Convert double hyphens to em-dash

src/markdown.rs

@@ -19,13 +19,23 @@ fn strip_comments(mut content: String) -> String {
     content.trim().to_string()
 }
 
+/// Convert hyphens to em-dashes
+fn convert_hyphens_to_em_dashes(mut content: String) -> String {
+    let re = Regex::new(r"(\s+--\s+)").unwrap();
+    content = Regex::replace_all(&re, content.as_str(), "—").to_string();
+    content.trim().to_string()
+}
+
 /// Convert the content of a Markdown into a collection of paragraphs.
 fn content_to_paragraphs(mut content: String) -> Vec<Paragraph> {
     // Pre-process the content
 
     // Add support single and multi-line %% comment blocks %%
     content = strip_comments(content);
 
+    // Replace double-hyphens to em-dashes
+    content = convert_hyphens_to_em_dashes(content);
+
     let mut paragraphs: Vec<Paragraph> = vec![];
     let sep = Paragraph::new()
         .add_run(Run::new().add_text("#"))
@@ -262,6 +272,14 @@ mod tests {
         assert!(content.is_empty());
     }
 
+    #[test]
+    fn test_convert_hyphens_to_em_dashes() {
+        let content = convert_hyphens_to_em_dashes(
+            "This is a test -- only a test -- he was told.".to_string(),
+        );
+        assert!(content == "This is a test—only a test—he was told.");
+    }
+
     #[test]
     fn test_trim_doublespace() {
         let s = "This is a test.  This is only a test.\nIf this were an actual emergency, you would be instructed where to go and what to do.";