assert_eq!(17, *m.get("aaa").unwrap());
}
#[test]
fn test_from_char_iterator() {
let examples = [
// Simple keyword-like strings
("if", false),
("for", false),
("impl", false),
// Strings containing two-byte characters
("パーティーへ行かないか", true),
("パーティーへ行か", true),
("パーティーへ行_", false),
("和製漢語", false),
("部落格", false),
("사회과학원 어학연구소", true),
// String containing diverse characters
("表ポあA鷗ŒéＢ逍Üߪąñ丂㐀𠀀", true),
];
for (raw, is_heap) in &examples {
let s: SmolStr = raw.chars().collect();
assert_eq!(s.as_str(), *raw);
assert_eq!(s.is_heap_allocated(), *is_heap);
}
// String which has too many characters to even consider inlining: Chars::size_hint uses
// (`len` + 3) / 4. With `len` = 89, this results in 23, so `from_iter` will immediately
// heap allocate
let raw = "a".repeat(23 * 4 + 1);
let s: SmolStr = raw.chars().collect();
assert_eq!(s.as_str(), raw);
assert!(s.is_heap_allocated());
}
#[test]
fn test_bad_size_hint_char_iter() {
struct BadSizeHint<I>(I);
impl<T, I: Iterator<Item = T>> Iterator for BadSizeHint<I> {
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
self.0.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
(1024, None)
}
}
let data = "testing";
let collected: SmolStr = BadSizeHint(data.chars()).collect();
let new = SmolStr::new(data);
assert!(!collected.is_heap_allocated());
assert!(!new.is_heap_allocated());
assert_eq!(new, collected);
}
#[test]
fn test_to_smolstr() {
use smol_str::ToSmolStr;
for i in 0..26 {
let a = &"abcdefghijklmnopqrstuvwxyz"[i..];
assert_eq!(a, a.to_smolstr());
assert_eq!(a, smol_str::format_smolstr!("{}", a));
}
}
#[test]
fn test_builder_push_str() {
//empty
let builder = SmolStrBuilder::new();
assert_eq!("", builder.finish());
// inline push
let mut builder = SmolStrBuilder::new();
builder.push_str("a");
builder.push_str("b");
let s = builder.finish();
assert!(!s.is_heap_allocated());
assert_eq!("ab", s);
// inline max push
let mut builder = SmolStrBuilder::new();
builder.push_str(&"a".repeat(23));
let s = builder.finish();
assert!(!s.is_heap_allocated());
assert_eq!("a".repeat(23), s);
// heap push immediate
let mut builder = SmolStrBuilder::new();
builder.push_str(&"a".repeat(24));
let s = builder.finish();
assert!(s.is_heap_allocated());
assert_eq!("a".repeat(24), s);
// heap push succession
let mut builder = SmolStrBuilder::new();
builder.push_str(&"a".repeat(23));
builder.push_str(&"a".repeat(23));
let s = builder.finish();
assert!(s.is_heap_allocated());
assert_eq!("a".repeat(46), s);
// heap push on multibyte char
let mut builder = SmolStrBuilder::new();
builder.push_str("ohnonononononononono!");
builder.push('🤯');
let s = builder.finish();
assert!(s.is_heap_allocated());
assert_eq!("ohnonononononononono!🤯", s);
}
#[test]
fn test_builder_push() {
//empty
let builder = SmolStrBuilder::new();
assert_eq!("", builder.finish());
// inline push
let mut builder = SmolStrBuilder::new();
builder.push('a');
builder.push('b');
let s = builder.finish();
assert!(!s.is_heap_allocated());
assert_eq!("ab", s);
// inline max push
let mut builder = SmolStrBuilder::new();
for _ in 0..23 {
builder.push('a');
}
let s = builder.finish();
assert!(!s.is_heap_allocated());
assert_eq!("a".repeat(23), s);
// heap push
let mut builder = SmolStrBuilder::new();
for _ in 0..24 {
builder.push('a');
}
let s = builder.finish();
assert!(s.is_heap_allocated());
assert_eq!("a".repeat(24), s);
}
#[cfg(test)]
mod test_str_ext {
use smol_str::StrExt;
#[test]
fn large() {
let lowercase = "aaaaaaAAAAAaaaaaaaaaaaaaaaaaaaaaAAAAaaaaaaaaaaaaaa".to_lowercase_smolstr();
assert_eq!(
lowercase,
"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
);
assert!(lowercase.is_heap_allocated());
}
#[test]
fn to_lowercase() {
let lowercase = "aßΔC".to_lowercase_smolstr();
assert_eq!(lowercase, "aßδc");
assert!(!lowercase.is_heap_allocated());
}
#[test]
fn to_uppercase() {
let uppercase = "aßΔC".to_uppercase_smolstr();
assert_eq!(uppercase, "ASSΔC");
