使用Xerces C ++在XML解析期间集成架构元数据 [英] Integrate schema metatdata during XML Parsing with Xerces C++

问题描述

当我遍历DOM时，我想解析XML文件并在XML模式文件(.xsd)中查找属性和实体的数据类型.

I want to parse an XML file and look up the datatype of attributes and entities in an XML schema file (.xsd) when I traverse the DOM.

我发现我可以使用后架构验证信息集(PSVI)来获取该信息.为此，我应该能够通过getFeature方法获取节点信息:

I found out that I can use the post schema validation infoset (PSVI) to get that information. For this I should be able to get a nodes info by the getFeature method:

info = (xercesc::DOMPSVITypeInfo*) domNode->getFeature(xercesc::XMLUni::fgXercesDOMHasPSVIInfo, xercesc::XMLUni::fgVersion1_1);

但是，我首先似乎必须启用此功能.由于解析器对象中没有setFeature方法，因此我尝试了"useImplementation"，但这只会使我的程序崩溃.

However I first seem to have to enable this feature. As there is no setFeature method in the parser object I tried "useImplementation", but this just crashes my program.

由于Xerces的文档相对于PSVI而言非常稀疏，因此也许有人在这里知道如何在使用XercesDOMParser解析XML文档时获取架构信息.

As the documentation of Xerces is pretty sparse in respect to PSVI, maybe someone here knows how to get schema information while parsing an XML document using a XercesDOMParser.

提前谢谢！

推荐答案

我同时发现了一个解决方案:

I found a solution meanwhile:

//create parser
static const XMLCh gLS[] = { xercesc::chLatin_L, xercesc::chLatin_S, xercesc::chNull };
xercesc::DOMImplementation *impl = xercesc::DOMImplementationRegistry::getDOMImplementation(gLS);
DOMLSParserImpl* parser = dynamic_cast<DOMLSParserImpl*>(impl->createLSParser(DOMImplementationLS::MODE_SYNCHRONOUS, 0));

//configure
parser->setParameter(xercesc::XMLUni::fgXercesDOMHasPSVIInfo, true);  //collect schema info
parser->setParameter(xercesc::XMLUni::fgDOMComments, false); //discard comments
parser->setExternalNoNamespaceSchemaLocation("schema.xsd");
parser->setDoSchema(true);
parser->setDoNamespaces(true);
parser->setValidationScheme(xercesc::XercesDOMParser::Val_Always);

parser->parseURI("file.xml");

...

xercesc::DOMAttr& attr = (xercesc::DOMAttr&) attributeNode;
cout << " name: " << transcode(attr.getName()) << " type: " << transcode(attr.getSchemaTypeInfo()->getTypeName()) << ", ";

将解析器转换为Impl类有点混乱，但这是我发现访问setParameter函数的唯一方法.我认为必须有一种正确"的方法来初始化解析器，但是...

It's a bit messy to cast the the parser down to the Impl class, but it's the only way I found to access the setParameter function. I think there must be a "correct" way to initialize the parser, though...

同样重要的是，设置验证方案并将DoSchema设置为true，否则解析器将不会将架构信息附加到DOM元素上.

Also it's important to set the validation scheme and set DoSchema to true, otherwise the parser won't attach the schema information the the DOM elements.

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