use ra_syntax::{ ast::{self, AstNode}, SyntaxKind::{ BLOCK_EXPR, BREAK_EXPR, COMMENT, LAMBDA_EXPR, LOOP_EXPR, MATCH_ARM, PATH_EXPR, RETURN_EXPR, WHITESPACE, }, SyntaxNode, TextUnit, }; use stdx::format_to; use test_utils::tested_by; use crate::{Assist, AssistCtx, AssistId}; // Assist: introduce_variable // // Extracts subexpression into a variable. // // ``` // fn main() { // <|>(1 + 2)<|> * 4; // } // ``` // -> // ``` // fn main() { // let var_name = (1 + 2); // var_name * 4; // } // ``` pub(crate) fn introduce_variable(ctx: AssistCtx) -> Option<Assist> { if ctx.frange.range.is_empty() { return None; } let node = ctx.covering_element(); if node.kind() == COMMENT { tested_by!(introduce_var_in_comment_is_not_applicable); return None; } let expr = node.ancestors().find_map(valid_target_expr)?; let (anchor_stmt, wrap_in_block) = anchor_stmt(expr.clone())?; let indent = anchor_stmt.prev_sibling_or_token()?.as_token()?.clone(); if indent.kind() != WHITESPACE { return None; } ctx.add_assist(AssistId("introduce_variable"), "Extract into variable", move |edit| { let mut buf = String::new(); let cursor_offset = if wrap_in_block { buf.push_str("{ let var_name = "); TextUnit::of_str("{ let ") } else { buf.push_str("let var_name = "); TextUnit::of_str("let ") }; format_to!(buf, "{}", expr.syntax()); let full_stmt = ast::ExprStmt::cast(anchor_stmt.clone()); let is_full_stmt = if let Some(expr_stmt) = &full_stmt { Some(expr.syntax().clone()) == expr_stmt.expr().map(|e| e.syntax().clone()) } else { false }; if is_full_stmt { tested_by!(test_introduce_var_expr_stmt); if !full_stmt.unwrap().has_semi() { buf.push_str(";"); } edit.replace(expr.syntax().text_range(), buf); } else { buf.push_str(";"); // We want to maintain the indent level, // but we do not want to duplicate possible // extra newlines in the indent block let text = indent.text(); if text.starts_with('\n') { buf.push_str("\n"); buf.push_str(text.trim_start_matches('\n')); } else { buf.push_str(text); } edit.target(expr.syntax().text_range()); edit.replace(expr.syntax().text_range(), "var_name".to_string()); edit.insert(anchor_stmt.text_range().start(), buf); if wrap_in_block { edit.insert(anchor_stmt.text_range().end(), " }"); } } edit.set_cursor(anchor_stmt.text_range().start() + cursor_offset); }) } /// Check whether the node is a valid expression which can be extracted to a variable. /// In general that's true for any expression, but in some cases that would produce invalid code. fn valid_target_expr(node: SyntaxNode) -> Option<ast::Expr> { match node.kind() { PATH_EXPR | LOOP_EXPR => None, BREAK_EXPR => ast::BreakExpr::cast(node).and_then(|e| e.expr()), RETURN_EXPR => ast::ReturnExpr::cast(node).and_then(|e| e.expr()), BLOCK_EXPR => { ast::BlockExpr::cast(node).filter(|it| it.is_standalone()).map(ast::Expr::from) } _ => ast::Expr::cast(node), } } /// Returns the syntax node which will follow the freshly introduced var /// and a boolean indicating whether we have to wrap it within a { } block /// to produce correct code. /// It can be a statement, the last in a block expression or a wanna be block /// expression like a lambda or match arm. fn anchor_stmt(expr: ast::Expr) -> Option<(SyntaxNode, bool)> { expr.syntax().ancestors().find_map(|node| { if let Some(expr) = node.parent().and_then(ast::Block::cast).and_then(|it| it.expr()) { if expr.syntax() == &node { tested_by!(test_introduce_var_last_expr); return Some((node, false)); } } if let Some(parent) = node.parent() { if parent.kind() == MATCH_ARM || parent.kind() == LAMBDA_EXPR { return Some((node, true)); } } if ast::Stmt::cast(node.clone()).is_some() { return Some((node, false)); } None }) } #[cfg(test)] mod tests { use test_utils::covers; use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target}; use super::*; #[test] fn test_introduce_var_simple() { check_assist( introduce_variable, " fn foo() { foo(<|>1 + 1<|>); }", " fn foo() { let <|>var_name = 1 + 1; foo(var_name); }", ); } #[test] fn introduce_var_in_comment_is_not_applicable() { covers!(introduce_var_in_comment_is_not_applicable); check_assist_not_applicable(introduce_variable, "fn main() { 1 + /* <|>comment<|> */ 1; }"); } #[test] fn test_introduce_var_expr_stmt() { covers!