use ra_syntax::{ ast::{self, edit::AstNodeEdit, make, AstNode, NameOwner, TypeBoundsOwner}, SyntaxElement, SyntaxKind::*, }; 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: SyntaxElement = match parent.kind() { FN_DEF => ast::FnDef::cast(parent)?.body()?.syntax().clone().into(), TRAIT_DEF => ast::TraitDef::cast(parent)?.item_list()?.syntax().clone().into(), IMPL_DEF => ast::ImplDef::cast(parent)?.item_list()?.syntax().clone().into(), ENUM_DEF => ast::EnumDef::cast(parent)?.variant_list()?.syntax().clone().into(), STRUCT_DEF => parent .children_with_tokens() .find(|it| it.kind() == RECORD_FIELD_DEF_LIST || it.kind() == SEMI)?, _ => return None, }; ctx.add_assist(AssistId("move_bounds_to_where_clause"), "Move to where clause", |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); edit.target(type_param_list.syntax().text_range()); }) } 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::helpers::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; "#, ); } }