Encoded the first state in the SummaryParser

src/loader/summary.rs

@@ -25,7 +25,8 @@ use pulldown_cmark::{self, Event, Tag};
 /// [Title of prefix element](relative/path/to/markdown.md)
 /// ```
 ///
-/// **Numbered Chapter:** Numbered chapters are the main content of the book, they
+/// **Numbered Chapter:** Numbered chapters are the main content of the book,
+/// they
 /// will be numbered and can be nested, resulting in a nice hierarchy (chapters,
 /// sub-chapters, etc.)
 ///
@@ -69,6 +70,16 @@ enum SummaryItem {
     Separator,
 }
 
+#[derive(Debug, Copy, Clone, PartialEq)]
+enum State {
+    Begin,
+    PrefixChapters,
+    /// Numbered chapters, including the nesting level.
+    NumberedChapters(u32),
+    SuffixChapters,
+    End,
+}
+
 /// A stateful parser for parsing a `SUMMARY.md` file.
 ///
 /// # Grammar
@@ -76,7 +87,8 @@ enum SummaryItem {
 /// The `SUMMARY.md` file has a grammar which looks something like this:
 ///
 /// ```text
-/// summary           ::= title prefix_chapters numbered_chapters suffix_chapters
+/// summary           ::= title prefix_chapters numbered_chapters
+/// suffix_chapters
 /// title             ::= "# " TEXT
 ///                     | EPSILON
 /// prefix_chapters   ::= item*
@@ -96,6 +108,7 @@ enum SummaryItem {
 struct SummaryParser<'a> {
     stream: pulldown_cmark::Parser<'a>,
     summary: Summary,
+    state: State,
 }
 
 /// Reads `Events` from the provided stream until the corresponding
@@ -127,8 +140,7 @@ macro_rules! collect_events {
     }
 }
 
-impl<'a> SummaryParser<'a> 
-{
+impl<'a> SummaryParser<'a> {
     fn new(text: &str) -> SummaryParser {
         let pulldown_parser = pulldown_cmark::Parser::new(text);
         let intermediate_summary = Summary::default();
@@ -136,6 +148,7 @@ impl<'a> SummaryParser<'a>
         SummaryParser {
             stream: pulldown_parser,
             summary: intermediate_summary,
+            state: State::Begin,
         }
     }
 
@@ -146,6 +159,27 @@ impl<'a> SummaryParser<'a>
         Ok(self.summary)
     }
 
+    fn step(&mut self) -> Result<(), Box<Error>> {
+        let next_event = self.stream.next().expect("TODO: error-chain");
+        trace!("[*] Current state = {:?}, Next Event = {:?}", self.state, next_event);
+    
+        match self.state {
+            State::Begin => self.step_start(next_event),
+            other => unimplemented!()
+        }
+    }
+
+    /// The very first state, we should see a `BeginParagraph` token or
+    /// it's an error...
+    fn step_start(&mut self, event: Event<'a>) -> Result<(), Box<Error>> {
+        match event {
+            Event::Start(Tag::Paragraph) => self.state = State::PrefixChapters,
+            other => panic!("Unexpected tag! {:?}", other),
+        }
+
+        Ok(())
+    }
+
     fn parse_title(&mut self) -> Option<String> {
         if let Some(Event::Start(Tag::Header(1))) = self.stream.next() {
             debug!("[*] Found a h1 in the SUMMARY");
@@ -179,15 +213,15 @@ impl<'a> SummaryParser<'a>
     }
 }
 
-/// Extract just the text from a bunch of events and concatenate it into a
-/// single string.
+/// Extracts the text from formatted markdown.
 fn stringify_events<'a>(events: Vec<Event<'a>>) -> String {
-    events.into_iter()
-                .filter_map(|t| match t {
-                    Event::Text(text) => Some(text),
-                    _ => None,
-                })
-                .collect()
+    events
+        .into_iter()
+        .filter_map(|t| match t {
+            Event::Text(text) => Some(text.into_owned()),
+            _ => None,
+        })
+        .collect()
 }
 
 /// A section number like "1.2.3", basically just a newtype'd `Vec<u32>`.
@@ -196,9 +230,11 @@ struct SectionNumber(Vec<u32>);
 
 impl Display for SectionNumber {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        let dotted_number: String = self.0.iter().map(|i| format!("{}", i))
-        .collect::<Vec<String>>()
-        .join(".");
+        let dotted_number: String = self.0
+            .iter()
+            .map(|i| format!("{}", i))
+            .collect::<Vec<String>>()
+            .join(".");
 
         write!(f, "{}", dotted_number)
     }
@@ -274,4 +310,27 @@ mod tests {
 
         assert_eq!(got, should_be);
     }
+
+    #[test]
+    fn convert_markdown_events_to_a_string() {
+        let src = "Hello *World*, `this` is some text [and a link](./path/to/link)";
+        let should_be = "Hello World, this is some text and a link";
+
+        let events = pulldown_cmark::Parser::new(src).collect();
+        let got = stringify_events(events);
+
+        assert_eq!(got, should_be);
+
+    }
+
+    #[test]
+    fn can_step_past_first_token() {
+        let src = "hello world";
+        let should_be = State::PrefixChapters;
+
+        let mut parser = SummaryParser::new(src);
+        assert_eq!(parser.state, State::Begin);
+        parser.step().unwrap();
+        assert_eq!(parser.state, should_be);
+    }
 }