Lazily initialize set of classes and reduce its API surface to be abl…

…e to use a simpler collection type.

src/node.rs

@@ -2,12 +2,11 @@
 
 #[cfg(not(feature = "deterministic"))]
 use ahash::AHashMap as HashMap;
-use ahash::AHashSet as HashSet;
 #[cfg(not(feature = "deterministic"))]
 use std::collections::hash_map;
-use std::collections::hash_set;
 use std::fmt;
 use std::ops::Deref;
+use std::slice::Iter as SliceIter;
 
 use crate::{CaseSensitivity, StrTendril};
 use html5ever::{Attribute, LocalName, QualName};
@@ -228,33 +227,27 @@ pub struct Element {
  /// The element name.
  pub name: QualName,
 
- /// The element classes.
- pub classes: HashSet<LocalName>,
-
  /// The element attributes.
  pub attrs: Attributes,
 
  id: OnceCell<Option<StrTendril>>,
+
+ classes: OnceCell<Vec<LocalName>>,
 }
 
 impl Element {
  #[doc(hidden)]
  pub fn new(name: QualName, attributes: Vec<Attribute>) -> Self {
- let mut classes: HashSet<LocalName> = HashSet::new();
- let mut attrs = Attributes::with_capacity(attributes.len());
-
- for a in attributes {
- if a.name.local.deref() == "class" {
- classes.extend(a.value.deref().split_whitespace().map(LocalName::from));
- }
- attrs.insert(a.name, crate::tendril_util::make(a.value));
- }
+ let attrs = attributes
+ .into_iter()
+ .map(|a| (a.name, crate::tendril_util::make(a.value)))
+ .collect();
 
  Element {
  attrs,
  name,
  id: OnceCell::new(),
- classes,
+ classes: OnceCell::new(),
  }
  }
 
@@ -283,8 +276,22 @@ impl Element {
 
  /// Returns an iterator over the element's classes.
  pub fn classes(&self) -> Classes {
+ let classes = self.classes.get_or_init(|| {
+ let mut classes: Vec<LocalName> = self
+ .attrs
+ .iter()
+ .filter(|(name, _)| name.local.as_ref() == "class")
+ .flat_map(|(_, value)| value.split_whitespace().map(LocalName::from))
+ .collect();
+
+ classes.sort_unstable();
+ classes.dedup();
+
+ classes
+ });
+
  Classes {
- inner: self.classes.iter(),
+ inner: classes.iter(),
  }
  }
 
@@ -306,7 +313,7 @@ impl Element {
 #[allow(missing_debug_implementations)]
 #[derive(Clone)]
 pub struct Classes<'a> {
- inner: hash_set::Iter<'a, LocalName>,
+ inner: SliceIter<'a, LocalName>,
 }
 
 impl<'a> Iterator for Classes<'a> {