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Move buffer cast operation out of macro

This commit is contained in:
David Tolnay 2021-12-12 11:59:10 -08:00
parent e2609a2fb7
commit f7502e28ab
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GPG Key ID: F9BA143B95FF6D82
1 changed files with 12 additions and 33 deletions
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45
src/lib.rs
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@ -88,7 +88,12 @@ impl Buffer {
/// Print an integer into this buffer and return a reference to its string
/// representation within the buffer.
pub fn format<I: Integer>(&mut self, i: I) -> &str {
i.write(self)
i.write(unsafe {
mem::transmute::<
&mut [MaybeUninit<u8>; I128_MAX_LEN],
&mut <I as private::Sealed>::Buffer,
>(&mut self.bytes)
})
}
}
@ -100,10 +105,8 @@ pub trait Integer: private::Sealed {}
// Seal to prevent downstream implementations of the Integer trait.
mod private {
pub trait Sealed: Copy {
fn write(self, buf: &mut crate::Buffer) -> &str;
type Buffer;
fn write2(self, buf: &mut Self::Buffer) -> &str;
type Buffer: 'static;
fn write(self, buf: &mut Self::Buffer) -> &str;
}
}
@ -121,23 +124,11 @@ macro_rules! impl_Integer {
impl Integer for $t {}
impl private::Sealed for $t {
#[inline]
fn write(self, buf: &mut Buffer) -> &str {
unsafe {
debug_assert!($max_len <= I128_MAX_LEN);
let buf = mem::transmute::<
&mut [MaybeUninit<u8>; I128_MAX_LEN],
&mut [MaybeUninit<u8>; $max_len],
>(&mut buf.bytes);
self.write2(buf)
}
}
type Buffer = [MaybeUninit<u8>; $max_len];
#[allow(unused_comparisons)]
#[inline]
fn write2(self, buf: &mut [MaybeUninit<u8>; $max_len]) -> &str {
fn write(self, buf: &mut [MaybeUninit<u8>; $max_len]) -> &str {
let is_nonnegative = self >= 0;
let mut n = if is_nonnegative {
self as $conv_fn
@ -234,23 +225,11 @@ macro_rules! impl_Integer128 {
impl Integer for $t {}
impl private::Sealed for $t {
#[inline]
fn write(self, buf: &mut Buffer) -> &str {
unsafe {
debug_assert!($max_len <= I128_MAX_LEN);
let buf = mem::transmute::<
&mut [MaybeUninit<u8>; I128_MAX_LEN],
&mut [MaybeUninit<u8>; $max_len],
>(&mut buf.bytes);
self.write2(buf)
}
}
type Buffer = [MaybeUninit<u8>; $max_len];
#[allow(unused_comparisons)]
#[inline]
fn write2(self, buf: &mut [MaybeUninit<u8>; $max_len]) -> &str {
fn write(self, buf: &mut [MaybeUninit<u8>; $max_len]) -> &str {
let is_nonnegative = self >= 0;
let n = if is_nonnegative {
self as u128
@ -265,7 +244,7 @@ macro_rules! impl_Integer128 {
// Divide by 10^19 which is the highest power less than 2^64.
let (n, rem) = udiv128::udivmod_1e19(n);
let buf1 = buf_ptr.offset(curr - U64_MAX_LEN as isize) as *mut [MaybeUninit<u8>; U64_MAX_LEN];
curr -= rem.write2(&mut *buf1).len() as isize;
curr -= rem.write(&mut *buf1).len() as isize;
if n != 0 {
// Memset the base10 leading zeros of rem.
@ -276,7 +255,7 @@ macro_rules! impl_Integer128 {
// Divide by 10^19 again.
let (n, rem) = udiv128::udivmod_1e19(n);
let buf2 = buf_ptr.offset(curr - U64_MAX_LEN as isize) as *mut [MaybeUninit<u8>; U64_MAX_LEN];
curr -= rem.write2(&mut *buf2).len() as isize;
curr -= rem.write(&mut *buf2).len() as isize;
if n != 0 {
// Memset the leading zeros.