feat: render wml decks with paginated card sub-documents

wap/src/escape.rs

@@ -29,6 +29,21 @@ pub fn attr(value: &str) -> String {
     out
 }
 
+/// Escape text for WML element content.
+#[cfg(feature = "wml")]
+///
+/// WML reads `$` as the start of a variable reference, so a literal one has to be
+/// doubled; otherwise a handset would substitute something or fail to parse.
+pub fn wml(value: &str) -> String {
+    text(value).replace('$', "$$")
+}
+
+/// Escape text for a WML attribute value.
+#[cfg(feature = "wml")]
+pub fn wml_attr(value: &str) -> String {
+    attr(value).replace('$', "$$")
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -41,6 +56,17 @@ mod tests {
         assert_eq!(attr("say \"hi\" & bye"), "say "hi" & bye");
     }
 
+    #[test]
+    #[cfg(feature = "wml")]
+    fn wml_doubles_a_literal_dollar() {
+        assert_eq!(wml("Permit fee: $5"), "Permit fee: $$5");
+        assert_eq!(wml("a & $b"), "a & $$b");
+        assert_eq!(wml_attr("/x?a=1&b=$2"), "/x?a=1&b=$$2");
+        // The doubling runs after the markup escape, so an escaped entity is not
+        // itself rewritten.
+        assert_eq!(wml("<$>"), "&lt;$$&gt;");
+    }
+
     #[test]
     fn leaves_ordinary_text_alone() {
         assert_eq!(text("plain text 123"), "plain text 123");