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use std::simd::{u8x32, SimdPartialEq, ToBitMask};
use crate::{
safer_unchecked::GetSaferUnchecked,
stringparse::{handle_unicode_codepoint, ESCAPE_MAP},
Deserializer, ErrorType, Result, SillyWrapper,
};
#[cfg_attr(not(feature = "no-inline"), inline)]
pub(crate) unsafe fn parse_str<'invoke, 'de>(
input: SillyWrapper<'de>,
data: &'invoke [u8],
buffer: &'invoke mut [u8],
mut idx: usize,
) -> Result<&'de str> {
let input = input.input;
use ErrorType::{InvalidEscape, InvalidUnicodeCodepoint};
const SLASH: u8x32 = u8x32::from_array([b'\\'; 32]);
const QUOTE: u8x32 = u8x32::from_array([b'"'; 32]);
// Add 1 to skip the initial "
idx += 1;
//let mut read: usize = 0;
// we include the terminal '"' so we know where to end
// This is safe since we check sub's length in the range access above and only
// create sub sliced form sub to `sub.len()`.
let src: &[u8] = data.get_kinda_unchecked(idx..);
let mut src_i: usize = 0;
let mut len = src_i;
loop {
let v = u8x32::from_array(*src.as_ptr().add(src_i).cast::<[u8; 32]>());
// store to dest unconditionally - we can overwrite the bits we don't like
// later
let bs_bits: u32 = v.simd_eq(SLASH).to_bitmask();
let quote_bits = v.simd_eq(QUOTE).to_bitmask();
if (bs_bits.wrapping_sub(1) & quote_bits) != 0 {
// we encountered quotes first. Move dst to point to quotes and exit
// find out where the quote is...
let quote_dist: u32 = quote_bits.trailing_zeros();
///////////////////////
// Above, check for overflow in case someone has a crazy string (>=4GB?)
// But only add the overflow check when the document itself exceeds 4GB
// Currently unneeded because we refuse to parse docs larger or equal to 4GB.
////////////////////////
// we advance the point, accounting for the fact that we have a NULl termination
len += quote_dist as usize;
let v = std::str::from_utf8_unchecked(std::slice::from_raw_parts(input.add(idx), len));
return Ok(v);
// we compare the pointers since we care if they are 'at the same spot'
// not if they are the same value
}
if (quote_bits.wrapping_sub(1) & bs_bits) == 0 {
// they are the same. Since they can't co-occur, it means we encountered
// neither.
src_i += 32;
len += 32;
} else {
// Move to the 'bad' character
let bs_dist: u32 = bs_bits.trailing_zeros();
len += bs_dist as usize;
src_i += bs_dist as usize;
break;
}
}
let mut dst_i: usize = 0;
// To be more conform with upstream
loop {
let v = u8x32::from_array(*src.as_ptr().add(src_i).cast::<[u8; 32]>());
buffer
.as_mut_ptr()
.add(dst_i)
.cast::<[u8; 32]>()
.write(*v.as_array());
// store to dest unconditionally - we can overwrite the bits we don't like
// later
let bs_bits: u32 = v.simd_eq(SLASH).to_bitmask();
let quote_bits = v.simd_eq(QUOTE).to_bitmask();
if (bs_bits.wrapping_sub(1) & quote_bits) != 0 {
// we encountered quotes first. Move dst to point to quotes and exit
// find out where the quote is...
let quote_dist: u32 = quote_bits.trailing_zeros();
///////////////////////
// Above, check for overflow in case someone has a crazy string (>=4GB?)
// But only add the overflow check when the document itself exceeds 4GB
// Currently unneeded because we refuse to parse docs larger or equal to 4GB.
////////////////////////
// we advance the point, accounting for the fact that we have a NULl termination
dst_i += quote_dist as usize;
input
.add(idx + len)
.copy_from_nonoverlapping(buffer.as_ptr(), dst_i);
let v = std::str::from_utf8_unchecked(std::slice::from_raw_parts(
input.add(idx),
len + dst_i,
));
return Ok(v);
// we compare the pointers since we care if they are 'at the same spot'
// not if they are the same value
}
if (quote_bits.wrapping_sub(1) & bs_bits) == 0 {
// they are the same. Since they can't co-occur, it means we encountered
// neither.
src_i += 32;
dst_i += 32;
} else {
// find out where the backspace is
let bs_dist: u32 = bs_bits.trailing_zeros();
let escape_char: u8 = *src.get_kinda_unchecked(src_i + bs_dist as usize + 1);
// we encountered backslash first. Handle backslash
if escape_char == b'u' {
// move src/dst up to the start; they will be further adjusted
// within the unicode codepoint handling code.
src_i += bs_dist as usize;
dst_i += bs_dist as usize;
let (o, s) = handle_unicode_codepoint(
src.get_kinda_unchecked(src_i..),
buffer.get_kinda_unchecked_mut(dst_i..),
)
.map_err(|_| Deserializer::error_c(src_i, 'u', InvalidUnicodeCodepoint))?;
if o == 0 {
return Err(Deserializer::error_c(src_i, 'u', InvalidUnicodeCodepoint));
};
// We moved o steps forward at the destination and 6 on the source
src_i += s;
dst_i += o;
} else {
// simple 1:1 conversion. Will eat bs_dist+2 characters in input and
// write bs_dist+1 characters to output
// note this may reach beyond the part of the buffer we've actually
// seen. I think this is ok
let escape_result: u8 = *ESCAPE_MAP.get_kinda_unchecked(escape_char as usize);
if escape_result == 0 {
return Err(Deserializer::error_c(
src_i,
escape_char as char,
InvalidEscape,
));
}
*buffer.get_kinda_unchecked_mut(dst_i + bs_dist as usize) = escape_result;
src_i += bs_dist as usize + 2;
dst_i += bs_dist as usize + 1;
}
}
}
}