fmt: cleanup comments code (#8901)

vlib/v/fmt/comments.v

@@ -5,18 +5,18 @@ module fmt
 
 import v.ast
 
-enum CommentsLevel {
+pub enum CommentsLevel {
 	keep
 	indent
 }
 
 // CommentsOptions defines the way comments are going to be written
-// - has_nl: adds an newline at the end of the list of comments
-// - inline: single-line comments will be on the same line as the last statement
-// - iembed: a /* ... */ embedded comment; used in expressions; // comments the whole line
+// - has_nl: adds an newline at the end of a list of comments
+// - inline: line comments will be on the same line as the last statement
 // - level:  either .keep (don't indent), or .indent (increment indentation)
-// - prev_line: the line number of the previous token
-struct CommentsOptions {
+// - iembed: a /* ... */ block comment used inside expressions; // comments the whole line
+// - prev_line: the line number of the previous token to save linebreaks
+pub struct CommentsOptions {
 	has_nl    bool = true
 	inline    bool
 	level     CommentsLevel
@@ -25,6 +25,7 @@ struct CommentsOptions {
 }
 
 pub fn (mut f Fmt) comment(node ast.Comment, options CommentsOptions) {
+	// Shebang in .vsh files
 	if node.text.starts_with('#!') {
 		f.writeln(node.text)
 		return
@@ -33,13 +34,13 @@ pub fn (mut f Fmt) comment(node ast.Comment, options CommentsOptions) {
 		f.indent++
 	}
 	if options.iembed {
-		x := node.text.trim_left('\x01')
+		x := node.text.trim_left('\x01').trim_space()
 		if x.contains('\n') {
 			f.writeln('/*')
-			f.writeln(x.trim_space())
+			f.writeln(x)
 			f.write('*/')
 		} else {
-			f.write('/* ${x.trim(' ')} */')
+			f.write('/* $x */')
 		}
 	} else if !node.text.contains('\n') {
 		is_separate_line := !options.inline || node.text.starts_with('\x01')
@@ -52,7 +53,7 @@ pub fn (mut f Fmt) comment(node ast.Comment, options CommentsOptions) {
 			out_s += s
 		}
 		if !is_separate_line && f.indent > 0 {
-			f.remove_new_line() // delete the generated \n
+			f.remove_new_line({}) // delete the generated \n
 			f.write(' ')
 		}
 		f.write(out_s)
@@ -69,7 +70,7 @@ pub fn (mut f Fmt) comment(node ast.Comment, options CommentsOptions) {
 			f.empty_line = false
 		}
 		if no_new_lines {
-			f.remove_new_line()
+			f.remove_new_line({})
 		} else {
 			f.empty_line = true
 		}
@@ -118,21 +119,14 @@ pub fn (mut f Fmt) import_comments(comments []ast.Comment, options CommentsOptio
 		return
 	}
 	if options.inline {
-		mut i := 0
-		for i = f.out_imports.len - 1; i >= 0; i-- {
-			if !f.out_imports.buf[i].is_space() { // != `\n` {
-				break
-			}
-		}
-		f.out_imports.go_back(f.out_imports.len - i - 1)
+		f.remove_new_line(imports_buffer: true)
 	}
 	for c in comments {
 		ctext := c.text.trim_left('\x01')
 		if ctext == '' {
 			continue
 		}
-		mut out_s := if options.inline { ' ' } else { '' }
-		out_s += '//'
+		mut out_s := if options.inline { ' ' } else { '' } + '//'
 		if is_first_char_alphanumeric(ctext) {
 			out_s += ' '
 		}

vlib/v/fmt/fmt.v

@@ -152,14 +152,19 @@ pub fn (mut f Fmt) wrap_long_line(penalty_idx int, add_indent bool) bool {
 	return true
 }
 
-pub fn (mut f Fmt) remove_new_line() {
+pub struct RemoveNewLineConfig {
+	imports_buffer bool // Work on f.out_imports instead of f.out
+}
+
+pub fn (mut f Fmt) remove_new_line(cfg RemoveNewLineConfig) {
+	mut buffer := if cfg.imports_buffer { &f.out_imports } else { &f.out }
 	mut i := 0
-	for i = f.out.len - 1; i >= 0; i-- {
-		if !f.out.buf[i].is_space() { // != `\n` {
+	for i = buffer.len - 1; i >= 0; i-- {
+		if !buffer.buf[i].is_space() { // != `\n` {
 			break
 		}
 	}
-	f.out.go_back(f.out.len - i - 1)
+	buffer.go_back(buffer.len - i - 1)
 	f.empty_line = false
 }
 
@@ -1883,7 +1888,7 @@ pub fn (mut f Fmt) match_expr(it ast.MatchExpr) {
 			}
 			f.stmts(branch.stmts)
 			if single_line {
-				f.remove_new_line()
+				f.remove_new_line({})
 				f.writeln(' }')
 			} else {
 				f.writeln('}')
@@ -2181,7 +2186,7 @@ pub fn (mut f Fmt) struct_init(it ast.StructInit) {
 					single_line_fields = false
 					f.out.go_back_to(fields_start)
 					f.line_len = fields_start
-					f.remove_new_line()
+					f.remove_new_line({})
 					continue fields_loop
 				}
 			}
@@ -2394,7 +2399,7 @@ pub fn (mut f Fmt) for_c_stmt(node ast.ForCStmt) {
 	f.expr(node.cond)
 	f.write('; ')
 	f.stmt(node.inc)
-	f.remove_new_line()
+	f.remove_new_line({})
 	f.write(' {')
 	if node.stmts.len > 0 || node.pos.line_nr < node.pos.last_line {
 		f.writeln('')

vlib/v/scanner/scanner.v

@@ -950,6 +950,8 @@ fn (mut s Scanner) text_scan() token.Token {
 							}
 						}
 						if is_separate_line_comment {
+							// NB: ´\x01´ is used to preserve the initial whitespace in comments
+							//     that are on a separate line
 							comment = '\x01' + comment
 						}
 						return s.new_token(.comment, comment, comment.len + 2)