Implement underline and strikethrough tokens

src/syntax/content/parser/token/strike.rs

@@ -0,0 +1,58 @@
+use crate::{
+    syntax::content::{Parseable, Lexeme},
+};
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct Strike {
+    open: bool,
+}
+
+impl Strike {
+    pub fn new(open: bool) -> Strike {
+        Strike { open }
+    }
+}
+
+impl Parseable for Strike {
+    fn probe(lexeme: &Lexeme) -> bool {
+        lexeme.match_as_char('~') && lexeme.match_next_as_char('~')
+    }
+
+    fn lex(_lexeme: &Lexeme) -> Strike {
+        panic!("Attempt to lex a strike tag directly from a lexeme")
+    }
+
+    fn render(&self) -> String {
+        let tag = if self.open { "<s>" } else { "</s>" };
+        String::from(tag)
+    }
+}
+
+impl std::fmt::Display for Strike {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        let display_open_state = if self.open { "open" } else { "closed" };
+        write!(f, "Strike [{display_open_state}]")
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn render() {
+        let code_open = Strike::new(true);
+        assert_eq!(code_open.render(), "<s>");
+
+        let code_closed = Strike::new(false);
+        assert_eq!(code_closed.render(), "</s>");
+    }
+
+    #[test]
+    #[should_panic(
+        expected = "Attempt to lex a strike tag directly from a lexeme"
+    )]
+    fn lex() {
+        Strike::lex(&Lexeme::new("", ""));
+    }
+}