I'm getting started using YAML, and the yaml-cpp library to intepret my file. I extended the "monsters" example with some information from my own project. The code and yaml file are below, but here's my question first:
Is it necessary to place all the data that I'll be getting out of the project into one massive structure? In the monsters example, reading the values in from the document doc[i] was easy because it was a list of monsters. In my example, I'll have some lists, but also scalars, etc. The only way that I found to do this, is to make a list that technically only has one entry (i.e., there's a single '-' at the top of the file, and everything is indented into a block). I think the answer is to take some of the content of the 'problemformulation' version of the overloaded >> operator, but I couldn't get it to work properly without having that content inside that function. Any help or advice is appreciated.
ea_test.cpp:
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
#include "yaml-cpp/yaml.h"
struct Vec2 {
double x, y;
};
struct DecVar {
std::string name;
std::string tag;
Vec2 range;
std::string description;
};
struct ProblemFormulation {
std::vector<DecVar> decvars;
int numrealizations;
};
void operator>>(const YAML::Node& node, Vec2& v) {
node[0] >> v.x;
node[1] >> v.y;
}
void operator>>(const YAML::Node& node, DecVar& decvar) {
node["name"] >> decvar.name;
node["tag"] >> decvar.tag;
node["range"] >> decvar.range;
node["description"] >> decvar.description;
}
void operator>>(const YAML::Node& node,
ProblemFormulation& problemformulation) {
node["realizations"] >> problemformulation.numrealizations;
std::cout << " read realizations!" << std::endl;
const YAML::Node& decvarNode = node["decisions"];
for (unsigned int i = 0; i < decvarNode.size(); i++) {
DecVar decvar;
decvarNode[i] >> decvar;
problemformulation.decvars.push_back(decvar);
}
}
int main() {
std::ifstream fin("./ea.yaml");
YAML::Parser parser(fin);
YAML::Node doc;
parser.GetNextDocument(doc);
std::cout << "entering loop" << std::endl;
ProblemFormulation problemformulation;
for (unsigned int i = 0; i < doc.size(); i++) {
doc[i] >> problemformulation;
}
return 0;
}
And, ea.yaml:
- realizations: 10
decisions:
- name: reservoir
tag: res_tag
range:
- 0
- 1
description: |
This is a description.
- name: flow
tag: flow_tag
range:
- 0
- 2
description: |
This is how much flow is in the system.
Thanks in advance for your help and tips!
Edit: I will probably only be running one yaml document, and there's only one problemformulation object that will ever be created. My code adapts what you'd do for a list, but only does it once. I would like to know the proper way to, "just do it once", since I think that would be cleaner and make a better looking YAML file (without all the things indented one block for no reason).
