use nu::{ serve_plugin, CallInfo, Plugin, ReturnSuccess, ReturnValue, ShellError, Signature, SyntaxShape, Tagged, Value, }; pub type ColumnPath = Tagged>>; struct Edit { field: Option, value: Option, } impl Edit { fn new() -> Edit { Edit { field: None, value: None, } } fn edit(&self, value: Tagged) -> Result, ShellError> { let value_tag = value.tag(); match (value.item, self.value.clone()) { (obj @ Value::Row(_), Some(v)) => match &self.field { Some(f) => match obj.replace_data_at_column_path(value_tag, &f, v) { Some(v) => return Ok(v), None => { return Err(ShellError::labeled_error( "edit could not find place to insert column", "column name", &f.tag, )) } }, None => Err(ShellError::untagged_runtime_error( "edit needs a column when changing a value in a table", )), }, _ => Err(ShellError::labeled_error( "Unrecognized type in stream", "original value", value_tag, )), } } } impl Plugin for Edit { fn config(&mut self) -> Result { Ok(Signature::build("edit") .desc("Edit an existing column to have a new value.") .required( "Field", SyntaxShape::ColumnPath, "the name of the column to edit", ) .required( "Value", SyntaxShape::String, "the new value to give the cell(s)", ) .filter()) } fn begin_filter(&mut self, call_info: CallInfo) -> Result, ShellError> { if let Some(args) = call_info.args.positional { match &args[0] { table @ Tagged { item: Value::Table(_), .. } => { self.field = Some(table.as_column_path()?); } value => return Err(ShellError::type_error("table", value.tagged_type_name())), } match &args[1] { Tagged { item: v, .. } => { self.value = Some(v.clone()); } } } Ok(vec![]) } fn filter(&mut self, input: Tagged) -> Result, ShellError> { Ok(vec![ReturnSuccess::value(self.edit(input)?)]) } } fn main() { serve_plugin(&mut Edit::new()); }