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Implement int_from_ascii (rust-lang#134821)
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Provides unstable `T::from_ascii()` and `T::from_ascii_radix()` for integer
types `T`, as drafted in tracking issue rust-lang#134821.

To deduplicate documentation without additional macros, implementations of
`isize` and `usize` no longer delegate to equivalent integer types.
After rust-lang#132870 they are inlined anyway.
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@niklasf
niklasf committed Dec 27, 2024
1 parent 6d3db55 commit 830425d
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Showing 2 changed files with 131 additions and 93 deletions.
212 changes: 123 additions & 89 deletions library/core/src/num/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1453,20 +1453,6 @@ pub enum FpCategory {
Normal,
}

macro_rules! from_str_radix_int_impl {
($($t:ty)*) => {$(
#[stable(feature = "rust1", since = "1.0.0")]
impl FromStr for $t {
type Err = ParseIntError;
#[inline]
fn from_str(src: &str) -> Result<Self, ParseIntError> {
<$t>::from_str_radix(src, 10)
}
}
)*}
}
from_str_radix_int_impl! { isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128 }

/// Determines if a string of text of that length of that radix could be guaranteed to be
/// stored in the given type T.
/// Note that if the radix is known to the compiler, it is just the check of digits.len that
Expand All @@ -1482,18 +1468,58 @@ pub const fn can_not_overflow<T>(radix: u32, is_signed_ty: bool, digits: &[u8])
#[cfg_attr(feature = "panic_immediate_abort", inline)]
#[cold]
#[track_caller]
const fn from_str_radix_panic(radix: u32) -> ! {
const fn from_ascii_radix_panic(radix: u32) -> ! {
const_panic!(
"from_str_radix_int: must lie in the range `[2, 36]`",
"from_str_radix_int: must lie in the range `[2, 36]` - found {radix}",
"from_ascii_radix: radix must lie in the range `[2, 36]`",
"from_ascii_radix: radix must lie in the range `[2, 36]` - found {radix}",
radix: u32 = radix,
)
}

macro_rules! from_str_radix {
macro_rules! from_str_int_impl {
($signedness:ident $($int_ty:ty)+) => {$(
#[stable(feature = "rust1", since = "1.0.0")]
impl FromStr for $int_ty {
type Err = ParseIntError;

/// Parses an integer from a string slice with decimal digits.
///
/// The characters are expected to be an optional
#[doc = sign_dependent_expr!{
$signedness ?
if signed {
" `+` or `-` "
}
if unsigned {
" `+` "
}
}]
/// sign followed by only digits. Leading and trailing non-digit characters (including
/// whitespace) represent an error. Underscores (which are accepted in Rust literals)
/// also represent an error.
///
/// # Examples
///
/// Basic usage:
/// ```
/// use std::str::FromStr;
///
#[doc = concat!("assert_eq!(", stringify!($int_ty), "::from_str(\"+10\"), Ok(10));")]
/// ```
/// Trailing space returns error:
/// ```
/// # use std::str::FromStr;
/// #
#[doc = concat!("assert!(", stringify!($int_ty), "::from_str(\"1 \").is_err());")]
/// ```
#[inline]
fn from_str(src: &str) -> Result<$int_ty, ParseIntError> {
<$int_ty>::from_str_radix(src, 10)
}
}

impl $int_ty {
/// Converts a string slice in a given base to an integer.
/// Parses an integer from a string slice with digits in a given base.
///
/// The string is expected to be an optional
#[doc = sign_dependent_expr!{
Expand All @@ -1506,7 +1532,7 @@ macro_rules! from_str_radix {
}
}]
/// sign followed by only digits. Leading and trailing non-digit characters (including
/// whitespace) represent an error. Underscores (which are accepted in rust literals)
/// whitespace) represent an error. Underscores (which are accepted in Rust literals)
/// also represent an error.
///
/// Digits are a subset of these characters, depending on `radix`:
Expand All @@ -1532,11 +1558,84 @@ macro_rules! from_str_radix {
#[rustc_const_stable(feature = "const_int_from_str", since = "1.82.0")]
#[inline]
pub const fn from_str_radix(src: &str, radix: u32) -> Result<$int_ty, ParseIntError> {
<$int_ty>::from_ascii_radix(src.as_bytes(), radix)
}

