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c++ - Xalan C++ : returning a node with XPath (reference to local pointer)

转载 作者:数据小太阳 更新时间:2023-10-29 02:45:22 24 4
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我是 Xalan 和 Xerces 的新手,我尝试通过 XPath 选择一个特定节点。应该可以通过引用返回 xml 数据,但也需要更改 - 这就是为什么我将其保存为 DOMDocument 以便能够通过 xerces 访问数据以操作它们的原因。我有两种方法,一种是读取 xml 文件并进行模式验证,另一种是获取特定节点。我正在使用 Visual Studio 2012,当然还有 Xalan 和 Xerces 库。我试图创建一个 SSCCE 来向您展示我的问题:

头文件:

#pragma once

#include <string.h>
#include <xercesc/util/PlatformUtils.hpp>
#include <xercesc/dom/DOM.hpp>
#include <xalanc/Include/PlatformDefinitions.hpp>
#include <xalanc/XalanTransformer/XalanTransformer.hpp>

XALAN_CPP_NAMESPACE_USE
XERCES_CPP_NAMESPACE_USE

namespace CodeTest{
class Test
{
public:
Test(std::string schemaFilePath, std::string xmlFilePath){
mSchemaFilePath = schemaFilePath;
mXMLFilePath = xmlFilePath;

XMLPlatformUtils::Initialize();
XalanTransformer::initialize();
readXMLFile();
}
~Test(){
XalanTransformer::terminate();
XMLPlatformUtils::Terminate();
}
const XalanNode* getNode(XalanDOMString& path)const;

private:
Test();
Test(const Test&);
void readXMLFile();
std::string mSchemaFilePath;
std::string mXMLFilePath;
DOMDocument* mXMLDocument;
DOMElement* mRootElement;
XalanDocument* mXalanDocument;
XalanDocument* convertXercesDomDocumentToXalanDocument();
};
}

源文件:

#include "Test.h"

#include <xercesc/parsers/XercesDOMParser.hpp>
#include <xalanc/XPath/XPath.hpp>
#include <xalanc/XPath/XPathEvaluator.hpp>
#include <xalanc/XercesParserLiaison/XercesParserLiaison.hpp>
#include <xalanc/XercesParserLiaison/XercesDOMSupport.hpp>
#include <xalanc/XalanTransformer/XercesDOMWrapperParsedSource.hpp>

namespace CodeTest{

void Test::readXMLFile(){

XercesDOMParser xmlParser;
if (xmlParser.loadGrammar(mSchemaFilePath.c_str(), Grammar::SchemaGrammarType) == NULL){
fprintf(stderr, "couldn't load schema\n");
return;
}
xmlParser.setValidationScheme(XercesDOMParser::Val_Auto);
xmlParser.setDoNamespaces(true);
xmlParser.setDoSchema(true);
xmlParser.setValidationConstraintFatal(true);
xmlParser.parse(mXMLFilePath.c_str());
mXMLDocument = xmlParser.adoptDocument();
mXMLDocument->normalize();
mRootElement = mXMLDocument->getDocumentElement();
}

const XalanNode* Test::getNode(XalanDOMString& path)const{
XPathEvaluator theEvaluator;
XercesParserLiaison theParserLiaison;
XercesDOMSupport theDOMSupport(theParserLiaison);
XSLTInputSource xmlInput = mXMLFilePath.c_str();
XercesDOMWrapperParsedSource parsedSource(mXMLDocument, theParserLiaison, theDOMSupport, XalanDOMString(xmlInput.getSystemId()));
XalanDocument* xalanDocument = parsedSource.getDocument();
const XalanNode* node = theEvaluator.selectSingleNode(theDOMSupport, xalanDocument, path.c_str());
return node;
}
}

和我的主要功能:

#include "Test.h"
#include <string.h>

int main(){
std::string schemaFile = "d:/testDate.xsd";
std::string xmlFile = "d:/test.xml";
CodeTest::Test xmlParser(schemaFile, xmlFile);
XalanDOMString path("personnel/person[1]");
const XalanNode* node = xmlParser.getNode(path);
return 0;
}

