I am using yaml-cpp 0.3.0 (old API version) to parse a yaml file (which I got from here ).
This is the yaml file:
- name: Ogre
position: [0, 5, 0]
powers:
- name: Club
damage: 10
- name: Fist
damage: 8
- name: Dragon
position: [1, 0, 10]
powers:
- name: Fire Breath
damage: 25
- name: Claws
damage: 15
- name: Wizard
position: [5, -3, 0]
powers:
- name: Acid Rain
damage: 50
- name: Staff
damage: 3
And now I try to parse the powers name and damage with this code:
#include "yaml-cpp/yaml.h"
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
// our data types
struct Vec3 {
float x, y, z;
};
struct Power {
std::string name;
int damage;
};
struct Monster {
std::string name;
Vec3 position;
std::vector <Power> powers;
};
// now the extraction operators for these types
void operator >> (const YAML::Node& node, Vec3& v) {
node[0] >> v.x;
node[1] >> v.y;
node[2] >> v.z;
}
void operator >> (const YAML::Node& node, Power& power) {
node["name"] >> power.name;
node["damage"] >> power.damage;
}
void operator >> (const YAML::Node& node, Monster& monster) {
node["name"] >> monster.name;
node["position"] >> monster.position;
const YAML::Node& powers = node["powers"];
for(unsigned i=0;i<powers.size();i++) {
Power power;
powers[i] >> power;
monster.powers.push_back(power);
}
}
int main()
{
std::ifstream fin("robot.yaml");
YAML::Parser parser(fin);
YAML::Node doc;
parser.GetNextDocument(doc);
for(unsigned i=0;i<doc.size();i++) {
Power power;
doc[i] ["powers"] >> power;
std::cout << power.name << "\n";
std::cout << power.damage << "\n";
}
return 0;
}
It seems that my code shows error like this:
terminate called after throwing an instance of 'YAML::TypedKeyNotFound<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >'
what(): yaml-cpp: error at line 4, column 5: key not found: name
Aborted (core dumped)
Please help me understand why can't I parse the powers element.
And please explain to me how can I parse all the key & values in one code since I am new with coding.
So the problem is here:
doc[i] ["powers"] >> power;
doc[i]["powers"]
does not have an index "name":
- name: Ogre
position: [0, 5, 0]
powers:
- name: Club
damage: 10- name: Fist
damage: 8
The "-" denotes items. So similarly to doc[i]
, you would need to index firstly:
Power power;
doc[i]["powers"][0] >> power;
std::cout << power.name //outputs "Club"
But I assume you want all powers for each item, so you would need another explicit for-loop:
for (unsigned i = 0; i < doc.size(); i++)
{
for (unsigned j = 0; j < doc[i]["powers"].size(); ++j)
{
Power power;
doc[i]["powers"][j] >> power;
std::cout << power.name << "\n";
std::cout << power.damage << "\n";
}
}
But that's a bit overkill. Better use your Monster
-class directly, since the power values are already stored there:
for(unsigned i=0;i<doc.size();i++) {
Monster monster;
doc[i] >> monster;
for (auto& power : monster.powers) // range-for loop
{
std::cout << power.name << "\n";
std::cout << power.damage << "\n";
}
std::cout << monster.name << "\n";
}
Maybe this is a good start. A continuation of the answer would depend on what you want to achieve.
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