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https://github.com/OpenNebula/one.git
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392 lines
11 KiB
C++
392 lines
11 KiB
C++
/* -------------------------------------------------------------------------- */
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/* Copyright 2002-2017, OpenNebula Project, OpenNebula Systems */
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/* */
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/* Licensed under the Apache License, Version 2.0 (the "License"); you may */
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/* not use this file except in compliance with the License. You may obtain */
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/* a copy of the License at */
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/* */
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/* http://www.apache.org/licenses/LICENSE-2.0 */
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/* */
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/* Unless required by applicable law or agreed to in writing, software */
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/* distributed under the License is distributed on an "AS IS" BASIS, */
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/* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */
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/* See the License for the specific language governing permissions and */
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/* limitations under the License. */
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/* -------------------------------------------------------------------------- */
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#ifndef OBJECT_XML_H_
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#define OBJECT_XML_H_
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#include <string>
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#include <vector>
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#include <sstream>
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#include <libxml/tree.h>
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#include <libxml/parser.h>
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#include <libxml/xpath.h>
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#include <libxml/xpathInternals.h>
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/**
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* This class represents a generic Object supported by a xml document.
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* The class provides basic methods to query attributes, and get xml nodes
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*/
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class ObjectXML
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{
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public:
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// ---------------------- Constructors ------------------------------------
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ObjectXML():xml(0),ctx(0){};
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/**
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* Constructs an object using a XML document
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*/
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ObjectXML(const std::string &xml_doc);
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/**
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* Constructs an object using a XML Node. The node is copied to the new
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* object
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*/
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ObjectXML(const xmlNodePtr node);
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virtual ~ObjectXML();
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/**
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* Gets elements by xpath.
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* @param values vector with the element values.
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* @param expr of the xml element
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*/
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template<typename T>
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void xpaths(std::vector<T>& values, const char * expr)
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{
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xmlXPathObjectPtr obj;
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xmlNodePtr cur;
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xmlChar * str_ptr;
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obj=xmlXPathEvalExpression(reinterpret_cast<const xmlChar *>(expr),ctx);
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if (obj == 0)
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{
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return;
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}
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switch (obj->type)
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{
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case XPATH_NUMBER:
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values.push_back(static_cast<T>(obj->floatval));
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break;
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case XPATH_NODESET:
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for(int i = 0; i < obj->nodesetval->nodeNr ; ++i)
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{
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cur = obj->nodesetval->nodeTab[i];
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if ( cur == 0 || cur->type != XML_ELEMENT_NODE )
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{
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continue;
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}
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str_ptr = xmlNodeGetContent(cur);
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if (str_ptr != 0)
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{
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std::istringstream iss(reinterpret_cast<char *>(str_ptr));
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T val;
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iss >> std::dec >> val;
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if (!iss.fail())
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{
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values.push_back(val);
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}
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xmlFree(str_ptr);
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}
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}
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break;
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default:
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break;
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}
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xmlXPathFreeObject(obj);
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};
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void xpaths(std::vector<std::string>& values, const char * xpath_expr);
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/**
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* Gets a xpath attribute, if the attribute is not found a default is used.
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* This function only returns the first element
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* @param value of the element
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* @param xpath_expr of the xml element
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* @param def default value if the element is not found
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*
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* @return -1 if default was set
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*/
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template<typename T>
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int xpath(T& value, const char * xpath_expr, const T& def)
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{
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std::vector<std::string> values;
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xpaths(values, xpath_expr);
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if (values.empty() == true)
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{
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value = def;
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return -1;
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}
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std::istringstream iss(values[0]);
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iss >> std::dec >> value;
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if (iss.fail() == true)
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{
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value = def;
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return -1;
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}
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return 0;
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}
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int xpath(std::string& value, const char * xpath_expr, const char * def);
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/**
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* Gets the value of an element from an xml string
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* @param value the value of the element
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* @param xml the xml string
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* @param xpath the xpath of the target element
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*
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* @return -1 if the element was not found
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*/
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static int xpath_value(std::string& value, const char *xml, const char *xpath);
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/**
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* Search the Object for a given attribute in a set of object specific
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* routes.
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* @param name of the attribute
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* @param value of the attribute
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*
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* @return -1 if the element was not found
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*/
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virtual int search(const char *name, std::string& value)
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{
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return __search(name, value);
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}
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virtual int search(const char *name, int& value)
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{
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return __search(name, value);
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}
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virtual int search(const char *name, float& value)
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{
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return __search(name, value);
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}
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/**
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* Search the Object for a given attribute in a set of object specific
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* routes.
