use itertools::{Itertools, chain}; use syntax::{ SyntaxKind::WHITESPACE, TextRange, ast::{ AstNode, BlockExpr, ElseBranch, Expr, IfExpr, MatchArm, Pat, edit::AstNodeEdit, make, prec::ExprPrecedence, syntax_factory::SyntaxFactory, }, syntax_editor::Element, }; use crate::{AssistContext, AssistId, Assists}; // Assist: move_guard_to_arm_body // // Moves match guard into match arm body. // // ``` // enum Action { Move { distance: u32 }, Stop } // // fn handle(action: Action) { // match action { // Action::Move { distance } $0if distance > 10 => foo(), // _ => (), // } // } // ``` // -> // ``` // enum Action { Move { distance: u32 }, Stop } // // fn handle(action: Action) { // match action { // Action::Move { distance } => if distance > 10 { // foo() // }, // _ => (), // } // } // ``` pub(crate) fn move_guard_to_arm_body(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> { let match_arm = ctx.find_node_at_offset::()?; let guard = match_arm.guard()?; if ctx.offset() > guard.syntax().text_range().end() { cov_mark::hit!(move_guard_inapplicable_in_arm_body); return None; } let rest_arms = rest_arms(&match_arm, ctx.selection_trimmed())?; let space_before_delete = chain( guard.syntax().prev_sibling_or_token(), rest_arms.iter().filter_map(|it| it.syntax().prev_sibling_or_token()), ); let space_after_arrow = match_arm.fat_arrow_token()?.next_sibling_or_token(); let arm_expr = match_arm.expr()?; let if_branch = chain([&match_arm], &rest_arms) .rfold(None, |else_branch, arm| { if let Some(guard) = arm.guard() { let then_branch = crate::utils::wrap_block(&arm.expr()?); let guard_condition = guard.condition()?.reset_indent(); Some(make::expr_if(guard_condition, then_branch, else_branch).into()) } else { arm.expr().map(|it| crate::utils::wrap_block(&it).into()) } })? .indent(arm_expr.indent_level()); let ElseBranch::IfExpr(if_expr) = if_branch else { return None }; let target = guard.syntax().text_range(); acc.add( AssistId::refactor_rewrite("move_guard_to_arm_body"), "Move guard to arm body", target, |builder| { let mut edit = builder.make_editor(match_arm.syntax()); for element in space_before_delete { if element.kind() == WHITESPACE { edit.delete(element); } } for rest_arm in &rest_arms { edit.delete(rest_arm.syntax()); } if let Some(element) = space_after_arrow && element.kind() == WHITESPACE { edit.replace(element, make::tokens::single_space()); } edit.delete(guard.syntax()); edit.replace(arm_expr.syntax(), if_expr.syntax()); builder.add_file_edits(ctx.vfs_file_id(), edit); }, ) } // Assist: move_arm_cond_to_match_guard // // Moves if expression from match arm body into a guard. // // ``` // enum Action { Move { distance: u32 }, Stop } // // fn handle(action: Action) { // match action { // Action::Move { distance } => $0if distance > 10 { foo() }, // _ => (), // } // } // ``` // -> // ``` // enum Action { Move { distance: u32 }, Stop } // // fn handle(action: Action) { // match action { // Action::Move { distance } if distance > 10 => foo(), // _ => (), // } // } // ``` pub(crate) fn move_arm_cond_to_match_guard( acc: &mut Assists, ctx: &AssistContext<'_>, ) -> Option<()> { let match_arm: MatchArm = ctx.find_node_at_offset::()?; let match_pat = match_arm.pat()?; let arm_body = match_arm.expr()?; let arm_guard = match_arm.guard().and_then(|it| it.condition()); let mut replace_node = None; let if_expr: IfExpr = IfExpr::cast(arm_body.syntax().clone()).or_else(|| { let block_expr = BlockExpr::cast(arm_body.syntax().clone())?; if block_expr.statements().next().is_some() { cov_mark::hit!(move_guard_non_naked_if); return None; } if let Expr::IfExpr(e) = block_expr.tail_expr()? { replace_node = Some(block_expr.syntax().clone()); Some(e) } else { None } })?; if ctx.offset() > if_expr.then_branch()?.syntax().text_range().start() { return None; } let replace_node = replace_node.unwrap_or_else(|| if_expr.syntax().clone()); let needs_dedent = replace_node != *if_expr.syntax(); let (conds_blocks, tail) = parse_if_chain(if_expr)?; acc.add( AssistId::refactor_rewrite("move_arm_cond_to_match_guard"), "Move condition to match guard", replace_node.text_range(), |builder| { let make = SyntaxFactory::without_mappings(); let mut replace_arms = vec![]; // Dedent if if_expr is in a BlockExpr let dedent = if needs_dedent { cov_mark::hit!(move_guard_ifelse_in_block); 1 } else { cov_mark::hit!