PROJECT #0 - C++ PRIMER [CMU 15-445/645]笔记

这是数据库领域的一门课程, 由卡内基梅隆大学副教授Andy Pavlo授课, 目前在网上有授课视频资料、实验以及配套的在线测评环境 (限时开放至2021年12月31日)

环境: wsl2 + Clion

还是很简单的,主要目的是让学生熟悉 C++17 的基本语法

代码如下:

//===----------------------------------------------------------------------===//
//
//                         BusTub
//
// p0_starter.h
//
// Identification: src/include/primer/p0_starter.h
//
// Copyright (c) 2015-2020, Carnegie Mellon University Database Group
//
//===----------------------------------------------------------------------===//#pragma once#include <memory>
#include <stdexcept>
#include <vector>
#include "common/exception.h"
#include "common/logger.h"namespace bustub {/*** The Matrix type defines a common* interface for matrix operations.*/
template <typename T>
class Matrix {protected:/*** TODO(P0): Add implementation** Construct a new Matrix instance.* @param rows The number of rows* @param cols The number of columns**/Matrix(int rows, int cols) : rows_(rows), cols_(cols) {linear_ = new T[rows_ * cols_];memset(linear_, 0, rows_ * cols_);}/** The number of rows in the matrix */int rows_;/** The number of columns in the matrix */int cols_;/*** TODO(P0): Allocate the array in the constructor.* TODO(P0): Deallocate the array in the destructor.* A flattened array containing the elements of the matrix.*/T *linear_;public:/** @return The number of rows in the matrix */virtual int GetRowCount() const = 0;/** @return The number of columns in the matrix */virtual int GetColumnCount() const = 0;/*** Get the (i,j)th matrix element.** Throw OUT_OF_RANGE if either index is out of range.** @param i The row index* @param j The column index* @return The (i,j)th matrix element* @throws OUT_OF_RANGE if either index is out of range*/virtual T GetElement(int i, int j) const = 0;/*** Set the (i,j)th matrix element.** Throw OUT_OF_RANGE if either index is out of range.** @param i The row index* @param j The column index* @param val The value to insert* @throws OUT_OF_RANGE if either index is out of range*/virtual void SetElement(int i, int j, T val) = 0;/*** Fill the elements of the matrix from `source`.** Throw OUT_OF_RANGE in the event that `source`* does not contain the required number of elements.** @param source The source container* @throws OUT_OF_RANGE if `source` is incorrect size*/virtual void FillFrom(const std::vector<T> &source) = 0;/*** Destroy a matrix instance.* TODO(P0): Add implementation*/virtual ~Matrix() {if (linear_ == nullptr) {return;}delete[] linear_;}
};/*** The RowMatrix type is a concrete matrix implementation.* It implements the interface defined by the Matrix type.*/
template <typename T>
class RowMatrix : public Matrix<T> {public:/*** TODO(P0): Add implementation** Construct a new RowMatrix instance.* @param rows The number of rows* @param cols The number of columns*/RowMatrix(int rows, int cols) : Matrix<T>(rows, cols) {data_ = new T *[rows];for (int i = 0; i < rows; ++i) {data_[i] = Matrix<T>::linear_ + i * cols;}}/*** TODO(P0): Add implementation* @return The number of rows in the matrix*/int GetRowCount() const override { return this->rows_; }/*** TODO(P0): Add implementation* @return The number of columns in the matrix*/int GetColumnCount() const override { return this->cols_; }/*** TODO(P0): Add implementation** Get the (i,j)th matrix element.** Throw OUT_OF_RANGE if either index is out of range.** @param i The row index* @param j The column index* @return The (i,j)th matrix element* @throws OUT_OF_RANGE if either index is out of range*/T GetElement(int i, int j) const override {if (i < 0 || i >= this->GetRowCount()) throw Exception(ExceptionType::OUT_OF_RANGE, "index is out of range");if (j < 0 || j >= this->GetColumnCount()) throw Exception(ExceptionType::OUT_OF_RANGE, "index is out of range");return std::move(data_[i][j]);}/*** Set the (i,j)th matrix element.** Throw OUT_OF_RANGE if either index is out of range.