feat: Support PostgreSQL exponentiation. (#813)

* Add Postgres exponent operator

* Parse caret as BinaryOperator::PGExp in PostgreSQL

* Update sqlparser_postgres.rs

* update tests to support PGExp

* cargo fmt

* improve extensibility

* cargo fmt

* redundant code and documentation lionks

Author: michael-2956

src/ast/operator.rs

@@ -88,6 +88,7 @@ pub enum BinaryOperator {
     PGBitwiseXor,
     PGBitwiseShiftLeft,
     PGBitwiseShiftRight,
+    PGExp,
     PGRegexMatch,
     PGRegexIMatch,
     PGRegexNotMatch,
@@ -124,6 +125,7 @@ impl fmt::Display for BinaryOperator {
             BinaryOperator::PGBitwiseXor => f.write_str("#"),
             BinaryOperator::PGBitwiseShiftLeft => f.write_str("<<"),
             BinaryOperator::PGBitwiseShiftRight => f.write_str(">>"),
+            BinaryOperator::PGExp => f.write_str("^"),
             BinaryOperator::PGRegexMatch => f.write_str("~"),
             BinaryOperator::PGRegexIMatch => f.write_str("~*"),
             BinaryOperator::PGRegexNotMatch => f.write_str("!~"),

src/parser.rs

@@ -1648,7 +1648,15 @@ impl<'a> Parser<'a> {
             Token::Mod => Some(BinaryOperator::Modulo),
             Token::StringConcat => Some(BinaryOperator::StringConcat),
             Token::Pipe => Some(BinaryOperator::BitwiseOr),
-            Token::Caret => Some(BinaryOperator::BitwiseXor),
+            Token::Caret => {
+                // In PostgreSQL, ^ stands for the exponentiation operation,
+                // and # stands for XOR. See https://www.postgresql.org/docs/current/functions-math.html
+                if dialect_of!(self is PostgreSqlDialect) {
+                    Some(BinaryOperator::PGExp)
+                } else {
+                    Some(BinaryOperator::BitwiseXor)
+                }
+            }
             Token::Ampersand => Some(BinaryOperator::BitwiseAnd),
             Token::Div => Some(BinaryOperator::Divide),
             Token::ShiftLeft if dialect_of!(self is PostgreSqlDialect | GenericDialect) => {

tests/sqlparser_common.rs

@@ -1228,16 +1228,27 @@ fn parse_string_agg() {
     );
 }
 
+/// selects all dialects but PostgreSQL
+pub fn all_dialects_but_pg() -> TestedDialects {
+    TestedDialects {
+        dialects: all_dialects()
+            .dialects
+            .into_iter()
+            .filter(|x| !x.is::<PostgreSqlDialect>())
+            .collect(),
+    }
+}
+
 #[test]
 fn parse_bitwise_ops() {
     let bitwise_ops = &[
-        ("^", BinaryOperator::BitwiseXor),
-        ("|", BinaryOperator::BitwiseOr),
-        ("&", BinaryOperator::BitwiseAnd),
+        ("^", BinaryOperator::BitwiseXor, all_dialects_but_pg()),
+        ("|", BinaryOperator::BitwiseOr, all_dialects()),
+        ("&", BinaryOperator::BitwiseAnd, all_dialects()),
     ];
 
-    for (str_op, op) in bitwise_ops {
-        let select = verified_only_select(&format!("SELECT a {} b", &str_op));
+    for (str_op, op, dialects) in bitwise_ops {
+        let select = dialects.verified_only_select(&format!("SELECT a {} b", &str_op));
         assert_eq!(
             SelectItem::UnnamedExpr(Expr::BinaryOp {
                 left: Box::new(Expr::Identifier(Ident::new("a"))),

tests/sqlparser_postgres.rs

@@ -1322,15 +1322,16 @@ fn parse_pg_returning() {
 }
 
 #[test]
-fn parse_pg_bitwise_binary_ops() {
-    let bitwise_ops = &[
-        // Sharp char cannot be used with Generic Dialect, it conflicts with identifiers
+fn parse_pg_binary_ops() {
+    let binary_ops = &[
+        // Sharp char and Caret cannot be used with Generic Dialect, it conflicts with identifiers
         ("#", BinaryOperator::PGBitwiseXor, pg()),
+        ("^", BinaryOperator::PGExp, pg()),
         (">>", BinaryOperator::PGBitwiseShiftRight, pg_and_generic()),
         ("<<", BinaryOperator::PGBitwiseShiftLeft, pg_and_generic()),
     ];
 
-    for (str_op, op, dialects) in bitwise_ops {
+    for (str_op, op, dialects) in binary_ops {
         let select = dialects.verified_only_select(&format!("SELECT a {} b", &str_op));
         assert_eq!(
             SelectItem::UnnamedExpr(Expr::BinaryOp {