Dynamic TreeNodes using ImGUI

treevec_imgui.hpp

#pragma once

#include <stack>
#include <vector>
#include <stack>
#include <utility>
#include <functional>
#include <tuple>
#include <imgui.h>

namespace ImGui
{

/*
 * dynamically draw TreeNodes with ImGui
 *
 * @param tree_list: a Depth first tree expressed in the form of vector of (level, value).
 * @param itr_func:  a lambda which generates string to pass to TreeNode function.
 *
 *
 * This function dynamically draw the tree nodes without hard coding the tree
 * structure. It carefully maintain the stack of tree and push and pop tree at
 * right moment. The minimum level should be 0.
 *
 */
template <typename T>
void TreeVec(const std::vector<std::pair<int, T>>& tree_list,
              std::function<std::string(const T&)> const itr_func)
{
    unsigned level = 0;
    bool expanded = true;      //expanding for curr level?
    bool local_expaned = true; //expanding for next level?

    std::stack<std::tuple<unsigned, bool, bool>> stack;

    auto itr = tree_list.begin();

    while (itr != tree_list.end())
    {
        if (itr->first >= level) //push
        {
            std::string id  = std::to_string(std::distance(tree_list.begin(),
                                                           itr));
            std::string txt = itr_func(itr->second);

            local_expaned = expanded &&
                TreeNode(id.c_str(), "%s", txt.c_str());
            stack.push(std::make_tuple(itr->first, local_expaned, expanded));

            expanded = local_expaned;
            level++;
            itr++;
        }
        else //reduce
        {
            std::tie(level, local_expaned, expanded) = stack.top();
            stack.pop();
            if (local_expaned)
                TreePop();
        }
    }
    while (!stack.empty())
    {
            std::tie(level, local_expaned, expanded) = stack.top();
            stack.pop();
            if (local_expaned)
                TreePop();
    }

}

}