(svn r25256) -Add: small matrix type (like vector, but for matrices) (fonsinchen)

1 files changed, 322 insertions, 0 deletions

diff --git a/src/core/smallmatrix_type.hpp b/src/core/smallmatrix_type.hpp
new file mode 100644
index 000000000..9ebf0372c
--- /dev/null
+++ b/src/core/smallmatrix_type.hpp
@@ -0,0 +1,322 @@
+/* $Id$ */
+
+/*
+ * 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 smallmatrix_type.hpp Simple matrix class that allows allocating an item without the need to copy this->data needlessly. */
+
+#ifndef SMALLMATRIX_TYPE_HPP
+#define SMALLMATRIX_TYPE_HPP
+
+#include "alloc_func.hpp"
+#include "mem_func.hpp"
+
+/**
+ * Simple matrix template class.
+ *
+ * Allocating a matrix in one piece reduces overhead in allocations compared
+ * with allocating a vector of vectors and saves some pointer dereferencing.
+ * However, you can only get rectangular matrixes like this and if you're
+ * changing their height very often performance will probably be worse than
+ * with a vector of vectors, due to more frequent copying of memory blocks.
+ *
+ * No iterators are provided as iterating the columns would require persistent
+ * column objects. Those do not exist. Providing iterators with transient
+ * column objects would tie each iterator to a column object, thus replacing
+ * previously retrieved columns when iterating and defeating the point of
+ * iteration.
+ *
+ * It's expected that the items don't need to be constructed or deleted by the
+ * container. Only memory allocation and deallocation is performed. This is the
+ * same for all openttd "SmallContainer" classes.
+ *
+ * @tparam T The type of the items stored
+ */
+template <typename T>
+class SmallMatrix {
+protected:
+	T *data;       ///< The pointer to the first item
+	uint width;    ///< Number of items over first axis
+	uint height;   ///< Number of items over second axis
+	uint capacity; ///< The available space for storing items
+
+public:
+
+	SmallMatrix() : data(NULL), width(0), height(0), capacity(0) {}
+
+	/**
+	 * Copy constructor.
+	 * @param other The other matrix to copy.
+	 */
+	SmallMatrix(const SmallMatrix &other) : data(NULL), width(0), height(0), capacity(0)
+	{
+		this->Assign(other);
+	}
+
+	~SmallMatrix()
+	{
+		free(this->data);
+	}
+
+	/**
+	 * Assignment.
+	 * @param other The other matrix to assign.
+	 */
+	SmallMatrix &operator=(const SmallMatrix &other)
+	{
+		this->Assign(other);
+		return *this;
+	}
+
+	/**
+	 * Assign items from other vector.
+	 */
+	inline void Assign(const SmallMatrix &other)
+	{
+		if (&other == this) return;
+
+		this->height = other.Height();
+		this->width = other.Width();
+		uint num_items = this->width * this->height;
+		if (num_items > this->capacity) {
+			this->capacity = num_items;
+			free(this->data);
+			this->data = MallocT<T>(num_items);
+			MemCpyT(this->data, other[0], num_items);
+		} else if (num_items > 0) {
+			MemCpyT(this->data, other[0], num_items);
+		}
+	}
+
+	/**
+	 * Remove all rows from the matrix.
+	 */
+	inline void Clear()
+	{
+		/* In fact we just reset the width avoiding the need to
+		 * probably reallocate the same amount of memory the matrix was
+		 * previously using. */
+		this->width = 0;
+	}
+
+	/**
+	 * Remove all items from the list and free allocated memory.
+	 */
+	inline void Reset()
+	{
+		this->height = 0;
+		this->width = 0;
+		this->capacity = 0;
+		free(this->data);
+		this->data = NULL;
+	}
+
+	/**
+	 * Compact the matrix down to the smallest possible size.
+	 */
+	inline void Compact()
+	{
+		uint capacity = this->height * this->width;
+		if (capacity >= this->capacity) return;
+		this->capacity = capacity;
+		this->data = ReallocT(this->data, this->capacity);
+	}
+
+	/**
+	 * Erase a column, replacing it with the last one.
+	 * @param x Position of the column.
+	 */
+	void EraseColumn(uint x)
+	{
+		if (x < --this->width) {
+			MemCpyT<T>(this->data + x * this->height,
+					this->data + this->width * this->height,
+					this->height);
+		}
+	}
+
+	/**
+	 * Remove columns from the matrix while preserving the order of other columns.
+	 * @param x First column to remove.
+	 * @param count Number of consecutive columns to remove.
+	 */
+	void EraseColumnPreservingOrder(uint x, uint count = 1)
+	{
+		if (count == 0) return;
+		assert(x < this->width);
+		assert(x + count <= this->width);
+		this->width -= count;
+		uint to_move = (this->width - x) * this->height;
+		if (to_move > 0) {
+			MemMoveT(this->data + x * this->height,
+					this->data + (x + count) * this->height, to_move);
+		}
+	}
+
+	/**
+	 * Erase a row, replacing it with the last one.
