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Diffstat (limited to 'third_party/rust/ron/src/parse.rs')
| -rw-r--r-- | third_party/rust/ron/src/parse.rs | 978 |
1 files changed, 978 insertions, 0 deletions
diff --git a/third_party/rust/ron/src/parse.rs b/third_party/rust/ron/src/parse.rs new file mode 100644 index 0000000000..b0cc632f30 --- /dev/null +++ b/third_party/rust/ron/src/parse.rs @@ -0,0 +1,978 @@ +#![allow(clippy::identity_op)] + +use std::{ + char::from_u32 as char_from_u32, + str::{from_utf8, from_utf8_unchecked, FromStr}, +}; + +use crate::{ + error::{Error, Position, Result, SpannedError, SpannedResult}, + extensions::Extensions, +}; + +// We have the following char categories. +const INT_CHAR: u8 = 1 << 0; // [0-9A-Fa-f_] +const FLOAT_CHAR: u8 = 1 << 1; // [0-9\.Ee+-_] +const IDENT_FIRST_CHAR: u8 = 1 << 2; // [A-Za-z_] +const IDENT_OTHER_CHAR: u8 = 1 << 3; // [A-Za-z_0-9] +const IDENT_RAW_CHAR: u8 = 1 << 4; // [A-Za-z_0-9\.+-] +const WHITESPACE_CHAR: u8 = 1 << 5; // [\n\t\r ] + +// We encode each char as belonging to some number of these categories. +const DIGIT: u8 = INT_CHAR | FLOAT_CHAR | IDENT_OTHER_CHAR | IDENT_RAW_CHAR; // [0-9] +const ABCDF: u8 = INT_CHAR | IDENT_FIRST_CHAR | IDENT_OTHER_CHAR | IDENT_RAW_CHAR; // [ABCDFabcdf] +const UNDER: u8 = INT_CHAR | FLOAT_CHAR | IDENT_FIRST_CHAR | IDENT_OTHER_CHAR | IDENT_RAW_CHAR; // [_] +const E____: u8 = INT_CHAR | FLOAT_CHAR | IDENT_FIRST_CHAR | IDENT_OTHER_CHAR | IDENT_RAW_CHAR; // [Ee] +const G2Z__: u8 = IDENT_FIRST_CHAR | IDENT_OTHER_CHAR | IDENT_RAW_CHAR; // [G-Zg-z] +const PUNCT: u8 = FLOAT_CHAR | IDENT_RAW_CHAR; // [\.+-] +const WS___: u8 = WHITESPACE_CHAR; // [\t\n\r ] +const _____: u8 = 0; // everything else + +// Table of encodings, for fast predicates. (Non-ASCII and special chars are +// shown with '·' in the comment.) +#[rustfmt::skip] +const ENCODINGS: [u8; 256] = [ +/* 0 1 2 3 4 5 6 7 8 9 */ +/* 0+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, WS___, +/* 10+: ·········· */ WS___, _____, _____, WS___, _____, _____, _____, _____, _____, _____, +/* 20+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 30+: ·· !"#$%&' */ _____, _____, WS___, _____, _____, _____, _____, _____, _____, _____, +/* 40+: ()*+,-./01 */ _____, _____, _____, PUNCT, _____, PUNCT, PUNCT, _____, DIGIT, DIGIT, +/* 50+: 23456789:; */ DIGIT, DIGIT, DIGIT, DIGIT, DIGIT, DIGIT, DIGIT, DIGIT, _____, _____, +/* 60+: <=>?@ABCDE */ _____, _____, _____, _____, _____, ABCDF, ABCDF, ABCDF, ABCDF, E____, +/* 70+: FGHIJKLMNO */ ABCDF, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, +/* 80+: PQRSTUVWZY */ G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, +/* 90+: Z[\]^_`abc */ G2Z__, _____, _____, _____, _____, UNDER, _____, ABCDF, ABCDF, ABCDF, +/* 100+: defghijklm */ ABCDF, E____, ABCDF, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, +/* 110+: nopqrstuvw */ G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, G2Z__, +/* 120+: xyz{|}~··· */ G2Z__, G2Z__, G2Z__, _____, _____, _____, _____, _____, _____, _____, +/* 130+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 140+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 150+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 160+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 170+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 