Make SELECT conformance tests pass (#134)

This PR includes the required changes to ensure the current
SELECT conformance tests pass.

Author: am357

partiql-parser/src/lib.rs

@@ -13,8 +13,8 @@
 //! assert_eq!(errs[0].to_string(), "Unexpected end of input");
 //!
 //! let errs_at: Vec<ParserError> =
-//!     parse_partiql("SELECT * FROM a AS a CROSS JOIN c AS c AT q").unwrap_err();
-//! assert_eq!(errs_at[0].to_string(), "Unexpected token `AT` at `(1:40..1:42)`");
+//!     parse_partiql("SELECT * FROM a AY a CROSS JOIN c AS c AT q").unwrap_err();
+//! assert_eq!(errs_at[0].to_string(), "Unexpected token `<a:UNQUOTED_IDENT>` at `(1:20..1:21)`");
 //! ```
 //!
 //! [partiql]: https://partiql.org

partiql-parser/src/parse/mod.rs

@@ -451,6 +451,16 @@ mod tests {
                     FROM UNPIVOT R.returnValueMap.success AS "list" AT symb"#
             );
         }
+
+        #[test]
+        fn select_with_cross_join_and_at() {
+            parse!(r#"SELECT * FROM a AS a CROSS JOIN c AS c AT q"#);
+        }
+
+        #[test]
+        fn select_with_at_and_cross_join_and_at() {
+            parse!(r#"SELECT * FROM a AS a AT b CROSS JOIN c AS c AT q"#);
+        }
     }
 
     mod set_ops {
@@ -574,74 +584,6 @@ mod tests {
         };
         use std::borrow::Cow;
 
-        #[test]
-        fn improper_at() {
-            let res = parse_partiql(r#"SELECT * FROM a AS a CROSS JOIN c AS c AT q"#);
-            assert!(res.is_err());
-            let errors = res.unwrap_err();
-            assert_eq!(1, errors.len());
-            assert_eq!(
-                "Unexpected token `AT` at `(1:40..1:42)`",
-                errors[0].to_string()
-            );
-        }
-
-        #[test]
-        fn improper_at_multi() {
-            let res = parse_partiql(r#"SELECT * FROM a AS a AT b CROSS JOIN c AS c AT q"#);
-            assert!(res.is_err());
-            let errors = res.unwrap_err();
-            assert_eq!(2, errors.len());
-            assert_eq!(
-                "Unexpected token `AT` at `(1:22..1:24)`",
-                errors[0].to_string()
-            );
-            assert_eq!(
-                "Unexpected token `AT` at `(1:45..1:47)`",
-                errors[1].to_string()
-            );
-            assert_eq!(
-                errors[0],
-                ParseError::UnexpectedToken(UnexpectedToken {
-                    inner: UnexpectedTokenData {
-                        token: Cow::from("AT")
-                    },
-                    location: Location {
-                        start: LineAndCharPosition {
-                            line: LineOffset(0),
-                            char: CharOffset(21)
-                        }
-                        .into(),
-                        end: LineAndCharPosition {
-                            line: LineOffset(0),
-                            char: CharOffset(23)
-                        }
-                        .into(),
-                    },
-                })
-            );
-            assert_eq!(
-                errors[1],
-                ParseError::UnexpectedToken(UnexpectedToken {
-                    inner: UnexpectedTokenData {
-                        token: Cow::from("AT")
-                    },
-                    location: Location {
-                        start: LineAndCharPosition {
-                            line: LineOffset(0),
-                            char: CharOffset(44)
-                        }
-                        .into(),
-                        end: LineAndCharPosition {
-                            line: LineOffset(0),
-                            char: CharOffset(46)
-                        }
-                        .into(),
-                    },
-                })
-            );
-        }
-
         #[test]
         fn eof() {
             let res = parse_partiql(r#"SELECT"#);

partiql-parser/src/parse/partiql.lalrpop

@@ -242,22 +242,22 @@ TableNonJoin: ast::FromClauseAst = {
 
 #[inline]
 TableBaseReference: ast::FromLetAst = {
-    <lo:@L> <e:ExprQuery> <hi:@R> => {
+    <lo:@L> <e:ExprQuery> <as_alias:SymbolPrimitive> <hi:@R> => {
         ast::FromLet {
             expr: e,
             kind: ast::FromLetKind::Scan,
-            as_alias: None,
+            as_alias: Some(as_alias),
             at_alias: None,
             by_alias: None
         }.ast(lo..hi)
     },
-    <lo:@L> <e:ExprQuery> "AS"? <as_alias:SymbolPrimitive> <hi:@R> => {
+    <lo:@L> <e:ExprQuery> <as_alias:AsIdent?> <at_alias:AtIdent?> <by_alias:ByIdent?> <hi:@R> => {
         ast::FromLet {
             expr: e,
             kind: ast::FromLetKind::Scan,
-            as_alias: Some(as_alias),
-            at_alias: None,
-            by_alias: None
+            as_alias,
+            at_alias,
+            by_alias
         }.ast(lo..hi)
     }
 }
@@ -1164,6 +1164,10 @@ AtIdent: ast::SymbolPrimitive = {
     "AT" <SymbolPrimitive>
 }
 
+ByIdent: ast::SymbolPrimitive = {
+    "BY" <SymbolPrimitive>
+}
+
 // ------------------------------------------------------------------------------ //
 //                                                                                //
 //                                    Lexer                                       //