1 use rustc_ast::ast::{Lit, LitFloatType, LitIntType, LitKind};
4 #[derive(Debug, PartialEq, Copy, Clone)]
13 /// Returns a reasonable digit group size for this radix.
15 fn suggest_grouping(self) -> usize {
17 Self::Binary | Self::Hexadecimal => 4,
18 Self::Octal | Self::Decimal => 3,
23 /// A helper method to format numeric literals with digit grouping.
24 /// `lit` must be a valid numeric literal without suffix.
25 pub fn format(lit: &str, type_suffix: Option<&str>, float: bool) -> String {
26 NumericLiteral::new(lit, type_suffix, float).format()
30 pub struct NumericLiteral<'a> {
31 /// Which radix the literal was represented in.
33 /// The radix prefix, if present.
34 pub prefix: Option<&'a str>,
36 /// The integer part of the number.
38 /// The fraction part of the number.
39 pub fraction: Option<&'a str>,
40 /// The exponent separator (b'e' or b'E') including preceding underscore if present
41 /// and the exponent part.
42 pub exponent: Option<(&'a str, &'a str)>,
44 /// The type suffix, including preceding underscore if present.
45 pub suffix: Option<&'a str>,
48 impl<'a> NumericLiteral<'a> {
49 pub fn from_lit(src: &'a str, lit: &Lit) -> Option<NumericLiteral<'a>> {
50 NumericLiteral::from_lit_kind(src, &lit.kind)
53 pub fn from_lit_kind(src: &'a str, lit_kind: &LitKind) -> Option<NumericLiteral<'a>> {
54 if lit_kind.is_numeric() && src.chars().next().map_or(false, |c| c.is_digit(10)) {
55 let (unsuffixed, suffix) = split_suffix(src, lit_kind);
56 let float = matches!(lit_kind, LitKind::Float(..));
57 Some(NumericLiteral::new(unsuffixed, suffix, float))
64 pub fn new(lit: &'a str, suffix: Option<&'a str>, float: bool) -> Self {
65 // Determine delimiter for radix prefix, if present, and radix.
66 let radix = if lit.starts_with("0x") {
68 } else if lit.starts_with("0b") {
70 } else if lit.starts_with("0o") {
76 // Grab part of the literal after prefix, if present.
77 let (prefix, mut sans_prefix) = if let Radix::Decimal = radix {
80 let (p, s) = lit.split_at(2);
84 if suffix.is_some() && sans_prefix.ends_with('_') {
85 // The '_' before the suffix isn't part of the digits
86 sans_prefix = &sans_prefix[..sans_prefix.len() - 1];
89 let (integer, fraction, exponent) = Self::split_digit_parts(sans_prefix, float);
101 pub fn is_decimal(&self) -> bool {
102 self.radix == Radix::Decimal
105 pub fn split_digit_parts(digits: &str, float: bool) -> (&str, Option<&str>, Option<(&str, &str)>) {
106 let mut integer = digits;
107 let mut fraction = None;
108 let mut exponent = None;
111 for (i, c) in digits.char_indices() {
114 integer = &digits[..i];
115 fraction = Some(&digits[i + 1..]);
118 let exp_start = if digits[..i].ends_with('_') { i - 1 } else { i };
120 if integer.len() > exp_start {
121 integer = &digits[..exp_start];
123 fraction = Some(&digits[integer.len() + 1..exp_start]);
125 exponent = Some((&digits[exp_start..=i], &digits[i + 1..]));
133 (integer, fraction, exponent)
136 /// Returns literal formatted in a sensible way.
137 pub fn format(&self) -> String {
138 let mut output = String::new();
140 if let Some(prefix) = self.prefix {
141 output.push_str(prefix);
144 let group_size = self.radix.suggest_grouping();
151 self.radix == Radix::Hexadecimal,
154 if let Some(fraction) = self.fraction {
156 Self::group_digits(&mut output, fraction, group_size, false, false);
159 if let Some((separator, exponent)) = self.exponent {
160 output.push_str(separator);
161 Self::group_digits(&mut output, exponent, group_size, true, false);
164 if let Some(suffix) = self.suffix {
166 output.push_str(suffix);
172 pub fn group_digits(output: &mut String, input: &str, group_size: usize, partial_group_first: bool, pad: bool) {
173 debug_assert!(group_size > 0);
175 let mut digits = input.chars().filter(|&c| c != '_');
177 let first_group_size;
179 if partial_group_first {
180 first_group_size = (digits.clone().count() - 1) % group_size + 1;
182 for _ in 0..group_size - first_group_size {
187 first_group_size = group_size;
190 for _ in 0..first_group_size {
191 if let Some(digit) = digits.next() {
196 for (c, i) in iter::zip(digits, (0..group_size).cycle()) {
205 fn split_suffix<'a>(src: &'a str, lit_kind: &LitKind) -> (&'a str, Option<&'a str>) {
206 debug_assert!(lit_kind.is_numeric());
207 lit_suffix_length(lit_kind).map_or((src, None), |suffix_length| {
208 let (unsuffixed, suffix) = src.split_at(src.len() - suffix_length);
209 (unsuffixed, Some(suffix))
213 fn lit_suffix_length(lit_kind: &LitKind) -> Option<usize> {
214 debug_assert!(lit_kind.is_numeric());
215 let suffix = match lit_kind {
216 LitKind::Int(_, int_lit_kind) => match int_lit_kind {
217 LitIntType::Signed(int_ty) => Some(int_ty.name_str()),
218 LitIntType::Unsigned(uint_ty) => Some(uint_ty.name_str()),
219 LitIntType::Unsuffixed => None,
221 LitKind::Float(_, float_lit_kind) => match float_lit_kind {
222 LitFloatType::Suffixed(float_ty) => Some(float_ty.name_str()),
223 LitFloatType::Unsuffixed => None,