accept empty string as escape char

Signed-off-by: TennyZhuang <zty0826@gmail.com>
risingwavelabs · Mar 29, 2024 · b05cb06 · b05cb06
1 parent 034efe4
commit b05cb06
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Showing 5 changed files with 51 additions and 21 deletions.
diff --git a/src/frontend/src/binder/expr/mod.rs b/src/frontend/src/binder/expr/mod.rs
@@ -19,8 +19,8 @@ use risingwave_common::util::iter_util::zip_eq_fast;
 use risingwave_common::{bail_no_function, bail_not_implemented, not_implemented};
 use risingwave_pb::plan_common::{AdditionalColumn, ColumnDescVersion};
 use risingwave_sqlparser::ast::{
-    Array, BinaryOperator, DataType as AstDataType, Expr, Function, JsonPredicateType, ObjectName,
-    Query, StructField, TrimWhereField, UnaryOperator,
+    Array, BinaryOperator, DataType as AstDataType, EscapeChar, Expr, Function, JsonPredicateType,
+    ObjectName, Query, StructField, TrimWhereField, UnaryOperator,
 };
 
 use crate::binder::expr::function::SYS_FUNCTION_WITHOUT_ARGS;
@@ -461,7 +461,7 @@ impl Binder {
         expr: Expr,
         negated: bool,
         pattern: Expr,
-        escape_char: Option<char>,
+        escape_char: Option<EscapeChar>,
     ) -> Result<ExprImpl> {
         if matches!(pattern, Expr::AllOp(_) | Expr::SomeOp(_)) {
             if escape_char.is_some() {
@@ -511,13 +511,16 @@ impl Binder {
         expr: Expr,
         negated: bool,
         pattern: Expr,
-        escape_char: Option<char>,
+        escape_char: Option<EscapeChar>,
     ) -> Result<ExprImpl> {
         let expr = self.bind_expr_inner(expr)?;
         let pattern = self.bind_expr_inner(pattern)?;
 
         let esc_inputs = if let Some(escape_char) = escape_char {
-            let escape_char = ExprImpl::literal_varchar(escape_char.to_string());
+            let escape_char = ExprImpl::literal_varchar(match escape_char.as_char() {
+                Some(c) => c.to_string(),
+                None => "".to_string(),
+            });
             vec![pattern, escape_char]
         } else {
             vec![pattern]

diff --git a/src/sqlparser/src/ast/mod.rs b/src/sqlparser/src/ast/mod.rs
@@ -256,6 +256,34 @@ impl fmt::Display for Array {
     }
 }
 
+/// An escape character, to represent '' or a single character.
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct EscapeChar(Option<char>);
+
+impl EscapeChar {
+    pub fn escape(ch: char) -> Self {
+        Self(Some(ch))
+    }
+
+    pub fn empty() -> Self {
+        Self(None)
+    }
+
+    pub fn as_char(&self) -> Option<char> {
+        self.0
+    }
+}
+
+impl fmt::Display for EscapeChar {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.0 {
+            Some(ch) => write!(f, "'{}'", ch),
+            None => f.write_str("''"),
+        }
+    }
+}
+
 /// An SQL expression of any type.
 ///
 /// The parser does not distinguish between expressions of different types
@@ -334,21 +362,21 @@ pub enum Expr {
         negated: bool,
         expr: Box<Expr>,
         pattern: Box<Expr>,
-        escape_char: Option<char>,
+        escape_char: Option<EscapeChar>,
     },
     /// ILIKE (case-insensitive LIKE)
     ILike {
         negated: bool,
         expr: Box<Expr>,
         pattern: Box<Expr>,
-        escape_char: Option<char>,
+        escape_char: Option<EscapeChar>,
     },
     /// `<expr> [ NOT ] SIMILAR TO <pat> ESCAPE <esc_text>`
     SimilarTo {
         negated: bool,
         expr: Box<Expr>,
         pattern: Box<Expr>,
-        escape_char: Option<char>,
+        escape_char: Option<EscapeChar>,
     },
     /// Binary operation e.g. `1 + 1` or `foo > bar`
     BinaryOp {

diff --git a/src/sqlparser/src/parser.rs b/src/sqlparser/src/parser.rs
@@ -1625,9 +1625,16 @@ impl Parser {
     }
 
