biome_js_formatter 0.0.1

Biome's JavaScript formatter
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
131
132
133

use crate::prelude::*;
use crate::utils::AnyJsAssignmentLike;

use crate::parentheses::{
    is_arrow_function_body, is_first_in_statement, FirstInStatementMode, NeedsParentheses,
};
use biome_formatter::write;

use biome_js_syntax::{
    AnyJsAssignmentPattern, AnyJsForInitializer, JsArrowFunctionExpression, JsAssignmentExpression,
    JsComputedMemberName, JsExpressionStatement, JsForStatement, JsSequenceExpression,
    JsSyntaxKind, JsSyntaxNode,
};
use biome_rowan::{match_ast, AstNode};

#[derive(Debug, Clone, Default)]
pub(crate) struct FormatJsAssignmentExpression;

impl FormatNodeRule<JsAssignmentExpression> for FormatJsAssignmentExpression {
    fn fmt_fields(&self, node: &JsAssignmentExpression, f: &mut JsFormatter) -> FormatResult<()> {
        write![f, [AnyJsAssignmentLike::from(node.clone())]]
    }

    fn needs_parentheses(&self, item: &JsAssignmentExpression) -> bool {
        item.needs_parentheses()
    }
}

impl NeedsParentheses for JsAssignmentExpression {
    fn needs_parentheses_with_parent(&self, parent: &JsSyntaxNode) -> bool {
        match_ast! {
            match parent {
                JsAssignmentExpression(_) => false,
                // `[a = b]`
                JsComputedMemberName(_) => false,

                JsArrowFunctionExpression(_) => {
                    is_arrow_function_body(self.syntax(), parent)
                },

                JsForStatement(for_statement) => {
                     let is_initializer = match for_statement.initializer() {
                        Some(AnyJsForInitializer::AnyJsExpression(expression)) => {
                            expression.syntax() == self.syntax()
                        }
                        None | Some(_) => false,
                    };

                    let is_update = for_statement
                        .update()
                        .map(AstNode::into_syntax)
                        .as_ref()
                        == Some(self.syntax());

                    !(is_initializer || is_update)
                },
                JsExpressionStatement(_) => {
                    // Parenthesize `{ a } = { a: 5 }`
                    is_first_in_statement(
                        self.clone().into(),
                        FirstInStatementMode::ExpressionStatementOrArrow,
                    ) && matches!(
                        self.left(),
                        Ok(AnyJsAssignmentPattern::JsObjectAssignmentPattern(_))
                    )
                },
                JsSequenceExpression(_) => {
                     let mut child = parent.clone();

                    for ancestor in parent.ancestors().skip(1) {
                        match ancestor.kind() {
                            JsSyntaxKind::JS_SEQUENCE_EXPRESSION
                            | JsSyntaxKind::JS_PARENTHESIZED_EXPRESSION => child = ancestor,
                            JsSyntaxKind::JS_FOR_STATEMENT => {
                                let for_statement = JsForStatement::unwrap_cast(ancestor);

                                let is_initializer = match for_statement.initializer() {
                                    Some(AnyJsForInitializer::AnyJsExpression(expression)) => {
                                        expression.syntax() == &child
                                    }
                                    None | Some(_) => false,
                                };

                                let is_update =
                                    for_statement.update().map(AstNode::into_syntax).as_ref()
                                        == Some(&child);

                                return !(is_initializer || is_update);
                            }
                            _ => break,
                        }
                    }

                    true
                },
                _ => {
                    true
                }
            }
        }
    }
}

#[cfg(test)]
mod tests {

    use crate::{assert_needs_parentheses, assert_not_needs_parentheses};
    use biome_js_syntax::JsAssignmentExpression;

    #[test]
    fn needs_parentheses() {
        assert_not_needs_parentheses!("({ [a = 3]: value })", JsAssignmentExpression);
        assert_not_needs_parentheses!("class Test { [a = 3]: value }", JsAssignmentExpression);
        assert_not_needs_parentheses!("type Test  = { [a = 3]: value }", JsAssignmentExpression);
        assert_not_needs_parentheses!("interface Test { [a = 3]: value }", JsAssignmentExpression);

        assert_needs_parentheses!("a => (a = 3)", JsAssignmentExpression);
        assert_not_needs_parentheses!("a => { a = 3 }", JsAssignmentExpression);

        assert_not_needs_parentheses!("for(a = 3;;) {}", JsAssignmentExpression);
        assert_not_needs_parentheses!("for(a = 3, b = 2;;) {}", JsAssignmentExpression[1]);
        assert_not_needs_parentheses!("for(a = 3, b = 2, c= 3;;) {}", JsAssignmentExpression[2]);
        assert_needs_parentheses!("for(; a = 3; ) {}", JsAssignmentExpression);
        assert_not_needs_parentheses!("for(;;a = 3) {}", JsAssignmentExpression);

        assert_not_needs_parentheses!("for ((a, a = 3);;) {}", JsAssignmentExpression);
        assert_needs_parentheses!("for (; (a, a = 3);) {}", JsAssignmentExpression);
        assert_not_needs_parentheses!("for (;;(a, a = 3)) {}", JsAssignmentExpression);

        assert_not_needs_parentheses!("a = 3", JsAssignmentExpression);
        assert_needs_parentheses!("({ a } = { a: 3 })", JsAssignmentExpression);
    }
}