问题是我需要通过引用返回节点及其所有属性。但问题是点头只是一个局部指针,如果他超出范围则无效。我已经尝试将其保存为成员变量,但指针的所有权属于 XercesDOMWrapperParsedSource,我无法将其创建为全局变量,因为我收到默认构造函数是私有(private)的错误消息。

所以我希望你们中的任何人都可以给我一些建议。

最佳答案

您不能只保留 XalanNode * 而忘记所有其他内容。如果您想在您的应用程序周围传递 XmlNode,您必须将它封装到您自己的类中,该类将在内部包含 XalanNode * 需要的所有内容。

为了证明这一点,我将附上我在我的项目中使用的一些辅助文件。这些文件将“按原样”粘贴,即你可能会在编译时遇到一些困难,因为它们是一个更大项目的一部分,并且有一些我将忽略的依赖项(比如 boost logging,boost::filesystem::path ; 你可以很容易地摆脱这些依赖)。然而,如果有人需要它,那么我相信他们会很容易地为您的项目调整它并理解这个想法。

提供的类旨在将 xml 文档加载到内存中,并允许使用 XPath 表达式读取它。

这是我的类的用法示例。

#include "tools/xalan/XalanRegistration.h"
#include "tools/xalan/XmlDoc.h"
#include "tools/xalan/XmlNode.h"

tools::xalan::XmlNode do_stuff_and_get_node() {

XmlDoc myDoc("file_to_load.xml");
return myDoc.getNode("/path/to/my/node");

}

int main(){
//this always goes to the main application scope
tools::xalan::XalanRegistration xalan;

//the rest may appear anywhere in your application

const tools::xalan::XmlNode my_node = do_stuff_and_get_node();

if (my_node.getBool("xpath/relative/to/my_node[@boolean_attr]")) {
std::out << my_node.getString("xpath/relative/to/my_node/text()");
}

const tools::xalan::XmlNode other_node = my_node("other/node");

//node holds internally the whole document so you can use also
//absolute xpath
auto more_nodes = other_node.getNodes("/i/want/more");
for (const tools::xalan::XmlNode &node: more_nodes) {
...
}
}

这里是包含的类(抱歉,如果这不是在本网站上附加更大内容的最佳方式)

主要实现在 XalanXmlDoc 中,它包含所有上下文但不可复制。 XmlDoc 和 XmlNode 可以方便地包装 XalanXmlDoc,以便可以轻松地在应用程序中传递文档或节点。

工具/xalan/XercesRegistration.h

#ifndef TOOLS_XERCES_XERCESREGISTRATION_H_
#define TOOLS_XERCES_XERCESREGISTRATION_H_

#include "NS-OPEN"

class XercesRegistration {
public:

/**
* This constructor calls:
* XMLPlatformUtils::Initialize();
*/
XercesRegistration();

/**
* This destructor calls:
* XMLPlatformUtils::Terminate();
*/
~XercesRegistration();

};

#include "NS-CLOSE"
#endif

工具/xalan/XercesRegistration.cpp

#include "XercesRegistration.h"

#include <xercesc/util/PlatformUtils.hpp>

#include "NS-OPEN"

XercesRegistration::XercesRegistration() {
using xercesc::XMLPlatformUtils;

//may throw xercesc::XMLException
XMLPlatformUtils::Initialize();
}

XercesRegistration::~XercesRegistration() {
using xercesc::XMLPlatformUtils;

XMLPlatformUtils::Terminate();
}

#include "NS-CLOSE"

工具/xalan/XalanRegistration.h

#ifndef TOOLS_XALAN_XALANREGISTRATION_H_
#define TOOLS_XALAN_XALANREGISTRATION_H_

#include "tools/xerces/XercesRegistration.h"
#include <xalanc/XalanSourceTree/XalanSourceTreeInit.hpp>

#include "NS-OPEN"

/**
* \brief XalanRegistration
*
* \author David Laštovička
*/
class XalanRegistration {
private:
typedef xerces::XercesRegistration XercesRegistration;
typedef xalanc::XalanSourceTreeInit XalanSourceTreeInit;

//may throw xercesc::XMLException
XercesRegistration xercesRegistration;

