507 lines
18 KiB
Rust
507 lines
18 KiB
Rust
//! Lints concerned with the grouping of digits with underscores in integral or
|
|
//! floating-point literal expressions.
|
|
|
|
use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass, in_external_macro, LintContext};
|
|
use rustc::{declare_tool_lint, lint_array};
|
|
use if_chain::if_chain;
|
|
use syntax::ast::*;
|
|
use syntax_pos;
|
|
use crate::utils::{snippet_opt, span_lint_and_sugg};
|
|
|
|
/// **What it does:** Warns if a long integral or floating-point constant does
|
|
/// not contain underscores.
|
|
///
|
|
/// **Why is this bad?** Reading long numbers is difficult without separators.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// 61864918973511
|
|
/// ```
|
|
declare_clippy_lint! {
|
|
pub UNREADABLE_LITERAL,
|
|
style,
|
|
"long integer literal without underscores"
|
|
}
|
|
|
|
/// **What it does:** Warns if an integral or floating-point constant is
|
|
/// grouped inconsistently with underscores.
|
|
///
|
|
/// **Why is this bad?** Readers may incorrectly interpret inconsistently
|
|
/// grouped digits.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// 618_64_9189_73_511
|
|
/// ```
|
|
declare_clippy_lint! {
|
|
pub INCONSISTENT_DIGIT_GROUPING,
|
|
style,
|
|
"integer literals with digits grouped inconsistently"
|
|
}
|
|
|
|
/// **What it does:** Warns if the digits of an integral or floating-point
|
|
/// constant are grouped into groups that
|
|
/// are too large.
|
|
///
|
|
/// **Why is this bad?** Negatively impacts readability.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// 6186491_8973511
|
|
/// ```
|
|
declare_clippy_lint! {
|
|
pub LARGE_DIGIT_GROUPS,
|
|
style,
|
|
"grouping digits into groups that are too large"
|
|
}
|
|
|
|
/// **What it does:** Warns if there is a better representation for a numeric literal.
|
|
///
|
|
/// **Why is this bad?** Especially for big powers of 2 a hexadecimal representation is more
|
|
/// readable than a decimal representation.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// `255` => `0xFF`
|
|
/// `65_535` => `0xFFFF`
|
|
/// `4_042_322_160` => `0xF0F0_F0F0`
|
|
declare_clippy_lint! {
|
|
pub DECIMAL_LITERAL_REPRESENTATION,
|
|
restriction,
|
|
"using decimal representation when hexadecimal would be better"
|
|
}
|
|
|
|
#[derive(Debug, PartialEq)]
|
|
pub(super) enum Radix {
|
|
Binary,
|
|
Octal,
|
|
Decimal,
|
|
Hexadecimal,
|
|
}
|
|
|
|
impl Radix {
|
|
/// Return a reasonable digit group size for this radix.
|
|
crate fn suggest_grouping(&self) -> usize {
|
|
match *self {
|
|
Radix::Binary | Radix::Hexadecimal => 4,
|
|
Radix::Octal | Radix::Decimal => 3,
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
pub(super) struct DigitInfo<'a> {
|
|
/// Characters of a literal between the radix prefix and type suffix.
|
|
crate digits: &'a str,
|
|
/// Which radix the literal was represented in.
|
|
crate radix: Radix,
|
|
/// The radix prefix, if present.
|
|
crate prefix: Option<&'a str>,
|
|
/// The type suffix, including preceding underscore if present.
|
|
crate suffix: Option<&'a str>,
|
|
/// True for floating-point literals.
|
|
crate float: bool,
|
|
}
|
|
|
|
impl<'a> DigitInfo<'a> {
|
|
crate fn new(lit: &'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, sans_prefix) = if let Radix::Decimal = radix {
|
|
(None, lit)
|
|
} else {
|
|
let (p, s) = lit.split_at(2);
|
|
(Some(p), s)
|
|
};
|
|
|
|
let mut last_d = '\0';
|
|
for (d_idx, d) in sans_prefix.char_indices() {
|
|
if !float && (d == 'i' || d == 'u') || float && (d == 'f' || d == 'e' || d == 'E') {
|
|
let suffix_start = if last_d == '_' { d_idx - 1 } else { d_idx };
|
|
let (digits, suffix) = sans_prefix.split_at(suffix_start);
|
|
return Self {
|
|
digits,
|
|
radix,
|
|
prefix,
|
|
suffix: Some(suffix),
|
|
float,
|
|
};
|
|
}
|
|
last_d = d
|
|
}
|
|
|
|
// No suffix found
|
|
Self {
|
|
digits: sans_prefix,
|
|
radix,
|
|
prefix,
|
|
suffix: None,
|
|
float,
|
|
}
|
|
}
|
|
|
|
/// Returns digits grouped in a sensible way.
