Introduce a macro for empty iterators.

src/iter/ast_node_iter.rs

@@ -1,14 +1,21 @@
 use std::marker::PhantomData;
 
 use super::ast_node::AstNode;
-use super::macros::simple_iter;
+use super::macros::children_iter;
+use super::macros::empty_iter;
 use crate::types::Bold;
 use crate::types::Code;
 use crate::types::Italic;
 use crate::types::Object;
 use crate::types::StrikeThrough;
 use crate::types::Underline;
+use crate::types::Verbatim;
 
+/// Iterator over the AST nodes contained within the starting node.
+///
+/// This only iterates over the children, not the starting node itself. So an AstNodeIter::PlainList would only return PlainListItems, not the PlainList.
+///
+/// This only iterates over AST nodes, so an AstNodeIter::Heading would iterate over both the title and section contents, but it would not iterate over simple strings like the TODO keyword or priority.
 pub enum AstNodeIter<'r, 's> {
     // Document Nodes
     // Document(DocumentIter<'r, 's>),
@@ -43,7 +50,7 @@ pub enum AstNodeIter<'r, 's> {
     Underline(UnderlineIter<'r, 's>),
     StrikeThrough(StrikeThroughIter<'r, 's>),
     Code(CodeIter<'r, 's>),
-    // Verbatim(VerbatimIter<'r, 's>),
+    Verbatim(VerbatimIter<'r, 's>),
     // PlainText(PlainTextIter<'r, 's>),
     // RegularLink(RegularLinkIter<'r, 's>),
     // RadioLink(RadioLinkIter<'r, 's>),
@@ -91,13 +98,13 @@ impl<'r, 's> IntoIterator for &'r Bold<'s> {
     }
 }
 
-simple_iter!(Italic<'s>, ItalicIter, std::slice::Iter<'r, Object<'s>>);
-simple_iter!(
+children_iter!(Italic<'s>, ItalicIter, std::slice::Iter<'r, Object<'s>>);
+children_iter!(
     Underline<'s>,
     UnderlineIter,
     std::slice::Iter<'r, Object<'s>>
 );
-simple_iter!(
+children_iter!(
     StrikeThrough<'s>,
     StrikeThroughIter,
     std::slice::Iter<'r, Object<'s>>
@@ -126,3 +133,5 @@ impl<'r, 's> IntoIterator for &'r Code<'s> {
         }
     }
 }
+
+empty_iter!(Verbatim<'s>, VerbatimIter);