toolbox::file::memory_mapped_file_t Class Reference

RAII wrapper for memory-mapped files. / 内存映射文件的 RAII 封装。 More...

#include <memory_mapped_file.hpp>

Public Member Functions
	memory_mapped_file_t ()=default
	Default constructor. / 默认构造函数。
	~memory_mapped_file_t ()
	Destructor. Automatically closes the mapped file. / 析构函数。自动关闭映射的文件。
	memory_mapped_file_t (const memory_mapped_file_t &)=delete
	Copy constructor (deleted). / 拷贝构造函数（已删除）。
memory_mapped_file_t &	operator= (const memory_mapped_file_t &)=delete
	Copy assignment operator (deleted). / 拷贝赋值运算符（已删除）。
	memory_mapped_file_t (memory_mapped_file_t &&)=delete
	Move constructor (deleted). / 移动构造函数（已删除）。
memory_mapped_file_t &	operator= (memory_mapped_file_t &&)=delete
	Move assignment operator (deleted). / 移动赋值运算符（已删除）。
bool	open (const std::filesystem::path &path)
	Opens and memory-maps the specified file. / 打开并内存映射指定的文件。
void	close ()
	Closes the memory-mapped file and releases resources. / 关闭内存映射文件并释放资源。
const unsigned char *	data () const
	Gets a pointer to the mapped memory region. / 获取指向映射内存区域的指针。
size_t	size () const
	Gets the size of the mapped file. / 获取映射文件的大小。
bool	is_open () const
	Checks if a file is currently mapped. / 检查文件当前是否已映射。

Detailed Description

RAII wrapper for memory-mapped files. / 内存映射文件的 RAII 封装。

This class provides a cross-platform way to map a file into memory for read-only access. It handles the opening, mapping, and closing of the file automatically using RAII.

这个类提供了一种跨平台的方式将文件映射到内存中进行只读访问。 它使用 RAII 自动处理文件的打开、映射和关闭。

#include <cpp-toolbox/file/memory_mapped_file.hpp>
#include <iostream>
#include <fstream>
 
int main() {
    const std::filesystem::path test_file = "test_mmap.txt";
    // Create a dummy file
    {
        std::ofstream ofs(test_file);
        ofs << "Hello, Memory Map!";
    }
 
    toolbox::file::memory_mapped_file_t mapped_file;
    if (mapped_file.open(test_file)) {
        std::cout << "File mapped successfully. Size: " << mapped_file.size()
<< std::endl;
        // Access data (example: print first 5 chars)
        const unsigned char* data = mapped_file.data();
        if (data && mapped_file.size() >= 5) {
             std::cout << "First 5 chars: ";
             for(size_t i = 0; i < 5; ++i) {
                 std::cout << data[i];
             }
             std::cout << std::endl;
        }
        // File is automatically unmapped and closed when mapped_file goes
out of scope } else { std::cerr << "Failed to map file: " << test_file <<
std::endl;
    }
 
    std::filesystem::remove(test_file); // Clean up
    return 0;
}

Constructor & Destructor Documentation

memory_mapped_file_t() [1/3]

toolbox::file::memory_mapped_file_t::memory_mapped_file_t ( )

default

Default constructor. / 默认构造函数。

toolbox::file::memory_mapped_file_t mmap_file;
// Now you can call open() to map a file

~memory_mapped_file_t()

toolbox::file::memory_mapped_file_t::~memory_mapped_file_t

(

)

Destructor. Automatically closes the mapped file. / 析构函数。自动关闭映射的文件。

Calls close() to ensure all resources are properly released. / 调用 close() 确保所有资源被正确释放。

memory_mapped_file_t() [2/3]

toolbox::file::memory_mapped_file_t::memory_mapped_file_t ( const memory_mapped_file_t &  )

delete

Copy constructor (deleted). / 拷贝构造函数（已删除）。

memory_mapped_file_t() [3/3]

toolbox::file::memory_mapped_file_t::memory_mapped_file_t ( memory_mapped_file_t &&  )

delete

Move constructor (deleted). / 移动构造函数（已删除）。

Member Function Documentation

close()

void toolbox::file::memory_mapped_file_t::close

(

)

Closes the memory-mapped file and releases resources. / 关闭内存映射文件并释放资源。

This is called automatically by the destructor, but can be called manually. / 这个函数由析构函数自动调用，但也可以手动调用。

toolbox::file::memory_mapped_file_t mf;
if (mf.open("data.bin")) {
    // Process the file
    // ...
 
