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feat(minifier): improve .charCodeAt(arg) when arg is valid (#8534)

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This commit is contained in:
Boshen 2025-01-16 06:36:34 +00:00
parent b1d018622b
commit 927f43ff84
3 changed files with 40 additions and 30 deletions
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24
crates/oxc_ecmascript/src/string_char_at.rs
View file

@ -9,26 +9,32 @@ pub trait StringCharAt {
impl StringCharAt for &str {
#[expect(clippy::cast_sign_loss)]
fn char_at(&self, index: Option<f64>) -> Option<char> {
let index = index.map_or(0, |x| x.to_int_32() as isize);
let index = index.unwrap_or(0.0);
if index.fract() != 0.0 || index.is_nan() || index.is_infinite() {
return None;
}
let index = index.to_int_32() as isize;
if index < 0 {
None
} else {
self.chars().nth(index as usize)
self.encode_utf16().nth(index as usize).and_then(|n| char::from_u32(u32::from(n)))
}
}
}
#[cfg(test)]
mod test {
use super::StringCharAt;
#[test]
fn test_evaluate_string_char_at() {
use crate::string_char_at::StringCharAt;
assert_eq!("test".char_at(Some(0.0)), Some('t'));
assert_eq!("test".char_at(Some(1.0)), Some('e'));
assert_eq!("test".char_at(Some(2.0)), Some('s'));
assert_eq!("test".char_at(Some(-1.0)), None);
assert_eq!("test".char_at(Some(-1.1)), None);
assert_eq!("test".char_at(Some(-1_073_741_825.0)), None);
let s = "test";
assert_eq!(s.char_at(Some(0.0)), Some('t'));
assert_eq!(s.char_at(Some(1.0)), Some('e'));
assert_eq!(s.char_at(Some(2.0)), Some('s'));
assert_eq!(s.char_at(Some(0.5)), None);
assert_eq!(s.char_at(Some(-1.0)), None);
assert_eq!(s.char_at(Some(-1.1)), None);
assert_eq!(s.char_at(Some(-1_073_741_825.0)), None);
}
}

24
crates/oxc_ecmascript/src/string_char_code_at.rs
View file

@ -14,19 +14,21 @@ impl StringCharCodeAt for &str {
#[cfg(test)]
mod test {
use super::StringCharCodeAt;
#[test]
fn test_evaluate_char_code_at() {
use crate::StringCharCodeAt;
assert_eq!("abcde".char_code_at(Some(0.0)), Some(97));
assert_eq!("abcde".char_code_at(Some(1.0)), Some(98));
assert_eq!("abcde".char_code_at(Some(2.0)), Some(99));
assert_eq!("abcde".char_code_at(Some(3.0)), Some(100));
assert_eq!("abcde".char_code_at(Some(4.0)), Some(101));
assert_eq!("abcde".char_code_at(Some(5.0)), None);
assert_eq!("abcde".char_code_at(Some(-1.0)), None);
assert_eq!("abcde".char_code_at(None), Some(97));
assert_eq!("abcde".char_code_at(Some(0.0)), Some(97));
let s = "abcde";
assert_eq!(s.char_code_at(Some(0.0)), Some(97));
assert_eq!(s.char_code_at(Some(1.0)), Some(98));
assert_eq!(s.char_code_at(Some(2.0)), Some(99));
assert_eq!(s.char_code_at(Some(3.0)), Some(100));
assert_eq!(s.char_code_at(Some(4.0)), Some(101));
assert_eq!(s.char_code_at(Some(5.0)), None);
assert_eq!(s.char_code_at(Some(-1.0)), None);
assert_eq!(s.char_code_at(None), Some(97));
assert_eq!(s.char_code_at(Some(0.0)), Some(97));
assert_eq!(s.char_code_at(Some(f64::NAN)), None);
assert_eq!(s.char_code_at(Some(f64::INFINITY)), None);
}
}

22
crates/oxc_minifier/src/ast_passes/peephole_replace_known_methods.rs
View file

@ -185,6 +185,7 @@ impl<'a> PeepholeReplaceKnownMethods {
Some(ctx.ast.expression_string_literal(ce.span, result, None))
}
#[expect(clippy::cast_lossless)]
fn try_fold_string_char_code_at(
ce: &CallExpression<'a>,
object: &Expression<'a>,
@ -196,10 +197,14 @@ impl<'a> PeepholeReplaceKnownMethods {
Some(Argument::SpreadElement(_)) => None,
Some(e) => Ctx(ctx).get_side_free_number_value(e.to_expression()),
}?;
// TODO: if `result` is `None`, return `NaN` instead of skipping the optimization
let result = s.value.as_str().char_code_at(Some(char_at_index))?;
#[expect(clippy::cast_lossless)]
Some(ctx.ast.expression_numeric_literal(ce.span, result as f64, None, NumberBase::Decimal))
let value = if (0.0..65536.0).contains(&char_at_index) {
s.value.as_str().char_code_at(Some(char_at_index))? as f64
} else if char_at_index.is_nan() || char_at_index.is_infinite() {
return None;
} else {
f64::NAN
};
Some(ctx.ast.expression_numeric_literal(ce.span, value, None, NumberBase::Decimal))
}
fn try_fold_string_replace(
@ -606,18 +611,15 @@ mod test {
fold("x = 'abcde'.charCodeAt(2)", "x = 99");
fold("x = 'abcde'.charCodeAt(3)", "x = 100");
fold("x = 'abcde'.charCodeAt(4)", "x = 101");
fold_same("x = 'abcde'.charCodeAt(5)"); // or x = (0/0)
fold_same("x = 'abcde'.charCodeAt(-1)"); // or x = (0/0)
fold_same("x = 'abcde'.charCodeAt(5)");
fold("x = 'abcde'.charCodeAt(-1)", "x = NaN");
fold_same("x = 'abcde'.charCodeAt(y)");
// Seems that it does not handle this case
// fold("x = 'abcde'.charCodeAt()", "x = 97");
fold("x = 'abcde'.charCodeAt()", "x = 97");
fold("x = 'abcde'.charCodeAt(0, ++z)", "x = 97");
fold("x = 'abcde'.charCodeAt(null)", "x = 97");
fold("x = 'abcde'.charCodeAt(true)", "x = 98");
// fold("x = '\\ud834\udd1e'.charCodeAt(0)", "x = 55348");
// fold("x = '\\ud834\udd1e'.charCodeAt(1)", "x = 56606");
// Template strings
fold_same("x = `abcdef`.charCodeAt(0)");
fold_same("x = `abcdef ${abc}`.charCodeAt(0)");
}