180+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 190+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 200+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 210+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 220+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 230+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 240+: ·········· */ _____, _____, _____, _____, _____, _____, _____, _____, _____, _____, +/* 250+: ·········· */ _____, _____, _____, _____, _____, _____ +]; + +const fn is_int_char(c: u8) -> bool { + ENCODINGS[c as usize] & INT_CHAR != 0 +} + +const fn is_float_char(c: u8) -> bool { + ENCODINGS[c as usize] & FLOAT_CHAR != 0 +} + +pub const fn is_ident_first_char(c: u8) -> bool { + ENCODINGS[c as usize] & IDENT_FIRST_CHAR != 0 +} + +pub const fn is_ident_other_char(c: u8) -> bool { + ENCODINGS[c as usize] & IDENT_OTHER_CHAR != 0 +} + +const fn is_ident_raw_char(c: u8) -> bool { + ENCODINGS[c as usize] & IDENT_RAW_CHAR != 0 +} + +const fn is_whitespace_char(c: u8) -> bool { + ENCODINGS[c as usize] & WHITESPACE_CHAR != 0 +} + +#[derive(Clone, Debug, PartialEq)] +pub enum AnyNum { + F32(f32), + F64(f64), + I8(i8), + U8(u8), + I16(i16), + U16(u16), + I32(i32), + U32(u32), + I64(i64), + U64(u64), + #[cfg(feature = "integer128")] + I128(i128), + #[cfg(feature = "integer128")] + U128(u128), +} + +#[derive(Clone, Copy, Debug)] +pub struct Bytes<'a> { + /// Bits set according to the `Extensions` enum. + pub exts: Extensions, + bytes: &'a [u8], + cursor: Position, +} + +#[cfg(feature = "integer128")] +pub(crate) type LargeUInt = u128; +#[cfg(not(feature = "integer128"))] +pub(crate) type LargeUInt = u64; +#[cfg(feature = "integer128")] +pub(crate) type LargeSInt = i128; +#[cfg(not(feature = "integer128"))] +pub(crate) type LargeSInt = i64; + +impl<'a> Bytes<'a> { + pub fn new(bytes: &'a [u8]) -> SpannedResult<Self> { + let mut b = Bytes { + exts: Extensions::empty(), + bytes, + cursor: Position { line: 1, col: 1 }, + }; + + b.skip_ws().map_err(|e| b.span_error(e))?; + + // Loop over all extensions attributes + loop { + let attribute = b.extensions().map_err(|e| b.span_error(e))?; + + if attribute.is_empty() { + break; + } + + b.exts |= attribute; + b.skip_ws().map_err(|e| b.span_error(e))?; + } + + Ok(b) + } + + pub fn span_error(&self, code: Error) -> SpannedError { + SpannedError { + code, + position: self.cursor, + } + } + + pub fn advance(&mut self, bytes: usize) -> Result<()> { + for _ in 0..bytes { + self.advance_single()?; + } + + Ok(()) + } + + pub fn advance_single(&mut self) -> Result<()> { + if self.peek_or_eof()? == b'\n' { + self.cursor.line += 1; + self.cursor.col = 1; + } else { + self.cursor.col += 1; + } + + self.bytes = &self.bytes[1..]; + + Ok(()) + } + + fn any_integer<T: Num>(&mut self, sign: i8) -> Result<T> { + let base = if self.peek() == Some(b'0') { + match self.bytes.get(1).cloned() { + Some(b'x') => 16, + Some(b'b') => 2, + Some(b'o') => 8, + _ => 10, + } + } else { + 10 + }; + + if base != 10 { + // If we have `0x45A` for example, + // cut it to `45A`. + let _ = self.advance(2); + } + + let num_bytes = self.next_bytes_contained_in(is_int_char); + + if num_bytes == 0 { + return Err(Error::ExpectedInteger); + } + + let s = unsafe { from_utf8_unchecked(&self.bytes[0..num_bytes]) }; + + if s.as_bytes()[0] == b'_' { + return Err(Error::UnderscoreAtBeginning); + } + + fn