Introduce TerminatedArray<T> type to make data-structure used by RuleSet visible at the type level.

Source/wtf/TerminatedArray.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+#ifndef TerminatedArray_h
+#define TerminatedArray_h
+
+#include "wtf/FastAllocBase.h"
+#include "wtf/OwnPtr.h"
+
+namespace WTF {
+
+// TerminatedArray<T> represents a sequence of elements of type T in which each
+// element knows whether it is the last element in the sequence or not. For this
+// check type T must provide isLastInArray method.
+// TerminatedArray<T> can only be constructed by TerminatedArrayBuilder<T>.
+template<typename T>
+class TerminatedArray {
+    WTF_MAKE_FAST_ALLOCATED;
+    WTF_MAKE_NONCOPYABLE(TerminatedArray);
+public:
+    T& at(size_t index) { return reinterpret_cast<T*>(this)[index]; }
+    const T& at(size_t index) const { return reinterpret_cast<const T*>(this)[index]; }
+
+    template<typename U>
+    class iterator_base {
+    public:
+        iterator_base& operator++()
+        {
+            if (m_val->isLastInArray()) {
+                m_val = 0;
+            } else {
+                ++m_val;
+            }
+            return *this;
+        }
+
+        U& operator*() const { return *m_val; }
+
+        bool operator==(const iterator_base& other) const { return m_val == other.m_val; }
+        bool operator!=(const iterator_base& other) const { return !(*this == other); }
+
+    private:
+        iterator_base(U* val) : m_val(val) { }
+
+        U* m_val;
+
+        friend class TerminatedArray;
+    };
+
+    typedef iterator_base<T> iterator;
+    typedef iterator_base<const T> const_iterator;
+
+    iterator begin() { return iterator(reinterpret_cast<T*>(this)); }
+    const_iterator begin() const { return const_iterator(reinterpret_cast<const T*>(this)); }
+
+    iterator end() { return iterator(0); }
+    const_iterator end() const { return const_iterator(0); }
+
+    size_t size() const
+    {
+        size_t count = 0;
+        for (const_iterator it = begin(); it != end(); ++it)
+            count++;
+        return count;
+    }
+
+private:
+    static PassOwnPtr<TerminatedArray> create(size_t capacity)
+    {
+        return adoptPtr(static_cast<TerminatedArray*>(fastMalloc(capacity * sizeof(T))));
+    }
+
+    static PassOwnPtr<TerminatedArray> resize(PassOwnPtr<TerminatedArray> array, size_t capacity)
+    {
+        return adoptPtr(static_cast<TerminatedArray*>(fastRealloc(array.leakPtr(), capacity * sizeof(T))));
+    }
+
+    template<typename> friend class TerminatedArrayBuilder;
+};
+
+} // namespace WTF
+
+using WTF::TerminatedArray;
+
+#endif // TerminatedArray_h