/**
* As seen in xalan-c-1.11/c/samples/SimpleXPathAPI/SimpleXPathAPI.cpp
*/
XalanSourceTreeInit theSourceTreeInit;

public:

/**
* \brief This constructor instantiates the object.
*/
XalanRegistration();

~XalanRegistration();

};

#include "NS-CLOSE"
#endif

工具/xalan/XalanRegistration.cpp

#include "XalanRegistration.h"

#include <xalanc/XPath/XPathEvaluator.hpp>

#include "NS-OPEN"

XalanRegistration::XalanRegistration() {
using xalanc::XPathEvaluator;
XPathEvaluator::initialize();
}

XalanRegistration::~XalanRegistration() {
using xalanc::XPathEvaluator;
XPathEvaluator::terminate();
}

#include "NS-CLOSE"

工具/xalan/XmlDoc.h

#ifndef TOOLS_XALAN_XMLDOC_H_
#define TOOLS_XALAN_XMLDOC_H_

#include <memory>
#include <set>
#include "XalanXmlDoc.h"
#include "XmlNode.fwd.h"
#include "tools/exception/EntityNotFound.h"
#include "tools/exception/NotUnique.h"

#include "NS-OPEN"

/**
* \brief XmlDoc is a simple reader for XML documents.
*
* It is meant to be used to:
* - read only
* - small documents fitting the memory
* - fetching data from the document with XPath
*
* XmlDoc allows to obtain and pass around a XmlNode representing only
* a part of the document.
*
* XmlDoc/XmlNode can be simply copied or moved around. All their copies
* internally share one instance of XalanXmlDoc that is released when the last
* XmlDoc/XmlNode is deleted.
*
* \author David Laštovička
*/
class XmlDoc {
private:

typedef std::string string;
typedef boost::filesystem::path path;
template<class T> using Container = std::vector<T>;
typedef tools::exception::EntityNotFound EntityNotFound;
typedef tools::exception::NotUnique NotUnique;

const std::shared_ptr<XalanXmlDoc> xalanXmlDoc;

public:

/**
* \brief This constructor instantiates the object.
*/
XmlDoc(const path &source);

XmlDoc(const std::shared_ptr<XalanXmlDoc> &xalanXmlDoc);

XmlDoc(const XmlDoc &) = default;

XmlDoc(XmlDoc &&) = default;

XmlNode getRoot() const;

string getString(const string &xpath) const
THROW(EntityNotFound);

Container<string> getStrings(const string &xpath) const;

std::set<string> getDistinctStrings(const string &xpath) const;

XmlNode getNode(const string &xpath) const
THROW(EntityNotFound);

Container<XmlNode> getNodes(const string &xpath) const;

};

#include "NS-CLOSE"

#endif /* TOOLS_XALAN_XMLDOC_H_ */

工具/xalan/XmlDoc.cpp

#include "XmlDoc.h"

#include "XmlNode.h"

#include "tools/llog/common.h"

#include "NS-OPEN"

XmlDoc::XmlDoc(const path &source)
: xalanXmlDoc(new XalanXmlDoc(source))
{
}

XmlDoc::XmlDoc(const std::shared_ptr<XalanXmlDoc> &xalanXmlDoc)
: xalanXmlDoc(xalanXmlDoc)
{

}

auto XmlDoc::getRoot() const
-> XmlNode
{
return getNode("/");
}

auto XmlDoc::getString(const string &xpath) const
THROW(EntityNotFound)
-> string
{
//may throw EntityNotFound, NotUnique
return xalanXmlDoc->getString(xpath);
}

auto XmlDoc::getStrings(const string &xpath) const
-> Container<string>
{
return xalanXmlDoc->getStrings(xpath);
}

auto XmlDoc::getDistinctStrings(const string &xpath) const
-> std::set<string>
{
using std::set;
//ToDo use distinct-values once XPath 2 available in Xalan
//auto depTypeCodeNodes = xmlDoc.getNodes("distinct-values(/module/dependencies/dependency/@type)");
auto values = getStrings(xpath);
set<string> res;
for (auto value: values)
res.insert(value);
return res;
}

