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

use nu_engine::command_prelude::*;
use nu_protocol::Signals;

use std::io::Write;

#[derive(Clone)]
pub struct StrJoin;

impl Command for StrJoin {
    fn name(&self) -> &str {
        "str join"
    }

    fn signature(&self) -> Signature {
        Signature::build("str join")
            .input_output_types(vec![
                (Type::List(Box::new(Type::Any)), Type::String),
                (Type::String, Type::String),
            ])
            .optional(
                "separator",
                SyntaxShape::String,
                "Optional separator to use when creating string.",
            )
            .allow_variants_without_examples(true)
            .category(Category::Strings)
    }

    fn usage(&self) -> &str {
        "Concatenate multiple strings into a single string, with an optional separator between each."
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["collect", "concatenate"]
    }

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

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let separator: Option<String> = call.opt(engine_state, stack, 0)?;
        run(engine_state, call, input, separator)
    }

    fn run_const(
        &self,
        working_set: &StateWorkingSet,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let separator: Option<String> = call.opt_const(working_set, 0)?;
        run(working_set.permanent(), call, input, separator)
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Create a string from input",
                example: "['nu', 'shell'] | str join",
                result: Some(Value::test_string("nushell")),
            },
            Example {
                description: "Create a string from input with a separator",
                example: "['nu', 'shell'] | str join '-'",
                result: Some(Value::test_string("nu-shell")),
            },
        ]
    }
}

fn run(
    engine_state: &EngineState,
    call: &Call,
    input: PipelineData,
    separator: Option<String>,
) -> Result<PipelineData, ShellError> {
    let config = engine_state.config.clone();

    let span = call.head;

    let metadata = input.metadata();
    let mut iter = input.into_iter();
    let mut first = true;

    let output = ByteStream::from_fn(
        span,
        Signals::empty(),
        ByteStreamType::String,
        move |buffer| {
            // Write each input to the buffer
            if let Some(value) = iter.next() {
                // Write the separator if this is not the first
                if first {
                    first = false;
                } else if let Some(separator) = &separator {
                    write!(buffer, "{}", separator)?;
                }

                match value {
                    Value::Error { error, .. } => {
                        return Err(*error);
                    }
                    // Hmm, not sure what we actually want.
                    // `to_expanded_string` formats dates as human readable which feels funny.
                    Value::Date { val, .. } => write!(buffer, "{val:?}")?,
                    value => write!(buffer, "{}", value.to_expanded_string("\n", &config))?,
                }
                Ok(true)
            } else {
                Ok(false)
            }
        },
    );

    Ok(PipelineData::ByteStream(output, metadata))
}

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

        test_examples(StrJoin {})
    }
}