Cleanup early return assist

Author: matklad

crates/ra_assists/src/assists/early_return.rs

@@ -10,6 +10,7 @@ use ra_syntax::{
 
 use crate::{
     assist_ctx::{Assist, AssistCtx},
+    assists::invert_if::invert_boolean_expression,
     AssistId,
 };
 
@@ -99,9 +100,13 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx) -> Option<Assist> {
         let new_block = match if_let_pat {
             None => {
                 // If.
-                let early_expression = &(early_expression.syntax().to_string() + ";");
-                let new_expr = if_indent_level
-                    .increase_indent(make::if_expression(cond_expr, early_expression));
+                let new_expr = {
+                    let then_branch =
+                        make::block_expr(once(make::expr_stmt(early_expression).into()), None);
+                    let cond = invert_boolean_expression(cond_expr);
+                    let e = make::expr_if(cond, then_branch);
+                    if_indent_level.increase_indent(e)
+                };
                 replace(new_expr.syntax(), &then_block, &parent_block, &if_expr)
             }
             Some((path, bound_ident)) => {

crates/ra_syntax/src/ast/make.rs

@@ -33,6 +33,21 @@ pub fn record_field(name: ast::NameRef, expr: Option<ast::Expr>) -> ast::RecordF
     }
 }
 
+pub fn block_expr(
+    stmts: impl IntoIterator<Item = ast::Stmt>,
+    tail_expr: Option<ast::Expr>,
+) -> ast::BlockExpr {
+    let mut text = "{\n".to_string();
+    for stmt in stmts.into_iter() {
+        text += &format!("    {}\n", stmt.syntax());
+    }
+    if let Some(tail_expr) = tail_expr {
+        text += &format!("    {}\n", tail_expr.syntax())
+    }
+    text += "}";
+    ast_from_text(&format!("fn f() {}", text))
+}
+
 pub fn block_from_expr(e: ast::Expr) -> ast::Block {
     return from_text(&format!("{{ {} }}", e.syntax()));
 
@@ -62,6 +77,9 @@ pub fn expr_return() -> ast::Expr {
 pub fn expr_match(expr: ast::Expr, match_arm_list: ast::MatchArmList) -> ast::Expr {
     expr_from_text(&format!("match {} {}", expr.syntax(), match_arm_list.syntax()))
 }
+pub fn expr_if(condition: ast::Expr, then_branch: ast::BlockExpr) -> ast::Expr {
+    expr_from_text(&format!("if {} {}", condition.syntax(), then_branch.syntax()))
+}
 pub fn expr_prefix(op: SyntaxKind, expr: ast::Expr) -> ast::Expr {
     let token = token(op);
     expr_from_text(&format!("{}{}", token, expr.syntax()))
@@ -162,21 +180,16 @@ pub fn where_clause(preds: impl IntoIterator<Item = ast::WherePred>) -> ast::Whe
     }
 }
 
-pub fn if_expression(condition: ast::Expr, statement: &str) -> ast::IfExpr {
-    ast_from_text(&format!(
-        "fn f() {{ if !{} {{\n    {}\n}}\n}}",
-        condition.syntax().text(),
-        statement
-    ))
-}
-
 pub fn let_stmt(pattern: ast::Pat, initializer: Option<ast::Expr>) -> ast::LetStmt {
     let text = match initializer {
         Some(it) => format!("let {} = {};", pattern.syntax(), it.syntax()),
         None => format!("let {};", pattern.syntax()),
     };
     ast_from_text(&format!("fn f() {{ {} }}", text))
 }
+pub fn expr_stmt(expr: ast::Expr) -> ast::ExprStmt {
+    ast_from_text(&format!("fn f() {{ {}; }}", expr.syntax()))
+}
 
 pub fn token(kind: SyntaxKind) -> SyntaxToken {
     tokens::SOURCE_FILE