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feat(minifier): implement folding indexOf and lastIndexOf string fns
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@camc314
camc314 committed Oct 11, 2024
1 parent 7645e5c commit 920fc92
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Showing 2 changed files with 283 additions and 21 deletions.
114 changes: 93 additions & 21 deletions crates/oxc_minifier/src/ast_passes/peephole_replace_known_methods/mod.rs
View file
Original file line number Diff line number Diff line change
@@ -1,6 +1,9 @@
use cow_utils::CowUtils;
use oxc_ast::ast::*;
use oxc_traverse::{Traverse, TraverseCtx};
use string_methods::StringUtils;

mod string_methods;

use crate::CompressorPass;

Expand Down Expand Up @@ -41,25 +44,94 @@ impl PeepholeReplaceKnownMethods {

let Expression::StaticMemberExpression(member) = &call_expr.callee else { return };
if let Expression::StringLiteral(string_lit) = &member.object {
if call_expr.arguments.len() == 0 {
let transformed_value = match member.property.name.as_str() {
"toLowerCase" => Some(
ctx.ast.string_literal(call_expr.span, string_lit.value.cow_to_lowercase()),
),
"toUpperCase" => Some(
ctx.ast.string_literal(call_expr.span, string_lit.value.cow_to_uppercase()),
),
"trim" => Some(ctx.ast.string_literal(call_expr.span, string_lit.value.trim())),
_ => None,
};

if let Some(transformed_value) = transformed_value {
self.changed = true;
*node = ctx.ast.expression_from_string_literal(transformed_value);
#[expect(clippy::match_same_arms)]
let replacement = match member.property.name.as_str() {
"toLowerCase" | "toUpperCase" | "trim" => {
let transformed_value =
match member.property.name.as_str() {
"toLowerCase" => Some(ctx.ast.string_literal(
call_expr.span,
string_lit.value.cow_to_lowercase(),
)),
"toUpperCase" => Some(ctx.ast.string_literal(
call_expr.span,
string_lit.value.cow_to_uppercase(),
)),
"trim" => Some(
ctx.ast.string_literal(call_expr.span, string_lit.value.trim()),
),
_ => None,
};

transformed_value.map(|transformed_value| {
ctx.ast.expression_from_string_literal(transformed_value)
})
}
"indexOf" | "lastIndexOf" => Self::try_fold_string_index_of(
call_expr.span,
call_expr,
member,
string_lit,
ctx,
),
// TODO: Implement the rest of the string methods
"substr" => None,
"substring" | "slice" => None,
"charAt" => None,
"charCodeAt" => None,
"replace" => None,
"replaceAll" => None,
_ => None,
};

if let Some(replacement) = replacement {
self.changed = true;
*node = replacement;
}
}
}

fn try_fold_string_index_of<'a>(
span: Span,
call_expr: &CallExpression<'a>,
member: &StaticMemberExpression<'a>,
string_lit: &StringLiteral<'a>,
ctx: &mut TraverseCtx<'a>,
) -> Option<Expression<'a>> {
let search_value = match call_expr.arguments.first() {
Some(Argument::StringLiteral(string_lit)) => Some(string_lit.value.as_str()),
None => None,
_ => return None,
};

let search_start_index = match call_expr.arguments.get(1) {
Some(Argument::NumericLiteral(numeric_lit)) => Some(numeric_lit.value),
None => None,
_ => return None,
};

let result = if member.property.name.as_str() == "indexOf" {
StringUtils::evaluate_string_index_of(
&string_lit.value,
search_value,
search_start_index,
)
} else {
StringUtils::evaluate_string_last_index_of(
&string_lit.value,
search_value,
search_start_index,
)
};

#[expect(clippy::cast_precision_loss)]
return Some(ctx.ast.expression_from_numeric_literal(ctx.ast.numeric_literal(
span,
result as f64,
result.to_string(),
NumberBase::Decimal,
)));
}
}

/// Port from: <https://github.com/google/closure-compiler/blob/master/test/com/google/javascript/jscomp/PeepholeReplaceKnownMethodsTest.java>
Expand Down Expand Up @@ -88,7 +160,6 @@ mod test {
}

#[test]
#[ignore]
fn test_string_index_of() {
fold("x = 'abcdef'.indexOf('g')", "x = -1");
fold("x = 'abcdef'.indexOf('b')", "x = 1");
Expand All @@ -102,11 +173,12 @@ mod test {