auto XmlDoc::getNode(const string &xpath) const
THROW(EntityNotFound)
-> XmlNode
{
//may throw EntityNotFound, NotUnique
return XmlNode(xalanXmlDoc,xalanXmlDoc->getNode(xpath));
}

auto XmlDoc::getNodes(const string &xpath) const
-> Container<XmlNode>
{
using std::transform;
auto xalanNodes = xalanXmlDoc->getNodes(xpath);
Container<XmlNode> res;
transform(
xalanNodes.begin(), xalanNodes.end(),
back_inserter(res),
[this](const XalanXmlDoc::NodeHandle &xalanNode)->XmlNode
{
assert(xalanNode);
return XmlNode(this->xalanXmlDoc,xalanNode);
}
);
return res;
}

#include "NS-CLOSE"

工具/xalan/XmlNode.h

#ifndef TOOLS_XALAN_XMLNODE_H_
#define TOOLS_XALAN_XMLNODE_H_

#include "XalanXmlDoc.h"
#include "XmlDoc.fwd.h"
#include "tools/exception/EntityNotFound.h"
#include "tools/exception/NotUnique.h"

#include "NS-OPEN"

/**
* \brief XmlDoc
*
* \author David Laštovička
*/
class XmlNode {
private:
typedef std::string string;
template<class T> using Container = std::vector<T>;
typedef tools::exception::EntityNotFound EntityNotFound;
typedef tools::exception::NotUnique NotUnique;

/**
* In order to support move assignment and move operator this member
* is not const
*/
std::shared_ptr<XalanXmlDoc> xalanXmlDoc;

/**
* In order to support (the default) move assignment and move operator
* implementation this member is not const.
*/
XalanXmlDoc::NodeHandle node;

public:

/**
* Default constructor creates an empty node corresponding to this xml:
* </>
*/
XmlNode();

XmlNode(
const std::shared_ptr<XalanXmlDoc> &xalanXmlDoc,
const XalanXmlDoc::NodeHandle &node
);

XmlNode(const XmlNode &) = default;

XmlNode(XmlNode &&) = default;

XmlDoc getDoc() const;

string getString(const string &xpath) const
THROW(EntityNotFound);

string getString(const string &xpath, const string &defaultValue) const;

Container<string> getStrings(const string &xpath) const;

XmlNode getNode(const string &xpath) const
THROW(EntityNotFound);

Container<XmlNode> getNodes(const string &xpath) const;

bool getBool(const string &xpath) const
THROW(EntityNotFound);

/**
* \brief like getBool(xpath) but instead of throwing returns \arg defaultValue
*
*
*/
bool getBool(const string &xpath, bool defaultValue) const;

string getNodeName() const;

XmlNode &operator=(const XmlNode &) = default;

XmlNode &operator=(XmlNode &&) = default;
};

#include "NS-CLOSE"

#endif /* TOOLS_XALAN_XMLNODE_H_ */

工具/xalan/XmlNode.cpp

#include "XmlNode.h"

#include "XmlDoc.h"

#include "tools/llog/common.h"

#include "NS-OPEN"

XmlNode::XmlNode()
: xalanXmlDoc(new XalanXmlDoc(std::string("<empty/>"))),
node(xalanXmlDoc->getNode("/"))
{
assert(this->node);
}

XmlNode::XmlNode(
const std::shared_ptr<XalanXmlDoc> &xalanXmlDoc,
const XalanXmlDoc::NodeHandle &node
)
: xalanXmlDoc(xalanXmlDoc),
node(node)
{
assert(this->node);
}

