From 18918769baf49acc4067eabdc0c3a0a98224d23f Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Thu, 23 Aug 2018 21:38:25 +0300
Subject: [PATCH] Smarter join lines

---
 crates/libeditor/src/lib.rs    |  2 +-
 crates/libeditor/src/typing.rs | 31 +++++++++++++++++++++++++++++++
 crates/libeditor/tests/test.rs |  4 ++--
 3 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/crates/libeditor/src/lib.rs b/crates/libeditor/src/lib.rs
index f8bc73ae9f..b29603da31 100644
--- a/crates/libeditor/src/lib.rs
+++ b/crates/libeditor/src/lib.rs
@@ -12,7 +12,7 @@ mod typing;
 use libsyntax2::{
     ast::{self, NameOwner},
     AstNode,
-    algo::{walk, find_leaf_at_offset, find_covering_node},
+    algo::{walk, find_leaf_at_offset},
     SyntaxKind::{self, *},
 };
 pub use libsyntax2::{ParsedFile, TextRange, TextUnit};
diff --git a/crates/libeditor/src/typing.rs b/crates/libeditor/src/typing.rs
index f49dd0fdc6..918f2325c0 100644
--- a/crates/libeditor/src/typing.rs
+++ b/crates/libeditor/src/typing.rs
@@ -5,6 +5,7 @@ use libsyntax2::{
         walk::preorder,
         find_covering_node,
     },
+    SyntaxKind::*,
 };
 
 use {ActionResult, EditBuilder};
@@ -68,6 +69,24 @@ fn remove_newline(
     node_text: &str,
     offset: TextUnit,
 ) {
+    if node.kind() == WHITESPACE && node_text.bytes().filter(|&b| b == b'\n').count() == 1 {
+        match (node.prev_sibling(), node.next_sibling()) {
+            (Some(prev), Some(next)) => {
+                if prev.kind() == COMMA && (next.kind() == R_PAREN || next.kind() == R_BRACK) {
+                    let range = TextRange::from_to(prev.range().start(), node.range().end());
+                    edit.delete(range);
+                } else {
+                    edit.replace(
+                        node.range(),
+                        compute_ws(prev, next).to_string(),
+                    );
+                }
+                return;
+            }
+            _ => (),
+        }
+    }
+
     let suff = &node_text[TextRange::from_to(
         offset - node.range().start() + TextUnit::of_char('\n'),
         TextUnit::of_str(node_text),
@@ -79,3 +98,15 @@ fn remove_newline(
         " ".to_string(),
     );
 }
+
+fn compute_ws(left: SyntaxNodeRef, right: SyntaxNodeRef) -> &'static str {
+    match left.kind() {
+        L_PAREN | L_BRACK => return "",
+        _ => (),
+    }
+    match right.kind() {
+        R_PAREN | R_BRACK => return "",
+        _ => (),
+    }
+    " "
+}
diff --git a/crates/libeditor/tests/test.rs b/crates/libeditor/tests/test.rs
index 6aa260a861..e5088ad274 100644
--- a/crates/libeditor/tests/test.rs
+++ b/crates/libeditor/tests/test.rs
@@ -195,7 +195,7 @@ fn foo() {
 }
 ", r"
 fn foo() {
-    <|>foo(1, )
+    <|>foo(1)
 }
 ");
 }
@@ -221,7 +221,7 @@ fn foo() {
 }
 ", r"
 fn foo() {
-    foo(1, 2, 3, )
+    foo(1, 2, 3)
 }
 ");
 }