|
|
crate fn grouping_hint(&self) -> String {
|
|
let group_size = self.radix.suggest_grouping();
|
|
if self.digits.contains('.') {
|
|
let mut parts = self.digits.split('.');
|
|
let int_part_hint = parts
|
|
.next()
|
|
.expect("split always returns at least one element")
|
|
.chars()
|
|
.rev()
|
|
.filter(|&c| c != '_')
|
|
.collect::<Vec<_>>()
|
|
.chunks(group_size)
|
|
.map(|chunk| chunk.into_iter().rev().collect())
|
|
.rev()
|
|
.collect::<Vec<String>>()
|
|
.join("_");
|
|
let frac_part_hint = parts
|
|
.next()
|
|
.expect("already checked that there is a `.`")
|
|
.chars()
|
|
.filter(|&c| c != '_')
|
|
.collect::<Vec<_>>()
|
|
.chunks(group_size)
|
|
.map(|chunk| chunk.into_iter().collect())
|
|
.collect::<Vec<String>>()
|
|
.join("_");
|
|
format!(
|
|
"{}.{}{}",
|
|
int_part_hint,
|
|
frac_part_hint,
|
|
self.suffix.unwrap_or("")
|
|
)
|
|
} else {
|
|
let filtered_digits_vec = self.digits
|
|
.chars()
|
|
.filter(|&c| c != '_')
|
|
.rev()
|
|
.collect::<Vec<_>>();
|
|
let mut hint = filtered_digits_vec
|
|
.chunks(group_size)
|
|
.map(|chunk| chunk.into_iter().rev().collect())
|
|
.rev()
|
|
.collect::<Vec<String>>()
|
|
.join("_");
|
|
// Forces hexadecimal values to be grouped by 4 being filled with zeroes (e.g 0x00ab_cdef)
|
|
let nb_digits_to_fill = filtered_digits_vec.len() % 4;
|
|
if self.radix == Radix::Hexadecimal && nb_digits_to_fill != 0 {
|
|
hint = format!("{:0>4}{}", &hint[..nb_digits_to_fill], &hint[nb_digits_to_fill..]);
|
|
}
|
|
format!(
|
|
"{}{}{}",
|
|
self.prefix.unwrap_or(""),
|
|
hint,
|
|
self.suffix.unwrap_or("")
|
|
)
|
|
}
|
|
}
|
|
}
|
|
|
|
enum WarningType {
|
|
UnreadableLiteral,
|
|
InconsistentDigitGrouping,
|
|
LargeDigitGroups,
|
|
DecimalRepresentation,
|
|
}
|
|
|
|
impl WarningType {
|
|
crate fn display(&self, grouping_hint: &str, cx: &EarlyContext<'_>, span: syntax_pos::Span) {
|
|
match self {
|
|
WarningType::UnreadableLiteral => span_lint_and_sugg(
|
|
cx,
|
|
UNREADABLE_LITERAL,
|
|
span,
|
|
"long literal lacking separators",
|
|
"consider",
|
|
grouping_hint.to_owned(),
|
|
),
|
|
WarningType::LargeDigitGroups => span_lint_and_sugg(
|
|
cx,
|
|
LARGE_DIGIT_GROUPS,
|
|
span,
|
|
"digit groups should be smaller",
|
|
"consider",
|
|
grouping_hint.to_owned(),
|
|
),
|
|
WarningType::InconsistentDigitGrouping => span_lint_and_sugg(
|
|
cx,
|
|
INCONSISTENT_DIGIT_GROUPING,
|
|
span,
|
|
"digits grouped inconsistently by underscores",
|
|
"consider",
|
|
grouping_hint.to_owned(),
|
|
),
|
|
WarningType::DecimalRepresentation => span_lint_and_sugg(
|
|
cx,
|
|
DECIMAL_LITERAL_REPRESENTATION,
|
|
span,
|
|
"integer literal has a better hexadecimal representation",
|
|
"consider",
|
|
grouping_hint.to_owned(),
|
|
),
|
|
};
|
|
}
|
|
}
|
|
|
|
#[derive(Copy, Clone)]
|
|
pub struct LiteralDigitGrouping;
|
|
|
|
impl LintPass for LiteralDigitGrouping {
|
|
fn get_lints(&self) -> LintArray {
|
|
lint_array!(
|
|
UNREADABLE_LITERAL,
|
|
INCONSISTENT_DIGIT_GROUPING,
|
|
LARGE_DIGIT_GROUPS
|
|
)
|
|
}
|
|
}
|
|
|
|
impl EarlyLintPass for LiteralDigitGrouping {
|
|
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
|
|
if in_external_macro(cx.sess(), expr.span) {
|
|
return;
|
|
}
|
|
|
|
if let ExprKind::Lit(ref lit) = expr.node {
|
|
self.check_lit(cx, lit)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl LiteralDigitGrouping {
|
|
fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
|
|
match lit.node {
|
|
LitKind::Int(..) => {
|
|
// Lint integral literals.