XmlDoc XmlNode::getDoc() const
{
return XmlDoc(xalanXmlDoc);
}

auto XmlNode::getString(const string &xpath) const
THROW(EntityNotFound)
-> string
{
assert(node);
//may throw EntityNotFound
return xalanXmlDoc->getString(node,xpath);
}

auto XmlNode::getString(const string &xpath, const string &defaultValue) const
-> string
{
//may throw EntityNotFound
return xalanXmlDoc->getString(node,xpath,defaultValue);
}

auto XmlNode::getStrings(const string &xpath) const
-> Container<string>
{
return xalanXmlDoc->getStrings(node,xpath);
}

auto XmlNode::getNode(const string &xpath) const
THROW(EntityNotFound)
-> XmlNode
{
BOOST_LOG_FUNCTION();
//may throw EntityNotFound, NotUnique
return XmlNode(xalanXmlDoc,xalanXmlDoc->getNode(node,xpath));
}

auto XmlNode::getNodes(const string &xpath) const
-> Container<XmlNode>
{
using std::transform;
auto xalanNodes = xalanXmlDoc->getNodes(node,xpath);
Container<XmlNode> res;
transform(
xalanNodes.begin(), xalanNodes.end(),
back_inserter(res),
[this](const XalanXmlDoc::NodeHandle &xalanNode)->XmlNode
{
return XmlNode(this->xalanXmlDoc,xalanNode);
}
);
return res;
}

auto XmlNode::getBool(const string &xpath) const
THROW(EntityNotFound)
-> bool
{
//may throw EntityNotFound
return xalanXmlDoc->getBool(node,xpath);
}

auto XmlNode::getBool(const string &xpath, bool defaultValue) const
-> bool
{
return xalanXmlDoc->getBool(node,xpath,defaultValue);
}

auto XmlNode::getNodeName() const
-> string
{
return xalanXmlDoc->getNodeName(node);
}
#include "NS-CLOSE"

XmlDoc.fwd.h

#ifndef TOOLS_XALAN_XMLDOC_FWD_H_
#define TOOLS_XALAN_XMLDOC_FWD_H_

#include "NS-OPEN"

class XmlDoc;

#include "NS-CLOSE"

#endif /* TOOLS_XALAN_XMLDOC_FWD_H_ */

XmlNode.fwd.h

#ifndef TOOLS_XALAN_XMLNODE_FWD_H_
#define TOOLS_XALAN_XMLNODE_FWD_H_

#include "NS-OPEN"

class XmlNode;

#include "NS-CLOSE"

#endif /* TOOLS_XALAN_XMLNODE_FWD_H_ */

XalanXmlDoc.h

#ifndef TOOLS_XALAN_XALANXMLDOC_H_
#define TOOLS_XALAN_XALANXMLDOC_H_

#include <string>
#include <boost/filesystem.hpp>
#include <mutex>
#include <vector>
#include <sstream>
#include <xercesc/parsers/XercesDOMParser.hpp>
#include <xercesc/dom/DOM.hpp>
#include <xalanc/XalanDOM/XalanDocument.hpp>
#include <xalanc/XalanSourceTree/XalanSourceTreeDOMSupport.hpp>
#include <xalanc/XalanSourceTree/XalanSourceTreeParserLiaison.hpp>
#include <xalanc/XPath/XPathEvaluator.hpp>
#include <xalanc/XSLT/XSLTInputSource.hpp>
#include "tools/exception/EntityNotFound.h"
#include "tools/exception/NotUnique.h"

#include "NS-OPEN"

/**
* \brief XalanXmlDoc
*
* This is expected to be used through XmlDoc and XmlNode rather than directly.
*
* \see xalan/build/linux-64/xalan-c-1.11/c/samples/XPathWrapper/XPathWrapper.cpp
*
* \author David Laštovička
*/
class XalanXmlDoc {
protected:

typedef std::string string;
typedef boost::filesystem::path path;
template<class T> using Container = std::vector<T>;
typedef xercesc::XercesDOMParser XercesDOMParser;
typedef xercesc::InputSource InputSource;
typedef xalanc::XalanDocument XalanDocument;
typedef xalanc::XalanSourceTreeDOMSupport XalanSourceTreeDOMSupport;
typedef xalanc::XercesParserLiaison XercesParserLiaison;
typedef xalanc::XalanSourceTreeParserLiaison XalanSourceTreeParserLiaison;
typedef xalanc::XalanElement XalanElement;
typedef xalanc::XalanNode XalanNode;
typedef std::mutex mutex;
typedef std::unique_lock<mutex> unique_lock;
typedef tools::exception::EntityNotFound EntityNotFound;
typedef tools::exception::NotUnique NotUnique;

public:
typedef const XalanNode* NodeHandle;
private:

