Boost::property tree 를 이용한 json 스크립트 파싱
jjuiddong
목차 |
여러개의 속성을 가진 child 정보를 가져오는 방법
"property" : [
{
"symbolname" : "CLobbyServer#1"
},
{
"symbolname" : "CLobbyServer#1"
}
]
boost::property_tree 를 이용한 json 스크립트 파싱
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
using boost::property_tree::ptree;
ptree props;
boost::property_tree::read_json("filename", props);
ptree &children = props.get_child("property");
BOOST_FOREACH(ptree::value_type &vt, children)
{
const string name = vt.second.get<string>("symbolname");
...
}
일반적인 JSon 파싱
{
"attribute1" : "100"
,"attribute2" : "0 0 100 100"
,"attribute3" : "0 0 100 100"
,"attribute4" : "200"
,"attribute5" : "5"
, "attribute6" :
[
{
"sub-attr1" : "data1"
,"sub-attr2" : "data2"
}
,{
"sub-attr1" : "data3"
,"sub-attr2" : "data4"
}
]
}
JSon Parsing Sample Code
bool cConfig::Read(const char *fileName)
{
using boost::property_tree::ptree;
Clear();
try
{
ptree props;
boost::property_tree::read_json(fileName, props);
m_attribute1 = props.get<int>("attribute1", 100);
m_attribute2 = props.get<string>("attribute2", "0 0 0 0");
m_attribute3 = props.get<string>("attribute3", "0 0 0 0");
m_attribute4 = props.get<int>("attribute4", 0);
m_attribute5 = props.get<int>("attribute5", 5);
auto &children = props.get_child("attribute6");
for (auto &vt : children)
{
string subAttr1 = vt.second.get<string>("sub-attr1", "");
string subAttr2 = vt.second.get<string>("sub-attr2", "");
}
}
catch (std::exception&e)
{
string err = e.what();
return false;
}
return true;
}
Array 파싱
"pos" : [1, 2, 3], "scale" : [1, 2, 3], "rot" : [1, 2, 3, 4], "widths" : [1, 2, 3, 4, 5, 6],
template <class T, size_t MAX>
bool GetArray(boost::property_tree::ptree &ptree, const string &key, OUT T out[])
{
int idx = 0;
auto it = ptree.get_child(key);
for (auto &kv : it)
{
out[idx++] = kv.second.get<T>("");
if (idx >= MAX)
break;
}
return true;
}
template <class T>
bool GetVector(boost::property_tree::ptree &ptree, const string &key , OUT vector<T> &out)
{
auto it = ptree.get_child(key);
for (auto &kv : it)
out.push_back(kv.second.get<T>(""));
return true;
}
// json string parsing and return vec3
// "key" : [1, 2, 3]
Vector3 GetVector3(boost::property_tree::ptree &ptree, const string &key)
{
float ar[3];
GetArray<float, 3>(ptree, key, ar);
return Vector3(ar[0], ar[1], ar[2]);
}
// json string parsing and return vec4
// "key" : [1, 2, 3, 4]
Vector4 GetVector4(boost::property_tree::ptree &ptree, const string &key)
{
float ar[4];
GetArray<float, 4>(ptree, key, ar);
return Vector4(ar[0], ar[1], ar[2], ar[3]);
}
Vector3 pos = GetVector3(props, "pos");
Vector3 scale = GetVector3(props, "scale");
Vector4 rot = GetVector4(props, "rot");
vector<float> widths;
GetVector<float>(props, "widths", widths);
다른방식의 json 파싱
json 은 key, value 값으로 구성된 스크립트지만, 다음처럼 value값이 없이도 사용할 수 있다.
"collapse" : [ "basic::s2c", "login::s2c" ]
이 스크립트의 정보를 가져오는 방법은 다음과 같다. (이 예제의 특징은 key value 만 있고, data value는 없다는 점이다.)
ptree &collapse = g_Props.get_child("collapse");
BOOST_FOREACH(auto &child, collapse)
{
if ("basic::s2c" == child.second.data())
return true;
}
property_tree find() 로 내부 데이타 얻는법
using boost::property_tree::ptree;
ptree props;
boost::property_tree::read_json(fileName.c_str(), props);
ptree &children = props.get_child("extract");
BOOST_FOREACH(auto &vt, children)
{
ptree::assoc_iterator fit = vt.second.find("field");
if (vt.second.not_found() != fit)
{
ptree &child_field = vt.second.get_child("field");
BOOST_FOREACH(auto &v, child_field)
{
Jjuiddong (토론)
}
}
}
boost::property_tree 데이타 저장
- 이미 존재하는 scale 키 에 sens 값을 업데이트 한다.
