diff options
Diffstat (limited to 'third_party/rust/naga/src/front/wgsl/number.rs')
| -rw-r--r-- | third_party/rust/naga/src/front/wgsl/number.rs | 442 |
1 files changed, 442 insertions, 0 deletions
diff --git a/third_party/rust/naga/src/front/wgsl/number.rs b/third_party/rust/naga/src/front/wgsl/number.rs new file mode 100644 index 0000000000..fafe1d2270 --- /dev/null +++ b/third_party/rust/naga/src/front/wgsl/number.rs @@ -0,0 +1,442 @@ +use std::borrow::Cow; + +use super::{NumberError, Token}; + +/// When using this type assume no Abstract Int/Float for now +#[derive(Copy, Clone, Debug, PartialEq)] +pub enum Number { + /// Abstract Int (-2^63 ≤ i < 2^63) + AbstractInt(i64), + /// Abstract Float (IEEE-754 binary64) + AbstractFloat(f64), + /// Concrete i32 + I32(i32), + /// Concrete u32 + U32(u32), + /// Concrete f32 + F32(f32), +} + +impl Number { + /// Convert abstract numbers to a plausible concrete counterpart. + /// + /// Return concrete numbers unchanged. If the conversion would be + /// lossy, return an error. + fn abstract_to_concrete(self) -> Result<Number, NumberError> { + match self { + Number::AbstractInt(num) => i32::try_from(num) + .map(Number::I32) + .map_err(|_| NumberError::NotRepresentable), + Number::AbstractFloat(num) => { + let num = num as f32; + if num.is_finite() { + Ok(Number::F32(num)) + } else { + Err(NumberError::NotRepresentable) + } + } + num => Ok(num), + } + } +} + +// TODO: when implementing Creation-Time Expressions, remove the ability to match the minus sign + +pub(super) fn consume_number(input: &str) -> (Token<'_>, &str) { + let (result, rest) = parse(input); + ( + Token::Number(result.and_then(Number::abstract_to_concrete)), + rest, + ) +} + +enum Kind { + Int(IntKind), + Float(FloatKind), +} + +enum IntKind { + I32, + U32, +} + +enum FloatKind { + F32, + F16, +} + +// The following regexes (from the WGSL spec) will be matched: + +// int_literal: +// | / 0 [iu]? / +// | / [1-9][0-9]* [iu]? / +// | / 0[xX][0-9a-fA-F]+ [iu]? / + +// decimal_float_literal: +// | / 0 [fh] / +// | / [1-9][0-9]* [fh] / +// | / [0-9]* \.[0-9]+ ([eE][+-]?[0-9]+)? [fh]? / +// | / [0-9]+ \.[0-9]* ([eE][+-]?[0-9]+)? [fh]? / +// | / [0-9]+ [eE][+-]?[0-9]+ [fh]? / + +// hex_float_literal: +// | / 0[xX][0-9a-fA-F]* \.[0-9a-fA-F]+ ([pP][+-]?[0-9]+ [fh]?)? / +// | / 0[xX][0-9a-fA-F]+ \.[0-9a-fA-F]* ([pP][+-]?[0-9]+ [fh]?)? / +// | / 0[xX][0-9a-fA-F]+ [pP][+-]?[0-9]+ [fh]? / + +// You could visualize the regex below via https://debuggex.com to get a rough idea what `parse` is doing +// -?(?:0[xX](?:([0-9a-fA-F]+\.[0-9a-fA-F]*|[0-9a-fA-F]*\.[0-9a-fA-F]+)(?:([pP][+-]?[0-9]+)([fh]?))?|([0-9a-fA-F]+)([pP][+-]?[0-9]+)([fh]?)|([0-9a-fA-F]+)([iu]?))|((?:[0-9]+[eE][+-]?[0-9]+|(?:[0-9]+\.[0-9]*|[0-9]*\.[0-9]+)(?:[eE][+-]?[0-9]+)?))([fh]?)|((?:[0-9]|[1-9][0-9]+))([iufh]?)) + +fn parse(input: &str) -> (Result<Number, NumberError>, &str) { + /// returns `true` and consumes `X` bytes from the given byte buffer + /// if the given `X` nr of patterns are found at the start of the buffer + macro_rules! consume { + ($bytes:ident, $($pattern:pat),*) => { + match $bytes { + &[$($pattern),*, ref rest @ ..] => { $bytes = rest; true }, + _ => false, + } + }; + } + + /// consumes one byte from the given byte buffer + /// if one of the given patterns