Fix escaping of trailing quote in quoted identifiers (#505)

* Generalize EscapeSingleQuoteString to arbitrary quote character

* Fix escaping of trailing quote in quoted identifiers

* Add new tests instead of modifying existing tests

Author: Riccardo Azzolini

src/ast/mod.rs

@@ -23,7 +23,7 @@ use alloc::{
     string::{String, ToString},
     vec::Vec,
 };
-use core::fmt::{self, Write};
+use core::fmt;
 
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
@@ -128,16 +128,8 @@ impl fmt::Display for Ident {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self.quote_style {
             Some(q) if q == '"' || q == '\'' || q == '`' => {
-                f.write_char(q)?;
-                let mut first = true;
-                for s in self.value.split_inclusive(q) {
-                    if !first {
-                        f.write_char(q)?;
-                    }
-                    first = false;
-                    f.write_str(s)?;
-                }
-                f.write_char(q)
+                let escaped = value::escape_quoted_string(&self.value, q);
+                write!(f, "{}{}{}", q, escaped, q)
             }
             Some(q) if q == '[' => write!(f, "[{}]", self.value),
             None => f.write_str(&self.value),

src/ast/value.rs

@@ -178,13 +178,16 @@ impl fmt::Display for DateTimeField {
     }
 }
 
-pub struct EscapeSingleQuoteString<'a>(&'a str);
+pub struct EscapeQuotedString<'a> {
+    string: &'a str,
+    quote: char,
+}
 
-impl<'a> fmt::Display for EscapeSingleQuoteString<'a> {
+impl<'a> fmt::Display for EscapeQuotedString<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        for c in self.0.chars() {
-            if c == '\'' {
-                write!(f, "\'\'")?;
+        for c in self.string.chars() {
+            if c == self.quote {
+                write!(f, "{q}{q}", q = self.quote)?;
             } else {
                 write!(f, "{}", c)?;
             }
@@ -193,8 +196,12 @@ impl<'a> fmt::Display for EscapeSingleQuoteString<'a> {
     }
 }
 
-pub fn escape_single_quote_string(s: &str) -> EscapeSingleQuoteString<'_> {
-    EscapeSingleQuoteString(s)
+pub fn escape_quoted_string(string: &str, quote: char) -> EscapeQuotedString<'_> {
+    EscapeQuotedString { string, quote }
+}
+
+pub fn escape_single_quote_string(s: &str) -> EscapeQuotedString<'_> {
+    escape_quoted_string(s, '\'')
 }
 
 pub struct EscapeEscapedStringLiteral<'a>(&'a str);

tests/sqlparser_mysql.rs

@@ -325,6 +325,40 @@ fn parse_quote_identifiers_2() {
     );
 }
 
+#[test]
+fn parse_quote_identifiers_3() {
+    let sql = "SELECT ```quoted identifier```";
+    assert_eq!(
+        mysql().verified_stmt(sql),
+        Statement::Query(Box::new(Query {
+            with: None,
+            body: SetExpr::Select(Box::new(Select {
+                distinct: false,
+                top: None,
+                projection: vec![SelectItem::UnnamedExpr(Expr::Identifier(Ident {
+                    value: "`quoted identifier`".into(),
+                    quote_style: Some('`'),
+                }))],
+                into: None,
+                from: vec![],
+                lateral_views: vec![],
+                selection: None,
+                group_by: vec![],
+                cluster_by: vec![],
+                distribute_by: vec![],
+                sort_by: vec![],
+                having: None,
+                qualify: None
+            })),
+            order_by: vec![],
+            limit: None,
+            offset: None,
+            fetch: None,
+            lock: None,
+        }))
+    );
+}
+
 #[test]
 fn parse_unterminated_escape() {
     let sql = r#"SELECT 'I\'m not fine\'"#;

tests/sqlparser_postgres.rs

@@ -1441,6 +1441,11 @@ fn parse_quoted_identifier() {
     pg_and_generic().verified_stmt(r#"SELECT "quoted "" ident""#);
 }
 
+#[test]
+fn parse_quoted_identifier_2() {
+    pg_and_generic().verified_stmt(r#"SELECT """quoted ident""""#);
+}
+
 #[test]
 fn parse_local_and_global() {
     pg_and_generic().verified_stmt("CREATE LOCAL TEMPORARY TABLE table (COL INT)");