Support for postgres String Constants with Unicode Escapes (#1355)

src/ast/value.rs

@@ -52,6 +52,10 @@ pub enum Value {
     /// See [Postgres docs](https://www.postgresql.org/docs/8.3/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS)
     /// for more details.
     EscapedStringLiteral(String),
+    /// u&'string value' (postgres extension)
+    /// See [Postgres docs](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-UESCAPE)
+    /// for more details.
+    UnicodeStringLiteral(String),
     /// B'string value'
     SingleQuotedByteStringLiteral(String),
     /// B"string value"
@@ -102,6 +106,7 @@ impl fmt::Display for Value {
             }
             Value::DollarQuotedString(v) => write!(f, "{v}"),
             Value::EscapedStringLiteral(v) => write!(f, "E'{}'", escape_escaped_string(v)),
+            Value::UnicodeStringLiteral(v) => write!(f, "U&'{}'", escape_unicode_string(v)),
             Value::NationalStringLiteral(v) => write!(f, "N'{v}'"),
             Value::HexStringLiteral(v) => write!(f, "X'{v}'"),
             Value::Boolean(v) => write!(f, "{v}"),
@@ -347,6 +352,41 @@ pub fn escape_escaped_string(s: &str) -> EscapeEscapedStringLiteral<'_> {
     EscapeEscapedStringLiteral(s)
 }
 
+pub struct EscapeUnicodeStringLiteral<'a>(&'a str);
+
+impl<'a> fmt::Display for EscapeUnicodeStringLiteral<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        for c in self.0.chars() {
+            match c {
+                '\'' => {
+                    write!(f, "''")?;
+                }
+                '\\' => {
+                    write!(f, r#"\\"#)?;
+                }
+                x if x.is_ascii() => {
+                    write!(f, "{}", c)?;
+                }
+                _ => {
+                    let codepoint = c as u32;
+                    // if the character fits in 32 bits, we can use the \XXXX format
+                    // otherwise, we need to use the \+XXXXXX format
+                    if codepoint <= 0xFFFF {
+                        write!(f, "\\{:04X}", codepoint)?;
+                    } else {
+                        write!(f, "\\+{:06X}", codepoint)?;
+                    }
+                }
+            }
+        }
+        Ok(())
+    }
+}
+
+pub fn escape_unicode_string(s: &str) -> EscapeUnicodeStringLiteral<'_> {
+    EscapeUnicodeStringLiteral(s)
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "visitor", derive(Visit, VisitMut))]