Support backslash escapes in Databricks string literals (#42)

Author: jmhain

src/dialect/databricks.rs

@@ -84,4 +84,9 @@ impl Dialect for DatabricksDialect {
     fn supports_nested_comments(&self) -> bool {
         true
     }
+
+    // https://docs.databricks.com/aws/en/sql/language-manual/data-types/string-type#literals
+    fn supports_string_literal_backslash_escape(&self) -> bool {
+        true
+    }
 }

src/lib.rs

@@ -153,6 +153,8 @@
 // Splitting complex nodes (expressions, statements, types) into separate types
 // would bloat the API and hide intent. Extra memory is a worthwhile tradeoff.
 #![allow(clippy::large_enum_variant)]
+// TODO: Fix and remove this.
+#![expect(clippy::unnecessary_unwrap)]
 
 // Allow proc-macros to find this crate
 extern crate self as sqlparser;

tests/sqlparser_databricks.rs

@@ -18,7 +18,7 @@
 use sqlparser::ast::helpers::attached_token::AttachedToken;
 use sqlparser::ast::*;
 use sqlparser::dialect::{DatabricksDialect, GenericDialect};
-use sqlparser::parser::ParserError;
+use sqlparser::parser::{ParserError, ParserOptions};
 use test_utils::*;
 
 #[macro_use]
@@ -28,6 +28,13 @@ fn databricks() -> TestedDialects {
     TestedDialects::new(vec![Box::new(DatabricksDialect {})])
 }
 
+fn databricks_no_unescape() -> TestedDialects {
+    TestedDialects::new_with_options(
+        vec![Box::new(DatabricksDialect {})],
+        ParserOptions::new().with_unescape(false),
+    )
+}
+
 fn databricks_and_generic() -> TestedDialects {
     TestedDialects::new(vec![
         Box::new(DatabricksDialect {}),
@@ -54,6 +61,22 @@ fn test_databricks_identifiers() {
     );
 }
 
+// Test examples from https://docs.databricks.com/aws/en/sql/language-manual/data-types/string-type#examples
+//
+// Note: string literals are broken on DBx when unescape in turned on (the default).
+#[test]
+fn test_databricks_string_literals() {
+    databricks_no_unescape().verified_expr(r"'O\'Connell'");
+    databricks_no_unescape().verified_expr(r"'Some\nText'");
+    databricks_no_unescape().verified_expr("'서울시'");
+    databricks_no_unescape().verified_expr(r"'\\'");
+
+    // FIXME: raw strings are broken
+    // databricks_no_unescape().verified_query(r"SELECT 'Hou$e', 'Hou\$e', r'Hou$e', r'Hou\$e'");
+    // databricks_no_unescape().verified_expr(r"r'Some\nText'");
+    // databricks_no_unescape().verified_expr(r"r'\\'");
+}
+
 #[test]
 fn test_databricks_exists() {
     // exists is a function in databricks