| use std::iter::once; |
| |
| use ra_syntax::{ |
| ast::{ |
| self, |
| edit::{AstNodeEdit, IndentLevel}, |
| make, |
| }, |
| AstNode, T, |
| }; |
| |
| use crate::{utils::TryEnum, AssistContext, AssistId, AssistKind, Assists}; |
| |
| // Assist: replace_let_with_if_let |
| // |
| // Replaces `let` with an `if-let`. |
| // |
| // ``` |
| // # enum Option<T> { Some(T), None } |
| // |
| // fn main(action: Action) { |
| // <|>let x = compute(); |
| // } |
| // |
| // fn compute() -> Option<i32> { None } |
| // ``` |
| // -> |
| // ``` |
| // # enum Option<T> { Some(T), None } |
| // |
| // fn main(action: Action) { |
| // if let Some(x) = compute() { |
| // } |
| // } |
| // |
| // fn compute() -> Option<i32> { None } |
| // ``` |
| pub(crate) fn replace_let_with_if_let(acc: &mut Assists, ctx: &AssistContext) -> Option<()> { |
| let let_kw = ctx.find_token_at_offset(T![let])?; |
| let let_stmt = let_kw.ancestors().find_map(ast::LetStmt::cast)?; |
| let init = let_stmt.initializer()?; |
| let original_pat = let_stmt.pat()?; |
| let ty = ctx.sema.type_of_expr(&init)?; |
| let happy_variant = TryEnum::from_ty(&ctx.sema, &ty).map(|it| it.happy_case()); |
| |
| let target = let_kw.text_range(); |
| acc.add( |
| AssistId("replace_let_with_if_let", AssistKind::RefactorRewrite), |
| "Replace with if-let", |
| target, |
| |edit| { |
| let with_placeholder: ast::Pat = match happy_variant { |
| None => make::placeholder_pat().into(), |
| Some(var_name) => make::tuple_struct_pat( |
| make::path_unqualified(make::path_segment(make::name_ref(var_name))), |
| once(make::placeholder_pat().into()), |
| ) |
| .into(), |
| }; |
| let block = |
| make::block_expr(None, None).indent(IndentLevel::from_node(let_stmt.syntax())); |
| let if_ = make::expr_if(make::condition(init, Some(with_placeholder)), block); |
| let stmt = make::expr_stmt(if_); |
| |
| let placeholder = |
| stmt.syntax().descendants().find_map(ast::PlaceholderPat::cast).unwrap(); |
| let stmt = stmt.replace_descendant(placeholder.into(), original_pat); |
| |
| edit.replace_ast(ast::Stmt::from(let_stmt), ast::Stmt::from(stmt)); |
| }, |
| ) |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use crate::tests::check_assist; |
| |
| use super::*; |
| |
| #[test] |
| fn replace_let_unknown_enum() { |
| check_assist( |
| replace_let_with_if_let, |
| r" |
| enum E<T> { X(T), Y(T) } |
| |
| fn main() { |
| <|>let x = E::X(92); |
| } |
| ", |
| r" |
| enum E<T> { X(T), Y(T) } |
| |
| fn main() { |
| if let x = E::X(92) { |
| } |
| } |
| ", |
| ) |
| } |
| } |