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use core::{
alloc::Layout, hint::unreachable_unchecked, ptr::dangling_mut, slice::from_raw_parts,
str::from_utf8_unchecked,
};
use std::alloc::{alloc, dealloc, realloc};
use crate::{
Parser,
config::Config,
misc::ESC_LUT,
pointer::JsonPointer,
source::{Source, Volatility},
value::{borrowed::String, builder::ErrorBuilder},
};
impl<'a, S: Source, C: Config> Parser<'a, S, C> {
/// Skips to the given path.
///
/// This will return early as soon as it reaches the specified path.
/// If the JSON is invalid or path does not exist, returns error.
///
/// # Example
/// ```
/// use flexon::Parser;
/// use serde::Deserialize;
///
/// let src = r#"{"one": 1, "two": 2}"#;
/// let mut parser = Parser::new(src);
///
/// parser.skip_to(["two"])?;
/// println!("two is {}", u32::deserialize(&mut parser)?);
///
/// # Ok::<(), flexon::serde::de::Error>(())
/// ```
pub fn skip_to<E, P>(&mut self, p: P) -> Result<(), E>
where
E: ErrorBuilder,
P: IntoIterator,
P::Item: JsonPointer,
{
self._skip_to(p)?;
self.dec_if_not_empty();
Ok(())
}
/// Skips to the given path without validation.
///
/// Same as [`Parser::skip_to`] but if the JSON is invalid or
/// the path does not exist, then there is no guarantee of this function.
pub unsafe fn skip_to_unchecked<P>(&mut self, p: P)
where
P: IntoIterator,
P::Item: JsonPointer,
{
self._skip_to_unchecked(p);
self.dec();
}
#[inline(always)]
pub(crate) fn _skip_to<E, P>(&mut self, p: P) -> Result<u8, E>
where
E: ErrorBuilder,
P: IntoIterator,
P::Item: JsonPointer,
{
let mut char = self.skip_whitespace();
'main: for pointer in p {
#[allow(unused_mut)]
let mut err = if let Some(key) = pointer.as_key()
&& char == b'{'
{
#[cfg(feature = "span")]
let start = self.idx();
char = self.skip_whitespace();
if char == b'}' {
let mut tmp = E::expected_value();
#[cfg(feature = "span")]
tmp.apply_span(start, self.idx());
return Err(tmp);
}
loop {
if char != b'"' {
break E::unexpected_token();
}
let new = unsafe { self.string2()? };
if self.skip_whitespace() != b':' {
break E::expected_colon();
}
char = self.skip_whitespace();
if &*new == key {
continue 'main;
}
match char {
b'"' => self.skip_string(),
b'{' => self.skip_object(),
b'[' => self.skip_array(),
_ => unsafe { self.skip_literal() },
}?;
char = self.skip_whitespace();
let comma = char == b',';
if comma {
char = self.skip_whitespace();
}
if char == b'}' {
if !comma || self.cfg.trailing_comma() {
let mut tmp = E::expected_value();
#[cfg(feature = "span")]
tmp.apply_span(start, self.idx());
return Err(tmp);
} else {
#[cfg(feature = "span")]
self.dec();
break E::trailing_comma();
}
}
if comma || self.cfg.comma() {
continue;
}
break match char {
0 => E::eof(),
_ => E::unexpected_token(),
};
}
} else if let Some(mut idx) = pointer.as_index()
&& char == b'['
{
#[cfg(feature = "span")]
let start = self.idx();
char = self.skip_whitespace();
if char == b']' {
let mut tmp = E::expected_value();
#[cfg(feature = "span")]
tmp.apply_span(start, self.idx());
return Err(tmp);
}
loop {
if idx == 0 {
continue 'main;
}
idx -= 1;
match char {
b'"' => self.skip_string(),
b'{' => self.skip_object(),
b'[' => self.skip_array(),
_ => unsafe { self.skip_literal() },
}?;
char = self.skip_whitespace();
let comma = char == b',';
if comma {
char = self.skip_whitespace();
}
if char == b']' {
if !comma || self.cfg.trailing_comma() {
let mut tmp = E::expected_value();
#[cfg(feature = "span")]
tmp.apply_span(start, self.idx());
return Err(tmp);
} else {
#[cfg(feature = "span")]
self.dec();
break E::trailing_comma();
}
}
if comma || self.cfg.comma() {
continue;
}
break match char {
0 => E::eof(),
_ => E::unexpected_token(),
};
}
} else {
match char {
0 => E::eof(),
_ => E::unexpected_token(),
}
};
#[cfg(feature = "span")]
err.apply_span(self.idx(), self.idx());
return Err(err);
}
Ok(char)
}
#[inline(always)]
pub(crate) unsafe fn _skip_to_unchecked<P>(&mut self, p: P) -> u8
where
P: IntoIterator,
P::Item: JsonPointer,
{
const {
assert!(
!S::Volatility::IS_VOLATILE,
"volatile source is problematic with unchecked skipping APIs, use checked ones instead"
)
}
let mut char = self.skip_whitespace();
'main: for pointer in p {
if let Some(key) = pointer.as_key() {
loop {
self.skip_whitespace(); // skip '"'
let new = self.string_unchecked2();
self.skip_whitespace(); // skip ':'
char = self.skip_whitespace();
if &*new == key {
continue 'main;