** @param i The row index* @param j The column index* @param val The value to insert* @throws OUT_OF_RANGE if either index is out of range*/void SetElement(int i, int j, T val) override {if (i < 0 || i >= Matrix<T>::rows_ || j < 0 || j >= Matrix<T>::cols_) {throw Exception(ExceptionType::OUT_OF_RANGE, "index is out of range");} elsedata_[i][j] = val;}/*** TODO(P0): Add implementation** Fill the elements of the matrix from `source`.** Throw OUT_OF_RANGE in the event that `source`* does not contain the required number of elements.** @param source The source container* @throws OUT_OF_RANGE if `source` is incorrect size*/void FillFrom(const std::vector<T> &source) override {int rowCount = this->GetRowCount();int colCount = this->GetColumnCount();if (source.size() != static_cast<std::size_t>(rowCount * colCount)) {throw Exception(ExceptionType::OUT_OF_RANGE, "index is out of range");}for (int i = 0; i < rowCount * colCount; ++i) {Matrix<T>::linear_[i] = source[i];}}/*** TODO(P0): Add implementation** Destroy a RowMatrix instance.*/~RowMatrix() override {//    for (int i = 0; i < this->GetRowCount(); ++i) {//      delete[] data_[i];//    }delete[] data_;}private:/*** A 2D array containing the elements of the matrix in row-major format.** TODO(P0):* - Allocate the array of row pointers in the constructor.* - Use these pointers to point to corresponding elements of the `linear` array.* - Don't forget to deallocate the array in the destructor.*/T **data_;
};/*** The RowMatrixOperations class defines operations* that may be performed on instances of `RowMatrix`.*/
template <typename T>
class RowMatrixOperations {public:/*** Compute (`matrixA` + `matrixB`) and return the result.* Return `nullptr` if dimensions mismatch for input matrices.* @param matrixA Input matrix* @param matrixB Input matrix* @return The result of matrix addition*/static std::unique_ptr<RowMatrix<T>> Add(const RowMatrix<T> *matrixA, const RowMatrix<T> *matrixB) {if (matrixA->GetRowCount() != matrixB->GetRowCount() || matrixA->GetColumnCount() != matrixB->GetColumnCount())return std::unique_ptr<RowMatrix<T>>(nullptr);int rowCount = matrixA->GetRowCount();int colCount = matrixB->GetColumnCount();std::unique_ptr<RowMatrix<T>> mat = std::make_unique<RowMatrix<T>>(rowCount, colCount);for (int i = 0; i < rowCount; ++i) {for (int j = 0; j < colCount; ++j) {T temp = matrixA->GetElement(i, j) + matrixB->GetElement(i, j);mat->SetElement(i, j, std::move(temp));}}return mat;}/*** Compute the matrix multiplication (`matrixA` * `matrixB` and return the result.* Return `nullptr` if dimensions mismatch for input matrices.* @param matrixA Input matrix* @param matrixB Input matrix* @return The result of matrix multiplication*/static std::unique_ptr<RowMatrix<T>> Multiply(const RowMatrix<T> *matrixA, const RowMatrix<T> *matrixB) {// TODO(P0): Add implementationif (matrixA->GetColumnCount() != matrixB->GetRowCount()) {return std::unique_ptr<RowMatrix<T>>(nullptr);}int row = matrixA->GetRowCount();int col = matrixB->GetColumnCount();T sum;std::unique_ptr<RowMatrix<T>> mat = std::make_unique<RowMatrix<T>>(row, col);for (int i = 0; i < row; ++i) {for (int j = 0; j < col; ++j) {sum = 0;for (int k = 0; k < matrixA->GetColumnCount(); ++k) {sum += matrixA->GetElement(i, k) * matrixB->GetElement(k, j);}mat->SetElement(i, j, sum);}}return mat;}/*** Simplified General Matrix Multiply operation. Compute (`matrixA` * `matrixB` + `matrixC`).* Return `nullptr` if dimensions mismatch for input matrices.* @param matrixA Input matrix* @param matrixB Input matrix* @param matrixC Input matrix* @return The result of general matrix multiply*/static std::unique_ptr<RowMatrix<T>> GEMM(const RowMatrix<T> *matrixA, const RowMatrix<T> *matrixB,const RowMatrix<T> *matrixC) {std::unique_ptr tempMat = std::move(Multiply(matrixA, matrixB));if (tempMat == nullptr) {return std::unique_ptr<RowMatrix<T>>(nullptr);}return Add(tempMat, matrixC);}
};
}  // namespace bustubx<T> *matrixB,const RowMatrix<T> *matrixC) {std::unique_ptr tempMat = std::move(Multiply(matrixA, matrixB));if (tempMat == nullptr) {return std::unique_ptr<RowMatrix<T>>(nullptr);}return Add(tempMat, matrixC);}
};
}  // namespace bustub