feat: HeadlineNode struct

src/lib.rs

@@ -219,9 +219,11 @@
 mod config;
 pub mod elements;
 pub mod export;
+mod node;
 mod org;
 mod parsers;
 
 pub use config::ParseConfig;
 pub use elements::Element;
+pub use node::HeadlineNode;
 pub use org::Org;

src/node.rs

@@ -0,0 +1,27 @@
+use indextree::NodeId;
+
+use crate::elements::{Element, Title};
+use crate::Org;
+
+#[derive(Copy, Clone)]
+pub struct HeadlineNode(pub(crate) NodeId);
+
+impl HeadlineNode {
+    pub fn get_title<'a>(self, org: &'a Org<'a>) -> &'a Title<'a> {
+        let title_node = org.arena[self.0].first_child().unwrap();
+        if let Element::Title(title) = org.arena[title_node].get() {
+            title
+        } else {
+            unreachable!()
+        }
+    }
+
+    pub fn get_title_mut<'a>(self, org: &'a mut Org<'a>) -> &'a mut Title<'a> {
+        let title_node = org.arena[self.0].first_child().unwrap();
+        if let Element::Title(title) = org.arena[title_node].get_mut() {
+            title
+        } else {
+            unreachable!()
+        }
+    }
+}

src/org.rs

@@ -2,12 +2,13 @@ use indextree::{Arena, NodeEdge, NodeId};
 use std::io::{Error, Write};
 
 use crate::config::ParseConfig;
-use crate::elements::*;
+use crate::elements::Element;
 use crate::export::*;
+use crate::node::HeadlineNode;
 use crate::parsers::*;
 
 pub struct Org<'a> {
-    arena: Arena<Element<'a>>,
+    pub(crate) arena: Arena<Element<'a>>,
     document: NodeId,
 }
 
@@ -68,6 +69,18 @@ impl Org<'_> {
             })
     }
 
+    pub fn headlines(&self) -> Vec<HeadlineNode> {
+        self.document
+            .descendants(&self.arena)
+            .skip(1)
+            .filter(|&node| match self.arena[node].get() {
+                Element::Headline => true,
+                _ => false,
+            })
+            .map(|node| HeadlineNode(node))
+            .collect()
+    }
+
     pub fn html<W: Write>(&self, wrtier: W) -> Result<(), Error> {
         self.html_with_handler(wrtier, DefaultHtmlHandler)
     }