(move_guard_ifelse_else_block); 0 }; let indent_level = match_arm.indent_level(); let make_guard = |cond: Option| { let condition = match (arm_guard.clone(), cond) { (None, None) => return None, (None, Some(it)) | (Some(it), None) => it, (Some(lhs), Some(rhs)) => { let op_expr = |expr: Expr| { if expr.precedence().needs_parentheses_in(ExprPrecedence::LAnd) { make.expr_paren(expr).into() } else { expr } }; let op = syntax::ast::BinaryOp::LogicOp(syntax::ast::LogicOp::And); let expr_bin = make.expr_bin(op_expr(lhs), op, op_expr(rhs)); expr_bin.into() } }; Some(make.match_guard(condition)) }; for (cond, block) in conds_blocks { let only_expr = block.statements().next().is_none(); let expr = match block.tail_expr() { Some(then_expr) if only_expr => then_expr, _ => block.dedent(dedent.into()).into(), }; let new_arm = make.match_arm(match_pat.clone(), make_guard(Some(cond)), expr); replace_arms.push(new_arm); } if let Some(block) = tail { cov_mark::hit!(move_guard_ifelse_else_tail); let only_expr = block.statements().next().is_none(); let expr = match block.tail_expr() { Some(expr) if only_expr => { cov_mark::hit!(move_guard_ifelse_expr_only); expr } _ => block.dedent(dedent.into()).into(), }; let new_arm = make.match_arm(match_pat, make_guard(None), expr); replace_arms.push(new_arm); } else { // There's no else branch. Add a pattern without guard, unless the following match // arm is `_ => ...` cov_mark::hit!(move_guard_ifelse_notail); match match_arm.syntax().next_sibling().and_then(MatchArm::cast) { Some(next_arm) if matches!(next_arm.pat(), Some(Pat::WildcardPat(_))) && next_arm.guard().is_none() => { cov_mark::hit!(move_guard_ifelse_has_wildcard); } _ => { let block_expr = make.expr_empty_block().into(); replace_arms.push(make.match_arm(match_pat, make_guard(None), block_expr)); } } } let mut edit = builder.make_editor(match_arm.syntax()); let newline = make.whitespace(&format!("\n{indent_level}")); let replace_arms = replace_arms.iter().map(|it| it.syntax().syntax_element()); let replace_arms = Itertools::intersperse(replace_arms, newline.syntax_element()); edit.replace_with_many(match_arm.syntax(), replace_arms.collect()); builder.add_file_edits(ctx.vfs_file_id(), edit); }, ) } fn rest_arms(match_arm: &MatchArm, selection: TextRange) -> Option> { match_arm .parent_match() .match_arm_list()? .arms() .skip_while(|it| it != match_arm) .skip(1) .take_while(move |it| { selection.is_empty() || crate::utils::is_selected(it, selection, false) }) .take_while(move |it| { it.pat() .zip(match_arm.pat()) .is_some_and(|(a, b)| a.syntax().text() == b.syntax().text()) }) .collect::>() .into() } // Parses an if-else-if chain to get the conditions and the then branches until we encounter an else // branch or the end. fn parse_if_chain(if_expr: IfExpr) -> Option<(Vec<(Expr, BlockExpr)>, Option)> { let mut conds_blocks = Vec::new(); let mut curr_if = if_expr; let tail = loop { let cond = curr_if.condition()?; conds_blocks.push((cond, curr_if.then_branch()?)); match curr_if.else_branch() { Some(ElseBranch::IfExpr(e)) => { curr_if = e; } Some(ElseBranch::Block(b)) => { break Some(b); } None => break None, } }; Some((conds_blocks, tail)) } #[cfg(test)] mod tests { use super::*; use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target}; #[test] fn move_guard_to_arm_body_range() { cov_mark::check!(move_guard_inapplicable_in_arm_body); check_assist_not_applicable( move_guard_to_arm_body, r#" fn main() { match 92 { x if x > 10 => $0false, _ => true } } "#, ); } #[test] fn move_non_naked_arm_cond_to_guard() { cov_mark::check!(move_guard_non_naked_if); check_assist_not_applicable( move_arm_cond_to_match_guard, r#" fn main() { match 92 { _ => { let cond = true; $0if cond { foo() } }, _ => true } } "#, ); check_assist_not_applicable( move_arm_cond_to_match_guard, r#" fn main() { match 92 { _ => { let cond = true; $0if cond { foo() } else { bar() } }, _ => true } } "#, ); } #[test] fn move_guard_to_arm_body_target() { check_assist_target( move_guard_to_arm_body, r#" fn main() { match 92 { x $0if x > 10 => false, _ => true } } "#, r#"if x > 10"#, ); } #[test] fn move_guard_to_arm_body_works() { check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { x $0if x > 10 => false, _ => true } } "#, r#" fn main() { match 92 { x => if x > 10 { false }, _ => true } } "#, ); } #[test] fn move_multiple_guard_to_arm_body_works() { check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { x @ 0..30 $0if x % 3 == 0 => false, x @ 0..30 if x % 2 == 0 => true, _ => false } } "#, r#" fn main() { match 92 { x @ 0..30 => if x % 3 == 0 { false } else if x % 2 == 0 { true }, _ => false } } "#, ); check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { x @ 0..30 $0if x % 3 == 0 => false, x @ 0..30 if x % 2 == 0 => true, x @ 0..30 => false, _ => true } } "#, r#" fn main() { match 92 { x @ 0..30 => if x % 3 == 0 { false } else if x % 2 == 0 { true } else { false }, _ => true } } "#, ); check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { x @ 0..30 if x % 3 == 0 => false, x @ 0..30 $0if x % 2 == 0$0 => true, x @ 0..30 => false, _ => true } } "#, r#" fn main() { match 92 { x @ 0..30 if x % 3 == 0 => false, x @ 0..30 => if x % 2 == 0 { true }, x @ 0..30 => false, _ => true } } "#, ); check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { x @ 0..30 $0if x % 3 == 0 => false, x @ 0..30 $0if x % 2 == 0 => true, x @ 0..30 => false, _ => true } } "#, r#" fn main() { match 92 { x @ 0..30 => if x % 3 == 0 { false } else if x % 2 == 0 { true }, x @ 0..30 => false, _ => true } } "#, ); } #[test] fn move_guard_to_block_arm_body_works() { check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { x $0if x > 10 => { let _ = true; false }, _ => true } } "#, r#" fn main() { match 92 { x => if x > 10 { let _ = true; false }, _ => true } } "#, ); } #[test] fn move_let_guard_to_arm_body_works() { check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { x $0if (let 1 = x) => false, _ => true } } "#, r#" fn main() { match 92 { x => if (let 1 = x) { false }, _ => true } } "#, ); } #[test] fn move_multiline_guard_to_arm_body_works() { check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { x $0if true && true && true => { { false } }, _ => true } } "#, r#" fn main() { match 92 { x => if true && true && true { { false } }, _ => true } } "#, ); } #[test] fn move_guard_to_arm_body_works_complex_match() { check_assist( move_guard_to_arm_body, r#" fn main() { match 92 { $0x @ 4 | x @ 5 if x > 5 => true, _ => false } } "#, r#" fn main() { match 92 { x @ 4 | x @ 5 => if x > 5 { true }, _ => false } } "#, ); } #[test] fn move_arm_cond_to_match_guard_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => if x > 10$0 { false }, _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => false, _ => true } } "#, ); } #[test] fn move_arm_cond_in_block_to_match_guard_works() { cov_mark::check!(move_guard_ifelse_has_wildcard); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => { $0if x > 10 { false } }, _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => false, _ => true } } "#, ); } #[test] fn move_arm_cond_in_block_to_match_guard_no_wildcard_works() { cov_mark::check_count!(move_guard_ifelse_has_wildcard, 0); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => { $0if x > 10 { false } } } } "#, r#" fn main() { match 92 { x if x > 10 => false, x => {} } } "#, ); } #[test] fn move_arm_cond_in_block_to_match_guard_wildcard_guard_works() { cov_mark::check_count!(move_guard_ifelse_has_wildcard, 0); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => { $0if x > 10 { false } } _ if x > 10 => true, } } "#, r#" fn main() { match 92 { x if x > 10 => false, x => {} _ if x > 10 => true, } } "#, ); } #[test] fn move_arm_cond_in_block_to_match_guard_add_comma_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => { $0if x > 10 { false } } _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => false, _ => true } } "#, ); } #[test] fn move_arm_cond_to_match_guard_if_let_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => if let 62 = x $0&& true { false }, _ => true } } "#, r#" fn main() { match 92 { x if let 62 = x && true => false, _ => true } } "#, ); } #[test] fn move_arm_cond_to_match_guard_if_empty_body_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => if x $0> 10 { }, _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => { } _ => true } } "#, ); } #[test] fn move_arm_cond_to_match_guard_if_multiline_body_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => if$0 x > 10 { 92; false }, _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => { 92; false } _ => true } } "#, ); } #[test] fn move_arm_cond_in_block_to_match_guard_if_multiline_body_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => { if x > $010 { 92; false } } _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => { 92; false } _ => true } } "#, ) } #[test] fn move_arm_cond_to_match_guard_with_else_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => if x > $010 { false } else { true } _ => true, } } "#, r#" fn main() { match 92 { x if x > 10 => false, x => true, _ => true, } } "#, ) } #[test] fn move_arm_cond_to_match_guard_with_else_block_works() { cov_mark::check!