oxc_ecmascript 0.125.0

A collection of JavaScript tools written in Rust.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

use oxc_ast::ast::{Expression, NumberBase};

use super::{ConstantEvaluation, ConstantEvaluationCtx, DetermineValueType, ValueType};

/// <https://tc39.es/ecma262/#sec-abstract-equality-comparison>
pub(super) fn abstract_equality_comparison<'a>(
    ctx: &impl ConstantEvaluationCtx<'a>,
    left_expr: &Expression<'a>,
    right_expr: &Expression<'a>,
) -> Option<bool> {
    let left = left_expr.value_type(ctx);
    let right = right_expr.value_type(ctx);
    if left != ValueType::Undetermined && right != ValueType::Undetermined {
        if left == right {
            return strict_equality_comparison(ctx, left_expr, right_expr);
        }
        if matches!(
            (left, right),
            (ValueType::Null, ValueType::Undefined) | (ValueType::Undefined, ValueType::Null)
        ) {
            return Some(true);
        }

        if matches!((left, right), (ValueType::Number, ValueType::String))
            || matches!(right, ValueType::Boolean)
        {
            if let Some(num) = right_expr.evaluate_value_to_number(ctx) {
                let number_literal_expr = ctx.ast().expression_numeric_literal(
                    oxc_span::SPAN,
                    num,
                    None,
                    if num.fract() == 0.0 { NumberBase::Decimal } else { NumberBase::Float },
                );
                return abstract_equality_comparison(ctx, left_expr, &number_literal_expr);
            }
            return None;
        }

        if matches!((left, right), (ValueType::String, ValueType::Number))
            || matches!(left, ValueType::Boolean)
        {
            if let Some(num) = left_expr.evaluate_value_to_number(ctx) {
                let number_literal_expr = ctx.ast().expression_numeric_literal(
                    oxc_span::SPAN,
                    num,
                    None,
                    if num.fract() == 0.0 { NumberBase::Decimal } else { NumberBase::Float },
                );
                return abstract_equality_comparison(ctx, &number_literal_expr, right_expr);
            }
            return None;
        }

        if matches!(left, ValueType::BigInt) || matches!(right, ValueType::BigInt) {
            let left_bigint = left_expr.evaluate_value_to_bigint(ctx);
            let right_bigint = right_expr.evaluate_value_to_bigint(ctx);
            if let (Some(l_big), Some(r_big)) = (left_bigint, right_bigint) {
                return Some(l_big.eq(&r_big));
            }
        }

        if matches!(left, ValueType::String | ValueType::Number | ValueType::BigInt)
            && matches!(right, ValueType::Object)
        {
            return None;
        }

        if matches!(left, ValueType::Object)
            && matches!(right, ValueType::String | ValueType::Number | ValueType::BigInt)
        {
            return None;
        }

        return Some(false);
    }
    None
}

/// <https://tc39.es/ecma262/#sec-strict-equality-comparison>
#[expect(clippy::float_cmp)]
pub(super) fn strict_equality_comparison<'a>(
    ctx: &impl ConstantEvaluationCtx<'a>,
    left_expr: &Expression<'a>,
    right_expr: &Expression<'a>,
) -> Option<bool> {
    let left = left_expr.value_type(ctx);
    let right = right_expr.value_type(ctx);
    if !left.is_undetermined() && !right.is_undetermined() {
        // Strict equality can only be true for values of the same type.
        if left != right {
            return Some(false);
        }
        return match left {
            ValueType::Number => {
                let lnum = left_expr.get_side_free_number_value(ctx)?;
                let rnum = right_expr.get_side_free_number_value(ctx)?;
                if lnum.is_nan() || rnum.is_nan() {
                    return Some(false);
                }
                Some(lnum == rnum)
            }
            ValueType::String => {
                let left = left_expr.get_side_free_string_value(ctx)?;
                let right = right_expr.get_side_free_string_value(ctx)?;
                Some(left == right)
            }
            ValueType::Undefined | ValueType::Null => Some(true),
            ValueType::Boolean => {
                let left = left_expr.evaluate_value_to_boolean(ctx)?;
                let right = right_expr.evaluate_value_to_boolean(ctx)?;
                Some(left == right)
            }
            ValueType::BigInt => {
                let left = left_expr.get_side_free_bigint_value(ctx)?;
                let right = right_expr.get_side_free_bigint_value(ctx)?;
                Some(left == right)
            }
            ValueType::Object => None,
            ValueType::Undetermined => unreachable!(),
        };
    }

    // Then, try to evaluate based on the value of the expression.
    // There's only one special case:
    // Any strict equality comparison against NaN returns false.
    if left_expr.is_nan() || right_expr.is_nan() {
        return Some(false);
    }
    None
}