From 9ba6f62faa798d6978723334f41836519d3c7761 Mon Sep 17 00:00:00 2001
From: Anthony Ramine <n.oxyde@gmail.com>
Date: Tue, 18 Aug 2015 18:11:58 +0200
Subject: [PATCH 1/2] Promise that add_attrs_if_missing() is called only on
 elements (fixes #121)

---
 examples/noop-tree-builder.rs  | 4 +++-
 examples/print-tree-actions.rs | 1 +
 src/rcdom.rs                   | 8 ++++----
 src/tree_builder/interface.rs  | 5 +++--
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/examples/noop-tree-builder.rs b/examples/noop-tree-builder.rs
index 998c46b1..c4336bb1 100644
--- a/examples/noop-tree-builder.rs
+++ b/examples/noop-tree-builder.rs
@@ -74,7 +74,9 @@ impl TreeSink for Sink {
     fn append(&mut self, _parent: usize, _child: NodeOrText<usize>) { }
 
     fn append_doctype_to_document(&mut self, _: StrTendril, _: StrTendril, _: StrTendril) { }
-    fn add_attrs_if_missing(&mut self, _target: usize, _attrs: Vec<Attribute>) { }
+    fn add_attrs_if_missing(&mut self, target: usize, _attrs: Vec<Attribute>) {
+        assert!(self.names.contains_key(&target), "not an element");
+    }
     fn remove_from_parent(&mut self, _target: usize) { }
     fn reparent_children(&mut self, _node: usize, _new_parent: usize) { }
     fn mark_script_already_started(&mut self, _node: usize) { }
diff --git a/examples/print-tree-actions.rs b/examples/print-tree-actions.rs
index 08324fdb..9eebcc14 100644
--- a/examples/print-tree-actions.rs
+++ b/examples/print-tree-actions.rs
@@ -104,6 +104,7 @@ impl TreeSink for Sink {
     }
 
     fn add_attrs_if_missing(&mut self, target: usize, attrs: Vec<Attribute>) {
+        assert!(self.names.contains_key(&target), "not an element");
         println!("Add missing attributes to {}:", target);
         for attr in attrs.into_iter() {
             println!("    {:?} = {}", attr.name, attr.value);
diff --git a/src/rcdom.rs b/src/rcdom.rs
index 062b8ef0..0d0dcf8a 100644
--- a/src/rcdom.rs
+++ b/src/rcdom.rs
@@ -244,10 +244,10 @@ impl TreeSink for RcDom {
 
     fn add_attrs_if_missing(&mut self, target: Handle, mut attrs: Vec<Attribute>) {
         let mut node = target.borrow_mut();
-        // FIXME: mozilla/rust#15609
-        let existing = match node.deref_mut().node {
-            Element(_, ref mut attrs) => attrs,
-            _ => return,
+        let existing = if let Element(_, ref mut attrs) = node.deref_mut().node {
+            attrs
+        } else {
+            panic!("not an element")
         };
 
         // FIXME: quadratic time
diff --git a/src/tree_builder/interface.rs b/src/tree_builder/interface.rs
index 5aee28f8..2f579544 100644
--- a/src/tree_builder/interface.rs
+++ b/src/tree_builder/interface.rs
@@ -103,8 +103,9 @@ pub trait TreeSink {
                                   public_id: StrTendril,
                                   system_id: StrTendril);
 
-    /// Add each attribute to the given element, if no attribute
-    /// with that name already exists.
+    /// Add each attribute to the given element, if no attribute with that name
+    /// already exists. The tree builder promises this will never be called
+    /// with something else than an element.
     fn add_attrs_if_missing(&mut self, target: Self::Handle, attrs: Vec<Attribute>);
 
     /// Detach the given node from its parent.

From dfd64ecdff4f597c213a1c4f0a60fd8c8e9dbad3 Mon Sep 17 00:00:00 2001
From: Anthony Ramine <n.oxyde@gmail.com>
Date: Tue, 18 Aug 2015 18:19:53 +0200
Subject: [PATCH 2/2] Fix the algorithmic complexity of
 RcDom::add_attrs_if_missing()

---
 src/rcdom.rs | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/rcdom.rs b/src/rcdom.rs
index 0d0dcf8a..667c75ae 100644
--- a/src/rcdom.rs
+++ b/src/rcdom.rs
@@ -13,6 +13,7 @@
 //! web browser using it. :)
 
 use std::cell::RefCell;
+use std::collections::HashSet;
 use std::default::Default;
 use std::borrow::Cow;
 use std::io::{self, Write};
@@ -242,7 +243,7 @@ impl TreeSink for RcDom {
         append(&self.document, new_node(Doctype(name, public_id, system_id)));
     }
 
-    fn add_attrs_if_missing(&mut self, target: Handle, mut attrs: Vec<Attribute>) {
+    fn add_attrs_if_missing(&mut self, target: Handle, attrs: Vec<Attribute>) {
         let mut node = target.borrow_mut();
         let existing = if let Element(_, ref mut attrs) = node.deref_mut().node {
             attrs
@@ -250,10 +251,11 @@ impl TreeSink for RcDom {
             panic!("not an element")
         };
 
-        // FIXME: quadratic time
-        attrs.retain(|attr|
-            !existing.iter().any(|e| e.name == attr.name));
-        existing.extend(attrs.into_iter());
+        let existing_names =
+            existing.iter().map(|e| e.name.clone()).collect::<HashSet<_>>();
+        existing.extend(attrs.into_iter().filter(|attr| {
+            !existing_names.contains(&attr.name)
+        }));
     }
 
     fn remove_from_parent(&mut self, target: Handle) {