6 BLOCK_EXPR, BREAK_EXPR, CLOSURE_EXPR, COMMENT, LOOP_EXPR, MATCH_ARM, MATCH_GUARD,
7 PATH_EXPR, RETURN_EXPR,
12 use crate::{utils::suggest_name, AssistContext, AssistId, AssistKind, Assists};
14 // Assist: extract_variable
16 // Extracts subexpression into a variable.
26 // let $0var_name = (1 + 2);
30 pub(crate) fn extract_variable(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
31 if ctx.has_empty_selection() {
35 let node = match ctx.covering_element() {
36 NodeOrToken::Node(it) => it,
37 NodeOrToken::Token(it) if it.kind() == COMMENT => {
38 cov_mark::hit!(extract_var_in_comment_is_not_applicable);
41 NodeOrToken::Token(it) => it.parent()?,
43 let node = node.ancestors().take_while(|anc| anc.text_range() == node.text_range()).last()?;
46 .take_while(|it| ctx.selection_trimmed().contains_range(it.text_range()))
47 .find_map(valid_target_expr)?;
49 if let Some(ty_info) = ctx.sema.type_of_expr(&to_extract) {
50 if ty_info.adjusted().is_unit() {
55 let is_mutable_reference = if let Some(receiver_type) = get_receiver_type(&ctx, &to_extract) {
56 receiver_type.is_mutable_reference()
61 let anchor = Anchor::from(&to_extract)?;
62 let indent = anchor.syntax().prev_sibling_or_token()?.as_token()?.clone();
63 let target = to_extract.syntax().text_range();
65 AssistId("extract_variable", AssistKind::RefactorExtract),
66 "Extract into variable",
70 match to_extract.syntax().parent().and_then(ast::RecordExprField::cast) {
71 Some(field) => field.name_ref(),
75 let mut buf = String::new();
77 let var_name = match &field_shorthand {
78 Some(it) => it.to_string(),
79 None => suggest_name::for_variable(&to_extract, &ctx.sema),
81 let expr_range = match &field_shorthand {
82 Some(it) => it.syntax().text_range().cover(to_extract.syntax().text_range()),
83 None => to_extract.syntax().text_range(),
86 let reference_modifier = if is_mutable_reference { "&mut " } else { "" };
89 Anchor::Before(_) | Anchor::Replace(_) => {
90 format_to!(buf, "let {} = {}", var_name, reference_modifier)
92 Anchor::WrapInBlock(_) => {
93 format_to!(buf, "{{ let {} = {}", var_name, reference_modifier)
96 format_to!(buf, "{}", to_extract.syntax());
98 if let Anchor::Replace(stmt) = anchor {
99 cov_mark::hit!(test_extract_var_expr_stmt);
100 if stmt.semicolon_token().is_none() {
103 match ctx.config.snippet_cap {
106 .replace(&format!("let {}", var_name), &format!("let $0{}", var_name));
107 edit.replace_snippet(cap, expr_range, snip)
109 None => edit.replace(expr_range, buf),
116 // We want to maintain the indent level,
117 // but we do not want to duplicate possible
118 // extra newlines in the indent block
119 let text = indent.text();
120 if text.starts_with('\n') {
122 buf.push_str(text.trim_start_matches('\n'));
127 edit.replace(expr_range, var_name.clone());
128 let offset = anchor.syntax().text_range().start();
129 match ctx.config.snippet_cap {
132 buf.replace(&format!("let {}", var_name), &format!("let $0{}", var_name));
133 edit.insert_snippet(cap, offset, snip)
135 None => edit.insert(offset, buf),
138 if let Anchor::WrapInBlock(_) = anchor {
139 edit.insert(anchor.syntax().text_range().end(), " }");
145 /// Check whether the node is a valid expression which can be extracted to a variable.
146 /// In general that's true for any expression, but in some cases that would produce invalid code.
