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在一个函数中，我使用 pugi 首先加载一个 XML 文件。然后，我遍历树的子 xml 节点并将一些子 xml 节点（xml_node 类型的对象）推送到 xml_node 的向量。但是一旦我退出这个函数，从 XML 文件加载的原始 XML 树结构对象被删除，导致 xml 节点向量中的元素变得无效。

下面是一个示例代码（快速编写）来显示这一点：

#include "pugixml.hpp"
#include <vector>

void ProcessXmlDeferred(  std::vector<pugi::xml_node> const &subTrees )
{
   for( auto & const node: subTrees)
   {
       // parse each xml_node node
   }
}

void IntermedProcXml( pugi::xml_node const &node)
{
   // parse node
}

std::vector<pugi::xml_node> BuildSubTrees(pugi::xml_node const & node )
{
  std::vector<pugi::xml_node> subTrees;

  pugi::xml_node temp = node.child("L1");
  subTrees.push_back( temp );

  temp = node.child.child("L2");
  subTrees.push_back( temp );

  temp = node.child.child.child("L3");
  subTrees.push_back( temp );

  return subTrees;
}

void LoadAndProcessDoc( const char* fileNameWithPath, std::vector<pugi::xml_node> & subTrees )
{
    pugi::xml_document doc;
    pugi::xml_parse_result result = doc.load( fileNameWithPath );

    subTrees = BuildSubTrees( result.child("TOP") );
    IntermedProcXml( result.child("CENTRE") );

    // Local pugi objects("doc" and "result") destroyed at exit of this 
    // function invalidating contents of xml nodes inside vector "subTrees"
}


int main()
{
    char fileName[] = "myFile.xml";
    std::vector<pugi::xml_node> myXmlSubTrees;  

    // Load XML file and return vector of XML sub-tree's for later parsing
    LoadAndProcessDoc( fileName, myXmlSubTrees );

    // At this point, the contents of xml node's inside the vector  
    // "myXmlSubTrees" are no longer valid and thus are unsafe to use

    // ....
    // Lots of intermediate code
    // ....

    // This function tries to process vector whose xml nodes 
    // are invalid and thus throws errors
    ProcessXmlDeferred( myXmlSubTrees );

    return 0;
}

因此，我需要一种方法来保存/复制/克隆/移动原始 XML 树的子树（xml 节点），以便即使在删除原始 XML 根树对象之后，我也可以在以后安全地解析它们。如何在 pugi 中做到这一点？

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1 回答 1

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Just pass the ownership of the xml_document object to the caller.

You can either do it by forcing the caller to supply an xml_document object (add a xml_document& argument to the function), or by returning a shared_ptr<xml_document> or unique_ptr<xml_document> from the function alongside the node vector.

于 2015-07-21T00:50:47.663 回答