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* @param name of the attribute
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* @results vector of attributes that matches the query
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*/
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template<typename T>
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void search(const char* name, std::vector<T>& results)
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{
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if (name[0] == '/')
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{
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xpaths(results, name);
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}
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else if (num_paths == 0)
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{
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results.clear();
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}
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else
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{
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std::ostringstream xpath;
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xpath << paths[0] << name;
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for (int i = 1; i < num_paths ; i++)
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{
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xpath << '|' << paths[i] << name;
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}
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xpaths(results, xpath.str().c_str());
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}
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}
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/**
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* Get xml nodes by Xpath
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* @param xpath_expr the Xpath for the elements
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* @param content nodes for the given Xpath expression. The nodes are
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* returned as pointers to the object nodes.
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* @return the number of nodes found
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*/
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int get_nodes(const std::string& xpath_expr,
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std::vector<xmlNodePtr>& content) const;
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/**
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* Adds a copy of the node as a child of the node in the xpath expression.
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* The source node must be cleaned by the caller.
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*
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* @param xpath_expr Path of the parent node
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* @param node Node copy and add
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* @param new_name New name for the node copy
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*
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* @return 0 on success, -1 otherwise
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*/
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int add_node(const char * xpath_expr, xmlNodePtr node, const char * new_name);
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/**
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* Frees a vector of XMLNodes, as returned by the get_nodes function
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* @param content the vector of xmlNodePtr
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*/
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void free_nodes(std::vector<xmlNodePtr>& content) const
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{
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std::vector<xmlNodePtr>::iterator it;
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for (it = content.begin(); it < content.end(); it++)
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{
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xmlFreeNode(*it);
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}
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};
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/**
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* Updates the object representation with a new XML document. Previous
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* XML resources are freed
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* @param xml_doc the new xml document
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*/
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int update_from_str(const std::string &xml_doc);
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/**
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* Updates the object representation with a new XML document. Previous
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* XML resources are freed
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* @param xml_doc the new xml document
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*/
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int update_from_node(const xmlNodePtr node);
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/**
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* Validates the xml string
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*
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* @param xml_doc string to parse
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* @return 0 if the xml validates
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*/
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static int validate_xml(const std::string &xml_doc);
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/**
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* Renames the nodes given in the xpath expression
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* @param xpath_expr xpath expression to find the nodes to rename
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* @param new_name new name for the xml elements
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*
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* @return the number of nodes renamed
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*/
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int rename_nodes(const char * xpath_expr, const char * new_name);
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// ---------------------------------------------------------
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// Lex & bison parser for requirements and rank expressions
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// ---------------------------------------------------------
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/**
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* Evaluates a requirement expression on the given host.
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* @param requirements string
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* @param result true if the host matches the requirements
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* @param errmsg string describing the error, must be freed by the
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* calling function
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* @return 0 on success
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*/
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int eval_bool(const std::string& expr, bool& result, char **errmsg);
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/**
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* Evaluates a rank expression on the given host.
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* @param rank string
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* @param result of the rank evaluation
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* @param errmsg string describing the error, must be freed by the
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* calling function
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* @return 0 on success
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*/
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int eval_arith(const std::string& expr, int& result, char **errmsg);
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/**
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* Function to write the Object in an output stream
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*/
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friend std::ostream& operator<<(std::ostream& os, ObjectXML& oxml)
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{
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xmlNodePtr root_node = xmlDocGetRootElement(oxml.xml);
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if ( root_node == 0 )
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{
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return os;
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}
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xmlBufferPtr buffer = xmlBufferCreate();
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xmlNodeDump(buffer, oxml.xml, root_node, 0, 0);
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std::string str(reinterpret_cast<char *>(buffer->content));
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os << str;
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xmlBufferFree(buffer);
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return os;
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};
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protected:
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/**
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* Array of paths to look for attributes in search methods
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*/
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const char **paths;
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/**
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* Number of elements in paths array
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*/
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int num_paths;
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private:
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/**
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* XML representation of the Object
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*/
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xmlDocPtr xml;
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/**
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* XPath Context to access Object elements
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*/
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xmlXPathContextPtr ctx;
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/**
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* Parse a XML documents and initializes XPath contexts
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*/
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void xml_parse(const std::string &xml_doc);
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/**
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* Search the Object for a given attribute in a set of object specific
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* routes.
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* @param name of the attribute
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* @param value of the attribute
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*
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* @return -1 if the element was not found
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*/
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template<typename T>
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int __search(const char *name, T& value)
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{
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std::vector<T> results;
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search(name, results);
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if (results.size() != 0)
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{
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value = results[0];
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return 0;
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}
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return -1;
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};
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};
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#endif /*OBJECT_XML_H_*/
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