     /// parse the ESCAPE CHAR portion of LIKE, ILIKE, and SIMILAR TO
-    pub fn parse_escape_char(&mut self) -> Result<Option<char>, ParserError> {
+    pub fn parse_escape_char(&mut self) -> Result<Option<EscapeChar>, ParserError> {
         if self.parse_keyword(Keyword::ESCAPE) {
-            Ok(Some(self.parse_literal_char()?))
+            let s = self.parse_literal_string()?;
+            if s.len() == 0 {
+                Ok(Some(EscapeChar::empty()))
+            } else if s.len() == 1 {
+                Ok(Some(EscapeChar::escape(s.chars().next().unwrap())))
+            } else {
+                parser_err!(format!("Expect a char or an empty string, found {s:?}"))
+            }
         } else {
             Ok(None)
         }
@@ -3503,14 +3510,6 @@ impl Parser {
         })
     }
 
-    fn parse_literal_char(&mut self) -> Result<char, ParserError> {
-        let s = self.parse_literal_string()?;
-        if s.len() != 1 {
-            return parser_err!(format!("Expect a char, found {s:?}"));
-        }
-        Ok(s.chars().next().unwrap())
-    }
-
     /// Parse a tab separated values in
     /// COPY payload
     fn parse_tsv(&mut self) -> Vec<Option<String>> {

diff --git a/src/sqlparser/tests/sqlparser_common.rs b/src/sqlparser/tests/sqlparser_common.rs
@@ -667,7 +667,7 @@ fn parse_like() {
                 expr: Box::new(Expr::Identifier(Ident::new_unchecked("name"))),
                 negated,
                 pattern: Box::new(Expr::Value(Value::SingleQuotedString("%a".to_string()))),
-                escape_char: Some('\\')
+                escape_char: Some(EscapeChar::escape('\\'))
             },
             select.selection.unwrap()
         );

diff --git a/src/sqlparser/tests/testdata/select.yaml b/src/sqlparser/tests/testdata/select.yaml
@@ -166,8 +166,8 @@
   formatted_sql: SELECT 'a' LIKE 'a'
   formatted_ast: 'Query(Query { with: None, body: Select(Select { distinct: All, projection: [UnnamedExpr(Like { negated: false, expr: Value(SingleQuotedString("a")), pattern: Value(SingleQuotedString("a")), escape_char: None })], from: [], lateral_views: [], selection: None, group_by: [], having: None }), order_by: [], limit: None, offset: None, fetch: None })'
 - input: select 'a' like 'a' escape '\';
-  formatted_sql: SELECT 'a' LIKE 'a' ESCAPE '\'
-  formatted_ast: 'Query(Query { with: None, body: Select(Select { distinct: All, projection: [UnnamedExpr(Like { negated: false, expr: Value(SingleQuotedString("a")), pattern: Value(SingleQuotedString("a")), escape_char: Some(''\\'') })], from: [], lateral_views: [], selection: None, group_by: [], having: None }), order_by: [], limit: None, offset: None, fetch: None })'
+  formatted_sql: SELECT 'a' LIKE 'a' ESCAPE ''\''
+  formatted_ast: 'Query(Query { with: None, body: Select(Select { distinct: All, projection: [UnnamedExpr(Like { negated: false, expr: Value(SingleQuotedString("a")), pattern: Value(SingleQuotedString("a")), escape_char: Some(EscapeChar(Some(''\\''))) })], from: [], lateral_views: [], selection: None, group_by: [], having: None }), order_by: [], limit: None, offset: None, fetch: None })'
 - input: select 'a' not like ANY(array['a', null]);
   formatted_sql: SELECT 'a' NOT LIKE SOME(ARRAY['a', NULL])
   formatted_ast: 'Query(Query { with: None, body: Select(Select { distinct: All, projection: [UnnamedExpr(Like { negated: true, expr: Value(SingleQuotedString("a")), pattern: SomeOp(Array(Array { elem: [Value(SingleQuotedString("a")), Value(Null)], named: true })), escape_char: None })], from: [], lateral_views: [], selection: None, group_by: [], having: None }), order_by: [], limit: None, offset: None, fetch: None })'