From 9f9bfb98bdb9e97833f736cb69760e50ebd10c5b Mon Sep 17 00:00:00 2001
From: Tomoki Yamaguchi <tyamagu2@gmail.com>
Date: Thu, 17 Aug 2023 03:08:32 +0900
Subject: [PATCH] fix: starting position of comment (#507)

Fix Begin of Comment to point to the position of the opening slash.
---
 parser/lexer.go       |  4 ++--
 parser/parser_test.go | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/parser/lexer.go b/parser/lexer.go
index 5b06c05f..f6544905 100644
--- a/parser/lexer.go
+++ b/parser/lexer.go
@@ -237,7 +237,7 @@ func (p *parser) scan() (tkn token.Token, literal string, idx file.Idx) { //noli
 				case '/':
 					if p.mode&StoreComments != 0 {
 						literal := string(p.readSingleLineComment())
-						p.comments.AddComment(ast.NewComment(literal, p.idx))
+						p.comments.AddComment(ast.NewComment(literal, idx))
 						continue
 					}
 					p.skipSingleLineComment()
@@ -245,7 +245,7 @@ func (p *parser) scan() (tkn token.Token, literal string, idx file.Idx) { //noli
 				case '*':
 					if p.mode&StoreComments != 0 {
 						literal = string(p.readMultiLineComment())
-						p.comments.AddComment(ast.NewComment(literal, p.idx))
+						p.comments.AddComment(ast.NewComment(literal, idx))
 						continue
 					}
 					p.skipMultiLineComment()
diff --git a/parser/parser_test.go b/parser/parser_test.go
index 727d83c0..d94aa3e9 100644
--- a/parser/parser_test.go
+++ b/parser/parser_test.go
@@ -1186,6 +1186,24 @@ func TestPosition(t *testing.T) {
 		node = program.Body[0].(*ast.DoWhileStatement)
 		is(node.Idx0(), 1)
 		is(parser.slice(node.Idx0(), node.Idx1()), "do { i++; } while (i < 10 )")
+
+		parser = newParser("", "(function() { // single-line comment\n })", 1, nil)
+		parser.mode |= StoreComments
+		program, err = parser.parse()
+		is(err, nil)
+		block = program.Body[0].(*ast.ExpressionStatement).Expression.(*ast.FunctionLiteral).Body.(*ast.BlockStatement)
+		comment := parser.comments.CommentMap[block][0]
+		is(comment.Begin, 15)
+		is(parser.slice(comment.Begin, file.Idx(int(comment.Begin)+len(comment.Text)+2)), "// single-line comment")
+
+		parser = newParser("", "(function() { /* multi-line comment */ })", 1, nil)
+		parser.mode |= StoreComments
+		program, err = parser.parse()
+		is(err, nil)
+		block = program.Body[0].(*ast.ExpressionStatement).Expression.(*ast.FunctionLiteral).Body.(*ast.BlockStatement)
+		comment = parser.comments.CommentMap[block][0]
+		is(comment.Begin, 15)
+		is(parser.slice(comment.Begin, file.Idx(int(comment.Begin)+len(comment.Text)+4)), "/* multi-line comment */")
 	})
 }