[chore] Revert @sigma table factor

src/ast/mod.rs

@@ -462,8 +462,6 @@ pub enum Expr {
     Identifier(Ident),
     /// Multi-part identifier, e.g. `table_alias.column` or `schema.table.col`
     CompoundIdentifier(Vec<Ident>),
-    /// A reference to a Sigma scalar value, e.g. `@sigma.my_parameter`.
-    SigmaParameter(Ident),
     /// Access data nested in a value containing semi-structured data, such as
     /// the `VARIANT` type on Snowflake. for example `src:customer[0].name`.
     ///
@@ -950,7 +948,6 @@ impl fmt::Display for Expr {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             Expr::Identifier(s) => write!(f, "{s}"),
-            Expr::SigmaParameter(s) => write!(f, "@sigma.{s}"),
             Expr::MapAccess { column, keys } => {
                 write!(f, "{column}{}", display_separated(keys, ""))
             }

src/ast/query.rs

@@ -916,11 +916,6 @@ pub enum TableFactor {
         /// [Partition selection](https://dev.mysql.com/doc/refman/8.0/en/partitioning-selection.html), supported by MySQL.
         partitions: Vec<Ident>,
     },
-    /// A reference to an element in a Sigma workbook.
-    SigmaElement {
-        element: Ident,
-        alias: Option<TableAlias>,
-    },
     Derived {
         lateral: bool,
         subquery: Box<Query>,
@@ -1317,13 +1312,6 @@ impl fmt::Display for TableFactor {
                 }
                 Ok(())
             }
-            TableFactor::SigmaElement { element, alias } => {
-                write!(f, "@sigma.{element}")?;
-                if let Some(alias) = alias {
-                    write!(f, " AS {alias}")?;
-                }
-                Ok(())
-            }
             TableFactor::Derived {
                 lateral,
                 subquery,

src/keywords.rs

@@ -20,7 +20,7 @@
 //!     As a matter of fact, most of these keywords are not used at all
 //!     and could be removed.
 //! 3) a `RESERVED_FOR_TABLE_ALIAS` array with keywords reserved in a
 //! "table alias" context.
 
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
@@ -655,7 +655,6 @@
     SETTINGS,
     SHARE,
     SHOW,
-    SIGMA,
     SIMILAR,
     SKIP,
     SLOW,

src/parser/mod.rs

@@ -1152,10 +1152,6 @@ impl<'a> Parser<'a> {
             }, // End of Token::Word
             // array `[1, 2, 3]`
             Token::LBracket => self.parse_array_expr(false),
-            Token::AtSign if self.parse_keyword(Keyword::SIGMA) => {
-                self.expect_token(&Token::Period)?;
-                Ok(Expr::SigmaParameter(self.parse_identifier(false)?))
-            }
             tok @ Token::Minus | tok @ Token::Plus => {
                 let op = if tok == Token::Plus {
                     UnaryOperator::Plus
@@ -9152,7 +9148,6 @@ impl<'a> Parser<'a> {
                     match &mut table_and_joins.relation {
                         TableFactor::Derived { alias, .. }
                         | TableFactor::Table { alias, .. }
-                        | TableFactor::SigmaElement { alias, .. }
                         | TableFactor::Function { alias, .. }
                         | TableFactor::UNNEST { alias, .. }
                         | TableFactor::JsonTable { alias, .. }
@@ -9267,11 +9262,6 @@ impl<'a> Parser<'a> {
                 columns,
                 alias,
             })
-        } else if self.parse_sigma_directive() {
-            self.expect_token(&Token::Period)?;
-            let element = self.parse_identifier(true)?;
-            let alias = self.parse_optional_table_alias(keywords::RESERVED_FOR_TABLE_ALIAS)?;
-            Ok(TableFactor::SigmaElement { element, alias })
         } else {
             let name = self.parse_object_name(true)?;
 
@@ -9334,15 +9324,6 @@ impl<'a> Parser<'a> {
         }
     }
 
-    pub fn parse_sigma_directive(&mut self) -> bool {
-        self.maybe_parse(|p| {
-            p.expect_token(&Token::AtSign)?;
-            p.expect_keyword(Keyword::SIGMA)?;
-            Ok(())
-        })
-        .is_some()
-    }
-
     fn parse_match_recognize(&mut self, table: TableFactor) -> Result<TableFactor, ParserError> {
         self.expect_token(&Token::LParen)?;