calc_num<T: Num>( + bytes: &Bytes, + s: &str, + base: u8, + mut f: impl FnMut(&mut T, u8) -> bool, + ) -> Result<T> { + let mut num_acc = T::from_u8(0); + + for &byte in s.as_bytes() { + if byte == b'_' { + continue; + } + + if num_acc.checked_mul_ext(base) { + return Err(Error::IntegerOutOfBounds); + } + + let digit = bytes.decode_hex(byte)?; + + if digit >= base { + return Err(Error::ExpectedInteger); + } + + if f(&mut num_acc, digit) { + return Err(Error::IntegerOutOfBounds); + } + } + + Ok(num_acc) + } + + let res = if sign > 0 { + calc_num(self, s, base, T::checked_add_ext) + } else { + calc_num(self, s, base, T::checked_sub_ext) + }; + + let _ = self.advance(num_bytes); + + res + } + + pub fn any_num(&mut self) -> Result<AnyNum> { + // We are not doing float comparisons here in the traditional sense. + // Instead, this code checks if a f64 fits inside an f32. + #[allow(clippy::float_cmp)] + fn any_float(f: f64) -> Result<AnyNum> { + if f == f64::from(f as f32) { + Ok(AnyNum::F32(f as f32)) + } else { + Ok(AnyNum::F64(f)) + } + } + + let bytes_backup = self.bytes; + + let first_byte = self.peek_or_eof()?; + let is_signed = first_byte == b'-' || first_byte == b'+'; + let is_float = self.next_bytes_is_float(); + + if is_float { + let f = self.float::<f64>()?; + + any_float(f) + } else { + let max_u8 = LargeUInt::from(std::u8::MAX); + let max_u16 = LargeUInt::from(std::u16::MAX); + let max_u32 = LargeUInt::from(std::u32::MAX); + #[cfg_attr(not(feature = "integer128"), allow(clippy::useless_conversion))] + let max_u64 = LargeUInt::from(std::u64::MAX); + + let min_i8 = LargeSInt::from(std::i8::MIN); + let max_i8 = LargeSInt::from(std::i8::MAX); + let min_i16 = LargeSInt::from(std::i16::MIN); + let max_i16 = LargeSInt::from(std::i16::MAX); + let min_i32 = LargeSInt::from(std::i32::MIN); + let max_i32 = LargeSInt::from(std::i32::MAX); + #[cfg_attr(not(feature = "integer128"), allow(clippy::useless_conversion))] + let min_i64 = LargeSInt::from(std::i64::MIN); + #[cfg_attr(not(feature = "integer128"), allow(clippy::useless_conversion))] + let max_i64 = LargeSInt::from(std::i64::MAX); + + if is_signed { + match self.signed_integer::<LargeSInt>() { + Ok(x) => { + if x >= min_i8 && x <= max_i8 { + Ok(AnyNum::I8(x as i8)) + } else if x >= min_i16 && x <= max_i16 { + Ok(AnyNum::I16(x as i16)) + } else if x >= min_i32 && x <= max_i32 { + Ok(AnyNum::I32(x as i32)) + } else if x >= min_i64 && x <= max_i64 { + Ok(AnyNum::I64(x as i64)) + } else { + #[cfg(feature = "integer128")] + { + Ok(AnyNum::I128(x)) + } + #[cfg(not(feature = "integer128"))] + { + Ok(AnyNum::I64(x)) + } + } + } + Err(_) => { + self.bytes = bytes_backup; + + any_float(self.float::<f64>()?) + } + } + } else { + match self.unsigned_integer::<LargeUInt>() { + Ok(x) => { + if x <= max_u8 { + Ok(AnyNum::U8(x as u8)) + } else if x <= max_u16 { + Ok(AnyNum::U16(x as u16)) + } else if x <= max_u32 { + Ok(AnyNum::U32(x as u32)) + } else if x <= max_u64 { + Ok(AnyNum::U64(x as u64)) + } else { + #[cfg(feature = "integer128")] + { + Ok(AnyNum::U128(x)) + } + #[cfg(not(feature = "integer128"))] + { + Ok(AnyNum::U64(x)) + } + } + } + Err(_) => { + self.bytes = bytes_backup; + + any_float(self.float::<f64>()?) + } + } + } + } + } + + pub fn bool(&mut self) -> Result<bool> { + if self.consume("true") { + Ok(true) + } else if