7 files changed, 72 insertions, 60 deletions

diff --git a/crates/ra_assists/src/assists/apply_demorgan.rs b/crates/ra_assists/src/assists/apply_demorgan.rs
index 0d59a0d24..7c57c0560 100644
--- a/crates/ra_assists/src/assists/apply_demorgan.rs
+++ b/crates/ra_assists/src/assists/apply_demorgan.rs
@@ -1,6 +1,6 @@
+use super::invert_if::invert_boolean_expression;
 use hir::db::HirDatabase;
 use ra_syntax::ast::{self, AstNode};
-use ra_syntax::SyntaxNode;
 
 use crate::{Assist, AssistCtx, AssistId};
 
@@ -32,18 +32,18 @@ pub(crate) fn apply_demorgan(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist>
     if !cursor_in_range {
         return None;
     }
-    let lhs = expr.lhs()?.syntax().clone();
-    let lhs_range = lhs.text_range();
-    let rhs = expr.rhs()?.syntax().clone();
-    let rhs_range = rhs.text_range();
-    let not_lhs = undo_negation(lhs)?;
-    let not_rhs = undo_negation(rhs)?;
+    let lhs = expr.lhs()?;
+    let lhs_range = lhs.syntax().text_range();
+    let rhs = expr.rhs()?;
+    let rhs_range = rhs.syntax().text_range();
+    let not_lhs = invert_boolean_expression(&lhs)?;
+    let not_rhs = invert_boolean_expression(&rhs)?;
 
     ctx.add_assist(AssistId("apply_demorgan"), "apply demorgan's law", |edit| {
         edit.target(op_range);
         edit.replace(op_range, opposite_op);
-        edit.replace(lhs_range, format!("!({}", not_lhs));
-        edit.replace(rhs_range, format!("{})", not_rhs));
+        edit.replace(lhs_range, format!("!({}", not_lhs.syntax().text()));
+        edit.replace(rhs_range, format!("{})", not_rhs.syntax().text()));
     })
 }
 
@@ -56,28 +56,6 @@ fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> {
     }
 }
 
-// This function tries to undo unary negation, or inequality
-pub(crate) fn undo_negation(node: SyntaxNode) -> Option<String> {
-    match ast::Expr::cast(node)? {
-        ast::Expr::BinExpr(bin) => match bin.op_kind()? {
-            ast::BinOp::NegatedEqualityTest => {
-                let lhs = bin.lhs()?.syntax().text();
-                let rhs = bin.rhs()?.syntax().text();
-                Some(format!("{} == {}", lhs, rhs))
-            }
-            _ => None,
-        },
-        ast::Expr::PrefixExpr(pe) => match pe.op_kind()? {
-            ast::PrefixOp::Not => {
-                let child = pe.expr()?.syntax().text();
-                Some(String::from(child))
-            }
-            _ => None,
-        },
-        _ => None,
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
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 } }")
     }
 }
diff --git a/crates/ra_assists/src/doc_tests/generated.rs b/crates/ra_assists/src/doc_tests/generated.rs
index 1ccc016d3..3c716c2d1 100644
--- a/crates/ra_assists/src/doc_tests/generated.rs
+++ b/crates/ra_assists/src/doc_tests/generated.rs
@@ -347,12 +347,12 @@ fn doctest_invert_if() {
         "invert_if",
         r#####"
 fn main() {
-    if<|> !y {A} else {B}
+    if<|> !y { A } else { B }
 }
 "#####,
         r#####"
 fn main() {
-    if y {B} else {A}
+    if y { B } else { A }
 }
 "#####,
     )
diff --git a/crates/ra_syntax/src/ast/edit.rs b/crates/ra_syntax/src/ast/edit.rs
index 6f005a2d8..95bf9db14 100644
--- a/crates/ra_syntax/src/ast/edit.rs
+++ b/crates/ra_syntax/src/ast/edit.rs
@@ -13,11 +13,21 @@ use crate::{
         make::{self, tokens},
         AstNode, TypeBoundsOwner,
     },
-    AstToken, Direction, InsertPosition, SmolStr, SyntaxElement,
+    AstToken, Direction, InsertPosition, SmolStr, SyntaxElement, SyntaxKind,
     SyntaxKind::{ATTR, COMMENT, WHITESPACE},
     SyntaxNode, SyntaxToken, T,
 };
 
+impl ast::BinExpr {
+    #[must_use]
+    pub fn replace_op(&self, op: SyntaxKind) -> Option<ast::BinExpr> {
+        let op_node: SyntaxElement = self.op_details()?.0.into();
+        let to_insert: Option<SyntaxElement> = Some(tokens::op(op).into());
+        let replace_range = RangeInclusive::new(op_node.clone(), op_node);
+        Some(replace_children(self, replace_range, to_insert.into_iter()))
+    }
+}
+
 impl ast::FnDef {
     #[must_use]
     pub fn with_body(&self, body: ast::Block) -> ast::FnDef {
diff --git a/crates/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 7c53aa934..2fd039837 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -127,7 +127,7 @@ pub enum BinOp {
 }
 
 impl ast::BinExpr {
-    fn op_details(&self) -> Option<(SyntaxToken, BinOp)> {
+    pub fn op_details(&self) -> Option<(SyntaxToken, BinOp)> {
         self.syntax().children_with_tokens().filter_map(|it| it.into_token()).find_map(|c| {
             let bin_op = match c.kind() {
                 T![||] => BinOp::BooleanOr,
diff --git a/crates/ra_syntax/src/ast/make.rs b/crates/ra_syntax/src/ast/make.rs
index 9749327fa..40db570da 100644
--- a/crates/ra_syntax/src/ast/make.rs
+++ b/crates/ra_syntax/src/ast/make.rs
@@ -173,10 +173,21 @@ fn ast_from_text<N: AstNode>(text: &str) -> N {
 }
 
 pub mod tokens {
-    use crate::{AstNode, Parse, SourceFile, SyntaxKind::*, SyntaxToken, T};
+    use crate::{AstNode, Parse, SourceFile, SyntaxKind, SyntaxKind::*, SyntaxToken, T};
     use once_cell::sync::Lazy;
 
-    static SOURCE_FILE: Lazy<Parse<SourceFile>> = Lazy::new(|| SourceFile::parse(",\n; ;"));
+    static SOURCE_FILE: Lazy<Parse<SourceFile>> =
+        Lazy::new(|| SourceFile::parse("const C: () = (1 != 1, 2 == 2)\n;"));
+
+    pub fn op(op: SyntaxKind) -> SyntaxToken {
+        SOURCE_FILE
+            .tree()
+            .syntax()
+            .descendants_with_tokens()
+            .filter_map(|it| it.into_token())
+            .find(|it| it.kind() == op)
+            .unwrap()
+    }
 
     pub fn comma() -> SyntaxToken {
         SOURCE_FILE
diff --git a/docs/user/assists.md b/docs/user/assists.md
index 6e7811bd6..6f4c30bee 100644
--- a/docs/user/assists.md
+++ b/docs/user/assists.md
@@ -339,12 +339,12 @@ on `if`.
 ```rust
 // BEFORE
 fn main() {
-    if┃ !y {A} else {B}
+    if┃ !y { A } else { B }
 }
 
 // AFTER
 fn main() {
-    if y {B} else {A}
+    if y { B } else { A }
 }
 ```