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
134
135
136
137
138
139
140
141

use nu_engine::CallExt;
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
};

#[derive(Clone)]
pub struct SubCommand;

impl Command for SubCommand {
    fn name(&self) -> &str {
        "math round"
    }

    fn signature(&self) -> Signature {
        Signature::build("math round")
            .input_output_types(vec![
                (Type::Number, Type::Number),
                (
                    Type::List(Box::new(Type::Number)),
                    Type::List(Box::new(Type::Number)),
                ),
            ])
            .allow_variants_without_examples(true)
            .named(
                "precision",
                SyntaxShape::Number,
                "digits of precision",
                Some('p'),
            )
            .category(Category::Math)
    }

    fn usage(&self) -> &str {
        "Returns the input number rounded to the specified precision."
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["approx", "closest", "nearest"]
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let precision_param: Option<i64> = call.get_flag(engine_state, stack, "precision")?;
        let head = call.head;
        // This doesn't match explicit nulls
        if matches!(input, PipelineData::Empty) {
            return Err(ShellError::PipelineEmpty { dst_span: head });
        }
        input.map(
            move |value| operate(value, head, precision_param),
            engine_state.ctrlc.clone(),
        )
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Apply the round function to a list of numbers",
                example: "[1.5 2.3 -3.1] | math round",
                result: Some(Value::list(
                    vec![Value::test_int(2), Value::test_int(2), Value::test_int(-3)],
                    Span::test_data(),
                )),
            },
            Example {
                description: "Apply the round function with precision specified",
                example: "[1.555 2.333 -3.111] | math round -p 2",
                result: Some(Value::list(
                    vec![
                        Value::test_float(1.56),
                        Value::test_float(2.33),
                        Value::test_float(-3.11),
                    ],
                    Span::test_data(),
                )),
            },
            Example {
                description: "Apply negative precision to a list of numbers",
                example: "[123, 123.3, -123.4] | math round -p -1",
                result: Some(Value::list(
                    vec![
                        Value::test_int(120),
                        Value::test_int(120),
                        Value::test_int(-120),
                    ],
                    Span::test_data(),
                )),
            },
        ]
    }
}

fn operate(value: Value, head: Span, precision: Option<i64>) -> Value {
    // We treat int values as float values in order to avoid code repetition in the match closure
    let span = value.span();
    let value = if let Value::Int { val, .. } = value {
        Value::float(val as f64, span)
    } else {
        value
    };

    match value {
        Value::Float { val, .. } => match precision {
            Some(precision_number) => Value::float(
                (val * ((10_f64).powf(precision_number as f64))).round()
                    / (10_f64).powf(precision_number as f64),
                span,
            ),
            None => Value::int(val.round() as i64, span),
        },
        Value::Error { .. } => value,
        other => Value::error(
            ShellError::OnlySupportsThisInputType {
                exp_input_type: "numeric".into(),
                wrong_type: other.get_type().to_string(),
                dst_span: head,
                src_span: other.span(),
            },
            head,
        ),
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_examples() {
        use crate::test_examples;

        test_examples(SubCommand {})
    }
}