/// Parses an integer from an ASCII-byte slice with decimal digits.
///
/// The characters are expected to be an optional
#[doc = sign_dependent_expr!{
$signedness ?
if signed {
" `+` or `-` "
}
if unsigned {
" `+` "
}
}]
/// sign followed by only digits. Leading and trailing non-digit characters (including
/// whitespace) represent an error. Underscores (which are accepted in Rust literals)
/// also represent an error.
///
/// # Examples
///
/// Basic usage:
/// ```
#[doc = concat!("assert_eq!(", stringify!($int_ty), "::from_ascii(b\"+10\"), Ok(10));")]
/// ```
/// Trailing space returns error:
/// ```
#[doc = concat!("assert!(", stringify!($int_ty), "::from_ascii(b\"1 \").is_err());")]
/// ```
#[unstable(feature = "int_from_ascii", issue = "134821")]
#[inline]
pub const fn from_ascii(src: &[u8]) -> Result<$int_ty, ParseIntError> {
<$int_ty>::from_ascii_radix(src, 10)
}

/// Parses an integer from an ASCII-byte slice with digits in a given base.
///
/// The characters are expected to be an optional
#[doc = sign_dependent_expr!{
$signedness ?
if signed {
" `+` or `-` "
}
if unsigned {
" `+` "
}
}]
/// sign followed by only digits. Leading and trailing non-digit characters (including
/// whitespace) represent an error. Underscores (which are accepted in Rust literals)
/// also represent an error.
///
/// Digits are a subset of these characters, depending on `radix`:
/// * `0-9`
/// * `a-z`
/// * `A-Z`
///
/// # Panics
///
/// This function panics if `radix` is not in the range from 2 to 36.
///
/// # Examples
///
/// Basic usage:
/// ```
#[doc = concat!("assert_eq!(", stringify!($int_ty), "::from_ascii_radix(b\"A\", 16), Ok(10));")]
/// ```
/// Trailing space returns error:
/// ```
#[doc = concat!("assert!(", stringify!($int_ty), "::from_ascii_radix(b\"1 \", 10).is_err());")]
/// ```
#[unstable(feature = "int_from_ascii", issue = "134821")]
#[inline]
pub const fn from_ascii_radix(src: &[u8], radix: u32) -> Result<$int_ty, ParseIntError> {
use self::IntErrorKind::*;
use self::ParseIntError as PIE;

if 2 > radix || radix > 36 {
from_str_radix_panic(radix);
from_ascii_radix_panic(radix);
}

if src.is_empty() {
Expand All @@ -1546,12 +1645,6 @@ macro_rules! from_str_radix {
#[allow(unused_comparisons)]
let is_signed_ty = 0 > <$int_ty>::MIN;

// all valid digits are ascii, so we will just iterate over the utf8 bytes
// and cast them to chars. .to_digit() will safely return None for anything
// other than a valid ascii digit for the given radix, including the first-byte
// of multi-byte sequences
let src = src.as_bytes();

let (is_positive, mut digits) = match src {
[b'+' | b'-'] => {
return Err(PIE { kind: InvalidDigit });
Expand Down Expand Up @@ -1627,67 +1720,8 @@ macro_rules! from_str_radix {
Ok(result)
}
}
)+}
}

from_str_radix! { unsigned u8 u16 u32 u64 u128 }
from_str_radix! { signed i8 i16 i32 i64 i128 }