/**
* ToDo review Xalan/Xerces behaviour when called concurrently. Maybe the
* mutex here is not necessary.
*/
mutex accessMutex;

mutable XalanSourceTreeDOMSupport domSupport;
XalanSourceTreeParserLiaison parserLiaison;

XalanDocument *xalanDoc;

public:

/**
* \brief This constructor instantiates the object.
*/
XalanXmlDoc(const path &sourceFile);

XalanXmlDoc(const string &xmlString);

XalanXmlDoc(const XalanXmlDoc &) = delete;

XalanXmlDoc(XalanXmlDoc &&) = delete;

~XalanXmlDoc();

NodeHandle get_root() const;

string getString(const string &xpath) const
THROW(EntityNotFound);

Container<string> getStrings(const string &xpath) const;

NodeHandle getNode(const string &xpath) const
THROW(EntityNotFound);

Container<NodeHandle> getNodes(const string &xpath) const;

string getString(const NodeHandle &xalanNode, const string &xpath) const
THROW(EntityNotFound);

string getString(const NodeHandle &xalanNode, const string &xpath, const string &defaultValue) const;

Container<string> getStrings(const NodeHandle &xalanNode, const string &xpath) const;

NodeHandle getNode(const NodeHandle &xalanNode, const string &xpath) const
THROW(EntityNotFound);

Container<NodeHandle> getNodes(
const NodeHandle &xalanNode, const string &xpath
) const;

/**
* When more elements do match xpath so the first one is returned.
* \throw EntityNotFound
*/
bool getBool(const NodeHandle &xalanNode, const string &xpath) const
THROW(EntityNotFound);

/**
* \brief like getBool(xalanNode, xpath) but instead of throwing EntityNotFound returns \arg defaultValue
*
*/
bool getBool(const NodeHandle &xalanNode, const string &xpath, bool defaultValue) const;

string getNodeName(const NodeHandle &xalanNode) const;

};

#include "NS-CLOSE"

#endif /* TOOLS_XALAN_XALANXMLDOC_H_ */

XalanXmlDoc.cpp

#include "XalanXmlDoc.h"

#include <xercesc/sax/HandlerBase.hpp>
#include <xalanc/XPath/XPathEvaluator.hpp>
#include <xalanc/XPath/NodeRefList.hpp>
#include <xalanc/XalanDOM/XalanElement.hpp>
#include <xalanc/XalanDOM/XalanNamedNodeMap.hpp>
#include "tools/llog/common.h"
#include <sstream>
#include <vector>
#include "tools/text/ostream_iterator.h"
#include <xercesc/framework/MemBufInputSource.hpp>
#include <xercesc/framework/LocalFileInputSource.hpp>
#include "tools/exception/Other.h"
#include "tools/exception/util/backtraceFactory.obj.h"
#include <xalanc/DOMSupport/XalanDocumentPrefixResolver.hpp>

#include "NS-OPEN"

static std::string toString(const xalanc::XalanDOMString &val)
{
return std::string(val.begin(), val.end());
}

static void outputAttrs(std::ostream &oss, xalanc::XalanNode const * const node)
{
using std::ostringstream;
using xalanc::XalanNode;
using xalanc::XalanElement;
using xalanc::XalanSize_t;
if (node->getNodeType()==XalanNode::ELEMENT_NODE) {
XalanElement const * const element = static_cast<XalanElement const * const>(node);
oss << "[";
for (XalanSize_t i = 0; i<element->getAttributes()->getLength(); i++) {
if (i>0) oss << ' ';
oss << '@' << toString(element->getAttributes()->item(i)->getNodeName())
<< "='"
<< toString(element->getAttributes()->item(i)->getNodeValue())
<< "'";
}
oss << "]";
}
}

static void outputFullPathWithAttrs(
std::ostream &oss,
xalanc::XalanNode const * const node,
bool outputAttrsRequested
)
{
using std::ostringstream;
using std::string;
using std::vector;
using tools::text::ostream_iterator;
using std::copy;
using xalanc::XalanNode;

vector<string> nodeNames;
{
for(XalanNode const *it = node; it!=nullptr; it=it->getParentNode())
{
ostringstream oss;
oss << toString(it->getNodeName());
if (outputAttrsRequested)
outputAttrs(oss, it);
nodeNames.push_back(oss.str());
}
}

copy(
nodeNames.rbegin(), nodeNames.rend(),
ostream_iterator<string>(oss,nullptr,nullptr,"/")
);

