source/xpath/xpathapi.cxx

/**************************************************************
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 *************************************************************/


#include <xpathapi.hxx>

#include <stdarg.h>
#include <string.h>

#include <libxml/tree.h>
#include <libxml/xmlerror.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>

#include <rtl/ustrbuf.hxx>

#include <nodelist.hxx>
#include <xpathobject.hxx>

#include "../dom/node.hxx"
#include "../dom/document.hxx"


using ::com::sun::star::lang::XMultiServiceFactory;


namespace XPath
{
    // factory
    Reference< XInterface > CXPathAPI::_getInstance(const Reference< XMultiServiceFactory >& rSMgr)
    {
        return Reference< XInterface >(static_cast<XXPathAPI*>(new CXPathAPI(rSMgr)));
    }

    // ctor
    CXPathAPI::CXPathAPI(const Reference< XMultiServiceFactory >& rSMgr)
        : m_aFactory(rSMgr)
    {
    }

    const char* CXPathAPI::aImplementationName = "com.sun.star.comp.xml.xpath.XPathAPI";
    const char* CXPathAPI::aSupportedServiceNames[] = {
        "com.sun.star.xml.xpath.XPathAPI",
        NULL
    };

    OUString CXPathAPI::_getImplementationName()
    {
        return OUString::createFromAscii(aImplementationName);
    }

    Sequence<OUString> CXPathAPI::_getSupportedServiceNames()
    {
        Sequence<OUString> aSequence;
        for (int i=0; aSupportedServiceNames[i]!=NULL; i++) {
            aSequence.realloc(i+1);
            aSequence[i]=(OUString::createFromAscii(aSupportedServiceNames[i]));
        }
        return aSequence;
    }

    Sequence< OUString > SAL_CALL CXPathAPI::getSupportedServiceNames()
        throw (RuntimeException)
    {
        return CXPathAPI::_getSupportedServiceNames();
    }

    OUString SAL_CALL CXPathAPI::getImplementationName()
        throw (RuntimeException)
    {
        return CXPathAPI::_getImplementationName();
    }

    sal_Bool SAL_CALL CXPathAPI::supportsService(const OUString& aServiceName)
        throw (RuntimeException)
    {
        Sequence< OUString > supported = CXPathAPI::_getSupportedServiceNames();
        for (sal_Int32 i=0; i<supported.getLength(); i++)
        {
            if (supported[i] == aServiceName) return sal_True;
        }
        return sal_False;
    }

    // -------------------------------------------------------------------

    void SAL_CALL CXPathAPI::registerNS(
            const OUString& aPrefix,
            const OUString& aURI)
        throw (RuntimeException)
    {
        ::osl::MutexGuard const g(m_Mutex);

        m_nsmap.insert(nsmap_t::value_type(aPrefix, aURI));
    }

    void SAL_CALL CXPathAPI::unregisterNS(
            const OUString& aPrefix,
            const OUString& aURI)
        throw (RuntimeException)
    {
        ::osl::MutexGuard const g(m_Mutex);

        if ((m_nsmap.find(aPrefix))->second.equals(aURI)) {
            m_nsmap.erase(aPrefix);
        }
    }

    // register all namespaces stored in the namespace list for this object
    // with the current xpath evaluation context
    static void lcl_registerNamespaces(
            xmlXPathContextPtr ctx,
            const nsmap_t& nsmap)
    {
        nsmap_t::const_iterator i = nsmap.begin();
        OString oprefix, ouri;
        xmlChar *p, *u;
        while (i != nsmap.end())
        {
            oprefix = OUStringToOString(i->first,  RTL_TEXTENCODING_UTF8);
            ouri    = OUStringToOString(i->second, RTL_TEXTENCODING_UTF8);
            p = (xmlChar*)oprefix.getStr();
            u = (xmlChar*)ouri.getStr();
            xmlXPathRegisterNs(ctx, p, u);
            i++;
        }
    }

    // get all ns decls on a node (and parent nodes, if any)
    static void lcl_collectNamespaces(
            nsmap_t & rNamespaces, Reference< XNode > const& xNamespaceNode)
    {
        DOM::CNode *const pCNode(DOM::CNode::GetImplementation(xNamespaceNode));
        if (!pCNode) { throw RuntimeException(); }

        ::osl::MutexGuard const g(pCNode->GetOwnerDocument().GetMutex());

        xmlNodePtr pNode = pCNode->GetNodePtr();
        while (pNode != 0) {
            xmlNsPtr curDef = pNode->nsDef;
            while (curDef != 0) {
                const xmlChar* xHref = curDef->href;
                OUString aURI((sal_Char*)xHref, strlen((char*)xHref), RTL_TEXTENCODING_UTF8);
                const xmlChar* xPre = curDef->prefix;
                OUString aPrefix((sal_Char*)xPre, strlen((char*)xPre), RTL_TEXTENCODING_UTF8);
                // we could already have this prefix from a child node
                if (rNamespaces.find(aPrefix) == rNamespaces.end())
                {
                    rNamespaces.insert(::std::make_pair(aPrefix, aURI));
                }
                curDef = curDef->next;
            }
            pNode = pNode->parent;
        }
    }

    static void lcl_collectRegisterNamespaces(
            CXPathAPI & rAPI, Reference< XNode > const& xNamespaceNode)
    {
        nsmap_t namespaces;
        lcl_collectNamespaces(namespaces, xNamespaceNode);
        for (nsmap_t::const_iterator iter = namespaces.begin();
                iter != namespaces.end(); ++iter)
        {
            rAPI.registerNS(iter->first, iter->second);
        }
    }

