use crate::prelude::*; use nu_engine::WholeStreamCommand; use nu_errors::ShellError; use nu_protocol::ShellTypeName; use nu_protocol::{ ColumnPath, Primitive, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value, }; pub struct SubCommand; struct Arguments { column_paths: Vec, } impl WholeStreamCommand for SubCommand { fn name(&self) -> &str { "str reverse" } fn signature(&self) -> Signature { Signature::build("str reverse").rest( "rest", SyntaxShape::ColumnPath, "optionally reverse text by column paths", ) } fn usage(&self) -> &str { "outputs the reversals of the strings in the pipeline" } fn run_with_actions(&self, args: CommandArgs) -> Result { operate(args) } fn examples(&self) -> Vec { vec![Example { description: "Return the reversals of multiple strings", example: "echo 'Nushell' | str reverse", result: Some(vec![UntaggedValue::string("llehsuN").into_untagged_value()]), }] } } fn operate(args: CommandArgs) -> Result { let (options, input) = ( Arguments { column_paths: args.rest(0)?, }, args.input, ); Ok(input .map(move |v| { if options.column_paths.is_empty() { ReturnSuccess::value(action(&v, v.tag())?) } else { let mut ret = v; for path in &options.column_paths { ret = ret.swap_data_by_column_path( path, Box::new(move |old| action(old, old.tag())), )?; } ReturnSuccess::value(ret) } }) .into_action_stream()) } fn action(input: &Value, tag: impl Into) -> Result { match &input.value { UntaggedValue::Primitive(Primitive::String(s)) => { Ok(UntaggedValue::string(s.chars().rev().collect::()).into_value(tag)) } other => { let got = format!("got {}", other.type_name()); Err(ShellError::labeled_error( "value is not string", got, tag.into().span, )) } } } #[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 {}) } }