我知道我似乎有习惯回答自己的问题，但是到目前为止，我仍然坚持这一问题，需要一些帮助。
我已经编写了一些代码以将json格式的文件加载到类系统中。我将所有代码放在这里:
https://github.com/tomzooi/readreq
简而言之，我想做的是:
首先，我创建了一些代码，可以读取“需求”文件，并使用class.h中的Requirement类将其存储
再次，我可以以人类可读的格式输出屏幕，或将其存储在json文件中。这可行。
然后，我希望能够读取JSON文件，并再次使用相同的Requirement对象将其存储在内存中，但是到目前为止效果不佳。
现在的主要问题是我遍历属性树的部分，这主要是在此递归函数中完成的:
void display(const int depth, const boost::property_tree::ptree& tree, Requirement * cur_requirement, std::vector<Requirement> &requirements) {
unsigned int count;
std::string label,level,description;
boost::property_tree::ptree kids = tree.get_child("");
bool godown = false;
for (const auto& v : kids) { // v is of type ptree::value_type
std::cout << std::string("").assign(depth+1,'#') << " ";
std::string nodestr = tree.get<std::string>(v.first);
//std::cout << v.first << " = " << nodestr << std::endl;
if (v.first == "label") {
label = nodestr;
std::cout << "lbl: " << label << std::endl;
}
else if(v.first == "level") {
//std::cout << "LABEL!";
level = nodestr;
std::cout << "lvl: " << level << std::endl;
}
else if(v.first == "description") {
description = nodestr;
std::cout << "dsc: " << description << std::endl;
}
else if(v.first == "children") { //going down, store stuff first
if(depth == 0) { //zero depth
std::cout << "zero depth...";
requirements.emplace_back(level, description, label,cur_requirement);
cur_requirement = &requirements.back();
}
else { //one or higher depth
std::cout << "at depth " << depth << "..." << std::flush;
cur_requirement->children.emplace_back(level,description,label,cur_requirement->parent);
cur_requirement = &cur_requirement->children.back();
}
std::cout << "going down" << std::endl;
//cur_requirement = &cur_requirement->children.back();
display(depth+1, v.second, cur_requirement,requirements);
}
else if(v.first == "") {
std::cout << "empty v.first ... level: " << level << std::endl;
if(depth == 0) { //zero depth
std::cout << "store at zero depth...";
requirements.emplace_back(level, description, label,cur_requirement);
cur_requirement = &requirements.back();
}
else { //one or higher depth
std::cout << "store at depth " << depth << " : " << level << "--" << description << std::flush;
cur_requirement->children.emplace_back(level,description,label,cur_requirement->parent);
//cur_requirement = &cur_requirement->children.back();
}
std:: cout << " going to next " << std::endl;
//cur_requirement = &cur_requirement->children.back();
display(depth, v.second, cur_requirement,requirements);
}
else {
std:: cout << "what else..." << std::endl;
}
// v.first is the name of the child
// v.second is the child tree
}
};
我目前得到的输出是这样的:
[tom@tomtop dev]$ ./readreq The_system.F.req.json
name: The system prefix: F
# lvl: should
# dsc: very well performance wise
# lbl: goperf
# zero depth...going down
## empty v.first ... level:
store at depth 1 : -- going to next
## lvl: should
## dsc: be listening to spaces as well
## lbl: lisspace
## empty v.first ... level:
store at depth 1 : -- going to next
## lvl: will
## dsc: a lot of levels back down again
## at depth 1...going down
### empty v.first ... level:
store at depth 2 : -- going to next
### lvl: empty
### dsc: empty
### lbl: empty
### at depth 2...going down
#### empty v.first ... level:
store at depth 3 : -- going to next
#### lvl: can
#### dsc: skip all the way back here
#### lbl: skiphere
#### empty v.first ... level:
store at depth 3 : -- going to next
#### lvl: can
#### dsc: take three linestr
#### lbl: threelines
level: should description:very well performance wise label: goperf
level: description: label:
level: description: label:
level: will description:a lot of levels back down again label:
level: description: label:
level: empty description:empty label: empty
level: description: label:
level: description: label:
其中大多数是有道理的，并且大多数似乎都有效，但是有一件事使我感到困惑。属性树的组织方式是在每个“子”之前以及数组元素之间都有一个“空”节点。 (如果我错了，请纠正我，我对属性树不那么熟悉)。
因此，在遇到“ child ”或“ child ”(空)元素之后，我想存储以前收集的数据，并将其存储在变量级别，描述和标签中。
这是一个有趣的部分，当元素是“children”时，它就像一个魅力，但是，当元素是“”时，变量突然为空，即使变量没有重新初始化，我也没有更深入地研究在属性树中，我仅迭代到for循环中的下一个“ child ”。
所以我期望的输出是这样的:
## lvl: should
## dsc: be listening to spaces as well
## lbl: lisspace
## empty v.first ... level: should
store at depth 1 : should -- be listening to spaces as well going to next
最后一行(由
)显示以下内容:
store at depth 1 : -- going to next
给人的印象是标签，描述和级别在什么地方是空的，而没有地方可以使它们为空。
因此，如果有人可以向我解释这种愚蠢的行为，我将非常高兴。
最佳答案
我尝试了15分钟。我无法解决您要达到的目标。
查看更新
笔记
