use rustc_hash::FxHashSet; use syntax::{ ast::{self, GenericParamsOwner, NameOwner}, AstNode, SyntaxKind, TextRange, TextSize, }; use crate::{assist_context::AssistBuilder, AssistContext, AssistId, AssistKind, Assists}; static ASSIST_NAME: &str = "introduce_named_lifetime"; static ASSIST_LABEL: &str = "Introduce named lifetime"; // Assist: introduce_named_lifetime // // Change an anonymous lifetime to a named lifetime. // // ``` // impl Cursor<'_<|>> { // fn node(self) -> &SyntaxNode { // match self { // Cursor::Replace(node) | Cursor::Before(node) => node, // } // } // } // ``` // -> // ``` // impl<'a> Cursor<'a> { // fn node(self) -> &SyntaxNode { // match self { // Cursor::Replace(node) | Cursor::Before(node) => node, // } // } // } // ``` // FIXME: How can we handle renaming any one of multiple anonymous lifetimes? // FIXME: should also add support for the case fun(f: &Foo) -> &<|>Foo pub(crate) fn introduce_named_lifetime(acc: &mut Assists, ctx: &AssistContext) -> Option<()> { let lifetime_token = ctx .find_token_at_offset(SyntaxKind::LIFETIME) .filter(|lifetime| lifetime.text() == "'_")?; if let Some(fn_def) = lifetime_token.ancestors().find_map(ast::Fn::cast) { generate_fn_def_assist(acc, &fn_def, lifetime_token.text_range()) } else if let Some(impl_def) = lifetime_token.ancestors().find_map(ast::Impl::cast) { generate_impl_def_assist(acc, &impl_def, lifetime_token.text_range()) } else { None } } /// Generate the assist for the fn def case fn generate_fn_def_assist( acc: &mut Assists, fn_def: &ast::Fn, lifetime_loc: TextRange, ) -> Option<()> { let param_list: ast::ParamList = fn_def.param_list()?; let new_lifetime_param = generate_unique_lifetime_param_name(&fn_def.generic_param_list())?; let end_of_fn_ident = fn_def.name()?.ident_token()?.text_range().end(); let self_param = // use the self if it's a reference and has no explicit lifetime param_list.self_param().filter(|p| p.lifetime_token().is_none() && p.amp_token().is_some()); // compute the location which implicitly has the same lifetime as the anonymous lifetime let loc_needing_lifetime = if let Some(self_param) = self_param { // if we have a self reference, use that Some(self_param.self_token()?.text_range().start()) } else { // otherwise, if there's a single reference parameter without a named liftime, use that let fn_params_without_lifetime: Vec<_> = param_list .params() .filter_map(|param| match param.ty() { Some(ast::Type::RefType(ascribed_type)) if ascribed_type.lifetime_token() == None => { Some(ascribed_type.amp_token()?.text_range().end()) } _ => None, }) .collect(); match fn_params_without_lifetime.len() { 1 => Some(fn_params_without_lifetime.into_iter().nth(0)?), 0 => None, // multiple unnnamed is invalid. assist is not applicable _ => return None, } }; acc.add(AssistId(ASSIST_NAME, AssistKind::Refactor), ASSIST_LABEL, lifetime_loc, |builder| { add_lifetime_param(fn_def, builder, end_of_fn_ident, new_lifetime_param); builder.replace(lifetime_loc, format!("'{}", new_lifetime_param)); loc_needing_lifetime.map(|loc| builder.insert(loc, format!("'{} ", new_lifetime_param))); }) } /// Generate the assist for the impl def case fn generate_impl_def_assist( acc: &mut Assists, impl_def: &ast::Impl, lifetime_loc: TextRange, ) -> Option<()> { let new_lifetime_param = generate_unique_lifetime_param_name(&impl_def.generic_param_list())?; let end_of_impl_kw = impl_def.impl_token()?.text_range().end(); acc.add(AssistId(ASSIST_NAME, AssistKind::Refactor), ASSIST_LABEL, lifetime_loc, |builder| { add_lifetime_param(impl_def, builder, end_of_impl_kw, new_lifetime_param); builder.replace(lifetime_loc, format!("'{}", new_lifetime_param)); }) } /// Given a type parameter list, generate a unique lifetime parameter name /// which is not in the list fn generate_unique_lifetime_param_name( existing_type_param_list: &Option, ) -> Option { match existing_type_param_list { Some(type_params) => { let used_lifetime_params: FxHashSet<_> = type_params .lifetime_params() .map(|p| p.syntax().text().to_string()[1..].to_owned()) .collect(); (b'a'..