|
|
if_chain! {
|
|
if let Some(src) = snippet_opt(cx, lit.span);
|
|
if let Some(firstch) = src.chars().next();
|
|
if char::to_digit(firstch, 10).is_some();
|
|
then {
|
|
let digit_info = DigitInfo::new(&src, false);
|
|
let _ = Self::do_lint(digit_info.digits).map_err(|warning_type| {
|
|
warning_type.display(&digit_info.grouping_hint(), cx, lit.span)
|
|
});
|
|
}
|
|
}
|
|
},
|
|
LitKind::Float(..) | LitKind::FloatUnsuffixed(..) => {
|
|
// Lint floating-point literals.
|
|
if_chain! {
|
|
if let Some(src) = snippet_opt(cx, lit.span);
|
|
if let Some(firstch) = src.chars().next();
|
|
if char::to_digit(firstch, 10).is_some();
|
|
then {
|
|
let digit_info = DigitInfo::new(&src, true);
|
|
// Separate digits into integral and fractional parts.
|
|
let parts: Vec<&str> = digit_info
|
|
.digits
|
|
.split_terminator('.')
|
|
.collect();
|
|
|
|
// Lint integral and fractional parts separately, and then check consistency of digit
|
|
// groups if both pass.
|
|
let _ = Self::do_lint(parts[0])
|
|
.map(|integral_group_size| {
|
|
if parts.len() > 1 {
|
|
// Lint the fractional part of literal just like integral part, but reversed.
|
|
let fractional_part = &parts[1].chars().rev().collect::<String>();
|
|
let _ = Self::do_lint(fractional_part)
|
|
.map(|fractional_group_size| {
|
|
let consistent = Self::parts_consistent(integral_group_size,
|
|
fractional_group_size,
|
|
parts[0].len(),
|
|
parts[1].len());
|
|
if !consistent {
|
|
WarningType::InconsistentDigitGrouping.display(&digit_info.grouping_hint(),
|
|
cx,
|
|
lit.span);
|
|
}
|
|
})
|
|
.map_err(|warning_type| warning_type.display(&digit_info.grouping_hint(),
|
|
cx,
|
|
lit.span));
|
|
}
|
|
})
|
|
.map_err(|warning_type| warning_type.display(&digit_info.grouping_hint(), cx, lit.span));
|
|
}
|
|
}
|
|
},
|
|
_ => (),
|
|
}
|
|
}
|
|
|
|
/// Given the sizes of the digit groups of both integral and fractional
|
|
/// parts, and the length
|
|
/// of both parts, determine if the digits have been grouped consistently.
|
|
fn parts_consistent(int_group_size: usize, frac_group_size: usize, int_size: usize, frac_size: usize) -> bool {
|
|
match (int_group_size, frac_group_size) {
|
|
// No groups on either side of decimal point - trivially consistent.
|
|
(0, 0) => true,
|
|
// Integral part has grouped digits, fractional part does not.
|
|
(_, 0) => frac_size <= int_group_size,
|
|
// Fractional part has grouped digits, integral part does not.
|
|
(0, _) => int_size <= frac_group_size,
|
|
// Both parts have grouped digits. Groups should be the same size.
|
|
(_, _) => int_group_size == frac_group_size,
|
|
}
|
|
}
|
|
|
|
/// Performs lint on `digits` (no decimal point) and returns the group
|
|
/// size on success or `WarningType` when emitting a warning.
|
|
fn do_lint(digits: &str) -> Result<usize, WarningType> {
|
|
// Grab underscore indices with respect to the units digit.
|
|
let underscore_positions: Vec<usize> = digits
|
|
.chars()
|
|
.rev()
|
|
.enumerate()
|
|
.filter_map(|(idx, digit)| if digit == '_' { Some(idx) } else { None })
|
|
.collect();
|
|
|
|
if underscore_positions.is_empty() {
|
|
// Check if literal needs underscores.
|
|
if digits.len() > 5 {
|
|
Err(WarningType::UnreadableLiteral)
|
|
} else {
|
|
Ok(0)
|
|
}
|
|
} else {
|
|
// Check consistency and the sizes of the groups.