// Both elements must be strings. Don't do anything if either one is not
// string.
fold("x = 'abc1def'.indexOf(1)", "x = 3");
fold("x = 'abcNaNdef'.indexOf(NaN)", "x = 3");
fold("x = 'abcundefineddef'.indexOf(undefined)", "x = 3");
fold("x = 'abcnulldef'.indexOf(null)", "x = 3");
fold("x = 'abctruedef'.indexOf(true)", "x = 3");
// TODO: cast first arg to a string, and fold if possible.
// fold("x = 'abc1def'.indexOf(1)", "x = 3");
// fold("x = 'abcNaNdef'.indexOf(NaN)", "x = 3");
// fold("x = 'abcundefineddef'.indexOf(undefined)", "x = 3");
// fold("x = 'abcnulldef'.indexOf(null)", "x = 3");
// fold("x = 'abctruedef'.indexOf(true)", "x = 3");

// The following test case fails with JSC_PARSE_ERROR. Hence omitted.
// fold_same("x = 1.indexOf('bcd');");
Expand Down
190 changes: 190 additions & 0 deletions crates/oxc_minifier/src/ast_passes/peephole_replace_known_methods/string_methods.rs
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,190 @@
use oxc_syntax::number::ToJsInt32;

pub(super) struct StringUtils;

impl StringUtils {
#[expect(clippy::cast_possible_wrap, clippy::cast_sign_loss)]
pub(super) fn evaluate_string_index_of<'a>(
string: &'a str,
search_value: Option<&'a str>,
from_index: Option<f64>,
) -> isize {
let from_index = from_index.map_or(0, |x| x.to_js_int_32().max(0)) as usize;
let Some(search_value) = search_value else {
return -1;
};
let result = string.chars().skip(from_index).collect::<String>().find(search_value);
result.map(|index| index + from_index).map_or(-1, |index| index as isize)
}

#[expect(clippy::cast_possible_wrap, clippy::cast_sign_loss)]
pub(super) fn evaluate_string_last_index_of<'a>(
string: &'a str,
search_value: Option<&'a str>,
from_index: Option<f64>,
) -> isize {
let Some(search_value) = search_value else { return -1 };

let from_index = from_index
.map_or(usize::MAX, |x| x.to_js_int_32().max(0) as usize + search_value.len());

string
.chars()
.take(from_index)
.collect::<String>()
.rfind(search_value)
.map_or(-1, |index| index as isize)
}
}

#[cfg(test)]
mod test {
#[test]
fn test_evaluate_string_index_of() {
use super::StringUtils;

assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("t"), Some(0.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("t"), Some(1.0)),
3
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("t"), Some(4.0)),
5
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("t"), Some(4.1)),
5
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("t"), Some(0.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("t"), Some(-1.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("t"), Some(-1.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("t"), Some(-1.1)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of(
"test test test",
Some("t"),
Some(-1_073_741_825.0)
),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("e"), Some(0.0)),
1
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("s"), Some(0.0)),
2
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("test"), Some(4.0)),
5
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("test"), Some(5.0)),
5
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("test"), Some(6.0)),
10
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("test"), Some(0.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("test"), Some(-1.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("not found"), Some(-1.0)),
-1
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("test"), Some(-1.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of(
"test test test",
Some("test"),
Some(-1_073_741_825.0)
),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("test"), Some(0.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_index_of("test test test", Some("notpresent"), Some(0.0)),
-1
);
assert_eq!(StringUtils::evaluate_string_index_of("test test test", None, Some(0.0)), -1);
}

#[test]
fn test_evaluate_string_last_index_of() {
use super::StringUtils;
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", Some("test"), Some(15.0)),
10
);
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", Some("test"), Some(14.0)),
10
);
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", Some("test"), Some(10.0)),
10
);
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", Some("test"), Some(9.0)),
5
);
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", Some("test"), Some(6.0)),
5
);
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", Some("test"), Some(5.0)),
5
);
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", Some("test"), Some(4.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", Some("test"), Some(0.0)),
0
);
assert_eq!(
StringUtils::evaluate_string_last_index_of(
"test test test",
Some("notpresent"),
Some(0.0)
),
-1
);
assert_eq!(
StringUtils::evaluate_string_last_index_of("test test test", None, Some(1.0)),
-1
);
assert_eq!(StringUtils::evaluate_string_last_index_of("abcdef", Some("b"), None), 1);
}
}

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