+	 * @param x Position of the row.
+	 */
+	void EraseRow(uint y)
+	{
+		if (y < this->height - 1) {
+			for (uint x = 0; x < this->width; ++x) {
+				this->data[x * this->height + y] =
+						this->data[(x + 1) * this->height - 1];
+			}
+		}
+		this->Resize(this->width, this->height - 1);
+	}
+
+	/**
+	 * Remove columns from the matrix while preserving the order of other columns.
+	 * @param x First column to remove.
+	 * @param count Number of consecutive columns to remove.
+	 */
+	void EraseRowPreservingOrder(uint y, uint count = 1)
+	{
+		if (this->height > count + y) {
+			for (uint x = 0; x < this->width; ++x) {
+				MemMoveT(this->data + x * this->height + y,
+						this->data + x * this->height + y + count,
+						this->height - count - y);
+			}
+		}
+		this->Resize(this->width, this->height - count);
+	}
+
+	/**
+	 * Append rows.
+	 * @param to_add Number of rows to append.
+	 */
+	inline void AppendRow(uint to_add = 1)
+	{
+		this->Resize(this->width, to_add + this->height);
+	}
+
+	/**
+	 * Append rows.
+	 * @param to_add Number of rows to append.
+	 */
+	inline void AppendColumn(uint to_add = 1)
+	{
+		this->Resize(to_add + this->width, this->height);
+	}
+
+	/**
+	 * Set the size to a specific width and height, preserving item positions
+	 * as far as possible in the process.
+	 * @param width Target width.
+	 * @param height Target height.
+	 */
+	inline void Resize(uint new_width, uint new_height)
+	{
+		uint new_capacity = new_width * new_height;
+		T *new_data = NULL;
+		void (*copy)(T *dest, const T *src, size_t count) = NULL;
+		if (new_capacity > this->capacity) {
+			/* If the data doesn't fit into current capacity, resize and copy ... */
+			new_data = MallocT<T>(new_capacity);
+			copy = &MemCpyT<T>;
+		} else {
+			/* ... otherwise just move the columns around, if necessary. */
+			new_data = this->data;
+			copy = &MemMoveT<T>;
+		}
+		if (this->height != new_height || new_data != this->data) {
+			if (this->height > 0) {
+				if (new_height > this->height) {
+					/* If matrix is growing, copy from the back to avoid
+					 * overwriting uncopied data. */
+					for (uint x = this->width; x > 0; --x) {
+						if (x * new_height > new_capacity) continue;
+						(*copy)(new_data + (x - 1) * new_height,
+								this->data + (x - 1) * this->height,
+								min(this->height, new_height));
+					}
+				} else {
+					/* If matrix is shrinking copy from the front. */
+					for (uint x = 0; x < this->width; ++x) {
+						if ((x + 1) * new_height > new_capacity) break;
+						(*copy)(new_data + x * new_height,
+								this->data + x * this->height,
+								min(this->height, new_height));
+					}
+				}
+			}
+			this->height = new_height;
+			if (new_data != this->data) {
+				free(this->data);
+				this->data = new_data;
+				this->capacity = new_capacity;
+			}
+		}
+		this->width = new_width;
+	}
+
+	inline uint Height() const
+	{
+		return this->height;
+	}
+
+	inline uint Width() const
+	{
+		return this->width;
+	}
+
+	/**
+	 * Get item x/y (const).
+	 *
+	 * @param x X-position of the item.
+	 * @param y Y-position of the item.
+	 * @return Item at specified position.
+	 */
+	inline const T &Get(uint x, uint y) const
+	{
+		assert(x < this->width && y < this->height);
+		return this->data[x * this->height + y];
+	}
+
+	/**
+	 * Get item x/y.
+	 *
+	 * @param x X-position of the item.
+	 * @param y Y-position of the item.
+	 * @return Item at specified position.
+	 */
+	inline T &Get(uint x, uint y)
+	{
+		assert(x < this->width && y < this->height);
+		return this->data[x * this->height + y];
+	}
+
+	/**
+	 * Get column "number" (const)
+	 *
+	 * @param X Position of the column.
+	 * @return Column at "number".
+	 */
+	inline const T *operator[](uint x) const
+	{
+		assert(x < this->width);
+		return this->data + x * this->height;
+	}
+
+	/**
+	 * Get column "number" (const)
+	 *
+	 * @param X Position of the column.
+	 * @return Column at "number".
+	 */
+	inline T *operator[](uint x)
+	{
+		assert(x < this->width);
+		return this->data + x * this->height;
+	}
+};
+
+#endif /* SMALLMATRIX_TYPE_HPP */