1 files changed, 40 insertions, 0 deletions
diff --git a/src/librustdoc/html/escape.rs b/src/librustdoc/html/escape.rs
new file mode 100644
index 000000000..4a19d0a44
--- /dev/null
+++ b/src/librustdoc/html/escape.rs
@@ -0,0 +1,40 @@
+//! HTML escaping.
+//!
+//! This module contains one unit struct, which can be used to HTML-escape a
+//! string of text (for use in a format string).
+
+use std::fmt;
+
+/// Wrapper struct which will emit the HTML-escaped version of the contained
+/// string when passed to a format string.
+pub(crate) struct Escape<'a>(pub &'a str);
+
+impl<'a> fmt::Display for Escape<'a> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Because the internet is always right, turns out there's not that many
+        // characters to escape: http://stackoverflow.com/questions/7381974
+        let Escape(s) = *self;
+        let pile_o_bits = s;
+        let mut last = 0;
+        for (i, ch) in s.char_indices() {
+            let s = match ch {
+                '>' => "&gt;",
+                '<' => "&lt;",
+                '&' => "&amp;",
+                '\'' => "&#39;",
+                '"' => "&quot;",
+                _ => continue,
+            };
+            fmt.write_str(&pile_o_bits[last..i])?;
+            fmt.write_str(s)?;
+            // NOTE: we only expect single byte characters here - which is fine as long as we
+            // only match single byte characters
+            last = i + 1;
+        }
+
+        if last < s.len() {
+            fmt.write_str(&pile_o_bits[last..])?;
+        }
+        Ok(())
+    }
+}