use hir::db::HirDatabase; use ra_syntax::{ ast::{self, AstNode}, SyntaxKind::{ WHITESPACE, MATCH_ARM, LAMBDA_EXPR, PATH_EXPR, BREAK_EXPR, LOOP_EXPR, RETURN_EXPR, COMMENT }, SyntaxNode, TextUnit, }; use crate::{AssistCtx, Assist}; pub(crate) fn introduce_variable(ctx: AssistCtx) -> Option { let node = ctx.covering_node(); if !valid_covering_node(node) { return None; } let expr = node.ancestors().filter_map(valid_target_expr).next()?; let (anchor_stmt, wrap_in_block) = anchor_stmt(expr)?; let indent = anchor_stmt.prev_sibling()?; if indent.kind() != WHITESPACE { return None; } ctx.build("introduce 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 ") }; expr.syntax().text().push_to(&mut buf); let full_stmt = ast::ExprStmt::cast(anchor_stmt); let is_full_stmt = if let Some(expr_stmt) = full_stmt { Some(expr.syntax()) == expr_stmt.expr().map(|e| e.syntax()) } else { false }; if is_full_stmt { if !full_stmt.unwrap().has_semi() { buf.push_str(";"); } edit.replace(expr.syntax().range(), buf); } else { buf.push_str(";"); indent.text().push_to(&mut buf); edit.target(expr.syntax().range()); edit.replace(expr.syntax().range(), "var_name".to_string()); edit.insert(anchor_stmt.range().start(), buf); if wrap_in_block { edit.insert(anchor_stmt.range().end(), " }"); } } edit.set_cursor(anchor_stmt.range().start() + cursor_offset); }) } fn valid_covering_node(node: &SyntaxNode) -> bool { node.kind() != COMMENT } /// 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 => None, BREAK_EXPR => ast::BreakExpr::cast(node).and_then(|e| e.expr()), RETURN_EXPR => ast::ReturnExpr::cast(node).and_then(|e| e.expr()), LOOP_EXPR => ast::ReturnExpr::cast(node).and_then(|e| e.expr()), _ => 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 ast::Stmt::cast(node).is_some() { return Some((node, false)); } if let Some(expr) = node.parent().and_then(ast::Block::cast).and_then(|it| it.expr()) { if expr.syntax() == node { return Some((node, false)); } } if let Some(parent) = node.parent() { if parent.kind() == MATCH_ARM || parent.kind() == LAMBDA_EXPR { return Some((node, true)); } } None }) } #[cfg(test)] mod tests { use super::*; use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_range, check_assist_target, check_assist_range_target}; #[test] fn test_introduce_var_simple() { check_assist_range( introduce_variable, " fn foo() { foo(<|>1 + 1<|>); }", " fn foo() { let <|>var_name = 1 + 1; foo(var_name); }", ); } #[test] fn test_introduce_var_expr_stmt() { check_assist_range( introduce_variable, " fn foo() { <|>1 + 1<|>; }", " fn foo() { let <|>var_name = 1 + 1; }", ); } #[test] fn test_introduce_var_part_of_expr_stmt() { check_assist_range( introduce_variable, " fn foo() { <|>1<|> + 1; }", " fn foo() { let <|>var_name = 1; var_name + 1; }", ); } #[test] fn test_introduce_var_last_expr() { check_assist_range( introduce_variable, " fn foo() { bar(<|>1 + 1<|>) }", " fn foo() { let <|>var_name = 1 + 1; bar(var_name) }", ); } #[test] fn test_introduce_var_last_full_expr() { check_assist_range( introduce_variable, " fn foo() { <|>bar(1 + 1)<|> }", " fn foo() { let <|>var_name = bar(1 + 1); var_name }", ); } #[test] fn test_introduce_var_block_expr_second_to_last() { check_assist_range( 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_in_match_arm_no_block() { check_assist_range( 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_range( 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_range( 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_range( 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 = S<|>ome(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 = b<|>ar.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 { r<|>eturn 2 + 2; } ", " fn foo() -> u32 { let <|>var_name = 2 + 2; return var_name; } ", ); } #[test] fn test_introduce_var_break() { check_assist( introduce_variable, " fn main() { let result = loop { b<|>reak 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 a<|>s 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() { r<|>eturn; } ", ); } #[test] fn test_introduce_var_for_break_not_applicable() { check_assist_not_applicable( introduce_variable, " fn main() { loop { b<|>reak; }; } ", ); } #[test] fn test_introduce_var_in_comment_not_applicable() { check_assist_not_applicable( introduce_variable, " fn main() { let x = true; let tuple = match x { // c<|>omment true => (2 + 2, true) _ => (0, false) }; } ", ); } // 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 { r<|>eturn 2 + 2; } ", "2 + 2", ); check_assist_range_target( introduce_variable, " fn main() { let x = true; let tuple = match x { true => (<|>2 + 2<|>, true) _ => (0, false) }; } ", "2 + 2", ); } }