DuckDB dialect support for escape string literals

src/ast/value.rs

@@ -156,9 +156,10 @@ pub enum Value {
     /// Triple double quoted strings: Example """abc"""
     /// [BigQuery](https://cloud.google.com/bigquery/docs/reference/standard-sql/lexical#quoted_literals)
     TripleDoubleQuotedString(String),
-    /// e'string value' (postgres extension)
-    /// See [Postgres docs](https://www.postgresql.org/docs/8.3/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS)
-    /// for more details.
+    /// `E'...'` escape string literal.
+    ///
+    /// [PostgreSQL](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-ESCAPE)
+    /// [DuckDB](https://duckdb.org/docs/current/sql/data_types/literal_types#escape-string-literals)
     EscapedStringLiteral(String),
     /// u&'string value' (postgres extension)
     /// See [Postgres docs](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-UESCAPE)

src/dialect/duckdb.rs

@@ -142,4 +142,8 @@ impl Dialect for DuckDbDialect {
     fn supports_numeric_literal_underscores(&self) -> bool {
         true
     }
+
+    fn supports_string_escape_constant(&self) -> bool {
+        true
+    }
 }

src/dialect/mod.rs

@@ -1420,7 +1420,8 @@ pub trait Dialect: Debug + Any {
 
     /// Returns true if this dialect supports the E'...' syntax for string literals
     ///
-    /// Postgres: <https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-ESCAPE>
+    /// [PostgreSQL](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-ESCAPE)
+    /// [DuckDB](https://duckdb.org/docs/current/sql/data_types/literal_types#escape-string-literals)
     fn supports_string_escape_constant(&self) -> bool {
         false
     }

src/parser/mod.rs

@@ -1977,8 +1977,7 @@ impl<'a> Parser<'a> {
                     ),
                 })
             }
-            Token::EscapedStringLiteral(_) if dialect_is!(dialect is PostgreSqlDialect | GenericDialect) =>
-            {
+            Token::EscapedStringLiteral(_) if self.dialect.supports_string_escape_constant() => {
                 self.prev_token();
                 Ok(Expr::Value(self.parse_value()?))
             }
@@ -12688,7 +12687,7 @@ impl<'a> Parser<'a> {
             }) => Ok(value),
             Token::SingleQuotedString(s) => Ok(s),
             Token::DoubleQuotedString(s) => Ok(s),
-            Token::EscapedStringLiteral(s) if dialect_of!(self is PostgreSqlDialect | GenericDialect) => {
+            Token::EscapedStringLiteral(s) if self.dialect.supports_string_escape_constant() => {
                 Ok(s)
             }
             Token::UnicodeStringLiteral(s) => Ok(s),

tests/sqlparser_duckdb.rs

@@ -23,7 +23,7 @@ use sqlparser::tokenizer::Span;
 use test_utils::*;
 
 use sqlparser::ast::*;
-use sqlparser::dialect::{DuckDbDialect, GenericDialect};
+use sqlparser::dialect::{AnsiDialect, DuckDbDialect, GenericDialect};
 use sqlparser::parser::ParserError;
 
 fn duckdb() -> TestedDialects {
@@ -910,3 +910,39 @@ fn test_duckdb_lambda_function() {
     let sql_transform = "SELECT list_transform([1, 2, 3], lambda x : x * 2)";
     duckdb().verified_stmt(sql_transform);
 }
+
+#[test]
+fn test_escape_string_literal() {
+    duckdb().verified_stmt(r#"SELECT E'a\nb' AS value"#);
+
+    assert_eq!(
+        duckdb().verified_expr(r#"E'a\nb'"#),
+        Expr::Value((Value::EscapedStringLiteral("a\nb".to_string())).with_empty_span())
+    );
+    assert_eq!(
+        duckdb().verified_expr(r#"'a\nb'"#),
+        Expr::Value((Value::SingleQuotedString(r#"a\nb"#.to_string())).with_empty_span())
+    );
+    duckdb().one_statement_parses_to(
+        r#"COPY data TO E'out\n.csv'"#,
+        r#"COPY data TO 'out
+.csv'"#,
+    );
+
+    let err = duckdb()
+        .parse_sql_statements("SELECT E'unterminated")
+        .unwrap_err();
+    assert_eq!(
+        err,
+        ParserError::TokenizerError(
+            "Unterminated encoded string literal at Line: 1, Column: 8".to_string()
+        )
+    );
+
+    let ansi = TestedDialects::new(vec![Box::new(AnsiDialect {})]);
+    assert_eq!(
+        ansi.parse_sql_statements(r#"SELECT E'a\nb' AS value"#)
+            .unwrap_err(),
+        ParserError::ParserError("Expected: end of statement, found: AS".to_string())
+    );
+}