    // register function and variable lookup functions with the current
    // xpath evaluation context
    static void lcl_registerExtensions(
            xmlXPathContextPtr ctx,
            const extensions_t& extensions)
    {
        extensions_t::const_iterator i = extensions.begin();
        while (i != extensions.end())
        {
            Libxml2ExtensionHandle aHandle = (*i)->getLibxml2ExtensionHandle();
            if ( aHandle.functionLookupFunction != 0 )
            {
                xmlXPathRegisterFuncLookup(ctx,
                    reinterpret_cast<xmlXPathFuncLookupFunc>(
                        sal::static_int_cast<sal_IntPtr>(aHandle.functionLookupFunction)),
                    reinterpret_cast<void*>(
                        sal::static_int_cast<sal_IntPtr>(aHandle.functionData)));
            }
            if ( aHandle.variableLookupFunction != 0 )
            {
                xmlXPathRegisterVariableLookup(ctx,
                    reinterpret_cast<xmlXPathVariableLookupFunc>(
                        sal::static_int_cast<sal_IntPtr>(aHandle.variableLookupFunction)),
                    reinterpret_cast<void*>(
                        sal::static_int_cast<sal_IntPtr>(aHandle.variableData)));
            }
            i++;
        }
    }

    /**
     * Use an XPath string to select a nodelist.
     */
    Reference< XNodeList > SAL_CALL CXPathAPI::selectNodeList(
            const Reference< XNode >& contextNode,
            const OUString& expr)
        throw (RuntimeException, XPathException)
    {
        Reference< XXPathObject > xobj = eval(contextNode, expr);
        return xobj->getNodeList();
    }

    /**
     * same as selectNodeList but registers all name space decalratiosn found on namespaceNode
     */
    Reference< XNodeList > SAL_CALL CXPathAPI::selectNodeListNS(
            const Reference< XNode >&  contextNode,
            const OUString& expr,
            const Reference< XNode >&  namespaceNode)
        throw (RuntimeException, XPathException)
    {
        lcl_collectRegisterNamespaces(*this, namespaceNode);
        return selectNodeList(contextNode, expr);
    }

    /**
     * Same as selectNodeList but returns the first node (if any)
     */
    Reference< XNode > SAL_CALL CXPathAPI::selectSingleNode(
            const Reference< XNode >& contextNode,
            const OUString& expr)
        throw (RuntimeException, XPathException)
    {
        Reference< XNodeList > aList = selectNodeList(contextNode, expr);
        Reference< XNode > aNode = aList->item(0);
        return aNode;
    }

    /**
     * Same as selectSingleNode but registers all namespaces declared on
     * namespaceNode
     */
    Reference< XNode > SAL_CALL CXPathAPI::selectSingleNodeNS(
            const Reference< XNode >& contextNode,
            const OUString& expr,
            const Reference< XNode >&  namespaceNode )
        throw (RuntimeException, XPathException)
    {
        lcl_collectRegisterNamespaces(*this, namespaceNode);
        return selectSingleNode(contextNode, expr);
    }

#if LIBXML_VERSION >= 21200
    static OUString make_error_message(const xmlError *pError)
#else
    static OUString make_error_message(xmlError *pError)
#endif
    {
        ::rtl::OUStringBuffer buf;
        if (pError->message) {
            buf.appendAscii(pError->message);
        }
        int line = pError->line;
        if (line) {
            buf.appendAscii("Line: ");
            buf.append(static_cast<sal_Int32>(line));
            buf.appendAscii("\n");
        }
        int column = pError->int2;
        if (column) {
            buf.appendAscii("Column: ");
            buf.append(static_cast<sal_Int32>(column));
            buf.appendAscii("\n");
        }
        OUString msg = buf.makeStringAndClear();
        return msg;
    }

    extern "C" {

        static void generic_error_func(void *userData, const char *format, ...)
        {
            (void) userData;
            char str[1000];
            va_list args;

            va_start(args, format);
#ifdef _WIN32
#define vsnprintf _vsnprintf
#endif
            vsnprintf(str, sizeof(str), format, args);
            va_end(args);

            ::rtl::OUStringBuffer buf(
                OUString::createFromAscii("libxml2 error:\n"));
            buf.appendAscii(str);
            OString msg = OUStringToOString(buf.makeStringAndClear(),
                RTL_TEXTENCODING_ASCII_US);
            OSL_ENSURE(sal_False, msg.getStr());
        }