147 fn valid_target_expr(node: SyntaxNode) -> Option<ast::Expr> {
149 PATH_EXPR | LOOP_EXPR => None,
150 BREAK_EXPR => ast::BreakExpr::cast(node).and_then(|e| e.expr()),
151 RETURN_EXPR => ast::ReturnExpr::cast(node).and_then(|e| e.expr()),
153 ast::BlockExpr::cast(node).filter(|it| it.is_standalone()).map(ast::Expr::from)
155 _ => ast::Expr::cast(node),
159 fn get_receiver_type(ctx: &AssistContext, expression: &ast::Expr) -> Option<hir::Type> {
160 let receiver = get_receiver(expression.to_owned())?;
161 Some(ctx.sema.type_of_expr(&receiver)?.original())
164 fn get_receiver(expression: ast::Expr) -> Option<ast::Expr> {
166 ast::Expr::FieldExpr(field) if field.expr().is_some() => {
167 let nested_expression = &field.expr()?;
168 get_receiver(nested_expression.to_owned())
170 ast::Expr::PathExpr(_) => Some(expression),
178 Replace(ast::ExprStmt),
179 WrapInBlock(SyntaxNode),
183 fn from(to_extract: &ast::Expr) -> Option<Anchor> {
187 .take_while(|it| !ast::Item::can_cast(it.kind()) || ast::MacroCall::can_cast(it.kind()))
189 if ast::MacroCall::can_cast(node.kind()) {
193 node.parent().and_then(ast::StmtList::cast).and_then(|it| it.tail_expr())
195 if expr.syntax() == &node {
196 cov_mark::hit!(test_extract_var_last_expr);
197 return Some(Anchor::Before(node));
201 if let Some(parent) = node.parent() {
202 if parent.kind() == CLOSURE_EXPR {
203 cov_mark::hit!(test_extract_var_in_closure_no_block);
204 return Some(Anchor::WrapInBlock(node));
206 if parent.kind() == MATCH_ARM {
207 if node.kind() == MATCH_GUARD {
208 cov_mark::hit!(test_extract_var_in_match_guard);
210 cov_mark::hit!(test_extract_var_in_match_arm_no_block);
211 return Some(Anchor::WrapInBlock(node));
216 if let Some(stmt) = ast::Stmt::cast(node.clone()) {
217 if let ast::Stmt::ExprStmt(stmt) = stmt {
218 if stmt.expr().as_ref() == Some(to_extract) {
219 return Some(Anchor::Replace(stmt));
222 return Some(Anchor::Before(node));
228 fn syntax(&self) -> &SyntaxNode {
230 Anchor::Before(it) | Anchor::WrapInBlock(it) => it,
231 Anchor::Replace(stmt) => stmt.syntax(),
238 use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
243 fn test_extract_var_simple() {
252 let $0var_name = 1 + 1;
259 fn extract_var_in_comment_is_not_applicable() {
260 cov_mark::check!(extract_var_in_comment_is_not_applicable);
261 check_assist_not_applicable(extract_variable, "fn main() { 1 + /* $0comment$0 */ 1; }");
265 fn test_extract_var_expr_stmt() {
266 cov_mark::check!(test_extract_var_expr_stmt);
275 let $0var_name = 1 + 1;
287 let $0var_name = { let x = 0; x };
294 fn test_extract_var_part_of_expr_stmt() {
310 fn test_extract_var_last_expr() {
311 cov_mark::check!(test_extract_var_last_expr);
321 let $0var_name = 1 + 1;
333 fn bar(i: i32) -> i32 {
339 let $0bar = bar(1 + 1);
343 fn bar(i: i32) -> i32 {
351 fn test_extract_var_in_match_arm_no_block() {
352 cov_mark::check!(test_extract_var_in_match_arm_no_block);
358 let tuple = match x {
359 true => ($02 + 2$0, true)
367 let tuple = match x {
368 true => { let $0var_name = 2 + 2; (var_name, true) }
377 fn test_extract_var_in_match_arm_with_block() {
383 let tuple = match x {
395 let tuple = match x {
398 let $0var_name = 2 + y;
409 fn test_extract_var_in_match_guard() {
410 cov_mark::check!(test_extract_var_in_match_guard);
416 () if $010 > 0$0 => 1
