Changes per reviewer comments

Author: davidBar-On

src/comment.rs

@@ -160,13 +160,15 @@ pub(crate) fn is_last_comment_block(s: &str) -> bool {
     s.trim_end().ends_with("*/")
 }
 
-/// Returns true if the first line of the passed string starts with a comment
-/// that end on that line.
-fn is_first_comment_ends_on_first_line(s: &str) -> bool {
+/// Returns true if the last comment in the first line of the passed comments block
+/// ends on that line.
+fn is_first_comment_line_ends_comment(s: &str) -> bool {
     if s.starts_with("/*") {
-        s.lines().next().map_or(false, |l| l.contains("*/"))
+        // FIXME: mixed block and line comments on the line are not be properlly formatted,
+        // e.g. "/* Block comment /* // Line comment" at the end of the line.
+        s.lines().next().map_or(false, |l| l.ends_with("*/"))
     } else if s.starts_with("//") {
-        true
+        true // Comment is "// comment"
     } else {
         false
     }
@@ -237,12 +239,11 @@ pub(crate) fn combine_strs_with_missing_comments(
         Cow::from("")
     } else {
         let one_line_width = last_line_width(prev_str) + first_line_width(&missing_comment) + 1;
-        // First comment of a comments block can be in same line if ends in the first line
-        // (and meets other conditions)
+        // First comment in the comments block can be in same line if it ends in the first line.
         if prefer_same_line
             && one_line_width <= shape.width
             && (is_single_line(&missing_comment)
-                || is_first_comment_ends_on_first_line(&missing_comment))
+                || is_first_comment_line_ends_comment(&missing_comment))
         {
             Cow::from(" ")
         } else {
@@ -1019,32 +1020,32 @@ fn light_rewrite_comment(
     config: &Config,
     is_doc_comment: bool,
 ) -> String {
-    let lines: Vec<String> = orig
-        .lines()
-        .map(|l| {
-            // This is basically just l.trim(), but in the case that a line starts
-            // with `*` we want to leave one space before it, so it aligns with the
-            // `*` in `/*`.
-            let first_non_whitespace = l.find(|c| !char::is_whitespace(c));
-            let (blank, left_trimmed) = if let Some(fnw) = first_non_whitespace {
-                if l.as_bytes()[fnw] == b'*' {
-                    // Ensure '*' is preceeded by blank and not by a tab.
-                    (" ", &l[fnw..])
-                } else {
-                    ("", &l[fnw..])
-                }
-            } else {
-                ("", "")
-            };
-            // Preserve markdown's double-space line break syntax in doc comment.
-            format!(
-                "{}{}",
-                blank,
-                trim_end_unless_two_whitespaces(left_trimmed, is_doc_comment),
-            )
-        })
-        .collect();
-    lines.join(&format!("\n{}", offset.to_string(config)))
+    let mut result = String::with_capacity(orig.len() * 2);
+    let mut lines = orig.lines().peekable();
+
+    // This is basically just l.trim(), but in the case that a line starts with `*` we want to leave
+    // one space before it, so it aligns with the `*` in `/*`.
+    while let Some(full_line) = lines.next() {
+        let line = full_line.trim_start();
+
+        if line.is_empty() {
+            continue;
+        }
+
+        if line.starts_with('*') {
+            result.push(' ');
+        }
+
+        // Preserve markdown's double-space line break syntax in doc comment.
+        let trimmed = trim_end_unless_two_whitespaces(line, is_doc_comment);
+        result.push_str(trimmed);
+
+        let is_last = lines.peek().is_none();
+        if !is_last {
+            result.push_str(&offset.to_string_with_newline(config))
+        }
+    }
+    result
 }
 
 /// Trims comment characters and possibly a single space from the left of a string.

src/expr.rs

@@ -1896,8 +1896,8 @@ fn rewrite_assignment(
     op_span: Span,
     shape: Shape,
 ) -> Option<String> {
-    // 1 = space between lhs and operator.
     let operator_str = context.snippet(op_span);
+    // 1 = space between lhs and operator.
     let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
     let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
 

tests/source/lhs-to-rhs-between-comments/assignment-multi-line-comments.rs

@@ -27,13 +27,18 @@ var = /* Block comment single line */
 // Line comment
 /* Block comment line 1
 * Block comment line 2 */ third;
+var = /* Block comment single line 1 */ 
+/* Block comment single line 2*/ forth;
+var = /* Block comment single line 1 */ 
+/* Block comment single line 2*/
+fifth;
 var = /* Block comment line 1 longggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg
 * Block comment line 2 */
 // Line comment
-forth;
+sixth;
 var = // Line comment 
 /* Block comment line 1 longggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg
-* Block comment line 2 */ fifth;
+* Block comment line 2 */ seventh;
 }
 
 // BinOp Assignemnt - Multiline Block comments

tests/source/lhs-to-rhs-between-comments/assignment-single-line-comments.rs

@@ -6,6 +6,8 @@ var = second;
 fn main () {
 let var = /* Block comment */ first;
 var = /* Block comment */ second;
+var = /* Block comment */
+third;
 }
 fn main () {
 let var = // Line comment

tests/target/lhs-to-rhs-between-comments/assignment-multi-line-comments.rs

@@ -37,15 +37,21 @@ fn main() {
         /* Block comment line 1
          * Block comment line 2 */
         third;
+    var = /* Block comment single line 1 */
+        /* Block comment single line 2*/
+        forth;
+    var = /* Block comment single line 1 */
+        /* Block comment single line 2*/
+        fifth;
     var =
         /* Block comment line 1 longggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg
          * Block comment line 2 */
         // Line comment
-        forth;
+        sixth;
     var = // Line comment
         /* Block comment line 1 longggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg
          * Block comment line 2 */
-        fifth;
+        seventh;
 }
 
 // BinOp Assignemnt - Multiline Block comments

tests/target/lhs-to-rhs-between-comments/assignment-single-line-comments.rs

@@ -6,6 +6,7 @@ fn main() {
 fn main() {
     let var = /* Block comment */ first;
     var = /* Block comment */ second;
+    var = /* Block comment */ third;
 }
 fn main() {
     let var = // Line comment