1 files changed, 110 insertions, 0 deletions
diff --git a/layout/style/nsNthIndexCache.h b/layout/style/nsNthIndexCache.h
new file mode 100644
index 000000000..e24d98737
--- /dev/null
+++ b/layout/style/nsNthIndexCache.h
@@ -0,0 +1,110 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+#ifndef nsContentIndexCache_h__
+#define nsContentIndexCache_h__
+
+#include "js/HashTable.h"
+
+class nsIContent;
+
+namespace mozilla {
+namespace dom {
+class Element;
+} // namespace dom
+} // namespace mozilla
+
+/*
+ * A class that computes and caches the indices used for :nth-* pseudo-class
+ * matching.
+ */
+
+class nsNthIndexCache {
+private:
+  typedef mozilla::dom::Element Element;
+
+public:
+  /**
+   * Constructor and destructor out of line so that we don't try to
+   * instantiate the hashtable template all over the place.
+   */
+  nsNthIndexCache();
+  ~nsNthIndexCache();
+
+  // Returns a 1-based index of the child in its parent.  If the child
+  // is not in its parent's child list (i.e., it is anonymous content),
+  // returns 0.
+  // If aCheckEdgeOnly is true, the function will return 1 if the result
+  // is 1, and something other than 1 (maybe or maybe not a valid
+  // result) otherwise.
+  // This must only be called on nodes which have a non-null parent.
+  int32_t GetNthIndex(Element* aChild, bool aIsOfType, bool aIsFromEnd,
+                      bool aCheckEdgeOnly);
+
+  void Reset();
+
+private:
+  /**
+   * Returns true if aSibling and aElement should be considered in the same
+   * list for nth-index purposes, taking aIsOfType into account.
+   */
+  inline bool SiblingMatchesElement(nsIContent* aSibling, Element* aElement,
+                                    bool aIsOfType);
+
+  // This node's index for this cache.
+  // If -2, needs to be computed.
+  // If -1, needs to be computed but known not to be 1.
+  // If 0, the node is not at any index in its parent.
+  typedef int32_t CacheEntry;
+
+  class SystemAllocPolicy {
+  public:
+    void *malloc_(size_t bytes) { return ::malloc(bytes); }
+
+    template <typename T>
+    T *maybe_pod_calloc(size_t numElems) {
+      return static_cast<T *>(::calloc(numElems, sizeof(T)));
+    }
+
+    template <typename T>
+    T *pod_calloc(size_t numElems) {
+      return maybe_pod_calloc<T>(numElems);
+    }
+
+    void *realloc_(void *p, size_t bytes) { return ::realloc(p, bytes); }
+    void free_(void *p) { ::free(p); }
+    void reportAllocOverflow() const {}
+    bool checkSimulatedOOM() const { return true; }
+  };
+
+  typedef js::HashMap<nsIContent*, CacheEntry, js::DefaultHasher<nsIContent*>,
+                      SystemAllocPolicy> Cache;
+
+  /**
+   * Returns true if aResult has been set to the correct value for aChild and
+   * no more work needs to be done.  Returns false otherwise.
+   *
+   * aResult is an inout parameter.  The in value is the number of elements
+   * that are in the half-open range (aSibling, aChild] (so including aChild
+   * but not including aSibling) that match aChild.  The out value is the
+   * correct index for aChild if this function returns true and the number of
+   * elements in the closed range [aSibling, aChild] that match aChild
+   * otherwise.
+   */
+  inline bool IndexDeterminedFromPreviousSibling(nsIContent* aSibling,
+                                                 Element* aChild,
+                                                 bool aIsOfType,
+                                                 bool aIsFromEnd,
+                                                 const Cache& aCache,
+                                                 int32_t& aResult);
+
+  // Caches of indices for :nth-child(), :nth-last-child(),
+  // :nth-of-type(), :nth-last-of-type(), keyed by Element*.
+  //
+  // The first subscript is 0 for -child and 1 for -of-type, the second
+  // subscript is 0 for nth- and 1 for nth-last-.
+  Cache mCaches[2][2];
+};
+
+#endif /* nsContentIndexCache_h__ */