    // Explicitly close when done
    mf.close();
 
    // Can now open another file
    mf.open("another_file.bin");
}

data()

const unsigned char * toolbox::file::memory_mapped_file_t::data ( ) const

inline

Gets a pointer to the mapped memory region. / 获取指向映射内存区域的指针。

Returns

A const pointer to the start of the mapped data, or nullptr if not open. / 指向映射数据起始位置的 const 指针，如果未打开则为 nullptr。

toolbox::file::memory_mapped_file_t mf;
if (mf.open("image.dat") && mf.size() >= 1024) {
    const unsigned char* img_data = mf.data();
    // Now you can read the image data without loading it all into memory
    unsigned int header_value = img_data[0] | (img_data[1] << 8) |
(img_data[2] << 16) | (img_data[3] << 24);
}

is_open()

bool toolbox::file::memory_mapped_file_t::is_open ( ) const

inline

Checks if a file is currently mapped. / 检查文件当前是否已映射。

Returns

True if a file is mapped, false otherwise. / 如果文件已映射，返回 true，否则返回 false。

toolbox::file::memory_mapped_file_t mf;
// Check before using
if (!mf.is_open()) {
    if (!mf.open("config.dat")) {
        std::cerr << "Failed to open config file" << std::endl;
        return -1;
    }
}
 
// Now safe to use mf.data() and mf.size()

open()

bool toolbox::file::memory_mapped_file_t::open

(

const std::filesystem::path &

path

)

Opens and memory-maps the specified file. / 打开并内存映射指定的文件。

If a file is already open, it will be closed first. / 如果已有文件打开，会先关闭。

Parameters

path	The path to the file to map. / 要映射的文件的路径。

Returns

True if the file was successfully opened and mapped, false otherwise. / 如果文件成功打开并映射，返回 true，否则返回 false。

toolbox::file::memory_mapped_file_t mf;
if (mf.open("my_data.bin")) {
    // Use mf.data() and mf.size()
    const unsigned char* buffer = mf.data();
    size_t file_size = mf.size();
 
    // Process the data
    for (size_t i = 0; i < file_size; ++i) {
        // Do something with buffer[i]
    }
} else {
    // Handle error
    std::cerr << "Failed to open file" << std::endl;
}

operator=() [1/2]

memory_mapped_file_t & toolbox::file::memory_mapped_file_t::operator= ( const memory_mapped_file_t &  )

delete

Copy assignment operator (deleted). / 拷贝赋值运算符（已删除）。

operator=() [2/2]

memory_mapped_file_t & toolbox::file::memory_mapped_file_t::operator= ( memory_mapped_file_t &&  )

delete

Move assignment operator (deleted). / 移动赋值运算符（已删除）。

size()

size_t toolbox::file::memory_mapped_file_t::size ( ) const

inline

Gets the size of the mapped file. / 获取映射文件的大小。

Returns

The size of the mapped region in bytes, or 0 if not open. / 映射区域的大小（字节），如果未打开则为 0。

toolbox::file::memory_mapped_file_t mf;
if (mf.open("data.bin")) {
    std::cout << "File size: " << mf.size() << " bytes" << std::endl;
 
    // Check if file is large enough for our needs
    if (mf.size() < required_size) {
        std::cerr << "File is too small" << std::endl;
    }
}

---

The documentation for this class was generated from the following file:

• src/include/cpp-toolbox/file/memory_mapped_file.hpp