yaml-cpp的简单使用

yaml-cpp

以前一直以一种自定义的格式写自己程序的配置文件，非常不友好也不方便使用，最近正好想整理一下自己程序，打算使用yaml文件形式作为后续程序的配置文件，于是就上网找了下C++版本的yaml解析库，果然，开源大法好，找到了yaml-cpp，打算尝试一下。
$我的测试环境是WSL-Ubuntu20.04$

安装

我下载的是0.7.0 版本

mkdir yaml && cd yaml 
wget https://codeload.github.com/jbeder/yaml-cpp/tar.gz/refs/tags/yaml-cpp-0.7.0
tar -zvxf yaml-cpp-0.7.0

yaml-cpp是使用cmake管理，因此十分方便，

cd yaml-cpp-yaml-cpp-0.7.0
mkdir build && cd build 
cmake [-G generator] [-YAML_BUILD_SHARED_LIBS=on|OFF] ..
make -j4 
sudo make install

The generator option is the build system you’d like to use. Run cmake without arguments to see a full list of available generators.

• On Windows, you might use “Visual Studio 12 2013” (VS 2013 32-bits), or “Visual Studio 14 2015 Win64” (VS 2015 64-bits).
• On OS X, you might use “Xcode”.
• On a UNIX-like system, omit the option (for a Makefile).

yaml-cpp builds a static library by default, you may want to build a shared library by specifying -YAML_BUILD_SHARED_LIBS=ON.

这样就安装完成了

使用

接下来新建一个C++工程来尝试使用：

因为我这边平时参数设置涉及最多的其实就是数组，string，单个值，所以结合我自己使用的场景写了如下的 test.yaml：

data_name: EuRoc_data
camera_rate_hz: 20.0
image_size: [752, 480]
extri_R: [0.0148655429818, -0.999880929698, 0.00414029679422,
          0.999557249008, 0.0149672133247, 0.025715529948,
          -0.0257744366974, 0.00375618835797, 0.999660727178]
max_points: 256

yaml-cpp.cpp

/**
 * @file yaml-cpp.cpp
 * @author fwt ([email protected])
 * @brief 
 * @version 0.1
 * @date 2021-11-20
 * 
 * @copyright Copyright (c) 2021
 * 
 */
#include "yaml-cpp/yaml.h"
#include 
#include 
#include 

#define options_key(x) #x

int main(int argc, char const *argv[])
{
    double camera_rate_hz;
    int max_points;
    std::string data_name;
    std::vector<int> image_size;
    std::vector<double> extri_R;

    std::string config_path = PROJECT_PATH;
    config_path.append("/config/test.yaml");

    YAML::Node configures = YAML::LoadFile(config_path);
    std::cout << "--------------------------------------------------------" << std::endl;
    std::cout << "Yaml Node:" << std::endl;
    std::cout << configures << std::endl;
    std::cout << "--------------------------------------------------------" << std::endl;

    camera_rate_hz = configures[options_key(camera_rate_hz)].as<decltype(camera_rate_hz)>();
    max_points = configures[options_key(max_points)].as<decltype(max_points)>();
    data_name = configures[options_key(data_name)].as<decltype(data_name)>();
    image_size = configures[options_key(image_size)].as<decltype(image_size)>();
    extri_R = configures[options_key(extri_R)].as<decltype(extri_R)>();

    std::cout << "config:" << std::endl;
    std::cout << "camera_rate_hz: " << camera_rate_hz << std::endl;
    std::cout << "max_points: " << max_points << std::endl;
    std::cout << "data_name: " << data_name << std::endl;
    std::cout << "image_size: [" << image_size[0] << "," << image_size[1] <<"]"<< std::endl;
    std::cout << "extri_R: " ;
    for (size_t i = 0; i < 9; i++)
    {
        std::cout << extri_R[i] << ",";
    }
    std::cout << std::endl;
    std::cout << "--------------------------------------------------------" << std::endl;

    return 0;
}

简单写一下对应的CMakeLists.txt：

cmake_minimum_required( VERSION 3.2)
project(yaml_test)

add_definitions(-DPROJECT_PATH="${PROJECT_SOURCE_DIR}")

SET(CMAKE_CXX_COMPILE "g++")
SET(CMAKE_C_COMPILE "gcc")
SET( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11" )
SET( CMAKE_BUILD_TYPE "release")
SET(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)
SET(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)

find_package(yaml-cpp REQUIRED)

include_directories(${YAML_CPP_INCLUDE_DIR})
add_executable(${PROJECT_NAME} ${PROJECT_SOURCE_DIR}/src/yaml-test.cpp)
target_link_libraries(${PROJECT_NAME} yaml-cpp)

编译测试一下，与预期一样。

过程中，其实还有遇到一些坑，最开始写CMake文件的时候写的是target_link_libraries(${PROJECT_NAME} ${YAML_CPP_LIBRARIES})，link的时候一直报错undefined reference function，后来改成 target_link_libraries(${PROJECT_NAME} yaml-cpp) 就OK了，之所以写${YAML_CPP_LIBRARIES}是因为在yaml-cpp-config.cmake是这样写，不清楚为啥没有生效，有大佬知道的话希望可以指点一下~

结语

由于我只是使用yaml文件，所以没有深入学习yaml-cpp库本身。对于只是使用yaml作为配置使用来说暂时够用了~