use hir::db::HirDatabase; use ra_syntax::{ ast::{self, AstNode, AttrsOwner}, SyntaxKind::{WHITESPACE, COMMENT}, TextUnit, }; use crate::{AssistCtx, Assist}; pub(crate) fn add_derive(ctx: AssistCtx) -> Option { let nominal = ctx.node_at_offset::()?; let node_start = derive_insertion_offset(nominal)?; ctx.build("add `#[derive]`", |edit| { let derive_attr = nominal .attrs() .filter_map(|x| x.as_call()) .filter(|(name, _arg)| name == "derive") .map(|(_name, arg)| arg) .next(); let offset = match derive_attr { None => { edit.insert(node_start, "#[derive()]\n"); node_start + TextUnit::of_str("#[derive(") } Some(tt) => tt.syntax().range().end() - TextUnit::of_char(')'), }; edit.set_cursor(offset) }) } // Insert `derive` after doc comments. fn derive_insertion_offset(nominal: &ast::NominalDef) -> Option { let non_ws_child = nominal .syntax() .children() .find(|it| it.kind() != COMMENT && it.kind() != WHITESPACE)?; Some(non_ws_child.range().start()) } #[cfg(test)] mod tests { use super::*; use crate::helpers::check_assist; #[test] fn add_derive_new() { check_assist( add_derive, "struct Foo { a: i32, <|>}", "#[derive(<|>)]\nstruct Foo { a: i32, }", ); check_assist( add_derive, "struct Foo { <|> a: i32, }", "#[derive(<|>)]\nstruct Foo { a: i32, }", ); } #[test] fn add_derive_existing() { check_assist( add_derive, "#[derive(Clone)]\nstruct Foo { a: i32<|>, }", "#[derive(Clone<|>)]\nstruct Foo { a: i32, }", ); } #[test] fn add_derive_new_with_doc_comment() { check_assist( add_derive, " /// `Foo` is a pretty important struct. /// It does stuff. struct Foo { a: i32<|>, } ", " /// `Foo` is a pretty important struct. /// It does stuff. #[derive(<|>)] struct Foo { a: i32, } ", ); } }