|
|
let group_size = underscore_positions[0];
|
|
let consistent = underscore_positions
|
|
.windows(2)
|
|
.all(|ps| ps[1] - ps[0] == group_size + 1)
|
|
// number of digits to the left of the last group cannot be bigger than group size.
|
|
&& (digits.len() - underscore_positions.last()
|
|
.expect("there's at least one element") <= group_size + 1);
|
|
|
|
if !consistent {
|
|
return Err(WarningType::InconsistentDigitGrouping);
|
|
} else if group_size > 4 {
|
|
return Err(WarningType::LargeDigitGroups);
|
|
}
|
|
Ok(group_size)
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Copy, Clone)]
|
|
pub struct LiteralRepresentation {
|
|
threshold: u64,
|
|
}
|
|
|
|
impl LintPass for LiteralRepresentation {
|
|
fn get_lints(&self) -> LintArray {
|
|
lint_array!(DECIMAL_LITERAL_REPRESENTATION)
|
|
}
|
|
}
|
|
|
|
impl EarlyLintPass for LiteralRepresentation {
|
|
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
|
|
if in_external_macro(cx.sess(), expr.span) {
|
|
return;
|
|
}
|
|
|
|
if let ExprKind::Lit(ref lit) = expr.node {
|
|
self.check_lit(cx, lit)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl LiteralRepresentation {
|
|
pub fn new(threshold: u64) -> Self {
|
|
Self {
|
|
threshold,
|
|
}
|
|
}
|
|
fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
|
|
// Lint integral literals.
|
|
if_chain! {
|
|
if let LitKind::Int(..) = lit.node;
|
|
if let Some(src) = snippet_opt(cx, lit.span);
|
|
if let Some(firstch) = src.chars().next();
|
|
if char::to_digit(firstch, 10).is_some();
|
|
then {
|
|
let digit_info = DigitInfo::new(&src, false);
|
|
if digit_info.radix == Radix::Decimal {
|
|
let val = digit_info.digits
|
|
.chars()
|
|
.filter(|&c| c != '_')
|
|
.collect::<String>()
|
|
.parse::<u128>().unwrap();
|
|
if val < u128::from(self.threshold) {
|
|
return
|
|
}
|
|
let hex = format!("{:#X}", val);
|
|
let digit_info = DigitInfo::new(&hex[..], false);
|
|
let _ = Self::do_lint(digit_info.digits).map_err(|warning_type| {
|
|
warning_type.display(&digit_info.grouping_hint(), cx, lit.span)
|
|
});
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn do_lint(digits: &str) -> Result<(), WarningType> {
|
|
if digits.len() == 1 {
|
|
// Lint for 1 digit literals, if someone really sets the threshold that low
|
|
if digits == "1" || digits == "2" || digits == "4" || digits == "8" || digits == "3" || digits == "7"
|
|
|| digits == "F"
|
|
{
|
|
return Err(WarningType::DecimalRepresentation);
|
|
}
|
|
} else if digits.len() < 4 {
|
|
// Lint for Literals with a hex-representation of 2 or 3 digits
|
|
let f = &digits[0..1]; // first digit
|
|
let s = &digits[1..]; // suffix
|
|
// Powers of 2
|
|
if ((f.eq("1") || f.eq("2") || f.eq("4") || f.eq("8")) && s.chars().all(|c| c == '0'))
|
|
// Powers of 2 minus 1
|
|
|| ((f.eq("1") || f.eq("3") || f.eq("7") || f.eq("F")) && s.chars().all(|c| c == 'F'))
|
|
{
|
|
return Err(WarningType::DecimalRepresentation);
|
|
}
|
|
} else {
|
|
// Lint for Literals with a hex-representation of 4 digits or more
|
|
let f = &digits[0..1]; // first digit
|
|
let m = &digits[1..digits.len() - 1]; // middle digits, except last
|
|
let s = &digits[1..]; // suffix
|
|
// Powers of 2 with a margin of +15/-16
|
|
if ((f.eq("1") || f.eq("2") || f.eq("4") || f.eq("8")) && m.chars().all(|c| c == '0'))
|
|
|| ((f.eq("1") || f.eq("3") || f.eq("7") || f.eq("F")) && m.chars().all(|c| c == 'F'))
|
|
// Lint for representations with only 0s and Fs, while allowing 7 as the first
|
|
// digit
|
|
|| ((f.eq("7") || f.eq("F")) && s.chars().all(|c| c == '0' || c == 'F'))
|
|
{
|
|
return Err(WarningType::DecimalRepresentation);
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
}
|