1 files changed, 34 insertions, 21 deletions

diff --git a/crates/ra_assists/src/assists/invert_if.rs b/crates/ra_assists/src/assists/invert_if.rs
index c2c8529fe..bababa3e2 100644
--- a/crates/ra_assists/src/assists/invert_if.rs
+++ b/crates/ra_assists/src/assists/invert_if.rs
@@ -1,8 +1,7 @@
 use hir::db::HirDatabase;
 use ra_syntax::ast::{self, AstNode};
-use ra_syntax::{TextRange, TextUnit};
+use ra_syntax::T;
 
-use super::apply_demorgan::undo_negation;
 use crate::{Assist, AssistCtx, AssistId};
 
 // Assist: invert_if
@@ -14,42 +13,56 @@ use crate::{Assist, AssistCtx, AssistId};
 //
 // ```
 // fn main() {
-//     if<|> !y {A} else {B}
+//     if<|> !y { A } else { B }
 // }
 // ```
 // ->
 // ```
 // fn main() {
-//     if y {B} else {A}
+//     if y { B } else { A }
 // }
 // ```
 
 pub(crate) fn invert_if(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
-    let expr = ctx.find_node_at_offset::<ast::IfExpr>()?;
-    let expr_range = expr.syntax().text_range();
-    let if_range = TextRange::offset_len(expr_range.start(), TextUnit::from_usize(2));
+    let if_keyword = ctx.find_token_at_offset(T![if])?;
+    let expr = ast::IfExpr::cast(if_keyword.parent())?;
+    let if_range = if_keyword.text_range();
     let cursor_in_range = ctx.frange.range.is_subrange(&if_range);
     if !cursor_in_range {
         return None;
     }
 
-    let cond = expr.condition()?.expr()?.syntax().clone();
+    let cond = expr.condition()?.expr()?;
     let then_node = expr.then_branch()?.syntax().clone();
 
     if let ast::ElseBranch::Block(else_block) = expr.else_branch()? {
-        let flip_cond = undo_negation(cond.clone())?;
-        let cond_range = cond.text_range();
+        let flip_cond = invert_boolean_expression(&cond)?;
+        let cond_range = cond.syntax().text_range();
         let else_node = else_block.syntax();
         let else_range = else_node.text_range();
         let then_range = then_node.text_range();
-        ctx.add_assist(AssistId("invert_if"), "invert if branches", |edit| {
+        return ctx.add_assist(AssistId("invert_if"), "invert if branches", |edit| {
             edit.target(if_range);
-            edit.replace(cond_range, flip_cond);
+            edit.replace(cond_range, flip_cond.syntax().text());
             edit.replace(else_range, then_node.text());
             edit.replace(then_range, else_node.text());
-        })
-    } else {
-        None
+        });
+    }
+
+    None
+}
+
+pub(crate) fn invert_boolean_expression(expr: &ast::Expr) -> Option<ast::Expr> {
+    match expr {
+        ast::Expr::BinExpr(bin) => match bin.op_kind()? {
+            ast::BinOp::NegatedEqualityTest => bin.replace_op(T![==]).map(|it| it.into()),
+            _ => None,
+        },
+        ast::Expr::PrefixExpr(pe) => match pe.op_kind()? {
+            ast::PrefixOp::Not => pe.expr(),
+            _ => None,
+        },
+        _ => None,
     }
 }
 
@@ -63,8 +76,8 @@ mod tests {
     fn invert_if_remove_inequality() {
         check_assist(
             invert_if,
-            "fn f() { i<|>f x != 3 {1} else {3 + 2} }",
-            "fn f() { i<|>f x == 3 {3 + 2} else {1} }",
+            "fn f() { i<|>f x != 3 { 1 } else { 3 + 2 } }",
+            "fn f() { i<|>f x == 3 { 3 + 2 } else { 1 } }",
         )
     }
 
@@ -72,18 +85,18 @@ mod tests {
     fn invert_if_remove_not() {
         check_assist(
             invert_if,
-            "fn f() { <|>if !cond {3 * 2} else {1} }",
-            "fn f() { <|>if cond {1} else {3 * 2} }",
+            "fn f() { <|>if !cond { 3 * 2 } else { 1 } }",
+            "fn f() { <|>if cond { 1 } else { 3 * 2 } }",
         )
     }
 
     #[test]
     fn invert_if_doesnt_apply_with_cursor_not_on_if() {
-        check_assist_not_applicable(invert_if, "fn f() { if !<|>cond {3 * 2} else {1} }")
+        check_assist_not_applicable(invert_if, "fn f() { if !<|>cond { 3 * 2 } else { 1 } }")
     }
 
     #[test]
     fn invert_if_doesnt_apply_without_negated() {
-        check_assist_not_applicable(invert_if, "fn f() { i<|>f cond {3 * 2} else {1} }")
+        check_assist_not_applicable(invert_if, "fn f() { i<|>f cond { 3 * 2 } else { 1 } }")
     }
 }