Make SQLOrderByExpr::asc tri-state

i.e. ASC/DESC/unspecified - so that we don't lose information about
source code.

Also don't take any keyword other than ASC/DESC or Comma to mean
'ascending'.

src/sqlast/mod.rs

@@ -366,21 +366,21 @@ impl ToString for SQLAssignment {
 #[derive(Debug, Clone, PartialEq)]
 pub struct SQLOrderByExpr {
     pub expr: Box<ASTNode>,
-    pub asc: bool,
+    pub asc: Option<bool>,
 }
 
 impl SQLOrderByExpr {
-    pub fn new(expr: Box<ASTNode>, asc: bool) -> Self {
+    pub fn new(expr: Box<ASTNode>, asc: Option<bool>) -> Self {
         SQLOrderByExpr { expr, asc }
     }
 }
 
 impl ToString for SQLOrderByExpr {
     fn to_string(&self) -> String {
-        if self.asc {
+        match self.asc {
-            format!("{} ASC", self.expr.as_ref().to_string())
+            Some(true) => format!("{} ASC", self.expr.to_string()),
-        } else {
+            Some(false) => format!("{} DESC", self.expr.to_string()),
-            format!("{} DESC", self.expr.as_ref().to_string())
+            None => self.expr.to_string(),
         }
     }
 }

src/sqlparser.rs

@@ -1321,33 +1321,19 @@ impl Parser {
         loop {
             let expr = self.parse_expr(0)?;
 
-            // look for optional ASC / DESC specifier
+            let asc = if self.parse_keyword("ASC") {
-            let asc = match self.peek_token() {
+                Some(true)
-                Some(Token::Keyword(k)) => match k.to_uppercase().as_ref() {
+            } else if self.parse_keyword("DESC") {
-                    "ASC" => {
+                Some(false)
-                        self.next_token();
+            } else {
-                        true
+                None
-                    }
-                    "DESC" => {
-                        self.next_token();
-                        false
-                    }
-                    _ => true,
-                },
-                Some(Token::Comma) => true,
-                _ => true,
             };
 
             expr_list.push(SQLOrderByExpr::new(Box::new(expr), asc));
 
-            if let Some(t) = self.peek_token() {
+            if let Some(Token::Comma) = self.peek_token() {
-                if t == Token::Comma {
+                self.next_token();
-                    self.next_token();
-                } else {
-                    break;
-                }
             } else {
-                // EOF
                 break;
             }
         }

tests/sqlparser_generic.rs

@@ -230,7 +230,7 @@ fn parse_not_like() {
 #[test]
 fn parse_select_order_by() {
     let sql = String::from(
-        "SELECT id, fname, lname FROM customer WHERE id < 5 ORDER BY lname ASC, fname DESC",
+        "SELECT id, fname, lname FROM customer WHERE id < 5 ORDER BY lname ASC, fname DESC, id",
     );
     match verified(&sql) {
         ASTNode::SQLSelect { order_by, .. } => {
@@ -238,11 +238,15 @@ fn parse_select_order_by() {
                 Some(vec![
                     SQLOrderByExpr {
                         expr: Box::new(ASTNode::SQLIdentifier("lname".to_string())),
-                        asc: true,
+                        asc: Some(true),
                     },
                     SQLOrderByExpr {
                         expr: Box::new(ASTNode::SQLIdentifier("fname".to_string())),
-                        asc: false,
+                        asc: Some(false),
+                    },
+                    SQLOrderByExpr {
+                        expr: Box::new(ASTNode::SQLIdentifier("id".to_string())),
+                        asc: None,
                     },
                 ]),
                 order_by
@@ -266,11 +270,11 @@ fn parse_select_order_by_limit() {
                 Some(vec![
                     SQLOrderByExpr {
                         expr: Box::new(ASTNode::SQLIdentifier("lname".to_string())),
-                        asc: true,
+                        asc: Some(true),
                     },
                     SQLOrderByExpr {
                         expr: Box::new(ASTNode::SQLIdentifier("fname".to_string())),
-                        asc: false,
+                        asc: Some(false),
                     },
                 ]),
                 order_by