Initialize with OpenTTD 1.9.3

src/misc/fixedsizearray.hpp

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+/* $Id$ */
+
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file fixedsizearray.hpp A fixed size array that doesn't create items until needed. */
+
+#ifndef FIXEDSIZEARRAY_HPP
+#define FIXEDSIZEARRAY_HPP
+
+#include "../core/alloc_func.hpp"
+
+/**
+ * fixed size array
+ *  Upon construction it preallocates fixed size block of memory
+ *  for all items, but doesn't construct them. Item's construction
+ *  is delayed.
+ */
+template <class T, uint C>
+struct FixedSizeArray {
+protected:
+	/** header for fixed size array */
+	struct ArrayHeader
+	{
+		uint items;           ///< number of items in the array
+		uint reference_count; ///< block reference counter (used by copy constructor and by destructor)
+	};
+
+	/* make constants visible from outside */
+	static const uint Tsize = sizeof(T);                ///< size of item
+	static const uint HeaderSize = sizeof(ArrayHeader); ///< size of header
+
+	/**
+	 * the only member of fixed size array is pointer to the block
+	 *  of C array of items. Header can be found on the offset -sizeof(ArrayHeader).
+	 */
+	T *data;
+
+	/** return reference to the array header (non-const) */
+	inline ArrayHeader& Hdr()
+	{
+		return *(ArrayHeader*)(((byte*)data) - HeaderSize);
+	}
+
+	/** return reference to the array header (const) */
+	inline const ArrayHeader& Hdr() const
+	{
+		return *(ArrayHeader*)(((byte*)data) - HeaderSize);
+	}
+
+	/** return reference to the block reference counter */
+	inline uint& RefCnt()
+	{
+		return Hdr().reference_count;
+	}
+
+	/** return reference to number of used items */
+	inline uint& SizeRef()
+	{
+		return Hdr().items;
+	}
+
+public:
+	/** Default constructor. Preallocate space for items and header, then initialize header. */
+	FixedSizeArray()
+	{
+		/* Ensure the size won't overflow. */
+		assert_compile(C < (SIZE_MAX - HeaderSize) / Tsize);
+
+		/* allocate block for header + items (don't construct items) */
+		data = (T*)((MallocT<byte>(HeaderSize + C * Tsize)) + HeaderSize);
+		SizeRef() = 0; // initial number of items
+		RefCnt() = 1; // initial reference counter
+	}
+
+	/** Copy constructor. Preallocate space for items and header, then initialize header. */
+	FixedSizeArray(const FixedSizeArray<T, C> &src)
+	{
+		/* share block (header + items) with the source array */
+		data = src.data;
+		RefCnt()++; // now we share block with the source
+	}
+
+	/** destroy remaining items and free the memory block */
+	~FixedSizeArray()
+	{
+		/* release one reference to the shared block */
+		if ((--RefCnt()) > 0) return; // and return if there is still some owner
+
+		Clear();
+		/* free the memory block occupied by items */
+		free(((byte*)data) - HeaderSize);
+		data = NULL;
+	}
+
+	/** Clear (destroy) all items */
+	inline void Clear()
+	{
+		/* Walk through all allocated items backward and destroy them
+		 * Note: this->Length() can be zero. In that case data[this->Length() - 1] is evaluated unsigned
+		 *       on some compilers with some architectures. (e.g. gcc with x86) */
+		for (T *pItem = this->data + this->Length() - 1; pItem >= this->data; pItem--) {
+			pItem->~T();
+		}
+		/* number of items become zero */
+		SizeRef() = 0;
+	}
+
+	/** return number of used items */
+	inline uint Length() const
+	{
+		return Hdr().items;
+	}
+
+	/** return true if array is full */
+	inline bool IsFull() const
+	{
+		return Length() >= C;
+	}
+
+	/** return true if array is empty */
+	inline bool IsEmpty() const
+	{
+		return Length() <= 0;
+	}
+
+	/** add (allocate), but don't construct item */
+	inline T *Append()
+	{
+		assert(!IsFull());
+		return &data[SizeRef()++];
+	}
+
+	/** add and construct item using default constructor */
+	inline T *AppendC()
+	{
+		T *item = Append();
+		new(item)T;
+		return item;
+	}
+	/** return item by index (non-const version) */
+	inline T& operator[](uint index)
+	{
+		assert(index < Length());
+		return data[index];
+	}
+
+	/** return item by index (const version) */
+	inline const T& operator[](uint index) const
+	{
+		assert(index < Length());
+		return data[index];
+	}
+};
+
+#endif /* FIXEDSIZEARRAY_HPP */