are found at the start of the buffer + /// returning the corresponding expr for the matched pattern + macro_rules! consume_map { + ($bytes:ident, [$($pattern:pat_param => $to:expr),*]) => { + match $bytes { + $( &[$pattern, ref rest @ ..] => { $bytes = rest; Some($to) }, )* + _ => None, + } + }; + } + + /// consumes all consecutive bytes matched by the `0-9` pattern from the given byte buffer + /// returning the number of consumed bytes + macro_rules! consume_dec_digits { + ($bytes:ident) => {{ + let start_len = $bytes.len(); + while let &[b'0'..=b'9', ref rest @ ..] = $bytes { + $bytes = rest; + } + start_len - $bytes.len() + }}; + } + + /// consumes all consecutive bytes matched by the `0-9 | a-f | A-F` pattern from the given byte buffer + /// returning the number of consumed bytes + macro_rules! consume_hex_digits { + ($bytes:ident) => {{ + let start_len = $bytes.len(); + while let &[b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F', ref rest @ ..] = $bytes { + $bytes = rest; + } + start_len - $bytes.len() + }}; + } + + /// maps the given `&[u8]` (tail of the initial `input: &str`) to a `&str` + macro_rules! rest_to_str { + ($bytes:ident) => { + &input[input.len() - $bytes.len()..] + }; + } + + struct ExtractSubStr<'a>(&'a str); + + impl<'a> ExtractSubStr<'a> { + /// given an `input` and a `start` (tail of the `input`) + /// creates a new [ExtractSubStr] + fn start(input: &'a str, start: &'a [u8]) -> Self { + let start = input.len() - start.len(); + Self(&input[start..]) + } + /// given an `end` (tail of the initial `input`) + /// returns a substring of `input` + fn end(&self, end: &'a [u8]) -> &'a str { + let end = self.0.len() - end.len(); + &self.0[..end] + } + } + + let mut bytes = input.as_bytes(); + + let general_extract = ExtractSubStr::start(input, bytes); + + let is_negative = consume!(bytes, b'-'); + + if consume!(bytes, b'0', b'x' | b'X') { + let digits_extract = ExtractSubStr::start(input, bytes); + + let consumed = consume_hex_digits!(bytes); + + if consume!(bytes, b'.') { + let consumed_after_period = consume_hex_digits!(bytes); + + if consumed + consumed_after_period == 0 { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + + let significand = general_extract.end(bytes); + + if consume!(bytes, b'p' | b'P') { + consume!(bytes, b'+' | b'-'); + let consumed = consume_dec_digits!(bytes); + + if consumed == 0 { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + + let number = general_extract.end(bytes); + + let kind = consume_map!(bytes, [b'f' => FloatKind::F32, b'h' => FloatKind::F16]); + + (parse_hex_float(number, kind), rest_to_str!(bytes)) + } else { + ( + parse_hex_float_missing_exponent(significand, None), + rest_to_str!(bytes), + ) + } + } else { + if consumed == 0 { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + + let significand = general_extract.end(bytes); + let digits = digits_extract.end(bytes); + + let exp_extract = ExtractSubStr::start(input, bytes); + + if consume!(bytes, b'p' | b'P') { + consume!(bytes, b'+' | b'-'); + let consumed = consume_dec_digits!(bytes); + + if consumed == 0 { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + + let exponent = exp_extract.end(bytes); + + let kind = consume_map!(bytes, [b'f' => FloatKind::F32, b'h' => FloatKind::F16]); + + ( + parse_hex_float_missing_period(significand, exponent, kind), + rest_to_str!