nu-lint 1.1.0

Linter for Nu shell scripts that helpfully suggests improvements
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

use nu_protocol::{
    Span,
    ast::{Block, Call, Expr},
};

use crate::{
    Fix, LintLevel, Replacement,
    ast::{call::CallExt, expression::ExpressionExt},
    context::LintContext,
    rule::{DetectFix, Rule},
    violation::Detection,
};

fn get_single_if_call<'a>(block: &'a Block, context: &LintContext) -> Option<&'a Call> {
    let pipeline = (block.pipelines.len() == 1).then(|| block.pipelines.first())??;

    let element = (pipeline.elements.len() == 1).then(|| pipeline.elements.first())??;

    match &element.expr.expr {
        Expr::Call(call) if call.is_call_to_command("if", context) => Some(call),
        _ => None,
    }
}

fn get_nested_single_if<'a>(call: &Call, context: &'a LintContext<'a>) -> Option<&'a Call> {
    let then_block = call.get_positional_arg(1)?;
    let then_block_id = then_block.extract_block_id()?;
    get_single_if_call(context.working_set.get_block(then_block_id), context)
}

pub struct FixData {
    replace_span: Span,
    outer_condition: Span,
    inner_condition: Span,
    inner_body: Span,
}

struct CollapsibleIf;

impl DetectFix for CollapsibleIf {
    type FixInput<'a> = FixData;

    fn id(&self) -> &'static str {
        "collapsible_if"
    }

    fn short_description(&self) -> &'static str {
        "Nested if-statements collapsible with `and`"
    }

    fn source_link(&self) -> Option<&'static str> {
        Some("https://www.nushell.sh/book/control_flow.html")
    }

    fn level(&self) -> LintLevel {
        LintLevel::Warning
    }

    fn detect<'a>(&self, context: &'a LintContext) -> Vec<(Detection, Self::FixInput<'a>)> {
        context.detect_with_fix_data(|expr, ctx| match &expr.expr {
            Expr::Call(call) if call.is_call_to_command("if", ctx) => {
                if call.get_else_branch().is_some() {
                    return vec![];
                }

                let Some(inner_call) = get_nested_single_if(call, ctx) else {
                    return vec![];
                };

                if inner_call.get_else_branch().is_some() {
                    return vec![];
                }

                let Some(outer_condition) = call.get_first_positional_arg() else {
                    return vec![];
                };
                let Some(inner_condition) = inner_call.get_first_positional_arg() else {
                    return vec![];
                };
                let Some(inner_body) = inner_call.get_positional_arg(1) else {
                    return vec![];
                };

                let detected = Detection::from_global_span(
                    "Nested if statement can be collapsed using 'and'",
                    call.span(),
                )
                .with_primary_label("outer if")
                .with_extra_label(
                    "inner if can be merged with outer condition",
                    inner_call.span(),
                );

                let fix_data = FixData {
                    replace_span: call.span(),
                    outer_condition: outer_condition.span,
                    inner_condition: inner_condition.span,
                    inner_body: inner_body.span,
                };

                vec![(detected, fix_data)]
            }
            _ => vec![],
        })
    }

    fn fix(&self, context: &LintContext, fix_data: &Self::FixInput<'_>) -> Option<Fix> {
        let outer_cond = context.span_text(fix_data.outer_condition).trim();
        let inner_cond = context.span_text(fix_data.inner_condition).trim();
        let body = context.span_text(fix_data.inner_body).trim();

        let fix_text = format!("if {outer_cond} and {inner_cond} {body}");

        Some(Fix {
            explanation: "Collapse nested if statements".into(),
            replacements: vec![Replacement::new(fix_data.replace_span, fix_text)],
        })
    }
}

pub static RULE: &dyn Rule = &CollapsibleIf;

#[cfg(test)]
mod detect_bad;
#[cfg(test)]
mod generated_fix;
#[cfg(test)]
mod ignore_good;