downgrade Node, Context and Object document references to Weak

src/tree/document.rs

@@ -7,7 +7,7 @@ use std::cell::RefCell;
 use std::collections::HashMap;
 use std::ffi::{CStr, CString};
 use std::ptr;
-use std::rc::Rc;
+use std::rc::{Rc, Weak};
 use std::str;
 
 use bindings::*;
@@ -16,6 +16,7 @@ use c_helpers::*;
 use tree::node::Node;
 
 pub(crate) type DocumentRef = Rc<RefCell<_Document>>;
+pub(crate) type DocumentWeak = Weak<RefCell<_Document>>;
 
 #[derive(Debug)]
 pub(crate) struct _Document {

src/tree/mod.rs

@@ -7,7 +7,7 @@ mod node;
 mod nodetype;
 
 pub use tree::document::Document;
-pub(crate) use tree::document::DocumentRef;
+pub(crate) use tree::document::{DocumentRef, DocumentWeak};
 pub use tree::namespace::Namespace;
 pub use tree::node::set_node_rc_guard;
 pub use tree::node::{Node, NODE_RC_MAX_GUARD};

src/tree/node.rs

@@ -12,7 +12,7 @@ use std::ptr;
 use std::rc::Rc;
 use std::str;
 
-use tree::document::{Document, DocumentRef};
+use tree::document::{Document, DocumentRef, DocumentWeak};
 use tree::namespace::Namespace;
 use tree::nodetype::NodeType;
 use xpath::Context;
@@ -38,7 +38,7 @@ struct _Node {
  /// libxml's xmlNodePtr
  node_ptr: xmlNodePtr,
  /// Reference to parent `Document`
- document: DocumentRef,
+ document: DocumentWeak,
  /// Bookkeep removal from a parent
  unlinked: bool,
 }
@@ -139,7 +139,7 @@ impl Node {
  // If newly encountered pointer, wrap
  let node = _Node {
  node_ptr,
- document: document.clone(),
+ document: Rc::downgrade(&document),
  unlinked: false,
  };
  let wrapped_node = Node(Rc::new(RefCell::new(node)));
@@ -172,7 +172,7 @@ impl Node {
  unsafe { mem::transmute::<xmlNodePtr, usize>(self.node_ptr()) }
  }
 
- pub(crate) fn get_docref(&self) -> DocumentRef {
+ pub(crate) fn get_docref(&self) -> DocumentWeak {
  self.0.borrow().document.clone()
  }
 
@@ -644,7 +644,7 @@ impl Node {
  c_name.as_bytes().as_ptr(),
  ptr::null(),
  );
- Ok(Node::wrap(new_ptr, self.get_docref()))
+ Ok(Node::wrap(new_ptr, self.get_docref().upgrade().unwrap()))
  }
  }
 
@@ -668,7 +668,7 @@ impl Node {
  c_name.as_bytes().as_ptr(),
  c_content.as_bytes().as_ptr(),
  );
- Ok(Node::wrap(new_ptr, self.get_docref()))
+ Ok(Node::wrap(new_ptr, self.get_docref().upgrade().unwrap()))
  }
  }
 
@@ -722,7 +722,7 @@ impl Node {
  if node_ptr.is_null() {
  None
  } else {
- let new_node = Node::wrap(node_ptr, self.get_docref());
+ let new_node = Node::wrap(node_ptr, self.get_docref().upgrade().unwrap());
  Some(new_node)
  }
  }

src/xpath.rs

@@ -8,7 +8,7 @@ use std::cell::RefCell;
 use std::ffi::{CStr, CString};
 use std::rc::Rc;
 use std::str;
-use tree::{Document, DocumentRef, Node};
+use tree::{Document, DocumentRef, DocumentWeak, Node};
 
 ///Thinly wrapped libxml2 xpath context
 pub(crate) type ContextRef = Rc<RefCell<_Context>>;
@@ -31,14 +31,14 @@ pub struct Context {
  /// Safe reference to the libxml2 context pointer
  pub(crate) context_ptr: ContextRef,
  ///Document contains pointer, needed for ContextPtr, so we need to borrow Document to prevent it's freeing
- pub(crate) document: DocumentRef,
+ pub(crate) document: DocumentWeak,
 }
 
 ///Essentially, the result of the evaluation of some xpath expression
 pub struct Object {
  ///libxml's `ObjectPtr`
  pub ptr: xmlXPathObjectPtr,
- document: DocumentRef,
+ document: DocumentWeak,
 }
 
 impl Context {
@@ -50,7 +50,7 @@ impl Context {
  } else {
  Ok(Context {
  context_ptr: Rc::new(RefCell::new(_Context(ctxtptr))),
- document: doc.0.clone(),
+ document: Rc::downgrade(&doc.0),
  })
  }
  }
@@ -61,7 +61,7 @@ impl Context {
  } else {
  Ok(Context {
  context_ptr: Rc::new(RefCell::new(_Context(ctxtptr))),
- document: docref.clone(),
+ document: Rc::downgrade(&docref),
  })
  }
  }
@@ -74,7 +74,7 @@ impl Context {
  /// Instantiate a new Context for the Document of a given Node.
  /// Note: the Context is root-level for that document, use `.set_context_node` to limit scope to this node
  pub fn from_node(node: &Node) -> Result<Context, ()> {
- let docref = node.get_docref().clone();
+ let docref = node.get_docref().upgrade().unwrap();
  Context::new_ptr(docref)
  }
 
@@ -198,7 +198,7 @@ impl Object {
  if ptr.is_null() {
  panic!("rust-libxml: xpath: found null pointer result set");
  }
- let node = Node::wrap(ptr, self.document.clone());
+ let node = Node::wrap(ptr, self.document.upgrade().unwrap());
  vec.push(node);
  }
  vec