1 files changed, 83 insertions, 0 deletions
diff --git a/components/style/declarations_iterators.rs b/components/style/declarations_iterators.rs
new file mode 100644
index 00000000000..27e37e59e71
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+++ b/components/style/declarations_iterators.rs
@@ -0,0 +1,83 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! A set of simple iterators to be reused for doing the cascade.
+
+use properties::{Importance, PropertyDeclaration};
+
+
+/// An iterator that applies the declarations in a list that matches the given
+/// importance.
+#[derive(Clone)]
+pub struct SimpleDeclarationsIterator<'a> {
+    declarations: &'a [(PropertyDeclaration, Importance)],
+    importance: Importance,
+    index: usize,
+}
+
+impl<'a> SimpleDeclarationsIterator<'a> {
+    pub fn new(declarations: &'a [(PropertyDeclaration, Importance)],
+               importance: Importance) -> Self {
+        SimpleDeclarationsIterator {
+            declarations: declarations,
+            importance: importance,
+            index: 0,
+        }
+    }
+}
+
+impl<'a> Iterator for SimpleDeclarationsIterator<'a> {
+    type Item = &'a PropertyDeclaration;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            if self.index == self.declarations.len() {
+                return None;
+            }
+
+            let (ref decl, importance) =
+                self.declarations[self.declarations.len() - self.index - 1];
+
+            self.index += 1;
+
+            if importance == self.importance {
+                return Some(decl)
+            }
+        }
+    }
+}
+
+/// An iterator that applies the declarations in a list without checking any
+/// order.
+#[derive(Clone)]
+pub struct RawDeclarationsIterator<'a> {
+    declarations: &'a [(PropertyDeclaration, Importance)],
+    index: usize,
+}
+
+impl<'a> RawDeclarationsIterator<'a> {
+    pub fn new(declarations: &'a [(PropertyDeclaration, Importance)]) -> Self {
+        RawDeclarationsIterator {
+            declarations: declarations,
+            index: 0,
+        }
+    }
+}
+
+impl<'a> Iterator for RawDeclarationsIterator<'a> {
+    type Item = &'a PropertyDeclaration;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.index == self.declarations.len() {
+            return None;
+        }
+
+        let (ref decl, _) =
+            self.declarations[self.declarations.len() - self.index - 1];
+
+        self.index += 1;
+
+        return Some(decl)
+    }
+}