try
{
// boost property tree
using boost::property_tree::ptree;
using std::string;
ptree props;
boost::property_tree::read_json(fileName, props);
props.put<float>("scale", sens);
boost::property_tree::write_json(fileName + "1", props);
}
catch (std::exception&e)
{
::AfxMessageBox(CString(L"Error!!\n") + str2wstr(e.what()).c_str());
return false;
}
boost::property_tree 데이타 구성
ptree pt;
ptree children;
ptree child1, child2, child3;
child1.put("childkeyA", 1);
child1.put("childkeyB", 2);
child2.put("childkeyA", 3);
child2.put("childkeyB", 4);
child3.put("childkeyA", 5);
child3.put("childkeyB", 6);
children.push_back(std::make_pair("", child1));
children.push_back(std::make_pair("", child2));
children.push_back(std::make_pair("", child3));
pt.put("testkey", "testvalue");
pt.add_child("MyArray", children);
write_json("test2.json", pt);
{
"testkey": "testvalue",
"MyArray":
[
{
"childkeyA": "1",
"childkeyB": "2"
},
{
"childkeyA": "3",
"childkeyB": "4"
},
{
"childkeyA": "5",
"childkeyB": "6"
}
]
}
boost::property_tree 데이타 구성2
https://stackoverflow.com/questions/2114466/creating-json-arrays-in-boost-using-property-trees
ptree pt;
ptree children;
ptree child1, child2, child3;
child1.put("", 1);
child2.put("", 2);
child2.put("", 3);
children.push_back(std::make_pair("", child1));
children.push_back(std::make_pair("", child2));
children.push_back(std::make_pair("", child3));
pt.add_child("MyArray", children);
write_json("test2.json", pt);
{
"MyArray":
[
"1",
"2",
"3"
]
}
boost::property_tree 데이타 읽기와 저장
- Source JSon format
{
"point cloud" : [
{
"name" : "name 1",
"pos" : "1 2 3",
"description" : "memo 1"
},
{
"name" : "name 2",
"pos" : "1 2 3",
"description" : "memo 2"
}
]
}
- Read JSon file c++
try
{
ptree props;
boost::property_tree::read_json(fileName.c_str(), props);
// parse point cloud
ptree::assoc_iterator itor = props.find("point cloud");
if (props.not_found() != itor)
{
ptree &child_field = props.get_child("point cloud");
for (ptree::value_type &vt : child_field)
{
sPCData *pc = new sPCData;
pc->name = vt.second.get<string>("name");
const string posStr = vt.second.get<string>("pos");
vector<string> toks;
common::tokenizer(posStr, " ", "", toks);
if (toks.size() >= 3)
{
pc->pos = Vector3(
(float)atof(toks[0].c_str())
, (float)atof(toks[1].c_str())
, (float)atof(toks[2].c_str()));
}
pc->desc = vt.second.get<string>("description");
m_pcDatas.push_back(pc);
}
}
}
catch (std::exception &e)
{
Str128 msg;
msg.Format("Read Error!!, Point Cloud Data File [ %s ]\n%s"
, fileName.c_str(), e.what());
MessageBoxA(NULL, msg.c_str(), "ERROR", MB_OK);
return false;
}
- Write JSon file c++
try
{
ptree props;
ptree pcs;
for (auto &pc : m_pcDatas)
{
ptree z;
z.put("name", pc->name.c_str());
Str128 text;
text.Format("%f %f %f", pc->pos.x, pc->pos.y, pc->pos.z);
z.put("pos", text.c_str());
z.put("description", pc->desc.c_str());
pcs.push_back(std::make_pair("", z));
}
props.add_child("point cloud", pcs);
boost::property_tree::write_json(fileName.c_str(), props);
}
catch (std::exception &e)
{
Str128 msg;
msg.Format("Write Error!!, Point Cloud File [ %s ]\n%s"
, fileName.c_str(), e.what());
MessageBoxA(NULL, msg.c_str(), "ERROR", MB_OK);
return false;
}
