libxml2获取节点的xsd定义

我有一个.xml文件和.xsd 在使用libxml2解析和验证文件之后，如何从模式中获取节点定义（限制、注释…）

xmlInitParser();
xmlSchemaPtr schema = NULL;
xmlSchemaParserCtxtPtr schema_parser_ctxt = NULL;
int has_schema_errors = 0;
int ret = -1;
xmlSchemaValidCtxtPtr valid_ctxt = NULL;
schema_parser_ctxt = xmlSchemaNewParserCtxt("test.xsd");
xmlTextReaderPtr reader = NULL;
const char* filename = "file.xml";
reader = xmlReaderForFile(filename, NULL, 0);

if (reader != NULL)
{
    if (valid_ctxt)
        xmlTextReaderSchemaValidateCtxt(reader, valid_ctxt, 0);
    ret = xmlTextReaderRead(reader);
    while (ret == 1 && !has_schema_errors)
    {
        ret = xmlTextReaderRead(reader);
        xmlNodePtr node;
        node = xmlTextReaderCurrentNode(reader);
        // here i want get node definition from xsd

    }
}

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这在libxml2中是不可能的