(bytes), + ) + } else { + let kind = consume_map!(bytes, [b'i' => IntKind::I32, b'u' => IntKind::U32]); + + ( + parse_hex_int(is_negative, digits, kind), + rest_to_str!(bytes), + ) + } + } + } else { + let is_first_zero = bytes.first() == Some(&b'0'); + + let consumed = consume_dec_digits!(bytes); + + if consume!(bytes, b'.') { + let consumed_after_period = consume_dec_digits!(bytes); + + if consumed + consumed_after_period == 0 { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + + if consume!(bytes, b'e' | b'E') { + consume!(bytes, b'+' | b'-'); + let consumed = consume_dec_digits!(bytes); + + if consumed == 0 { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + } + + let number = general_extract.end(bytes); + + let kind = consume_map!(bytes, [b'f' => FloatKind::F32, b'h' => FloatKind::F16]); + + (parse_dec_float(number, kind), rest_to_str!(bytes)) + } else { + if consumed == 0 { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + + if consume!(bytes, b'e' | b'E') { + consume!(bytes, b'+' | b'-'); + let consumed = consume_dec_digits!(bytes); + + if consumed == 0 { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + + let number = general_extract.end(bytes); + + let kind = consume_map!(bytes, [b'f' => FloatKind::F32, b'h' => FloatKind::F16]); + + (parse_dec_float(number, kind), rest_to_str!(bytes)) + } else { + // make sure the multi-digit numbers don't start with zero + if consumed > 1 && is_first_zero { + return (Err(NumberError::Invalid), rest_to_str!(bytes)); + } + + let digits_with_sign = general_extract.end(bytes); + + let kind = consume_map!(bytes, [ + b'i' => Kind::Int(IntKind::I32), + b'u' => Kind::Int(IntKind::U32), + b'f' => Kind::Float(FloatKind::F32), + b'h' => Kind::Float(FloatKind::F16) + ]); + + ( + parse_dec(is_negative, digits_with_sign, kind), + rest_to_str!(bytes), + ) + } + } + } +} + +fn parse_hex_float_missing_exponent( + // format: -?0[xX] ( [0-9a-fA-F]+\.[0-9a-fA-F]* | [0-9a-fA-F]*\.[0-9a-fA-F]+ ) + significand: &str, + kind: Option<FloatKind>, +) -> Result<Number, NumberError> { + let hexf_input = format!("{}{}", significand, "p0"); + parse_hex_float(&hexf_input, kind) +} + +fn parse_hex_float_missing_period( + // format: -?0[xX] [0-9a-fA-F]+ + significand: &str, + // format: [pP][+-]?[0-9]+ + exponent: &str, + kind: Option<FloatKind>, +) -> Result<Number, NumberError> { + let hexf_input = format!("{}.{}", significand, exponent); + parse_hex_float(&hexf_input, kind) +} + +fn parse_hex_int( + is_negative: bool, + // format: [0-9a-fA-F]+ + digits: &str, + kind: Option<IntKind>, +) -> Result<Number, NumberError> { + let digits_with_sign = if is_negative { + Cow::Owned(format!("-{}", digits)) + } else { + Cow::Borrowed(digits) + }; + parse_int(&digits_with_sign, kind, 16, is_negative) +} + +fn parse_dec( + is_negative: bool, + // format: -? ( [0-9] | [1-9][0-9]+ ) + digits_with_sign: &str, + kind: Option<Kind>, +) -> Result<Number, NumberError> { + match kind { + None => parse_int(digits_with_sign, None, 10, is_negative), + Some(Kind::Int(kind)) => parse_int(digits_with_sign, Some(kind), 10, is_negative), + Some(Kind::Float(kind)) => parse_dec_float(digits_with_sign, Some(kind)), + } +} + +// Float parsing notes + +// The