1 files changed, 100 insertions, 0 deletions
diff --git a/askama_escape/src/lib.rs b/askama_escape/src/lib.rs
new file mode 100644
index 0000000..b967f1f
--- /dev/null
+++ b/askama_escape/src/lib.rs
@@ -0,0 +1,100 @@
+use std::fmt::{self, Display, Formatter};
+use std::str;
+
+#[derive(Debug, PartialEq)]
+pub enum MarkupDisplay<T>
+where
+    T: Display,
+{
+    Safe(T),
+    Unsafe(T),
+}
+
+impl<T> MarkupDisplay<T>
+where
+    T: Display,
+{
+    pub fn mark_safe(self) -> MarkupDisplay<T> {
+        match self {
+            MarkupDisplay::Unsafe(t) => MarkupDisplay::Safe(t),
+            _ => self,
+        }
+    }
+}
+
+impl<T> From<T> for MarkupDisplay<T>
+where
+    T: Display,
+{
+    fn from(t: T) -> MarkupDisplay<T> {
+        MarkupDisplay::Unsafe(t)
+    }
+}
+
+impl<T> Display for MarkupDisplay<T>
+where
+    T: Display,
+{
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match *self {
+            MarkupDisplay::Unsafe(ref t) => escape(&t.to_string()).fmt(f),
+            MarkupDisplay::Safe(ref t) => t.fmt(f),
+        }
+    }
+}
+
+pub fn escape(s: &str) -> Escaped {
+    Escaped {
+        bytes: s.as_bytes(),
+    }
+}
+
+macro_rules! escaping_body {
+    ($start:ident, $i:ident, $fmt:ident, $_self:ident, $quote:expr) => {{
+        if $start < $i {
+            $fmt.write_str(unsafe { str::from_utf8_unchecked(&$_self.bytes[$start..$i]) })?;
+        }
+        $fmt.write_str($quote)?;
+        $start = $i + 1;
+    }};
+}
+
+pub struct Escaped<'a> {
+    bytes: &'a [u8],
+}
+
+impl<'a> ::std::fmt::Display for Escaped<'a> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut start = 0;
+        for (i, b) in self.bytes.iter().enumerate() {
+            if b.wrapping_sub(b'"') <= FLAG {
+                match *b {
+                    b'<' => escaping_body!(start, i, fmt, self, "&lt;"),
+                    b'>' => escaping_body!(start, i, fmt, self, "&gt;"),
+                    b'&' => escaping_body!(start, i, fmt, self, "&amp;"),
+                    b'"' => escaping_body!(start, i, fmt, self, "&quot;"),
+                    b'\'' => escaping_body!(start, i, fmt, self, "&#x27;"),
+                    b'/' => escaping_body!(start, i, fmt, self, "&#x2f;"),
+                    _ => (),
+                }
+            }
+        }
+        fmt.write_str(unsafe { str::from_utf8_unchecked(&self.bytes[start..]) })?;
+        Ok(())
+    }
+}
+
+const FLAG: u8 = b'>' - b'"';
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_escape() {
+        assert_eq!(escape("").to_string(), "");
+        assert_eq!(escape("<&>").to_string(), "&lt;&amp;&gt;");
+        assert_eq!(escape("bla&").to_string(), "bla&amp;");
+        assert_eq!(escape("<foo").to_string(), "&lt;foo");
+        assert_eq!(escape("bla&h").to_string(), "bla&amp;h");
+    }
+}