Implement verse token, scaffold quote token

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

@@ -0,0 +1,72 @@
+use crate::syntax::content::{Parseable, parser::Lexeme};
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct Verse {
+    open: Option<bool>,
+    citation: Option<String>,
+}
+
+impl Verse {
+    pub fn new(open: bool) -> Verse {
+        Verse {
+            open: Some(open),
+            citation: None,
+        }
+    }
+
+    pub fn probe_end(lexeme: &Lexeme) -> bool {
+        lexeme.match_char_triple('\n', '&', '\n')
+    }
+}
+
+impl Parseable for Verse {
+    fn probe(lexeme: &Lexeme) -> bool {
+        lexeme.match_char_triple('\n', '&', '\n')
+    }
+
+    fn lex(_lexeme: &Lexeme) -> Verse {
+        Verse {
+            open: None,
+            citation: None,
+        }
+    }
+
+    fn render(&self) -> String {
+        if let Some(open) = self.open {
+            if open {
+                concat!("\n", r#"<p class="verse">"#).to_string()
+            } else {
+                "\n</p>\n".to_owned()
+            }
+        } else {
+            panic!("Attempt to render a verse tag while open state is unknown")
+        }
+    }
+
+    fn flatten(&self) -> String {
+        String::default()
+    }
+}
+
+impl std::fmt::Display for Verse {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        let display_open_state = match self.open {
+            Some(open_state) => {
+                if open_state {
+                    "open"
+                } else {
+                    "closed"
+                }
+            },
+            None => "unknown",
+        };
+
+        let citation = if self.citation.is_some() {
+            " cited"
+        } else {
+            ""
+        };
+
+        write!(f, "Verse [{display_open_state}{citation}]")
+    }
+}