Add Redshift dialect, handle square brackets properly (#471)

* Redshift square bracket handling

We need to detect `[` or `"` for Redshift quotes around indentifier and at the same time exclude
treating JSON paths as indentifer

* RedshiftSqlDialect documentation update

Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

* Renamed _chars to chars

* Fixed warnings

* Missing license

Co-authored-by: Maciej Skrzypkowski <maciej.skrzypkowski@satoricyber.com>
Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

tests/sqlparser_redshift.rs

@@ -0,0 +1,102 @@
+// Licensed 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.
+
+#[macro_use]
+mod test_utils;
+
+use test_utils::*;
+
+use sqlparser::ast::*;
+use sqlparser::dialect::RedshiftSqlDialect;
+
+#[test]
+fn test_square_brackets_over_db_schema_table_name() {
+    let select = redshift().verified_only_select("SELECT [col1] FROM [test_schema].[test_table]");
+    assert_eq!(
+        select.projection[0],
+        SelectItem::UnnamedExpr(Expr::Identifier(Ident {
+            value: "col1".to_string(),
+            quote_style: Some('[')
+        })),
+    );
+    assert_eq!(
+        select.from[0],
+        TableWithJoins {
+            relation: TableFactor::Table {
+                name: ObjectName(vec![
+                    Ident {
+                        value: "test_schema".to_string(),
+                        quote_style: Some('[')
+                    },
+                    Ident {
+                        value: "test_table".to_string(),
+                        quote_style: Some('[')
+                    }
+                ]),
+                alias: None,
+                args: vec![],
+                with_hints: vec![],
+            },
+            joins: vec![],
+        }
+    );
+}
+
+#[test]
+fn brackets_over_db_schema_table_name_with_whites_paces() {
+    match redshift().parse_sql_statements("SELECT [   col1  ] FROM [  test_schema].[ test_table]") {
+        Ok(statements) => {
+            assert_eq!(statements.len(), 1);
+        }
+        _ => unreachable!(),
+    }
+}
+
+#[test]
+fn test_double_quotes_over_db_schema_table_name() {
+    let select =
+        redshift().verified_only_select("SELECT \"col1\" FROM \"test_schema\".\"test_table\"");
+    assert_eq!(
+        select.projection[0],
+        SelectItem::UnnamedExpr(Expr::Identifier(Ident {
+            value: "col1".to_string(),
+            quote_style: Some('"')
+        })),
+    );
+    assert_eq!(
+        select.from[0],
+        TableWithJoins {
+            relation: TableFactor::Table {
+                name: ObjectName(vec![
+                    Ident {
+                        value: "test_schema".to_string(),
+                        quote_style: Some('"')
+                    },
+                    Ident {
+                        value: "test_table".to_string(),
+                        quote_style: Some('"')
+                    }
+                ]),
+                alias: None,
+                args: vec![],
+                with_hints: vec![],
+            },
+            joins: vec![],
+        }
+    );
+}
+
+fn redshift() -> TestedDialects {
+    TestedDialects {
+        dialects: vec![Box::new(RedshiftSqlDialect {})],
+    }
+}