Introduce macro to simplify this.

src/iter/ast_node_iter.rs

@@ -1,5 +1,6 @@
 use super::ast_node::AstNode;
 use crate::types::Bold;
+use crate::types::Italic;
 use crate::types::Object;
 
 pub enum AstNodeIter<'r, 's> {
@@ -32,7 +33,7 @@ pub enum AstNodeIter<'r, 's> {
     // LatexEnvironment(LatexEnvironmentIter<'r, 's>),
     // Objects
     Bold(BoldIter<'r, 's>),
-    // Italic(ItalicIter<'r, 's>),
+    Italic(ItalicIter<'r, 's>),
     // Underline(UnderlineIter<'r, 's>),
     // StrikeThrough(StrikeThroughIter<'r, 's>),
     // Code(CodeIter<'r, 's>),
@@ -83,3 +84,33 @@ impl<'r, 's> IntoIterator for &'r Bold<'s> {
         }
     }
 }
+
+macro_rules! simple_iter {
+    ($astnodetype:ty, $itertype:ident, $innertype:ty) => {
+        pub struct $itertype<'r, 's> {
+            next: $innertype,
+        }
+
+        impl<'r, 's> Iterator for $itertype<'r, 's> {
+            type Item = AstNode<'r, 's>;
+
+            fn next(&mut self) -> Option<Self::Item> {
+                self.next.next().map(Into::<AstNode>::into)
+            }
+        }
+
+        impl<'r, 's> IntoIterator for &'r $astnodetype {
+            type Item = AstNode<'r, 's>;
+
+            type IntoIter = $itertype<'r, 's>;
+
+            fn into_iter(self) -> Self::IntoIter {
+                $itertype {
+                    next: self.children.iter(),
+                }
+            }
+        }
+    };
+}
+
+simple_iter!(Italic<'s>, ItalicIter, std::slice::Iter<'r, Object<'s>>);