nushell/crates/nu-command/src/commands/str_/collect.rs

use crate::prelude::*;
use nu_engine::WholeStreamCommand;
use nu_errors::ShellError;
use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
use nu_source::Tagged;

pub struct SubCommand;

struct Arguments {
    separator: Option<Tagged<String>>,
}

impl Arguments {
    pub fn separator(&self) -> &str {
        self.separator.as_ref().map_or("", |sep| &sep.item)
    }
}

impl WholeStreamCommand for SubCommand {
    fn name(&self) -> &str {
        "str collect"
    }

    fn signature(&self) -> Signature {
        Signature::build("str collect").desc(self.usage()).optional(
            "separator",
            SyntaxShape::String,
            "the separator to put between the different values",
        )
    }

    fn usage(&self) -> &str {
        "collects a list of strings into a string"
    }

    fn run_with_actions(&self, args: CommandArgs) -> Result<ActionStream, ShellError> {
        collect(args)
    }

    fn examples(&self) -> Vec<Example> {
        vec![Example {
            description: "Collect a list of string",
            example: "echo ['a' 'b' 'c'] | str collect",
            result: Some(vec![Value::from("abc")]),
        }]
    }
}

pub fn collect(args: CommandArgs) -> Result<ActionStream, ShellError> {
    let tag = args.call_info.name_tag.clone();

    let (options, input) = args.extract(|params| {
        Ok(Arguments {
            separator: if let Some(arg) = params.opt(0) {
                Some(arg?)
            } else {
                None
            },
        })
    })?;

    let separator = options.separator();

    let strings: Vec<Result<String, ShellError>> = input.map(|value| value.as_string()).collect();
    let strings: Result<Vec<_>, _> = strings.into_iter().collect::<Result<_, _>>();

    match strings {
        Ok(strings) => {
            let output = strings.join(&separator);

            Ok(ActionStream::one(ReturnSuccess::value(
                UntaggedValue::string(output).into_value(tag),
            )))
        }
        Err(err) => match err.error {
            nu_errors::ProximateShellError::TypeError { actual, .. } => {
                if let Some(item) = actual.item {
                    Err(ShellError::labeled_error_with_secondary(
                        "could not convert to string",
                        format!("tried to convert '{}' in input to a string", item),
                        tag.span,
                        format!("'{}' value originated here", item),
                        actual.span,
                    ))
                } else {
                    Err(ShellError::labeled_error_with_secondary(
                        "could not convert to string",
                        "failed to convert input to strings",
                        tag.span,
                        "non-string found here",
                        actual.span,
                    ))
                }
            }
            _ => Err(err),
        },
    }
}

#[cfg(test)]
mod tests {
    use super::ShellError;
    use super::SubCommand;

    #[test]
    fn examples_work_as_expected() -> Result<(), ShellError> {
        use crate::examples::test as test_examples;

        test_examples(SubCommand {})
    }
}