Extract source comments (#2107)

Co-authored-by: Ifeanyi Ubah <ify1992@yahoo.com>

tests/sqlparser_comments.rs

@@ -0,0 +1,75 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#![warn(clippy::all)]
+//! Test comment extraction from SQL source code.
+
+#[cfg(test)]
+use pretty_assertions::assert_eq;
+
+use sqlparser::{
+    ast::comments::{Comment, CommentWithSpan},
+    dialect::GenericDialect,
+    parser::Parser,
+    tokenizer::Span,
+};
+
+#[test]
+fn parse_sql_with_comments() {
+    let sql = r#"
+-- second line comment
+select * from /* inline comment after `from` */ dual;
+
+/*select
+some
+more*/
+
+  -- end-of-script-with-no-newline"#;
+
+    let comments = match Parser::parse_sql_with_comments(&GenericDialect, sql) {
+        Ok((_, comments)) => comments,
+        Err(e) => panic!("Invalid sql script: {e}"),
+    };
+
+    assert_eq!(
+        Vec::from(comments),
+        vec![
+            CommentWithSpan {
+                comment: Comment::SingleLine {
+                    content: " second line comment\n".into(),
+                    prefix: "--".into()
+                },
+                span: Span::new((2, 1).into(), (3, 1).into()),
+            },
+            CommentWithSpan {
+                comment: Comment::MultiLine(" inline comment after `from` ".into()),
+                span: Span::new((3, 15).into(), (3, 48).into()),
+            },
+            CommentWithSpan {
+                comment: Comment::MultiLine("select\nsome\nmore".into()),
+                span: Span::new((5, 1).into(), (7, 7).into())
+            },
+            CommentWithSpan {
+                comment: Comment::SingleLine {
+                    content: " end-of-script-with-no-newline".into(),
+                    prefix: "--".into()
+                },
+                span: Span::new((9, 3).into(), (9, 35).into()),
+            }
+        ]
+    );
+}