| use rustc_ast::ast::{Lit, LitFloatType, LitIntType, LitKind}; |
| |
| #[derive(Debug, PartialEq)] |
| pub enum Radix { |
| Binary, |
| Octal, |
| Decimal, |
| Hexadecimal, |
| } |
| |
| impl Radix { |
| /// Returns a reasonable digit group size for this radix. |
| #[must_use] |
| fn suggest_grouping(&self) -> usize { |
| match *self { |
| Self::Binary | Self::Hexadecimal => 4, |
| Self::Octal | Self::Decimal => 3, |
| } |
| } |
| } |
| |
| /// A helper method to format numeric literals with digit grouping. |
| /// `lit` must be a valid numeric literal without suffix. |
| pub fn format(lit: &str, type_suffix: Option<&str>, float: bool) -> String { |
| NumericLiteral::new(lit, type_suffix, float).format() |
| } |
| |
| #[derive(Debug)] |
| pub struct NumericLiteral<'a> { |
| /// Which radix the literal was represented in. |
| pub radix: Radix, |
| /// The radix prefix, if present. |
| pub prefix: Option<&'a str>, |
| |
| /// The integer part of the number. |
| pub integer: &'a str, |
| /// The fraction part of the number. |
| pub fraction: Option<&'a str>, |
| /// The exponent separator (b'e' or b'E') including preceding underscore if present |
| /// and the exponent part. |
| pub exponent: Option<(&'a str, &'a str)>, |
| |
| /// The type suffix, including preceding underscore if present. |
| pub suffix: Option<&'a str>, |
| } |
| |
| impl<'a> NumericLiteral<'a> { |
| pub fn from_lit(src: &'a str, lit: &Lit) -> Option<NumericLiteral<'a>> { |
| NumericLiteral::from_lit_kind(src, &lit.kind) |
| } |
| |
| pub fn from_lit_kind(src: &'a str, lit_kind: &LitKind) -> Option<NumericLiteral<'a>> { |
| if lit_kind.is_numeric() && src.chars().next().map_or(false, |c| c.is_digit(10)) { |
| let (unsuffixed, suffix) = split_suffix(&src, lit_kind); |
| let float = matches!(lit_kind, LitKind::Float(..)); |
| Some(NumericLiteral::new(unsuffixed, suffix, float)) |
| } else { |
| None |
| } |
| } |
| |
| #[must_use] |
| pub fn new(lit: &'a str, suffix: Option<&'a str>, float: bool) -> Self { |
| // Determine delimiter for radix prefix, if present, and radix. |
| let radix = if lit.starts_with("0x") { |
| Radix::Hexadecimal |
| } else if lit.starts_with("0b") { |
| Radix::Binary |
| } else if lit.starts_with("0o") { |
| Radix::Octal |
| } else { |
| Radix::Decimal |
| }; |
| |
| // Grab part of the literal after prefix, if present. |
| let (prefix, mut sans_prefix) = if let Radix::Decimal = radix { |
| (None, lit) |
| } else { |
| let (p, s) = lit.split_at(2); |
| (Some(p), s) |
| }; |
| |
| if suffix.is_some() && sans_prefix.ends_with('_') { |
| // The '_' before the suffix isn't part of the digits |
| sans_prefix = &sans_prefix[..sans_prefix.len() - 1]; |
| } |
| |
| let (integer, fraction, exponent) = Self::split_digit_parts(sans_prefix, float); |
| |
| Self { |
| radix, |
| prefix, |
| integer, |
| fraction, |
| exponent, |
| suffix, |
| } |
| } |
| |
| pub fn is_decimal(&self) -> bool { |
| self.radix == Radix::Decimal |
| } |
| |
| pub fn split_digit_parts(digits: &str, float: bool) -> (&str, Option<&str>, Option<(&str, &str)>) { |
| let mut integer = digits; |
| let mut fraction = None; |
| let mut exponent = None; |
| |
| if float { |
| for (i, c) in digits.char_indices() { |
| match c { |
| '.' => { |
| integer = &digits[..i]; |
| fraction = Some(&digits[i + 1..]); |
| }, |
| 'e' | 'E' => { |
| let exp_start = if digits[..i].ends_with('_') { i - 1 } else { i }; |
| |
| if integer.len() > exp_start { |
| integer = &digits[..exp_start]; |
| } else { |
| fraction = Some(&digits[integer.len() + 1..exp_start]); |
| }; |
| exponent = Some((&digits[exp_start..=i], &digits[i + 1..])); |
| break; |
| }, |
| _ => {}, |
| } |
| } |
| } |
| |
| (integer, fraction, exponent) |
| } |
| |
| /// Returns literal formatted in a sensible way. |
| pub fn format(&self) -> String { |
| let mut output = String::new(); |
| |
| if let Some(prefix) = self.prefix { |
| output.push_str(prefix); |
| } |
| |
| let group_size = self.radix.suggest_grouping(); |
| |
| Self::group_digits( |
| &mut output, |
| self.integer, |
| group_size, |
| true, |
| self.radix == Radix::Hexadecimal, |
| ); |
| |
| if let Some(fraction) = self.fraction { |
| output.push('.'); |
| Self::group_digits(&mut output, fraction, group_size, false, false); |
| } |
| |
| if let Some((separator, exponent)) = self.exponent { |
| output.push_str(separator); |
| Self::group_digits(&mut output, exponent, group_size, true, false); |
| } |
| |
| if let Some(suffix) = self.suffix { |
| output.push('_'); |
| output.push_str(suffix); |
| } |
| |
| output |
| } |
| |
| pub fn group_digits(output: &mut String, input: &str, group_size: usize, partial_group_first: bool, pad: bool) { |
| debug_assert!(group_size > 0); |
| |
| let mut digits = input.chars().filter(|&c| c != '_'); |
| |
| let first_group_size; |
| |
| if partial_group_first { |
| first_group_size = (digits.clone().count() - 1) % group_size + 1; |
| if pad { |
| for _ in 0..group_size - first_group_size { |
| output.push('0'); |
| } |
| } |
| } else { |
| first_group_size = group_size; |
| } |
| |
| for _ in 0..first_group_size { |
| if let Some(digit) = digits.next() { |
| output.push(digit); |
| } |
| } |
| |
| for (c, i) in digits.zip((0..group_size).cycle()) { |
| if i == 0 { |
| output.push('_'); |
| } |
| output.push(c); |
| } |
| } |
| } |
| |
| fn split_suffix<'a>(src: &'a str, lit_kind: &LitKind) -> (&'a str, Option<&'a str>) { |
| debug_assert!(lit_kind.is_numeric()); |
| lit_suffix_length(lit_kind).map_or((src, None), |suffix_length| { |
| let (unsuffixed, suffix) = src.split_at(src.len() - suffix_length); |
| (unsuffixed, Some(suffix)) |
| }) |
| } |
| |
| fn lit_suffix_length(lit_kind: &LitKind) -> Option<usize> { |
| debug_assert!(lit_kind.is_numeric()); |
| let suffix = match lit_kind { |
| LitKind::Int(_, int_lit_kind) => match int_lit_kind { |
| LitIntType::Signed(int_ty) => Some(int_ty.name_str()), |
| LitIntType::Unsigned(uint_ty) => Some(uint_ty.name_str()), |
| LitIntType::Unsuffixed => None, |
| }, |
| LitKind::Float(_, float_lit_kind) => match float_lit_kind { |
| LitFloatType::Suffixed(float_ty) => Some(float_ty.name_str()), |
| LitFloatType::Unsuffixed => None, |
| }, |
| _ => None, |
| }; |
| |
| suffix.map(str::len) |
| } |