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
142
143
144
145
146
147
148

use nu_engine::command_prelude::*;

#[derive(Clone)]
pub struct SubCommand;

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

    fn signature(&self) -> Signature {
        Signature::build("str downcase")
            .input_output_types(vec![
                (Type::String, Type::String),
                (
                    Type::List(Box::new(Type::String)),
                    Type::List(Box::new(Type::String)),
                ),
                (Type::table(), Type::table()),
                (Type::record(), Type::record()),
            ])
            .allow_variants_without_examples(true)
            .rest(
                "rest",
                SyntaxShape::CellPath,
                "For a data structure input, convert strings at the given cell paths.",
            )
            .category(Category::Strings)
    }

    fn usage(&self) -> &str {
        "Make text lowercase."
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["lower case", "lowercase"]
    }

    fn is_const(&self) -> bool {
        true
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let column_paths: Vec<CellPath> = call.rest(engine_state, stack, 0)?;
        operate(engine_state, call, input, column_paths)
    }

    fn run_const(
        &self,
        working_set: &StateWorkingSet,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let column_paths: Vec<CellPath> = call.rest_const(working_set, 0)?;
        operate(working_set.permanent(), call, input, column_paths)
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Downcase contents",
                example: "'NU' | str downcase",
                result: Some(Value::test_string("nu")),
            },
            Example {
                description: "Downcase contents",
                example: "'TESTa' | str downcase",
                result: Some(Value::test_string("testa")),
            },
            Example {
                description: "Downcase contents",
                example: "[[ColA ColB]; [Test ABC]] | str downcase ColA",
                result: Some(Value::test_list(vec![Value::test_record(record! {
                    "ColA" => Value::test_string("test"),
                    "ColB" => Value::test_string("ABC"),
                })])),
            },
            Example {
                description: "Downcase contents",
                example: "[[ColA ColB]; [Test ABC]] | str downcase ColA ColB",
                result: Some(Value::test_list(vec![Value::test_record(record! {
                    "ColA" => Value::test_string("test"),
                    "ColB" => Value::test_string("abc"),
                })])),
            },
        ]
    }
}

fn operate(
    engine_state: &EngineState,
    call: &Call,
    input: PipelineData,
    column_paths: Vec<CellPath>,
) -> Result<PipelineData, ShellError> {
    let head = call.head;
    input.map(
        move |v| {
            if column_paths.is_empty() {
                action(&v, head)
            } else {
                let mut ret = v;
                for path in &column_paths {
                    let r =
                        ret.update_cell_path(&path.members, Box::new(move |old| action(old, head)));
                    if let Err(error) = r {
                        return Value::error(error, head);
                    }
                }
                ret
            }
        },
        engine_state.signals(),
    )
}

fn action(input: &Value, head: Span) -> Value {
    match input {
        Value::String { val, .. } => Value::string(val.to_lowercase(), head),
        Value::Error { .. } => input.clone(),
        _ => Value::error(
            ShellError::OnlySupportsThisInputType {
                exp_input_type: "string".into(),
                wrong_type: input.get_type().to_string(),
                dst_span: head,
                src_span: input.span(),
            },
            head,
        ),
    }
}

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

        test_examples(SubCommand {})
    }
}