Support for MSSQL CONVERT styles (apache#1219)

Author: iffyio

src/ast/mod.rs

@@ -567,6 +567,10 @@ pub enum Expr {
         charset: Option<ObjectName>,
         /// whether the target comes before the expr (MSSQL syntax)
         target_before_value: bool,
+        /// How to translate the expression.
+        ///
+        /// [MSSQL]: https://learn.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql?view=sql-server-ver16#style
+        styles: Vec<Expr>,
     },
     /// `CAST` an expression to a different data type e.g. `CAST(foo AS VARCHAR(123))`
     Cast {
@@ -979,6 +983,7 @@ impl fmt::Display for Expr {
                 target_before_value,
                 data_type,
                 charset,
+                styles,
             } => {
                 write!(f, "CONVERT(")?;
                 if let Some(data_type) = data_type {
@@ -994,6 +999,9 @@ impl fmt::Display for Expr {
                 } else {
                     write!(f, "{expr}") // This should never happen
                 }?;
+                if !styles.is_empty() {
+                    write!(f, ", {}", display_comma_separated(styles))?;
+                }
                 write!(f, ")")
             }
             Expr::Cast {

src/parser/mod.rs

@@ -1462,12 +1462,18 @@ impl<'a> Parser<'a> {
         let data_type = self.parse_data_type()?;
         self.expect_token(&Token::Comma)?;
         let expr = self.parse_expr()?;
+        let styles = if self.consume_token(&Token::Comma) {
+            self.parse_comma_separated(Parser::parse_expr)?
+        } else {
+            Default::default()
+        };
         self.expect_token(&Token::RParen)?;
         Ok(Expr::Convert {
             expr: Box::new(expr),
             data_type: Some(data_type),
             charset: None,
             target_before_value: true,
+            styles,
         })
     }
 
@@ -1489,6 +1495,7 @@ impl<'a> Parser<'a> {
                 data_type: None,
                 charset: Some(charset),
                 target_before_value: false,
+                styles: vec![],
             });
         }
         self.expect_token(&Token::Comma)?;
@@ -1504,6 +1511,7 @@ impl<'a> Parser<'a> {
             data_type: Some(data_type),
             charset,
             target_before_value: false,
+            styles: vec![],
         })
     }
 

tests/sqlparser_mssql.rs

@@ -20,6 +20,7 @@ use test_utils::*;
 
 use sqlparser::ast::*;
 use sqlparser::dialect::{GenericDialect, MsSqlDialect};
+use sqlparser::parser::ParserError;
 
 #[test]
 fn parse_mssql_identifiers() {
@@ -437,9 +438,39 @@ fn parse_cast_varchar_max() {
 
 #[test]
 fn parse_convert() {
+    let sql = "CONVERT(INT, 1, 2, 3, NULL)";
+    let Expr::Convert {
+        expr,
+        data_type,
+        charset,
+        target_before_value,
+        styles,
+    } = ms().verified_expr(sql)
+    else {
+        unreachable!()
+    };
+    assert_eq!(Expr::Value(number("1")), *expr);
+    assert_eq!(Some(DataType::Int(None)), data_type);
+    assert!(charset.is_none());
+    assert!(target_before_value);
+    assert_eq!(
+        vec![
+            Expr::Value(number("2")),
+            Expr::Value(number("3")),
+            Expr::Value(Value::Null),
+        ],
+        styles
+    );
+
     ms().verified_expr("CONVERT(VARCHAR(MAX), 'foo')");
     ms().verified_expr("CONVERT(VARCHAR(10), 'foo')");
     ms().verified_expr("CONVERT(DECIMAL(10,5), 12.55)");
+
+    let error_sql = "SELECT CONVERT(INT, 'foo',) FROM T";
+    assert_eq!(
+        ParserError::ParserError("Expected an expression:, found: )".to_owned()),
+        ms().parse_sql_statements(error_sql).unwrap_err()
+    );
 }
 
 #[test]