1 files changed, 100 insertions, 0 deletions
diff --git a/src/md/visitor/structure.rs b/src/md/visitor/structure.rs
new file mode 100644
index 0000000..d8faef6
--- /dev/null
+++ b/src/md/visitor/structure.rs
@@ -0,0 +1,100 @@
+use crate::md::panhelper;
+
+use pandoc_ast::{Block, Inline, MutVisitor};
+
+// A structure element in the document: a heading or a scenario snippet.
+#[derive(Debug)]
+pub enum Element {
+    // Headings consist of the text and the level of the heading.
+    Heading(String, i64),
+
+    // Scenario snippets consist just of the unparsed text.
+    Snippet(String),
+}
+
+impl Element {
+    pub fn heading(text: &str, level: i64) -> Element {
+        Element::Heading(text.to_string(), level)
+    }
+
+    pub fn snippet(text: &str) -> Element {
+        Element::Snippet(text.to_string())
+    }
+}
+
+// A MutVisitor for extracting document structure.
+pub struct StructureVisitor {
+    pub elements: Vec<Element>,
+}
+
+impl StructureVisitor {
+    pub fn new() -> Self {
+        Self { elements: vec![] }
+    }
+}
+
+impl MutVisitor for StructureVisitor {
+    fn visit_vec_block(&mut self, vec_block: &mut Vec<Block>) {
+        use panhelper::is_class;
+        for block in vec_block {
+            match block {
+                Block::Header(level, _attr, inlines) => {
+                    let text = join(inlines);
+                    let heading = Element::heading(&text, *level);
+                    self.elements.push(heading);
+                }
+                Block::CodeBlock(attr, s) => {
+                    if is_class(attr, "scenario") {
+                        let snippet = Element::snippet(s);
+                        self.elements.push(snippet);
+                    }
+                }
+                _ => {
+                    self.visit_block(block);
+                }
+            }
+        }
+    }
+}
+
+fn join(vec: &[Inline]) -> String {
+    let mut buf = String::new();
+    join_into_buffer(vec, &mut buf);
+    buf
+}
+
+fn join_into_buffer(vec: &[Inline], buf: &mut String) {
+    for item in vec {
+        match item {
+            Inline::Str(s) => buf.push_str(s),
+            Inline::Emph(v) => join_into_buffer(v, buf),
+            Inline::Strong(v) => join_into_buffer(v, buf),
+            Inline::Strikeout(v) => join_into_buffer(v, buf),
+            Inline::Superscript(v) => join_into_buffer(v, buf),
+            Inline::Subscript(v) => join_into_buffer(v, buf),
+            Inline::SmallCaps(v) => join_into_buffer(v, buf),
+            Inline::Quoted(qt, v) => {
+                let q = match qt {
+                    pandoc_ast::QuoteType::SingleQuote => "'",
+                    pandoc_ast::QuoteType::DoubleQuote => "\"",
+                };
+                buf.push_str(q);
+                join_into_buffer(v, buf);
+                buf.push_str(q);
+            }
+            Inline::Cite(_, v) => join_into_buffer(v, buf),
+            Inline::Code(_attr, s) => buf.push_str(s),
+            Inline::Space => buf.push(' '),
+            Inline::SoftBreak => buf.push(' '),
+            Inline::LineBreak => buf.push(' '),
+            Inline::Math(_, s) => buf.push_str(s),
+            Inline::RawInline(_, s) => buf.push_str(s),
+            Inline::Link(_, v, _) => join_into_buffer(v, buf),
+            Inline::Image(_, v, _) => join_into_buffer(v, buf),
+            Inline::Note(_) => buf.push_str(""),
+            Inline::Span(_attr, v) => join_into_buffer(v, buf),
+            #[cfg(feature = "pandoc_ast_08")]
+            Inline::Underline(v) => join_into_buffer(v, buf),
+        }
+    }
+}