(move_guard_ifelse_expr_only); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => { if x $0> 10 { false } else { true } } _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => false, x => true, _ => true } } "#, ) } #[test] fn move_arm_cond_to_match_guard_else_if_empty_body_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => if x > $010 { } else { }, _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => { } x => { } _ => true } } "#, ); } #[test] fn move_arm_cond_to_match_guard_with_else_multiline_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => if$0 x > 10 { 92; false } else { true } _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => { 92; false } x => true, _ => true } } "#, ) } #[test] fn move_arm_cond_to_match_guard_with_else_multiline_else_works() { cov_mark::check!(move_guard_ifelse_else_block); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => if x $0> 10 { false } else { 42; true } _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => false, x => { 42; true } _ => true } } "#, ) } #[test] fn move_arm_cond_to_match_guard_with_else_multiline_else_block_works() { cov_mark::check!(move_guard_ifelse_in_block); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { x => { if x > $010 { false } else { 42; true } } _ => true } } "#, r#" fn main() { match 92 { x if x > 10 => false, x => { 42; true } _ => true } } "#, ) } #[test] fn move_arm_cond_to_match_guard_with_else_last_arm_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { 3 => true, x => { if x > $010 { false } else { 92; true } } } } "#, r#" fn main() { match 92 { 3 => true, x if x > 10 => false, x => { 92; true } } } "#, ) } #[test] fn move_arm_cond_to_match_guard_with_else_comma_works() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { 3 => true, x => if x > $010 { false } else { 92; true }, } } "#, r#" fn main() { match 92 { 3 => true, x if x > 10 => false, x => { 92; true } } } "#, ) } #[test] fn move_arm_cond_to_match_guard_elseif() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { 3 => true, x => if x $0> 10 { false } else if x > 5 { true } else if x > 4 { false } else { true }, } } "#, r#" fn main() { match 92 { 3 => true, x if x > 10 => false, x if x > 5 => true, x if x > 4 => false, x => true, } } "#, ) } #[test] fn move_arm_cond_to_match_guard_elseif_in_block() { cov_mark::check!(move_guard_ifelse_in_block); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { 3 => true, x => { if x > $010 { false } else if x > 5 { true } else if x > 4 { false } else { true } } } } "#, r#" fn main() { match 92 { 3 => true, x if x > 10 => false, x if x > 5 => true, x if x > 4 => false, x => true, } } "#, ) } #[test] fn move_arm_cond_to_match_guard_elseif_chain() { cov_mark::check!(move_guard_ifelse_else_tail); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { 3 => 0, x => if x $0> 10 { 1 } else if x > 5 { 2 } else if x > 3 { 42; 3 } else { 4 }, } } "#, r#" fn main() { match 92 { 3 => 0, x if x > 10 => 1, x if x > 5 => 2, x if x > 3 => { 42; 3 } x => 4, } } "#, ) } #[test] fn move_arm_cond_to_match_guard_elseif_iflet() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { 3 => 0, x => if x $0> 10 { 1 } else if x > 5 { 2 } else if let 4 = 4 { 42; 3 } else { 4 }, } }"#, r#" fn main() { match 92 { 3 => 0, x if x > 10 => 1, x if x > 5 => 2, x if let 4 = 4 => { 42; 3 } x => 4, } }"#, ); } #[test] fn move_arm_cond_to_match_guard_elseif_notail() { cov_mark::check!(move_guard_ifelse_notail); check_assist( move_arm_cond_to_match_guard, r#" fn main() { match 92 { 3 => 0, x => if x > $010 { 1 } else if x > 5 { 2 } else if x > 4 { 42; 3 }, } } "#, r#" fn main() { match 92 { 3 => 0, x if x > 10 => 1, x if x > 5 => 2, x if x > 4 => { 42; 3 } x => {} } } "#, ) } #[test] fn move_arm_cond_to_match_guard_elseif_exist_guard() { check_assist( move_arm_cond_to_match_guard, r#" fn main() { let cond = true; match 92 { 3 => true, x if cond => if x $0> 10 { false } else if x > 5 { true } else if x > 4 || x < -2 { false } else { true }, } } "#, r#" fn main() { let cond = true; match 92 { 3 => true, x if cond && x > 10 => false, x if cond && x > 5 => true, x if cond && (x > 4 || x < -2) => false, x if cond => true, } } "#, ) } }