}
/*
static std::string createFullPath(xalanc::XalanNode const * const node)
{
using std::ostringstream;
ostringstream oss;
outputFullPathWithAttrs(oss,node,false);
return oss.str();
}
*/
static std::string createFullPathWithAttrs(xalanc::XalanNode const * const node)
{
using std::ostringstream;
ostringstream oss;
outputFullPathWithAttrs(oss,node,true);
return oss.str();
}

XalanXmlDoc::XalanXmlDoc(const path &source)
: //domSupport(parserLiaison),
parserLiaison(domSupport)
{
using xercesc::LocalFileInputSource;
using xalanc::XalanDOMString;
domSupport.setParserLiaison(&parserLiaison);
const XalanDOMString theFileName(source.native().c_str());
LocalFileInputSource theInputSource(theFileName.c_str());
xalanDoc = parserLiaison.parseXMLStream(theInputSource);
}

XalanXmlDoc::XalanXmlDoc(const string &xmlString)
: //domSupport(parserLiaison),
parserLiaison(domSupport)
{
using xercesc::MemBufInputSource;
using xalanc::XalanDOMString;
domSupport.setParserLiaison(&parserLiaison);
MemBufInputSource theInputSource(
(const XMLByte *)xmlString.c_str(),
xmlString.size(),
"XalanXmlDoc"
);
xalanDoc = parserLiaison.parseXMLStream(theInputSource);
}

XalanXmlDoc::~XalanXmlDoc()
{
}

auto XalanXmlDoc::get_root() const
-> NodeHandle
{
return xalanDoc;
}

auto XalanXmlDoc::getString(const string &xpath) const
THROW(EntityNotFound)
-> string
{
//may throw EntityNotFound, NotUnique
return getString(get_root(),xpath);
}

auto XalanXmlDoc::getStrings(const string &xpath) const
-> Container<string>
{
return getStrings(get_root(),xpath);
}

auto XalanXmlDoc::getNode(const string &xpath) const
THROW(EntityNotFound)
-> NodeHandle
{
//may throw EntityNotFound, NotUnique
return getNode(get_root(), xpath);
}

auto XalanXmlDoc::getNodes(const string &xpath) const
-> Container<NodeHandle>
{
return getNodes(get_root(), xpath);
}

auto XalanXmlDoc::getString(const NodeHandle &xalanNode, const string &xpath) const
THROW(EntityNotFound)
-> string
{
//may throw EntityNotFound, NotUnique
auto found = getNode(xalanNode, xpath);

return toString(found->getNodeValue());
}

auto XalanXmlDoc::getString(const NodeHandle &xalanNode, const string &xpath, const string &defaultValue) const
-> string
{
using exception::EntityNotFound;

string res;
try {
//may throw EntityNotFound
auto found = getNode(xalanNode, xpath);
res = toString(found->getNodeValue());
} catch (const EntityNotFound &e) {
res = defaultValue;
}
return res;
}

auto XalanXmlDoc::getStrings(const NodeHandle &xalanNode, const string &xpath) const
-> Container<string>
{
Container<string> res;
for (auto node: getNodes(xalanNode, xpath))
{
res.push_back(toString(node->getNodeValue()));
}
return res;
}

auto XalanXmlDoc::getNode(const NodeHandle &xalanNode, const string &xpath) const
THROW(EntityNotFound)
-> NodeHandle
{
BOOST_LOG_FUNCTION();

using xalanc::XalanNode;
using xalanc::XalanDOMString;
using xalanc::XPathEvaluator;
using std::ostringstream;
using xercesc::SAXParseException;
using xalanc::XalanDocumentPrefixResolver;

#ifndef NDEBUG
if (!xalanNode) {
BOOST_LOG_TRIVIAL(trace)
<< "Assertion failed evaluating " << xpath;
BOOST_LOG_TRIVIAL(trace)
<< tools::exception::util::backtraceFactory().createBacktraces();
}
assert(xalanNode);

