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use rustc::lint::*;
use syntax::ast::*;
use syntax_pos;
use utils::{in_external_macro, snippet_opt, span_lint_and_sugg};
declare_clippy_lint! {
pub UNREADABLE_LITERAL,
style,
"long integer literal without underscores"
}
declare_clippy_lint! {
pub INCONSISTENT_DIGIT_GROUPING,
style,
"integer literals with digits grouped inconsistently"
}
declare_clippy_lint! {
pub LARGE_DIGIT_GROUPS,
style,
"grouping digits into groups that are too large"
}
declare_clippy_lint! {
pub DECIMAL_LITERAL_REPRESENTATION,
restriction,
"using decimal representation when hexadecimal would be better"
}
#[derive(Debug, PartialEq)]
enum Radix {
Binary,
Octal,
Decimal,
Hexadecimal,
}
impl Radix {
pub fn suggest_grouping(&self) -> usize {
match *self {
Radix::Binary | Radix::Hexadecimal => 4,
Radix::Octal | Radix::Decimal => 3,
}
}
}
#[derive(Debug)]
struct DigitInfo<'a> {
pub digits: &'a str,
pub radix: Radix,
pub prefix: Option<&'a str>,
pub suffix: Option<&'a str>,
pub float: bool,
}
impl<'a> DigitInfo<'a> {
pub fn new(lit: &'a str, float: bool) -> Self {
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
};
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
}
Self {
digits: sans_prefix,
radix,
prefix,
suffix: None,
float,
}
}
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 hint = self.digits
.chars()
.rev()
.filter(|&c| c != '_')
.collect::<Vec<_>>()
.chunks(group_size)
.map(|chunk| chunk.into_iter().rev().collect())
.rev()
.collect::<Vec<String>>()
.join("_");
format!(
"{}{}{}",
self.prefix.unwrap_or(""),
hint,
self.suffix.unwrap_or("")
)
}
}
}
enum WarningType {
UnreadableLiteral,
InconsistentDigitGrouping,
LargeDigitGroups,
DecimalRepresentation,
}
impl WarningType {
pub 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, 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(..) => {
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(..) => {
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);
let parts: Vec<&str> = digit_info
.digits
.split_terminator('.')
.collect();
let _ = Self::do_lint(parts[0])
.map(|integral_group_size| {
if parts.len() > 1 {
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));
}
}
},
_ => (),
}
}
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) {
(0, 0) => true,
(_, 0) => frac_size <= int_group_size,
(0, _) => int_size <= frac_group_size,
(_, _) => int_group_size == frac_group_size,
}
}
fn do_lint(digits: &str) -> Result<usize, WarningType> {
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() {
if digits.len() > 5 {
Err(WarningType::UnreadableLiteral)
} else {
Ok(0)
}
} else {
let group_size = underscore_positions[0];
let consistent = underscore_positions
.windows(2)
.all(|ps| ps[1] - ps[0] == group_size + 1)
&& (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, 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) {
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 {
if digits == "1" || digits == "2" || digits == "4" || digits == "8" || digits == "3" || digits == "7"
|| digits == "F"
{
return Err(WarningType::DecimalRepresentation);
}
} else if digits.len() < 4 {
let f = &digits[0..1];
let s = &digits[1..];
if ((f.eq("1") || f.eq("2") || f.eq("4") || f.eq("8")) && s.chars().all(|c| c == '0'))
|| ((f.eq("1") || f.eq("3") || f.eq("7") || f.eq("F")) && s.chars().all(|c| c == 'F'))
{
return Err(WarningType::DecimalRepresentation);
}
} else {
let f = &digits[0..1];
let m = &digits[1..digits.len() - 1];
let s = &digits[1..];
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'))
|| ((f.eq("7") || f.eq("F")) && s.chars().all(|c| c == '0' || c == 'F'))
{
return Err(WarningType::DecimalRepresentation);
}
}
Ok(())
}
}