1 files changed, 152 insertions, 0 deletions
diff --git a/accessible/base/Pivot.h b/accessible/base/Pivot.h
new file mode 100644
index 0000000000..c00f1613a2
--- /dev/null
+++ b/accessible/base/Pivot.h
@@ -0,0 +1,152 @@
+/* -*- 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 mozilla_a11y_Pivot_h_
+#define mozilla_a11y_Pivot_h_
+
+#include <stdint.h>
+#include "Role.h"
+#include "mozilla/dom/ChildIterator.h"
+
+namespace mozilla {
+namespace a11y {
+
+class DocAccessible;
+class Accessible;
+
+class PivotRule {
+ public:
+  // A filtering function that returns a bitmask from
+  // nsIAccessibleTraversalRule: FILTER_IGNORE (0x0): Don't match this
+  // accessible. FILTER_MATCH (0x1): Match this accessible FILTER_IGNORE_SUBTREE
+  // (0x2): Ignore accessible's subtree.
+  virtual uint16_t Match(Accessible* aAcc) = 0;
+};
+
+// The Pivot class is used for searching for accessible nodes in a given subtree
+// with a given criteria. Since it only holds a weak reference to the root,
+// this class is meant to be used primarily on the stack.
+class Pivot final {
+ public:
+  explicit Pivot(Accessible* aRoot);
+  Pivot() = delete;
+  Pivot(const Pivot&) = delete;
+  Pivot& operator=(const Pivot&) = delete;
+
+  ~Pivot();
+
+  // Return the next accessible after aAnchor in pre-order that matches the
+  // given rule. If aIncludeStart, return aAnchor if it matches the rule.
+  Accessible* Next(Accessible* aAnchor, PivotRule& aRule,
+                   bool aIncludeStart = false);
+
+  // Return the previous accessible before aAnchor in pre-order that matches the
+  // given rule. If aIncludeStart, return aAnchor if it matches the rule.
+  Accessible* Prev(Accessible* aAnchor, PivotRule& aRule,
+                   bool aIncludeStart = false);
+
+  // Return the first accessible within the root that matches the pivot rule.
+  Accessible* First(PivotRule& aRule);
+
+  // Return the last accessible within the root that matches the pivot rule.
+  Accessible* Last(PivotRule& aRule);
+
+  // Return the next range of text according to the boundary type.
+  Accessible* NextText(Accessible* aAnchor, int32_t* aStartOffset,
+                       int32_t* aEndOffset, int32_t aBoundaryType);
+
+  // Return the previous range of text according to the boundary type.
+  Accessible* PrevText(Accessible* aAnchor, int32_t* aStartOffset,
+                       int32_t* aEndOffset, int32_t aBoundaryType);
+
+  // Return the accessible at the given screen coordinate if it matches the
+  // pivot rule.
+  Accessible* AtPoint(int32_t aX, int32_t aY, PivotRule& aRule);
+
+ private:
+  Accessible* AdjustStartPosition(Accessible* aAnchor, PivotRule& aRule,
+                                  uint16_t* aFilterResult);
+
+  // Search in preorder for the first accessible to match the rule.
+  Accessible* SearchForward(Accessible* aAnchor, PivotRule& aRule,
+                            bool aSearchCurrent);
+
+  // Reverse search in preorder for the first accessible to match the rule.
+  Accessible* SearchBackward(Accessible* aAnchor, PivotRule& aRule,
+                             bool aSearchCurrent);
+
+  // Search in preorder for the first text accessible.
+  Accessible* SearchForText(Accessible* aAnchor, bool aBackward);
+
+  Accessible* mRoot;
+};
+
+/**
+ * This rule matches accessibles on a given role, filtering out non-direct
+ * descendants if necessary.
+ */
+class PivotRoleRule : public PivotRule {
+ public:
+  explicit PivotRoleRule(role aRole);
+  explicit PivotRoleRule(role aRole, Accessible* aDirectDescendantsFrom);
+
+  virtual uint16_t Match(Accessible* aAcc) override;
+
+ protected:
+  role mRole;
+  Accessible* mDirectDescendantsFrom;
+};
+
+/**
+ * This rule matches accessibles with a given state.
+ */
+class PivotStateRule : public PivotRule {
+ public:
+  explicit PivotStateRule(uint64_t aState);
+
+  virtual uint16_t Match(Accessible* aAcc) override;
+
+ protected:
+  uint64_t mState;
+};
+
+/**
+ * This rule matches any local LocalAccessible (i.e. not RemoteAccessible) in
+ * the same document as the anchor. That is, it includes any descendant
+ * OuterDocAccessible, but not its descendants.
+ */
+class LocalAccInSameDocRule : public PivotRule {
+ public:
+  virtual uint16_t Match(Accessible* aAcc) override;
+};
+
+/**
+ * This rule matches remote radio button accessibles with the given name
+ * attribute. It assumes the cache is enabled.
+ */
+class PivotRadioNameRule : public PivotRule {
+ public:
+  explicit PivotRadioNameRule(const nsString& aName);
+
+  virtual uint16_t Match(Accessible* aAcc) override;
+
+ protected:
+  const nsString& mName;
+};
+
+/**
+ * This rule doesn't search iframes. Subtrees that should be
+ * pruned by way of nsAccUtils::MustPrune are also not searched.
+ */
+
+class MustPruneSameDocRule : public PivotRule {
+ public:
+  virtual uint16_t Match(Accessible* aAcc) override;
+};
+
+}  // namespace a11y
+}  // namespace mozilla
+
+#endif  // mozilla_a11y_Pivot_h_