self.consume("false") { + Ok(false) + } else { + Err(Error::ExpectedBoolean) + } + } + + pub fn bytes(&self) -> &[u8] { + self.bytes + } + + pub fn char(&mut self) -> Result<char> { + if !self.consume("'") { + return Err(Error::ExpectedChar); + } + + let c = self.peek_or_eof()?; + + let c = if c == b'\\' { + let _ = self.advance(1); + + self.parse_escape()? + } else { + // Check where the end of the char (') is and try to + // interpret the rest as UTF-8 + + let max = self.bytes.len().min(5); + let pos: usize = self.bytes[..max] + .iter() + .position(|&x| x == b'\'') + .ok_or(Error::ExpectedChar)?; + let s = from_utf8(&self.bytes[0..pos]).map_err(Error::from)?; + let mut chars = s.chars(); + + let first = chars.next().ok_or(Error::ExpectedChar)?; + if chars.next().is_some() { + return Err(Error::ExpectedChar); + } + + let _ = self.advance(pos); + + first + }; + + if !self.consume("'") { + return Err(Error::ExpectedChar); + } + + Ok(c) + } + + pub fn comma(&mut self) -> Result<bool> { + self.skip_ws()?; + + if self.consume(",") { + self.skip_ws()?; + + Ok(true) + } else { + Ok(false) + } + } + + /// Only returns true if the char after `ident` cannot belong + /// to an identifier. + pub fn check_ident(&mut self, ident: &str) -> bool { + self.test_for(ident) && !self.check_ident_other_char(ident.len()) + } + + fn check_ident_other_char(&self, index: usize) -> bool { + self.bytes + .get(index) + .map_or(false, |&b| is_ident_other_char(b)) + } + + /// Should only be used on a working copy + pub fn check_tuple_struct(mut self) -> Result<bool> { + if self.identifier().is_err() { + // if there's no field ident, this is a tuple struct + return Ok(true); + } + + self.skip_ws()?; + + // if there is no colon after the ident, this can only be a unit struct + self.eat_byte().map(|c| c != b':') + } + + /// Only returns true if the char after `ident` cannot belong + /// to an identifier. + pub fn consume_ident(&mut self, ident: &str) -> bool { + if self.check_ident(ident) { + let _ = self.advance(ident.len()); + + true + } else { + false + } + } + + pub fn consume_struct_name(&mut self, ident: &'static str) -> Result<bool> { + if self.check_ident("") { + Ok(false) + } else if ident.is_empty() { + Err(Error::ExpectedStructLike) + } else if self.check_ident(ident) { + let _ = self.advance(ident.len()); + + Ok(true) + } else { + // If the following is not even an identifier, then a missing + // opening `(` seems more likely + let maybe_ident = self + .identifier() + .map_err(|_| Error::ExpectedNamedStructLike(ident))?; + + let found = std::str::from_utf8(maybe_ident).map_err(Error::from)?; + + Err(Error::ExpectedDifferentStructName { + expected: ident, + found: String::from(found), + }) + } + } + + pub fn consume(&mut self, s: &str) -> bool { + if self.test_for(s) { + let _ = self.advance(s.len()); + + true + } else { + false + } + } + + fn consume_all(&mut self, all: &[&str]) -> Result<bool> { + all.iter() + .map(|elem| { + if self.consume(elem) { + self.skip_ws()?; + + Ok(true) + } else { + Ok(false) + } + }) + .fold(Ok(true), |acc, x| acc.and_then(|val| x.map(|x| x && val))) + } + + pub fn eat_byte(&mut self) -> Result<u8> { + let peek = self.peek_or_eof()?; + let _ = self.advance_single(); + + Ok(peek) + } + + pub fn expect_byte(&mut self, byte: u8, error: Error) -> Result<()> { + self.eat_byte() + .and_then(|b| if b == byte { Ok(()) } else { Err(error) }) + } + + /// Returns the extensions bit mask. + fn extensions(&mut self) -> Result<Extensions> { + if self.peek() != Some(b'#') { + return Ok(Extensions::empty()); + } + + if !self.consume_all(&["#", "!", "[", "enable", "("])? { + return Err(Error::ExpectedAttribute); + } + + self.skip_ws()?; + let mut extensions = Extensions::empty(); + + loop { + let ident = self.identifier()?; + let extension = Extensions::from_ident(ident).ok_or_else(|| { + Error::NoSuchExtension(String::from_utf8_lossy(ident).into_owned()) + })?; + + extensions |= extension; + + let comma = self.comma()?; + + // If we have no comma but another item, return an error + if !comma && self.check_ident_other_char(0) { + return Err(Error::ExpectedComma); + } + + // If there's no comma, assume the list ended. + // If there is, it might be a trailing one, thus we only + // continue the loop if we get an ident char. + if !comma || !self.check_ident_other_char(0) { + break; + } + } + + self.skip_ws()?; + + if self.consume_all(&[")", "]"])? { + Ok(extensions) + } else { + Err(Error::ExpectedAttributeEnd) + } + } + + pub fn float<T>(&mut self) -> Result<T> + where + T: FromStr, + { + for literal in &["inf", "+inf", "-inf", "NaN", "+NaN", "-NaN"] { + if self.consume_ident(literal) { + return FromStr::from_str(literal).map_err(|_| unreachable!()); // must not fail + } + } + + let num_bytes = self.next_bytes_contained_in(is_float_char); + + // Since `rustc` allows `1_0.0_1`, lint against underscores in floats + if let Some(err_bytes) = self.bytes[0..num_bytes].iter().position(|b| *b == b'_') { + let _ = self.advance(err_bytes); + + return Err(Error::FloatUnderscore); + } + + let s = unsafe { from_utf8_unchecked(&self.bytes[0..num_bytes]) }; + let res = FromStr::from_str(s).map_err(|_| Error::ExpectedFloat); + + let _ = self.advance(num_bytes); + + res + } + + pub fn identifier(&mut self) -> Result<&'a [u8]> { + let next = self.peek_or_eof()?; + if !is_ident_first_char(next) { + return Err(Error::ExpectedIdentifier); + } + + // If the next two bytes signify the start of a raw string literal, + // return an error. + let length = if next == b'r' { + match self.bytes.get(1).ok_or(Error::Eof)? { + b'"' => return Err(Error::ExpectedIdentifier), + b'#' => { + let after_next = self.bytes.get(2).cloned().unwrap_or_default(); + // Note: it's important to check this before advancing forward, so that + // the value-type deserializer can fall back to parsing it differently. + if !is_ident_raw_char(after_next) { + return Err(Error::ExpectedIdentifier); + } + // skip "r#" + let _ = self.advance(2); + self.next_bytes_contained_in(is_ident_raw_char) + } + _ => self.next_bytes_contained_in(is_ident_other_char), + } + } else { + self.next_bytes_contained_in(is_ident_other_char) + }; + + let ident = &self.bytes[..length]; + let _ = self.advance(length); + + Ok(ident) + } + + pub fn next_bytes_contained_in(&self, allowed: fn(u8) -> bool) -> usize { + self.bytes.iter().take_while(|&&b| allowed(b)).count() + } + + pub fn next_bytes_is_float(&self) -> bool { + if let Some(byte) = self.peek() { + let skip = match byte { + b'+' | b'-' => 1, + _ => 0, + }; + let flen = self + .bytes + .iter() + .skip(skip) + .take_while(|&&b| is_float_char(b)) + .count(); + let ilen = self + .bytes + .iter() + .skip(skip) + .take_while(|&&b| is_int_char(b)) + .count(); + flen > ilen + } else { + false + } + } + + pub fn skip_ws(&mut self) -> Result<()> { + loop { + while self.peek().map_or(false, is_whitespace_char) { + let _ = self.advance_single(); + } + + if !self.skip_comment()? { + return Ok(()); + } + } + } + + pub fn peek(&self) -> Option<u8> { + self.bytes.first().cloned() + } + + pub fn peek_or_eof(&self) -> Result<u8> { + self.bytes.first().cloned().ok_or(Error::Eof) + } + + pub fn signed_integer<T>(&mut self) -> Result<T> + where + T: Num, + { + match self.peek_or_eof()? { + b'+' => { + let _ = self.advance_single(); + + self.any_integer(1) + } + b'-' => { + let _ = self.advance_single(); + + self.any_integer(-1) + } + _ => self.any_integer(1), + } + } + + pub fn string(&mut self) -> Result<ParsedStr<'a>> { + if self.consume("\"") { + self.escaped_string() + } else if self.consume("r") { + self.raw_string() + } else { + Err(Error::ExpectedString) + } + } + + fn escaped_string(&mut self) -> Result<ParsedStr<'a>> { + use std::iter::repeat; + + let (i, end_or_escape) = self + .bytes + .iter() + .enumerate() + .find(|&(_, &b)| b == b'\\' || b == b'"') + .ok_or(Error::ExpectedStringEnd)?; + + if *end_or_escape == b'"' { + let s = from_utf8(&self.bytes[..i]).map_err(Error::from)?; + + // Advance by the number of bytes of the string + // + 1 for the `"`. + let _ = self.advance(i + 1); + + Ok(ParsedStr::Slice(s)) + } else { + let mut i = i; + let mut s: Vec<_> = self.bytes[..i].to_vec(); + + loop { + let _ = self.advance(i + 1); + let character = self.parse_escape()?; + match character.len_utf8() { + 1 => s.push(character as u8), + len => { + let start = s.len(); + s.extend(repeat(0).take(len)); + character.encode_utf8(&mut s[start..]); + } + } + + let (new_i, end_or_escape) = self + .bytes + .iter() + .enumerate() + .find(|&(_, &b)| b == b'\\' || b == b'"') + .ok_or(Error::ExpectedStringEnd)?; + + i = new_i; + s.extend_from_slice(&self.bytes[..i]); + + if *end_or_escape == b'"' { + let _ = self.advance(i + 1); + + let s = String::from_utf8(s).map_err(Error::from)?; + break Ok(ParsedStr::Allocated(s)); + } + } + } + } + + fn raw_string(&mut self) -> Result<ParsedStr<'a>> { + let num_hashes = self.bytes.iter().take_while(|&&b| b == b'#').count(); + let hashes = &self.bytes[..num_hashes]; + let _ = self.advance(num_hashes); + + if !self.consume("\"") { + return Err(Error::ExpectedString); + } + + let ending = [&[b'"'], hashes].concat(); + let i = self + .bytes + .windows(num_hashes + 1) + .position(|window| window == ending.as_slice()) + .ok_or(Error::ExpectedStringEnd)?; + + let s = from_utf8(&self.bytes[..i]).map_err(Error::from)?; + + // Advance by the number of bytes of the string + // + `num_hashes` + 1 for the `"`. + let _ = self.advance(i + num_hashes + 1); + + Ok(ParsedStr::Slice(s)) + } + + fn test_for(&self, s: &str) -> bool { + s.bytes() + .enumerate() + .all(|(i, b)| self.bytes.get(i).map_or(false, |t| *t == b)) + } + + pub fn unsigned_integer<T: Num>(&mut self) -> Result<T> { + self.any_integer(1) + } + + fn decode_ascii_escape(&mut self) -> Result<u8> { + let mut n = 0; + for _ in 0..2 { + n <<= 4; + let byte = self.eat_byte()?; + let decoded = self.decode_hex(byte)?; + n |= decoded; + } + + Ok(n) + } + + #[inline] + fn decode_hex(&self, c: u8) -> Result<u8> { + match c { + c @ b'0'..=b'9' => Ok(c - b'0'), + c @ b'a'..