1 files changed, 52 insertions, 0 deletions
diff --git a/src/tools/rustfmt/src/emitter/checkstyle/xml.rs b/src/tools/rustfmt/src/emitter/checkstyle/xml.rs
new file mode 100644
index 000000000..f251aabe8
--- /dev/null
+++ b/src/tools/rustfmt/src/emitter/checkstyle/xml.rs
@@ -0,0 +1,52 @@
+use std::fmt::{self, Display};
+
+/// Convert special characters into XML entities.
+/// This is needed for checkstyle output.
+pub(super) struct XmlEscaped<'a>(pub(super) &'a str);
+
+impl<'a> Display for XmlEscaped<'a> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for char in self.0.chars() {
+            match char {
+                '<' => write!(formatter, "&lt;"),
+                '>' => write!(formatter, "&gt;"),
+                '"' => write!(formatter, "&quot;"),
+                '\'' => write!(formatter, "&apos;"),
+                '&' => write!(formatter, "&amp;"),
+                _ => write!(formatter, "{}", char),
+            }?;
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn special_characters_are_escaped() {
+        assert_eq!(
+            "&lt;&gt;&quot;&apos;&amp;",
+            format!("{}", XmlEscaped(r#"<>"'&"#)),
+        );
+    }
+
+    #[test]
+    fn special_characters_are_escaped_in_string_with_other_characters() {
+        assert_eq!(
+            "The quick brown &quot;🦊&quot; jumps &lt;over&gt; the lazy 🐶",
+            format!(
+                "{}",
+                XmlEscaped(r#"The quick brown "🦊" jumps <over> the lazy 🐶"#)
+            ),
+        );
+    }
+
+    #[test]
+    fn other_characters_are_not_escaped() {
+        let string = "The quick brown 🦊 jumps over the lazy 🐶";
+        assert_eq!(string, format!("{}", XmlEscaped(string)));
+    }
+}