=b'z').map(char::from).find(|c| !used_lifetime_params.contains(&c.to_string())) } None => Some('a'), } } /// Add the lifetime param to `builder`. If there are type parameters in `type_params_owner`, add it to the end. Otherwise /// add new type params brackets with the lifetime parameter at `new_type_params_loc`. fn add_lifetime_param( type_params_owner: &TypeParamsOwner, builder: &mut AssistBuilder, new_type_params_loc: TextSize, new_lifetime_param: char, ) { match type_params_owner.generic_param_list() { // add the new lifetime parameter to an existing type param list Some(type_params) => { builder.insert( (u32::from(type_params.syntax().text_range().end()) - 1).into(), format!(", '{}", new_lifetime_param), ); } // create a new type param list containing only the new lifetime parameter None => { builder.insert(new_type_params_loc, format!("<'{}>", new_lifetime_param)); } } } #[cfg(test)] mod tests { use super::*; use crate::tests::{check_assist, check_assist_not_applicable}; #[test] fn test_example_case() { check_assist( introduce_named_lifetime, r#"impl Cursor<'_<|>> { fn node(self) -> &SyntaxNode { match self { Cursor::Replace(node) | Cursor::Before(node) => node, } } }"#, r#"impl<'a> Cursor<'a> { fn node(self) -> &SyntaxNode { match self { Cursor::Replace(node) | Cursor::Before(node) => node, } } }"#, ); } #[test] fn test_example_case_simplified() { check_assist( introduce_named_lifetime, r#"impl Cursor<'_<|>> {"#, r#"impl<'a> Cursor<'a> {"#, ); } #[test] fn test_example_case_cursor_after_tick() { check_assist( introduce_named_lifetime, r#"impl Cursor<'<|>_> {"#, r#"impl<'a> Cursor<'a> {"#, ); } #[test] fn test_impl_with_other_type_param() { check_assist( introduce_named_lifetime, "impl fmt::Display for SepByBuilder<'_<|>, I> where I: Iterator, I::Item: fmt::Display, {", "impl fmt::Display for SepByBuilder<'a, I> where I: Iterator, I::Item: fmt::Display, {", ) } #[test] fn test_example_case_cursor_before_tick() { check_assist( introduce_named_lifetime, r#"impl Cursor<<|>'_> {"#, r#"impl<'a> Cursor<'a> {"#, ); } #[test] fn test_not_applicable_cursor_position() { check_assist_not_applicable(introduce_named_lifetime, r#"impl Cursor<'_><|> {"#); check_assist_not_applicable(introduce_named_lifetime, r#"impl Cursor<|><'_> {"#); } #[test] fn test_not_applicable_lifetime_already_name() { check_assist_not_applicable(introduce_named_lifetime, r#"impl Cursor<'a<|>> {"#); check_assist_not_applicable(introduce_named_lifetime, r#"fn my_fun<'a>() -> X<'a<|>>"#); } #[test] fn test_with_type_parameter() { check_assist( introduce_named_lifetime, r#"impl Cursor>"#, r#"impl Cursor"#, ); } #[test] fn test_with_existing_lifetime_name_conflict() { check_assist( introduce_named_lifetime, r#"impl<'a, 'b> Cursor<'a, 'b, '_<|>>"#, r#"impl<'a, 'b, 'c> Cursor<'a, 'b, 'c>"#, ); } #[test] fn test_function_return_value_anon_lifetime_param() { check_assist( introduce_named_lifetime, r#"fn my_fun() -> X<'_<|>>"#, r#"fn my_fun<'a>() -> X<'a>"#, ); } #[test] fn test_function_return_value_anon_reference_lifetime() { check_assist( introduce_named_lifetime, r#"fn my_fun() -> &'_<|> X"#, r#"fn my_fun<'a>() -> &'a X"#, ); } #[test] fn test_function_param_anon_lifetime() { check_assist( introduce_named_lifetime, r#"fn my_fun(x: X<'_<|>>)"#, r#"fn my_fun<'a>(x: X<'a>)"#, ); } #[test] fn test_function_add_lifetime_to_params() { check_assist( introduce_named_lifetime, r#"fn my_fun(f: &Foo) -> X<'_<|>>"#, r#"fn my_fun<'a>(f: &'a Foo) -> X<'a>"#, ); } #[test] fn test_function_add_lifetime_to_params_in_presence_of_other_lifetime() { check_assist( introduce_named_lifetime, r#"fn my_fun<'other>(f: &Foo, b: &'other Bar) -> X<'_<|>>"#, r#"fn my_fun<'other, 'a>(f: &'a Foo, b: &'other Bar) -> X<'a>"#, ); } #[test] fn test_function_not_applicable_without_self_and_multiple_unnamed_param_lifetimes() { // this is not permitted under lifetime elision rules check_assist_not_applicable( introduce_named_lifetime, r#"fn my_fun(f: &Foo, b: &Bar) -> X<'_<|>>"#, ); } #[test] fn test_function_add_lifetime_to_self_ref_param() { check_assist( introduce_named_lifetime, r#"fn my_fun<'other>(&self, f: &Foo, b: &'other Bar) -> X<'_<|>>"#, r#"fn my_fun<'other, 'a>(&'a self, f: &Foo, b: &'other Bar) -> X<'a>"#, ); } #[test] fn test_function_add_lifetime_to_param_with_non_ref_self() { check_assist( introduce_named_lifetime, r#"fn my_fun<'other>(self, f: &Foo, b: &'other Bar) -> X<'_<|>>"#, r#"fn my_fun<'other, 'a>(self, f: &'a Foo, b: &'other Bar) -> X<'a>"#, ); } }