Merge pull request #254 from barskern/tabs-prevent-allocation

Use IntoIterator instead of Vec for tabs

src/widgets/tabs.rs

@@ -115,15 +115,18 @@ where
  /// * the function that will be called if a tab is selected by the user.
  /// It takes the index of the selected tab.
  pub fn new_with_tabs<F>(
- tabs: Vec<(TabId, TabLabel, Element<'a, Message, Theme, Renderer>)>,
+ tabs: impl IntoIterator<Item = (TabId, TabLabel, Element<'a, Message, Theme, Renderer>)>,
  on_select: F,
  ) -> Self
  where
  F: 'static + Fn(TabId) -> Message,
  {
- let mut tab_labels = Vec::with_capacity(tabs.len());
- let mut elements = Vec::with_capacity(tabs.len());
- let mut indices = Vec::with_capacity(tabs.len());
+ let tabs = tabs.into_iter();
+ let n_tabs = tabs.size_hint().0;
+
+ let mut tab_labels = Vec::with_capacity(n_tabs);
+ let mut elements = Vec::with_capacity(n_tabs);
+ let mut indices = Vec::with_capacity(n_tabs);
 
  for (id, tab_label, element) in tabs {
  tab_labels.push((id.clone(), tab_label));