423 let $0var_name = 10 > 0;
434 fn test_extract_var_in_closure_no_block() {
435 cov_mark::check!(test_extract_var_in_closure_no_block);
440 let lambda = |x: u32| $0x * 2$0;
445 let lambda = |x: u32| { let $0var_name = x * 2; var_name };
452 fn test_extract_var_in_closure_with_block() {
457 let lambda = |x: u32| { $0x * 2$0 };
462 let lambda = |x: u32| { let $0var_name = x * 2; var_name };
469 fn test_extract_var_path_simple() {
474 let o = $0Some(true)$0;
479 let $0var_name = Some(true);
487 fn test_extract_var_path_method() {
492 let v = $0bar.foo()$0;
497 let $0foo = bar.foo();
505 fn test_extract_var_return() {
515 let $0var_name = 2 + 2;
523 fn test_extract_var_does_not_add_extra_whitespace() {
537 let $0var_name = 2 + 2;
554 let $0var_name = 2 + 2;
579 let $0var_name = 2 + 2;
587 fn test_extract_var_break() {
600 let $0var_name = 2 + 2;
609 fn test_extract_var_for_cast() {
614 let v = $00f32 as u32$0;
619 let $0var_name = 0f32 as u32;
627 fn extract_var_field_shorthand() {
653 fn extract_var_name_from_type() {
667 let $0test = { Test(10) };
675 fn extract_var_name_from_parameter() {
679 fn bar(test: u32, size: u32)
686 fn bar(test: u32, size: u32)
697 fn extract_var_parameter_name_has_precedence_over_type() {
701 struct TextSize(u32);
702 fn bar(test: u32, size: TextSize)
705 bar(1, $0{ TextSize(1+1) }$0);
709 struct TextSize(u32);
710 fn bar(test: u32, size: TextSize)
713 let $0size = { TextSize(1+1) };
721 fn extract_var_name_from_function() {
725 fn is_required(test: u32, size: u32) -> bool
728 $0is_required(1, 2)$0
732 fn is_required(test: u32, size: u32) -> bool
735 let $0is_required = is_required(1, 2);
743 fn extract_var_name_from_method() {
749 fn bar(&self, n: u32) -> u32 { n }
759 fn bar(&self, n: u32) -> u32 { n }
763 let $0bar = S.bar(1);
771 fn extract_var_name_from_method_param() {
777 fn bar(&self, n: u32, size: u32) { n }
787 fn bar(&self, n: u32, size: u32) { n }
799 fn extract_var_name_from_ufcs_method_param() {
805 fn bar(&self, n: u32, size: u32) { n }
809 S::bar(&S, $01 + 1$0, 2)
815 fn bar(&self, n: u32, size: u32) { n }
827 fn extract_var_parameter_name_has_precedence_over_function() {
831 fn bar(test: u32, size: u32)
834 bar(1, $0symbol_size(1, 2)$0);
838 fn bar(test: u32, size: u32)
841 let $0size = symbol_size(1, 2);
849 fn extract_macro_call() {
875 fn test_extract_var_for_return_not_applicable() {
876 check_assist_not_applicable(extract_variable, "fn foo() { $0return$0; } ");
880 fn test_extract_var_for_break_not_applicable() {
881 check_assist_not_applicable(extract_variable, "fn main() { loop { $0break$0; }; }");
885 fn test_extract_var_unit_expr_not_applicable() {
886 check_assist_not_applicable(
900 // FIXME: This is not quite correct, but good enough(tm) for the sorting heuristic
902 fn extract_var_target() {
903 check_assist_target(extract_variable, "fn foo() -> u32 { $0return 2 + 2$0; }", "2 + 2");
910 let tuple = match x {
911 true => ($02 + 2$0, true)
921 fn extract_var_no_block_body() {
922 check_assist_not_applicable(
925 const X: usize = $0100$0;
931 fn test_extract_var_mutable_reference_parameter() {
948 let $0var_name = &mut s.vec;
955 fn test_extract_var_mutable_reference_parameter_deep_nesting() {
970 $0f.field.field.vec$0.push(0);
984 let $0var_name = &mut f.field.field.vec;