cur_requirement应该被初始化。 requirements.emplace_back(level, description, label, cur_requirement);
cur_requirement = &requirements.back();
您将在放置的需求中存储指向 vector 元素的指针。但是，嵌入可能会重新分配，使的所有指针和迭代器无效。
更新
因此，这是我的工作，需要清理
display函数(我将其重命名为parse_json，因为它就是这样做的):void parse_json(int depth, boost::property_tree::ptree const& tree, Requirement& cur)
{
cur.label = tree.get("label", "");
cur.level = tree.get("level", "");
cur.description = tree.get("description", "");
if (auto kids = tree.get_child_optional("children")) {
for (auto& kid : *kids) {
std::cout << "at depth " << depth << "... " << std::flush;
cur.children.emplace_back(&cur);
std::cout << "going down" << std::endl;
parse_json(depth + 1, kid.second, cur.children.back());
}
}
}
完整演示
看到整个程序被清理了。注意我已将
vector替换为list，以避免在读取更多子节点时使父指针无效Live On Coliru
#include <boost/property_tree/json_parser.hpp>
#include <boost/property_tree/ptree.hpp>
#include <exception>
#include <fstream>
#include <iostream>
#include <string>
#include <list>
class Requirement {
public:
bool empty;
std::string level;
std::string description;
std::string label;
Requirement const* parent;
std::list <Requirement> children;
Requirement(Requirement const* p);
Requirement(std::string l, std::string d, std::string la, Requirement const* p); // unused
void print(std::string indent = "");
void print_json(std::ostream &os, std::string indent = "");
};
Requirement::Requirement(Requirement const* p)
: empty(false), parent(p)
{
}
Requirement::Requirement(std::string l, std::string d, std::string la,Requirement const* p) // unused
: empty(false),
level(std::move(l)), description(std::move(d)), label(std::move(la)), parent(p)
{
}
void Requirement::print_json(std::ostream &os, std::string indent) {
os << "{";
indent += '\t';
os
<< "\n" << indent << "\"level\":\"" << level << "\", "
<< "\n" << indent << "\"description\":\"" << description << "\"";
if(label.length() > 1) {
os << ",\n" << indent << "\"label\":\"" << label <<"\"";
}
if (!children.empty()) {
os << ", \"children\":[\n";
bool first = true;
for(auto& child : children) {
if (!first)
os << ',';
first=false;
os << "\n" << indent;
child.print_json(os, indent);
}
os << "]";
}
indent.resize(indent.size() - 1);
os << "\n" << indent << "}";
}
void Requirement::print(std::string indent) {
std::cout << indent << "level: " << level << " description:" << description << " label: " << label << std::endl;
for (Requirement kid : children)
kid.print(indent + '\t');
}
void parse_json(int depth, boost::property_tree::ptree const& tree, Requirement& cur)
{
cur.label = tree.get("label", "");
cur.level = tree.get("level", "");
cur.description = tree.get("description", "");
if (auto kids = tree.get_child_optional("children")) {
for (auto& kid : *kids) {
std::cout << "at depth " << depth << "... " << std::flush;
cur.children.emplace_back(&cur);
std::cout << "going down" << std::endl;
parse_json(depth + 1, kid.second, cur.children.back());
}
}
}
int main(int argc, char* argv[])
{
if (argc>1) try {
std::ifstream ss(argv[1]);
boost::property_tree::ptree pt;
boost::property_tree::read_json(ss, pt);
Requirement root(nullptr);
parse_json(0, pt, root);
std::cout << std::endl << std::endl;
root.print("; debug: ");
root.print_json(std::cout);
}
catch (std::exception const& e) {
std::cerr << e.what() << std::endl;
return EXIT_FAILURE;
}
}
输出为:
at depth 0... going down
at depth 0... going down
at depth 1... going down
at depth 2... going down
at depth 2... going down
; debug: level: should description:very well performance wise label: goperf
; debug: level: should description:be listening to spaces as well label: lisspace
; debug: level: will description:a lot of levels back down again label:
; debug: level: empty description:empty label: empty
; debug: level: can description:skip all the way back here label: skiphere
; debug: level: can description:take three linestr label: threelines
{
"level":"should",
"description":"very well performance wise",
"label":"goperf", "children":[
{
"level":"should",
"description":"be listening to spaces as well",
"label":"lisspace"
},
{
"level":"will",
"description":"a lot of levels back down again", "children":[
{
"level":"empty",
"description":"empty",
"label":"empty", "children":[
{
"level":"can",
"description":"skip all the way back here",
"label":"skiphere"
},
{
"level":"can",
"description":"take three linestr",
"label":"threelines"
}]
}]
}]
}
请注意，代码的大小大约是一半:)