(test_introduce_var_expr_stmt); check_assist( introduce_variable, " fn foo() { <|>1 + 1<|>; }", " fn foo() { let <|>var_name = 1 + 1; }", ); check_assist( introduce_variable, " fn foo() { <|>{ let x = 0; x }<|> something_else(); }", " fn foo() { let <|>var_name = { let x = 0; x }; something_else(); }", ); } #[test] fn test_introduce_var_part_of_expr_stmt() { check_assist( introduce_variable, " fn foo() { <|>1<|> + 1; }", " fn foo() { let <|>var_name = 1; var_name + 1; }", ); } #[test] fn test_introduce_var_last_expr() { covers!(test_introduce_var_last_expr); check_assist( introduce_variable, " fn foo() { bar(<|>1 + 1<|>) }", " fn foo() { let <|>var_name = 1 + 1; bar(var_name) }", ); check_assist( introduce_variable, " fn foo() { <|>bar(1 + 1)<|> }", " fn foo() { let <|>var_name = bar(1 + 1); var_name }", ) } #[test] fn test_introduce_var_in_match_arm_no_block() { check_assist( introduce_variable, " fn main() { let x = true; let tuple = match x { true => (<|>2 + 2<|>, true) _ => (0, false) }; } ", " fn main() { let x = true; let tuple = match x { true => { let <|>var_name = 2 + 2; (var_name, true) } _ => (0, false) }; } ", ); } #[test] fn test_introduce_var_in_match_arm_with_block() { check_assist( introduce_variable, " fn main() { let x = true; let tuple = match x { true => { let y = 1; (<|>2 + y<|>, true) } _ => (0, false) }; } ", " fn main() { let x = true; let tuple = match x { true => { let y = 1; let <|>var_name = 2 + y; (var_name, true) } _ => (0, false) }; } ", ); } #[test] fn test_introduce_var_in_closure_no_block() { check_assist( introduce_variable, " fn main() { let lambda = |x: u32| <|>x * 2<|>; } ", " fn main() { let lambda = |x: u32| { let <|>var_name = x * 2; var_name }; } ", ); } #[test] fn test_introduce_var_in_closure_with_block() { check_assist( introduce_variable, " fn main() { let lambda = |x: u32| { <|>x * 2<|> }; } ", " fn main() { let lambda = |x: u32| { let <|>var_name = x * 2; var_name }; } ", ); } #[test] fn test_introduce_var_path_simple() { check_assist( introduce_variable, " fn main() { let o = <|>Some(true)<|>; } ", " fn main() { let <|>var_name = Some(true); let o = var_name; } ", ); } #[test] fn test_introduce_var_path_method() { check_assist( introduce_variable, " fn main() { let v = <|>bar.foo()<|>; } ", " fn main() { let <|>var_name = bar.foo(); let v = var_name; } ", ); } #[test] fn test_introduce_var_return() { check_assist( introduce_variable, " fn foo() -> u32 { <|>return 2 + 2<|>; } ", " fn foo() -> u32 { let <|>var_name = 2 + 2; return var_name; } ", ); } #[test] fn test_introduce_var_does_not_add_extra_whitespace() { check_assist( introduce_variable, " fn foo() -> u32 { <|>return 2 + 2<|>; } ", " fn foo() -> u32 { let <|>var_name = 2 + 2; return var_name; } ", ); check_assist( introduce_variable, " fn foo() -> u32 { <|>return 2 + 2<|>; } ", " fn foo() -> u32 { let <|>var_name = 2 + 2; return var_name; } ", ); check_assist( introduce_variable, " fn foo() -> u32 { let foo = 1; // bar <|>return 2 + 2<|>; } ", " fn foo() -> u32 { let foo = 1; // bar let <|>var_name = 2 + 2; return var_name; } ", ); } #[test] fn test_introduce_var_break() { check_assist( introduce_variable, " fn main() { let result = loop { <|>break 2 + 2<|>; }; } ", " fn main() { let result = loop { let <|>var_name = 2 + 2; break var_name; }; } ", ); } #[test] fn test_introduce_var_for_cast() { check_assist( introduce_variable, " fn main() { let v = <|>0f32 as u32<|>; } ", " fn main() { let <|>var_name = 0f32 as u32; let v = var_name; } ", ); } #[test] fn test_introduce_var_for_return_not_applicable() { check_assist_not_applicable(introduce_variable, "fn foo() { <|>return<|>; } "); } #[test] fn test_introduce_var_for_break_not_applicable() { check_assist_not_applicable(introduce_variable, "fn main() { loop { <|>break<|>; }; }"); } // FIXME: This is not quite correct, but good enough(tm) for the sorting heuristic #[test] fn introduce_var_target() { check_assist_target(introduce_variable, "fn foo() -> u32 { <|>return 2 + 2<|>; }", "2 + 2"); check_assist_target( introduce_variable, " fn main() { let x = true; let tuple = match x { true => (<|>2 + 2<|>, true) _ => (0, false) }; } ", "2 + 2", ); } }