=b'f' => Ok(10 + c - b'a'), + c @ b'A'..=b'F' => Ok(10 + c - b'A'), + _ => Err(Error::InvalidEscape("Non-hex digit found")), + } + } + + fn parse_escape(&mut self) -> Result<char> { + let c = match self.eat_byte()? { + b'\'' => '\'', + b'"' => '"', + b'\\' => '\\', + b'n' => '\n', + b'r' => '\r', + b't' => '\t', + b'0' => '\0', + b'x' => self.decode_ascii_escape()? as char, + b'u' => { + self.expect_byte(b'{', Error::InvalidEscape("Missing { in Unicode escape"))?; + + let mut bytes: u32 = 0; + let mut num_digits = 0; + + while num_digits < 6 { + let byte = self.peek_or_eof()?; + + if byte == b'}' { + break; + } else { + self.advance_single()?; + } + + let byte = self.decode_hex(byte)?; + bytes <<= 4; + bytes |= u32::from(byte); + + num_digits += 1; + } + + if num_digits == 0 { + return Err(Error::InvalidEscape( + "Expected 1-6 digits, got 0 digits in Unicode escape", + )); + } + + self.expect_byte( + b'}', + Error::InvalidEscape("No } at the end of Unicode escape"), + )?; + char_from_u32(bytes).ok_or(Error::InvalidEscape("Not a valid char"))? + } + _ => { + return Err(Error::InvalidEscape("Unknown escape character")); + } + }; + + Ok(c) + } + + fn skip_comment(&mut self) -> Result<bool> { + if self.consume("/") { + match self.eat_byte()? { + b'/' => { + let bytes = self.bytes.iter().take_while(|&&b| b != b'\n').count(); + + let _ = self.advance(bytes); + } + b'*' => { + let mut level = 1; + + while level > 0 { + let bytes = self + .bytes + .iter() + .take_while(|&&b| b != b'/' && b != b'*') + .count(); + + if self.bytes.is_empty() { + return Err(Error::UnclosedBlockComment); + } + + let _ = self.advance(bytes); + + // check whether / or * and take action + if self.consume("/*") { + level += 1; + } else if self.consume("*/") { + level -= 1; + } else { + self.eat_byte().map_err(|_| Error::UnclosedBlockComment)?; + } + } + } + b => return Err(Error::UnexpectedByte(b as char)), + } + + Ok(true) + } else { + Ok(false) + } + } +} + +pub trait Num { + fn from_u8(x: u8) -> Self; + + /// Returns `true` on overflow + fn checked_mul_ext(&mut self, x: u8) -> bool; + + /// Returns `true` on overflow + fn checked_add_ext(&mut self, x: u8) -> bool; + + /// Returns `true` on overflow + fn checked_sub_ext(&mut self, x: u8) -> bool; +} + +macro_rules! impl_num { + ($ty:ident) => { + impl Num for $ty { + fn from_u8(x: u8) -> Self { + x as $ty + } + + fn checked_mul_ext(&mut self, x: u8) -> bool { + match self.checked_mul(Self::from_u8(x)) { + Some(n) => { + *self = n; + false + } + None => true, + } + } + + fn checked_add_ext(&mut self, x: u8) -> bool { + match self.checked_add(Self::from_u8(x)) { + Some(n) => { + *self = n; + false + } + None => true, + } + } + + fn checked_sub_ext(&mut self, x: u8) -> bool { + match self.checked_sub(Self::from_u8(x)) { + Some(n) => { + *self = n; + false + } + None => true, + } + } + } + }; + ($($tys:ident)*) => { + $( impl_num!($tys); )* + }; +} + +#[cfg(feature = "integer128")] +impl_num!(u8 u16 u32 u64 u128 i8 i16 i32 i64 i128); +#[cfg(not(feature = "integer128"))] +impl_num!(u8 u16 u32 u64 i8 i16 i32 i64); + +#[derive(Clone, Debug)] +pub enum ParsedStr<'a> { + Allocated(String), + Slice(&'a str), +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn decode_x10() { + let mut bytes = Bytes::new(b"10").unwrap(); + assert_eq!(bytes.decode_ascii_escape(), Ok(0x10)); + } +} |