use ra_syntax::{ ast::{self, edit::AstNodeEdit, make, AstNode, NameOwner, TypeBoundsOwner}, match_ast, SyntaxKind::*, T, }; use crate::{Assist, AssistCtx, AssistId}; // Assist: move_bounds_to_where_clause // // Moves inline type bounds to a where clause. // // ``` // fn applyF: FnOnce(T) -> U>(f: F, x: T) -> U { // f(x) // } // ``` // -> // ``` // fn apply(f: F, x: T) -> U where F: FnOnce(T) -> U { // f(x) // } // ``` pub(crate) fn move_bounds_to_where_clause(ctx: AssistCtx) -> Option { let type_param_list = ctx.find_node_at_offset::()?; let mut type_params = type_param_list.type_params(); if type_params.all(|p| p.type_bound_list().is_none()) { return None; } let parent = type_param_list.syntax().parent()?; if parent.children_with_tokens().any(|it| it.kind() == WHERE_CLAUSE) { return None; } let anchor = match_ast! { match parent { ast::FnDef(it) => it.body()?.syntax().clone().into(), ast::TraitDef(it) => it.item_list()?.syntax().clone().into(), ast::ImplDef(it) => it.item_list()?.syntax().clone().into(), ast::EnumDef(it) => it.variant_list()?.syntax().clone().into(), ast::StructDef(it) => { it.syntax().children_with_tokens() .find(|it| it.kind() == RECORD_FIELD_DEF_LIST || it.kind() == T![;])? }, _ => return None } }; let target = type_param_list.syntax().text_range(); ctx.add_assist( AssistId("move_bounds_to_where_clause"), "Move to where clause", target, |edit| { let new_params = type_param_list .type_params() .filter(|it| it.type_bound_list().is_some()) .map(|type_param| { let without_bounds = type_param.remove_bounds(); (type_param, without_bounds) }); let new_type_param_list = type_param_list.replace_descendants(new_params); edit.replace_ast(type_param_list.clone(), new_type_param_list); let where_clause = { let predicates = type_param_list.type_params().filter_map(build_predicate); make::where_clause(predicates) }; let to_insert = match anchor.prev_sibling_or_token() { Some(ref elem) if elem.kind() == WHITESPACE => { format!("{} ", where_clause.syntax()) } _ => format!(" {}", where_clause.syntax()), }; edit.insert(anchor.text_range().start(), to_insert); }, ) } fn build_predicate(param: ast::TypeParam) -> Option { let path = { let name_ref = make::name_ref(¶m.name()?.syntax().to_string()); let segment = make::path_segment(name_ref); make::path_unqualified(segment) }; let predicate = make::where_pred(path, param.type_bound_list()?.bounds()); Some(predicate) } #[cfg(test)] mod tests { use super::*; use crate::tests::check_assist; #[test] fn move_bounds_to_where_clause_fn() { check_assist( move_bounds_to_where_clause, r#" fn fooF: FnOnce(T) -> T>() {} "#, r#" fn fooF>() where T: u32, F: FnOnce(T) -> T {} "#, ); } #[test] fn move_bounds_to_where_clause_impl() { check_assist( move_bounds_to_where_clause, r#" implT> A {} "#, r#" implT> A where U: u32 {} "#, ); } #[test] fn move_bounds_to_where_clause_struct() { check_assist( move_bounds_to_where_clause, r#" struct A<<|>T: Iterator> {} "#, r#" struct A<<|>T> where T: Iterator {} "#, ); } #[test] fn move_bounds_to_where_clause_tuple_struct() { check_assist( move_bounds_to_where_clause, r#" struct Pair<<|>T: u32>(T, T); "#, r#" struct Pair<<|>T>(T, T) where T: u32; "#, ); } }