Add Support in the "Position" Function (apache#463)

* Add support in the position function

* Add Test

* Add lint fixes

* Remove if

* Change from to in

* Remove special method for position

* Fix lint

* PR Review

Author: yuval-illumex

src/ast/mod.rs

@@ -262,6 +262,11 @@ pub enum Expr {
         field: DateTimeField,
         expr: Box<Expr>,
     },
+    /// POSITION(<expr> in <expr>)
+    Position {
+        expr: Box<Expr>,
+        r#in: Box<Expr>,
+    },
     /// SUBSTRING(<expr> [FROM <expr>] [FOR <expr>])
     Substring {
         expr: Box<Expr>,
@@ -418,6 +423,7 @@ impl fmt::Display for Expr {
             Expr::Cast { expr, data_type } => write!(f, "CAST({} AS {})", expr, data_type),
             Expr::TryCast { expr, data_type } => write!(f, "TRY_CAST({} AS {})", expr, data_type),
             Expr::Extract { field, expr } => write!(f, "EXTRACT({} FROM {})", field, expr),
+            Expr::Position { expr, r#in } => write!(f, "POSITION({} IN {})", expr, r#in),
             Expr::Collate { expr, collation } => write!(f, "{} COLLATE {}", expr, collation),
             Expr::Nested(ast) => write!(f, "({})", ast),
             Expr::Value(v) => write!(f, "{}", v),

src/parser.rs

@@ -447,6 +447,7 @@ impl<'a> Parser<'a> {
                 Keyword::TRY_CAST => self.parse_try_cast_expr(),
                 Keyword::EXISTS => self.parse_exists_expr(),
                 Keyword::EXTRACT => self.parse_extract_expr(),
+                Keyword::POSITION => self.parse_position_expr(),
                 Keyword::SUBSTRING => self.parse_substring_expr(),
                 Keyword::TRIM => self.parse_trim_expr(),
                 Keyword::INTERVAL => self.parse_literal_interval(),
@@ -826,6 +827,24 @@ impl<'a> Parser<'a> {
         })
     }
 
+    pub fn parse_position_expr(&mut self) -> Result<Expr, ParserError> {
+        // PARSE SELECT POSITION('@' in field)
+        self.expect_token(&Token::LParen)?;
+
+        // Parse the subexpr till the IN keyword
+        let expr = self.parse_subexpr(Self::BETWEEN_PREC)?;
+        if self.parse_keyword(Keyword::IN) {
+            let from = self.parse_expr()?;
+            self.expect_token(&Token::RParen)?;
+            Ok(Expr::Position {
+                expr: Box::new(expr),
+                r#in: Box::new(from),
+            })
+        } else {
+            return parser_err!("Position function must include IN keyword".to_string());
+        }
+    }
+
     pub fn parse_substring_expr(&mut self) -> Result<Expr, ParserError> {
         // PARSE SUBSTRING (EXPR [FROM 1] [FOR 3])
         self.expect_token(&Token::LParen)?;

tests/sqlparser_common.rs

@@ -4903,3 +4903,16 @@ fn parse_cursor() {
         _ => unreachable!(),
     }
 }
+
+#[test]
+fn parse_position() {
+    let sql = "SELECT POSITION('@' IN field)";
+    let select = verified_only_select(sql);
+    assert_eq!(
+        &Expr::Position {
+            expr: Box::new(Expr::Value(Value::SingleQuotedString("@".to_string()))),
+            r#in: Box::new(Expr::Identifier(Ident::new("field"))),
+        },
+        expr_from_projection(only(&select.projection))
+    );
+}