following chapters of IEEE 754-2019 are relevant: +// +// 7.4 Overflow (largest finite number is exceeded by what would have been +// the rounded floating-point result were the exponent range unbounded) +// +// 7.5 Underflow (tiny non-zero result is detected; +// for decimal formats tininess is detected before rounding when a non-zero result +// computed as though both the exponent range and the precision were unbounded +// would lie strictly between 2^−126) +// +// 7.6 Inexact (rounded result differs from what would have been computed +// were both exponent range and precision unbounded) + +// The WGSL spec requires us to error: +// on overflow for decimal floating point literals +// on overflow and inexact for hexadecimal floating point literals +// (underflow is not mentioned) + +// hexf_parse errors on overflow, underflow, inexact +// rust std lib float from str handles overflow, underflow, inexact transparently (rounds and will not error) + +// Therefore we only check for overflow manually for decimal floating point literals + +// input format: -?0[xX] ( [0-9a-fA-F]+\.[0-9a-fA-F]* | [0-9a-fA-F]*\.[0-9a-fA-F]+ ) [pP][+-]?[0-9]+ +fn parse_hex_float(input: &str, kind: Option<FloatKind>) -> Result<Number, NumberError> { + match kind { + None => match hexf_parse::parse_hexf64(input, false) { + Ok(num) => Ok(Number::AbstractFloat(num)), + // can only be ParseHexfErrorKind::Inexact but we can't check since it's private + _ => Err(NumberError::NotRepresentable), + }, + Some(FloatKind::F32) => match hexf_parse::parse_hexf32(input, false) { + Ok(num) => Ok(Number::F32(num)), + // can only be ParseHexfErrorKind::Inexact but we can't check since it's private + _ => Err(NumberError::NotRepresentable), + }, + Some(FloatKind::F16) => Err(NumberError::UnimplementedF16), + } +} + +// input format: -? ( [0-9]+\.[0-9]* | [0-9]*\.[0-9]+ ) ([eE][+-]?[0-9]+)? +// | -? [0-9]+ [eE][+-]?[0-9]+ +fn parse_dec_float(input: &str, kind: Option<FloatKind>) -> Result<Number, NumberError> { + match kind { + None => { + let num = input.parse::<f64>().unwrap(); // will never fail + num.is_finite() + .then(|| Number::AbstractFloat(num)) + .ok_or(NumberError::NotRepresentable) + } + Some(FloatKind::F32) => { + let num = input.parse::<f32>().unwrap(); // will never fail + num.is_finite() + .then(|| Number::F32(num)) + .ok_or(NumberError::NotRepresentable) + } + Some(FloatKind::F16) => Err(NumberError::UnimplementedF16), + } +} + +fn parse_int( + input: &str, + kind: Option<IntKind>, + radix: u32, + is_negative: bool, +) -> Result<Number, NumberError> { + fn map_err(e: core::num::ParseIntError) -> NumberError { + match *e.kind() { + core::num::IntErrorKind::PosOverflow | core::num::IntErrorKind::NegOverflow => { + NumberError::NotRepresentable + } + _ => unreachable!(), + } + } + match kind { + None => match i64::from_str_radix(input, radix) { + Ok(num) => Ok(Number::AbstractInt(num)), + Err(e) => Err(map_err(e)), + }, + Some(IntKind::I32) => match i32::from_str_radix(input, radix) { + Ok(num) => Ok(Number::I32(num)), + Err(e) => Err(map_err(e)), + }, + Some(IntKind::U32) if is_negative => Err(NumberError::NotRepresentable), + Some(IntKind::U32) => match u32::from_str_radix(input, radix) { + Ok(num) => Ok(Number::U32(num)), + Err(e) => Err(map_err(e)), + }, + } +} |