// Re-use the relevant implementation of from_str_radix for isize and usize to avoid outputting two
// identical functions.
macro_rules! from_str_radix_size_impl {
($($signedness:ident $t:ident $size:ty),*) => {$(
impl $size {
/// Converts a string slice in a given base to an integer.
///
/// The string is expected to be an optional
#[doc = sign_dependent_expr!{
$signedness ?
if signed {
" `+` or `-` "
}
if unsigned {
" `+` "
}
}]
/// sign followed by only digits. Leading and trailing non-digit characters (including
/// whitespace) represent an error. Underscores (which are accepted in rust literals)
/// also represent an error.
///
/// Digits are a subset of these characters, depending on `radix`:
/// * `0-9`
/// * `a-z`
/// * `A-Z`
///
/// # Panics
///
/// This function panics if `radix` is not in the range from 2 to 36.
///
/// # Examples
///
/// Basic usage:
/// ```
#[doc = concat!("assert_eq!(", stringify!($size), "::from_str_radix(\"A\", 16), Ok(10));")]
/// ```
/// Trailing space returns error:
/// ```
#[doc = concat!("assert!(", stringify!($size), "::from_str_radix(\"1 \", 10).is_err());")]
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_int_from_str", since = "1.82.0")]
#[inline]
pub const fn from_str_radix(src: &str, radix: u32) -> Result<$size, ParseIntError> {
match <$t>::from_str_radix(src, radix) {
Ok(x) => Ok(x as $size),
Err(e) => Err(e),
}
}
})*}
)*}
}

#[cfg(target_pointer_width = "16")]
from_str_radix_size_impl! { signed i16 isize, unsigned u16 usize }
#[cfg(target_pointer_width = "32")]
from_str_radix_size_impl! { signed i32 isize, unsigned u32 usize }
#[cfg(target_pointer_width = "64")]
from_str_radix_size_impl! { signed i64 isize, unsigned u64 usize }
from_str_int_impl! { signed isize i8 i16 i32 i64 i128 }
from_str_int_impl! { unsigned usize u8 u16 u32 u64 u128 }
12 changes: 8 additions & 4 deletions tests/ui/consts/const-eval/parse_ints.stderr
View file
Original file line number Diff line number Diff line change
@@ -1,30 +1,34 @@
error[E0080]: evaluation of constant value failed
--> $SRC_DIR/core/src/num/mod.rs:LL:COL
|
= note: the evaluated program panicked at 'from_str_radix_int: must lie in the range `[2, 36]`', $SRC_DIR/core/src/num/mod.rs:LL:COL
= note: the evaluated program panicked at 'from_ascii_radix: radix must lie in the range `[2, 36]`', $SRC_DIR/core/src/num/mod.rs:LL:COL
|
note: inside `core::num::<impl u64>::from_ascii_radix`
--> $SRC_DIR/core/src/num/mod.rs:LL:COL
note: inside `core::num::<impl u64>::from_str_radix`
--> $SRC_DIR/core/src/num/mod.rs:LL:COL
note: inside `_TOO_LOW`
--> $DIR/parse_ints.rs:5:24
|
LL | const _TOO_LOW: () = { u64::from_str_radix("12345ABCD", 1); };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: this error originates in the macro `from_str_radix` (in Nightly builds, run with -Z macro-backtrace for more info)
= note: this error originates in the macro `from_str_int_impl` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0080]: evaluation of constant value failed
--> $SRC_DIR/core/src/num/mod.rs:LL:COL
|
= note: the evaluated program panicked at 'from_str_radix_int: must lie in the range `[2, 36]`', $SRC_DIR/core/src/num/mod.rs:LL:COL
= note: the evaluated program panicked at 'from_ascii_radix: radix must lie in the range `[2, 36]`', $SRC_DIR/core/src/num/mod.rs:LL:COL
|
note: inside `core::num::<impl u64>::from_ascii_radix`
--> $SRC_DIR/core/src/num/mod.rs:LL:COL
note: inside `core::num::<impl u64>::from_str_radix`
--> $SRC_DIR/core/src/num/mod.rs:LL:COL
note: inside `_TOO_HIGH`
--> $DIR/parse_ints.rs:6:25
|
LL | const _TOO_HIGH: () = { u64::from_str_radix("12345ABCD", 37); };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: this error originates in the macro `from_str_radix` (in Nightly builds, run with -Z macro-backtrace for more info)
= note: this error originates in the macro `from_str_int_impl` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 2 previous errors

Expand Down

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