}
match char {
b'"' => self.skip_string_unchecked(),
b'{' | b'[' => self.skip_container_unchecked(),
_ => self.skip_literal_unchecked(),
}
self.skip_whitespace(); // skip ','
}
}
let Some(mut idx) = pointer.as_index() else {
unreachable_unchecked()
};
loop {
char = self.skip_whitespace();
if idx == 0 {
continue 'main;
}
idx -= 1;
match char {
b'"' => self.skip_string_unchecked(),
b'{' | b'[' => self.skip_container_unchecked(),
_ => self.skip_literal_unchecked(),
}
self.skip_whitespace(); // skip ','
}
}
char
}
unsafe fn string2<E: ErrorBuilder>(&mut self) -> Result<String<'a>, E> {
let mut offset = self.idx() + 1;
let mut buf = dangling_mut();
let mut cap = 0;
let mut len = 0;
'main: {
let err = loop {
if self.simd_str() {
continue;
}
self.inc(1);
if !S::NULL_PADDED && self.idx() >= self.src.len() {
break E::unclosed_string();
}
break match self.cur() {
b'"' => break 'main,
b'\\' => unsafe {
let count = self.idx() - offset;
let new_len = len + count + 4;
if cap < new_len {
let tmp = new_len * 5 / 4;
let layout = Layout::array::<u8>(tmp).unwrap_unchecked();
buf = if cap != 0 {
realloc(
buf,
Layout::array::<u8>(cap).unwrap_unchecked(),
layout.size(),
)
} else {
alloc(layout)
};
cap = tmp;
}
buf.add(len)
.copy_from_nonoverlapping(self.src.ptr(offset), count);
self.inc(1);
len += count;
offset = self.idx() + 1;
if !S::NULL_PADDED && self.idx() == self.src.len() {
break E::unclosed_string();
}
let tmp = self.cur();
let buf = buf.add(len);
let esc = ESC_LUT[tmp as usize];
if esc != 0 {
buf.write(esc);
len += 1;
continue;
}
if tmp == b'u'
&& let Some(v) = self.unicode_escape(&mut [0; 4])
{
buf.copy_from_nonoverlapping(v.as_ptr(), v.len());
offset = self.idx() + 1;
len += v.len();
continue;
}
E::invalid_escape()
},
0x20.. => continue,
_ => E::control_character(),
};
};
return unsafe {
if cap != 0 {
dealloc(buf, Layout::array::<u8>(cap).unwrap_unchecked())
}
Err(err)
};
}
if !S::Volatility::IS_VOLATILE && len == 0 {
return unsafe {
// utf-8 validation is unnecessary here its going to match against string slice
Ok(String::from(from_utf8_unchecked(from_raw_parts(
self.src.ptr(offset),
self.idx() - offset,
))))
};
}
let count = self.idx() - offset;
let new_len = len + count;
if cap < new_len {
buf = unsafe {
let layout = Layout::array::<u8>(new_len).unwrap_unchecked();
if !(S::Volatility::IS_VOLATILE && cap == 0) {
realloc(
buf,
Layout::array::<u8>(cap).unwrap_unchecked(),
layout.size(),
)
} else {
alloc(layout)
}
};
cap = new_len;
}
unsafe {
buf.add(len)
.copy_from_nonoverlapping(self.src.ptr(offset), count);
Ok(String::from_raw_parts(buf, new_len, cap))
}
}
/// This function is used for matching against object key when using
/// `parse_at_unchecked` and materializing lazy value.
/// Validation is not required.
pub(crate) fn string_unchecked2(&mut self) -> String<'a> {
let mut offset = self.idx() + 1;
let mut buf = dangling_mut();
let mut cap = 0;
let mut len = 0;
loop {
if self.simd_str_unchecked() {
continue;
}
self.inc(1);
match self.cur() {
b'"' => break,
b'\\' => unsafe {
let count = self.idx() - offset;
let new_len = len + count + 4;
if cap < new_len {
let tmp = new_len * 5 / 4;
let layout = Layout::array::<u8>(tmp).unwrap_unchecked();
buf = if cap != 0 {
realloc(
buf,
Layout::array::<u8>(cap).unwrap_unchecked(),
layout.size(),
)
} else {
alloc(layout)
};
cap = tmp;
}
buf.add(len)
.copy_from_nonoverlapping(self.src.ptr(offset), count);
self.inc(1);
len += count;
offset = self.idx() + 1;
let tmp = self.cur();
let buf = buf.add(len);
let esc = ESC_LUT[tmp as usize];
if esc != 0 {
buf.write(esc);
len += 1;
continue;
}
let tmp = &mut [0; 4];
let esc = self.unicode_escape(tmp).unwrap_unchecked();
buf.copy_from_nonoverlapping(esc.as_ptr(), esc.len());
offset = self.idx() + 1;
len += esc.len();
continue;
},
_ => continue,
};
}
if !S::Volatility::IS_VOLATILE && len == 0 {
return unsafe {
String::from(from_utf8_unchecked(from_raw_parts(
self.src.ptr(offset),
self.idx() - offset,
)))
};
}
unsafe {
let count = self.idx() - offset;
let new_len = len + count;
if cap < new_len {
let layout = Layout::array::<u8>(new_len).unwrap_unchecked();
buf = if !(S::Volatility::IS_VOLATILE && cap == 0) {
realloc(
buf,
Layout::array::<u8>(cap).unwrap_unchecked(),
layout.size(),
)
} else {
alloc(layout)
};
cap = new_len;
}
buf.add(len)
.copy_from_nonoverlapping(self.src.ptr(offset), count);
String::from_raw_parts(buf, new_len, cap)
}
}
}