Add more documentation comments

src/core/rope.rs

@@ -71,7 +71,7 @@ impl Rope {
         }
     }
 
-    // Return the total number of lines in the text
+    /// Return the total number of lines in the text
     pub fn total_lines(&self) -> usize {
         match self {
             Rope::Branch {
@@ -88,7 +88,12 @@ impl Rope {
         }
     }
 
-    pub fn join(left: Rc<Rope>, right: Rc<Rope>) -> Rc<Self> {
+    /// Concatenate two Ropes without rebalancing.
+    ///
+    /// Combines to ropes by creating a new parent node and adding `left` and
+    /// `right` as children. Having this separate from [Rope::concatenate()] is mostly
+    /// useful for testing purposes.
+    fn join(left: Rc<Rope>, right: Rc<Rope>) -> Rc<Self> {
         Rc::new(Rope::Branch {
             bytes_weight: left.total_bytes(),
             chars_weight: left.total_chars(),
@@ -98,6 +103,7 @@ impl Rope {
         })
     }
 
+    /// Returns true if this node is a leaf node, false otherwise
     pub fn is_leaf(&self) -> bool {
         match self {
             Rope::Branch { .. } => false,
@@ -105,10 +111,12 @@ impl Rope {
         }
     }
 
+    /// Returns an iterater over the leaf nodes
     fn iter_nodes(self: Rc<Self>) -> NodeIterator {
         NodeIterator::new(self)
     }
 
+    /// Returns an iterator over the chars of the text
     pub fn iter_chars(self: &Rc<Self>) -> CharIterator {
         CharIterator::new(self)
     }