Implement int_from_ascii_radix

Author: niklasf

library/core/src/num/int_macros.rs

@@ -63,7 +63,34 @@ macro_rules! int_impl {
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError> {
-            from_str_radix(src, radix)
+            from_ascii_radix(src.as_bytes(), radix)
+        }
+
+        /// Parses an integer in a given base from a slice of bytes.
+        ///
+        /// The bytes are interpreted as ASCII characters. Accepts an optional
+        /// `+` or `-` sign followed by digits. Leading and trailing whitespace
+        /// are rejected.
+        /// 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
+        ///
+        /// ```
+        /// #![feature(int_from_ascii_radix)]
+        ///
+        #[doc = concat!("assert_eq!(", stringify!($SelfT), "::from_ascii_radix(b\"+100\", 2), Ok(4));")]
+        /// ```
+        #[unstable(feature = "int_from_ascii_radix", issue = "none")]
+        pub fn from_ascii_radix(src: &[u8], radix: u32) -> Result<Self, ParseIntError> {
+            from_ascii_radix(src, radix)
         }
 
         /// Returns the number of ones in the binary representation of `self`.

library/core/src/num/mod.rs

@@ -1055,7 +1055,7 @@ pub enum FpCategory {
 }
 
 #[doc(hidden)]
-trait FromStrRadixHelper:
+trait FromAsciiRadixHelper:
     PartialOrd + Copy + Add<Output = Self> + Sub<Output = Self> + Mul<Output = Self>
 {
     const MIN: Self;
@@ -1071,15 +1071,15 @@ macro_rules! from_str_radix_int_impl {
         impl FromStr for $t {
             type Err = ParseIntError;
             fn from_str(src: &str) -> Result<Self, ParseIntError> {
-                from_str_radix(src, 10)
+                from_ascii_radix(src.as_bytes(), 10)
             }
         }
     )*}
 }
 from_str_radix_int_impl! { isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128 }
 
 macro_rules! impl_helper_for {
-    ($($t:ty)*) => ($(impl FromStrRadixHelper for $t {
+    ($($t:ty)*) => ($(impl FromAsciiRadixHelper for $t {
         const MIN: Self = Self::MIN;
         #[inline]
         fn from_u32(u: u32) -> Self { u as Self }
@@ -1110,28 +1110,18 @@ pub fn can_not_overflow<T>(radix: u32, is_signed_ty: bool, digits: &[u8]) -> boo
     radix <= 16 && digits.len() <= mem::size_of::<T>() * 2 - is_signed_ty as usize
 }
 
-fn from_str_radix<T: FromStrRadixHelper>(src: &str, radix: u32) -> Result<T, ParseIntError> {
+fn from_ascii_radix<T: FromAsciiRadixHelper>(src: &[u8], radix: u32) -> Result<T, ParseIntError> {
     use self::IntErrorKind::*;
     use self::ParseIntError as PIE;
 
-    assert!(
-        (2..=36).contains(&radix),
-        "from_str_radix_int: must lie in the range `[2, 36]` - found {}",
-        radix
-    );
+    assert!((2..=36).contains(&radix), "radix must lie in the range `[2, 36]` - found {}", radix);
 
     if src.is_empty() {
         return Err(PIE { kind: Empty });
     }
 
     let is_signed_ty = T::from_u32(0) > T::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, digits) = match src[0] {
         b'+' | b'-' if src[1..].is_empty() => {
             return Err(PIE { kind: InvalidDigit });

library/core/src/num/nonzero.rs

@@ -4,7 +4,7 @@ use crate::fmt;
 use crate::ops::{BitOr, BitOrAssign, Div, Rem};
 use crate::str::FromStr;
 
-use super::from_str_radix;
+use super::from_ascii_radix;
 use super::{IntErrorKind, ParseIntError};
 use crate::intrinsics;
 
@@ -182,7 +182,7 @@ macro_rules! from_str_radix_nzint_impl {
         impl FromStr for $t {
             type Err = ParseIntError;
             fn from_str(src: &str) -> Result<Self, Self::Err> {
-                Self::new(from_str_radix(src, 10)?)
+                Self::new(from_ascii_radix(src.as_bytes(), 10)?)
                     .ok_or(ParseIntError {
                         kind: IntErrorKind::Zero
                     })

library/core/src/num/uint_macros.rs

@@ -64,7 +64,34 @@ macro_rules! uint_impl {
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError> {
-            from_str_radix(src, radix)
+            from_ascii_radix(src.as_bytes(), radix)
+        }
+
+        /// Parses an integer in a given base from a slice of bytes.
+        ///
+        /// The bytes are interpreted as ASCII characters. Accepts an
+        /// optional `+` sign followed by digits. Leading and trailing
+        /// whitespace are rejected.
+        /// 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
+        ///
+        /// ```
+        /// #![feature(int_from_ascii_radix)]
+        ///
+        #[doc = concat!("assert_eq!(", stringify!($SelfT), "::from_ascii_radix(b\"+100\", 2), Ok(4));")]
+        /// ```
+        #[unstable(feature = "int_from_ascii_radix", issue = "none")]
+        pub fn from_ascii_radix(src: &[u8], radix: u32) -> Result<Self, ParseIntError> {
+            from_ascii_radix(src, radix)
         }
 
         /// Returns the number of ones in the binary representation of `self`.