assert!(!uppercase.is_heap_allocated());
}
#[test]
fn to_ascii_lowercase() {
let uppercase = "aßΔC".to_ascii_lowercase_smolstr();
assert_eq!(uppercase, "aßΔc");
assert!(!uppercase.is_heap_allocated());
}
#[test]
fn to_ascii_uppercase() {
let uppercase = "aßΔC".to_ascii_uppercase_smolstr();
assert_eq!(uppercase, "AßΔC");
assert!(!uppercase.is_heap_allocated());
}
#[test]
fn replace() {
let result = "foo_bar_baz".replace_smolstr("ba", "do");
assert_eq!(result, "foo_dor_doz");
assert!(!result.is_heap_allocated());
}
#[test]
fn replacen() {
let result = "foo_bar_baz".replacen_smolstr("ba", "do", 1);
assert_eq!(result, "foo_dor_baz");
assert!(!result.is_heap_allocated());
}
#[test]
fn replacen_1_ascii() {
let result = "foo_bar_baz".replacen_smolstr("o", "u", 1);
assert_eq!(result, "fuo_bar_baz");
assert!(!result.is_heap_allocated());
}
}
#[cfg(feature = "borsh")]
mod borsh_tests {
use borsh::BorshDeserialize;
use smol_str::{SmolStr, ToSmolStr};
use std::io::Cursor;
#[test]
fn borsh_serialize_stack() {
let smolstr_on_stack = "aßΔCaßδc".to_smolstr();
let mut buffer = Vec::new();
borsh::BorshSerialize::serialize(&smolstr_on_stack, &mut buffer).unwrap();
let mut cursor = Cursor::new(buffer);
let decoded: SmolStr = borsh::BorshDeserialize::deserialize_reader(&mut cursor).unwrap();
assert_eq!(smolstr_on_stack, decoded);
}
#[test]
fn borsh_serialize_heap() {
let smolstr_on_heap = "aßΔCaßδcaßΔCaßδcaßΔCaßδcaßΔCaßδcaßΔCaßδcaßΔCaßδcaßΔCaßδcaßΔCaßδcaßΔCaßδcaßΔCaßδcaßΔCaßδc".to_smolstr();
let mut buffer = Vec::new();
borsh::BorshSerialize::serialize(&smolstr_on_heap, &mut buffer).unwrap();
let mut cursor = Cursor::new(buffer);
let decoded: SmolStr = borsh::BorshDeserialize::deserialize_reader(&mut cursor).unwrap();
assert_eq!(smolstr_on_heap, decoded);
}
#[test]
fn borsh_non_utf8_stack() {
let invalid_utf8: Vec<u8> = vec![0xF0, 0x9F, 0x8F]; // Incomplete UTF-8 sequence
let wrong_utf8 = SmolStr::from(unsafe { String::from_utf8_unchecked(invalid_utf8) });
let mut buffer = Vec::new();
borsh::BorshSerialize::serialize(&wrong_utf8, &mut buffer).unwrap();
let mut cursor = Cursor::new(buffer);
let result = SmolStr::deserialize_reader(&mut cursor);
assert!(result.is_err());
}
#[test]
fn borsh_non_utf8_heap() {
let invalid_utf8: Vec<u8> = vec![
0xC1, 0x8A, 0x5F, 0xE2, 0x3A, 0x9E, 0x3B, 0xAA, 0x01, 0x08, 0x6F, 0x2F, 0xC0, 0x32,
0xAB, 0xE1, 0x9A, 0x2F, 0x4A, 0x3F, 0x25, 0x0D, 0x8A, 0x2A, 0x19, 0x11, 0xF0, 0x7F,
0x0E, 0x80,
];
let wrong_utf8 = SmolStr::from(unsafe { String::from_utf8_unchecked(invalid_utf8) });
let mut buffer = Vec::new();
borsh::BorshSerialize::serialize(&wrong_utf8, &mut buffer).unwrap();
let mut cursor = Cursor::new(buffer);
let result = SmolStr::deserialize_reader(&mut cursor);
assert!(result.is_err());
}
}

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#![cfg(not(miri))]
use std::{
env,
path::{Path, PathBuf},
process::{Command, Stdio},
};
fn project_root() -> PathBuf {
PathBuf::from(
env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| env!("CARGO_MANIFEST_DIR").to_owned()),
)
}
fn run(cmd: &str, dir: impl AsRef<Path>) -> Result<(), ()> {
let mut args: Vec<_> = cmd.split_whitespace().collect();
let bin = args.remove(0);
println!("> {}", cmd);
let output = Command::new(bin)
.args(args)
.current_dir(dir)
.stdin(Stdio::null())
.stdout(Stdio::piped())
.stderr(Stdio::inherit())
.output()
.map_err(drop)?;
if output.status.success() {
Ok(())
} else {
let stdout = String::from_utf8(output.stdout).map_err(drop)?;
print!("{}", stdout);
Err(())
}
}
#[test]
fn check_code_formatting() {
let dir = project_root();
if run("rustfmt +stable --version", &dir).is_err() {
panic!(
"failed to run rustfmt from toolchain 'stable'; \
please run `rustup component add rustfmt --toolchain stable` to install it.",
);
}
if run("cargo +stable fmt -- --check", &dir).is_err() {
panic!("code is not properly formatted; please format the code by running `cargo fmt`")
}
}