{
std::ostringstream oss;
outputFullPathWithAttrs(oss,xalanNode,true);
BOOST_LOG_TRIVIAL(trace)
<< "XalanXmlDoc::getNode " << xpath << " on type "
<< xalanNode->getNodeType()
<< " in " << oss.str();
}
#endif
//ToDo try can be removed the SAXParseException probably not thrown here but in the constructor
try {
XalanDocumentPrefixResolver thePrefixResolver(xalanDoc);
const XalanDOMString expression(xpath.c_str());
BOOST_LOG_TRIVIAL(trace) << "expression prepared";
XPathEvaluator evaluator;

//better use mutex when accessing the global domSupport etc.
unique_lock(accessMutex);
const XalanNode* found = evaluator.selectSingleNode(
domSupport,
const_cast<XalanNode *>(xalanNode),
expression.c_str(),
thePrefixResolver
);

if (!found) {
ostringstream oss;
oss << "Not found " << xpath << " on the node " << createFullPathWithAttrs(xalanNode);
throw EntityNotFound(SRCINF, oss.str());
}
assert(found);
BOOST_LOG_TRIVIAL(trace) << "returning node";
return found;
} catch (const SAXParseException &e) {
using std::ostringstream;
using exception::Other;
ostringstream oss;
oss << "SAXParseException line: " << e.getLineNumber() << " column: "
<< e.getColumnNumber() << " message: " << e.getMessage();
throw Other(SRCINF,oss.str());
}
}

auto XalanXmlDoc::getNodes(const NodeHandle &xalanNode, const string &xpath) const
-> Container<NodeHandle>
{
using xalanc::XalanNode;
using xalanc::XalanDOMString;
using xalanc::XPathEvaluator;
using xalanc::NodeRefList;
using xercesc::SAXParseException;
using xalanc::XalanDocumentPrefixResolver;

BOOST_LOG_TRIVIAL(trace)
<< "XalanXmlDoc::getNodes " << xpath;

//ToDo try can be removed the SAXParseException probably not thrown here but in the constructor
try {
XalanDocumentPrefixResolver thePrefixResolver(xalanDoc);
const XalanDOMString expression(xpath.c_str());

XPathEvaluator evaluator;

NodeRefList foundNodes;

{
//better use mutex when accessing the global domSupport etc.
unique_lock(accessMutex);

evaluator.selectNodeList(
foundNodes,
domSupport,
const_cast<XalanNode *>(xalanNode),
expression.c_str(),
thePrefixResolver
);
}
std::vector<const XalanNode*> res;
for (NodeRefList::size_type i=0;i<foundNodes.getLength();i++) {
assert(foundNodes.item(i));
res.push_back(foundNodes.item(i));
}
return res;
} catch (const SAXParseException &e) {
using std::ostringstream;
using exception::Other;
ostringstream oss;
oss << "SAXParseException line: " << e.getLineNumber() << " column: "
<< e.getColumnNumber() << " message: " << e.getMessage();
throw Other(SRCINF,oss.str());
}
}
auto XalanXmlDoc::getBool(const NodeHandle &xalanNode, const string &xpath) const
THROW(EntityNotFound)
-> bool
{
bool res;
//may throw EntityNotFound, NotUnique
std::istringstream(getString(xalanNode,xpath)) >> std::boolalpha >> res;
return res;
}

auto XalanXmlDoc::getBool(const NodeHandle &xalanNode, const string &xpath, bool defaultValue) const
-> bool
{
using exception::EntityNotFound;
bool res;
try {
//may throw EntityNotFound, NotUnique
res = getBool(xalanNode,xpath);
} catch (const EntityNotFound &e) {
res = defaultValue;
}
return res;
}

auto XalanXmlDoc::getNodeName(const NodeHandle &xalanNode) const
-> string
{
assert(xalanNode);
return toString(xalanNode->getNodeName());
}

#include "NS-CLOSE"

关于c++ - Xalan C++ : returning a node with XPath (reference to local pointer),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20514842/

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