nu-command 0.62.0

Nushell's built-in commands
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
134
135
136
137
138
139

use super::delimited::{from_delimited_data, trim_from_str};

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

#[derive(Clone)]
pub struct FromCsv;

impl Command for FromCsv {
    fn name(&self) -> &str {
        "from csv"
    }

    fn signature(&self) -> Signature {
        Signature::build("from csv")
            .named(
                "separator",
                SyntaxShape::String,
                "a character to separate columns, defaults to ','",
                Some('s'),
            )
            .switch(
                "noheaders",
                "don't treat the first row as column names",
                Some('n'),
            )
            .named(
                "trim",
                SyntaxShape::String,
                "drop leading and trailing whitespaces around headers names and/or field values",
                Some('t'),
            )
            .category(Category::Formats)
    }

    fn usage(&self) -> &str {
        "Parse text as .csv and create table."
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<nu_protocol::PipelineData, ShellError> {
        from_csv(engine_state, stack, call, input)
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Convert comma-separated data to a table",
                example: "open data.txt | from csv",
                result: None,
            },
            Example {
                description: "Convert comma-separated data to a table, ignoring headers",
                example: "open data.txt | from csv --noheaders",
                result: None,
            },
            Example {
                description: "Convert comma-separated data to a table, ignoring headers",
                example: "open data.txt | from csv -n",
                result: None,
            },
            Example {
                description: "Convert semicolon-separated data to a table",
                example: "open data.txt | from csv --separator ';'",
                result: None,
            },
            Example {
                description: "Convert semicolon-separated data to a table, dropping all possible whitespaces around header names and field values",
                example: "open data.txt | from csv --trim all",
                result: None,
            },
            Example {
                description: "Convert semicolon-separated data to a table, dropping all possible whitespaces around header names",
                example: "open data.txt | from csv --trim headers",
                result: None,
            },
            Example {
                description: "Convert semicolon-separated data to a table, dropping all possible whitespaces around field values",
                example: "open data.txt | from csv --trim fields",
                result: None,
            },
        ]
    }
}

fn from_csv(
    engine_state: &EngineState,
    stack: &mut Stack,
    call: &Call,
    input: PipelineData,
) -> Result<PipelineData, ShellError> {
    let name = call.head;

    let noheaders = call.has_flag("noheaders");
    let separator: Option<Value> = call.get_flag(engine_state, stack, "separator")?;
    let trim: Option<Value> = call.get_flag(engine_state, stack, "trim")?;
    let config = engine_state.get_config();

    let sep = match separator {
        Some(Value::String { val: s, span }) => {
            if s == r"\t" {
                '\t'
            } else {
                let vec_s: Vec<char> = s.chars().collect();
                if vec_s.len() != 1 {
                    return Err(ShellError::MissingParameter(
                        "single character separator".into(),
                        span,
                    ));
                };
                vec_s[0]
            }
        }
        _ => ',',
    };

    let trim = trim_from_str(trim)?;

    from_delimited_data(noheaders, sep, trim, input, name, config)
}

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

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

        test_examples(FromCsv {})
    }
}