#if LIBXML_VERSION >= 21200
        static void structured_error_func(void * userData, const xmlError *error)
#else
        static void structured_error_func(void * userData, xmlError *error)
#endif
        {
            (void) userData;
            ::rtl::OUStringBuffer buf(
                OUString::createFromAscii("libxml2 error:\n"));
            if (error) {
                buf.append(make_error_message(error));
            } else {
                buf.append(OUString::createFromAscii("no error argument!"));
            }
            OString msg = OUStringToOString(buf.makeStringAndClear(),
                RTL_TEXTENCODING_ASCII_US);
            OSL_ENSURE(sal_False, msg.getStr());
        }

    } // extern "C"

    /**
     * evaluates an XPath string. relative XPath expressions are evaluated relative to
     * the context Node
     */
    Reference< XXPathObject > SAL_CALL CXPathAPI::eval(
            Reference< XNode > const& xContextNode,
            const OUString& expr)
        throw (RuntimeException, XPathException)
    {
        if (!xContextNode.is()) { throw RuntimeException(); }

        nsmap_t nsmap;
        extensions_t extensions;

        {
            ::osl::MutexGuard const g(m_Mutex);
            nsmap = m_nsmap;
            extensions = m_extensions;
        }

        // get the node and document
        ::rtl::Reference<DOM::CDocument> const pCDoc(
                dynamic_cast<DOM::CDocument*>( DOM::CNode::GetImplementation(
                        xContextNode->getOwnerDocument())));
        if (!pCDoc.is()) { throw RuntimeException(); }

        DOM::CNode *const pCNode = DOM::CNode::GetImplementation(xContextNode);
        if (!pCNode) { throw RuntimeException(); }

        ::osl::MutexGuard const g(pCDoc->GetMutex()); // lock the document!

        xmlNodePtr const pNode = pCNode->GetNodePtr();
        if (!pNode) { throw RuntimeException(); }
        xmlDocPtr pDoc = pNode->doc;

        /* NB: workaround for #i87252#:
           libxml < 2.6.17 considers it an error if the context
           node is the empty document (i.e. its xpathCtx->doc has no
           children). libxml 2.6.17 does not consider it an error.
           Unfortunately, old libxml prints an error message to stderr,
           which (afaik) cannot be turned off in this case, so we handle it.
        */
        if (!pDoc->children) {
            throw XPathException();
        }

        /* Create xpath evaluation context */
        ::boost::shared_ptr<xmlXPathContext> const xpathCtx(
                xmlXPathNewContext(pDoc), xmlXPathFreeContext);
        if( !bool(xpathCtx)) { throw XPathException(); }

        // set context node
        xpathCtx->node = pNode;
        // error handling
        xpathCtx->error = structured_error_func;
        xmlSetGenericErrorFunc(NULL, generic_error_func);

        // register namespaces and extension
        lcl_registerNamespaces(xpathCtx.get(), nsmap);
        lcl_registerExtensions(xpathCtx.get(), extensions);

        /* run the query */
        OString o1 = OUStringToOString(expr, RTL_TEXTENCODING_UTF8);
        xmlChar *xStr = (xmlChar*)o1.getStr();
        ::boost::shared_ptr<xmlXPathObject> const xpathObj(
                xmlXPathEval(xStr, xpathCtx.get()), xmlXPathFreeObject);
        if (0 == xpathObj) {
            // OSL_ENSURE(xpathCtx->lastError == NULL, xpathCtx->lastError->message);
            throw XPathException();
        }
        Reference<XXPathObject> const xObj(
                new CXPathObject(pCDoc, pCDoc->GetMutex(), xpathObj));
        return xObj;
    }

    /**
     * same as eval but registers all namespace declarations found on namespaceNode
     */
    Reference< XXPathObject > SAL_CALL CXPathAPI::evalNS(
            const Reference< XNode >& contextNode,
            const OUString& expr,
            const Reference< XNode >& namespaceNode)
        throw (RuntimeException, XPathException)
    {
        lcl_collectRegisterNamespaces(*this, namespaceNode);
        return eval(contextNode, expr);
    }

    /**
     * uses the service manager to create an instance of the service denoted by aName.
     * If the returned object implements the XXPathExtension interface, it is added to the list
     * of extensions that are used when evaluating XPath strings with this XPathAPI instance
     */
    void SAL_CALL CXPathAPI::registerExtension(
            const OUString& aName)
        throw (RuntimeException)
    {
        ::osl::MutexGuard const g(m_Mutex);

        // get extension from service manager
        Reference< XXPathExtension > const xExtension(
                m_aFactory->createInstance(aName), UNO_QUERY_THROW);
        m_extensions.push_back(xExtension);
    }

    /**
     * registers the given extension instance to be used by XPath evaluations performed through this
     * XPathAPI instance
     */
    void SAL_CALL CXPathAPI::registerExtensionInstance(
            Reference< XXPathExtension> const& xExtension)
        throw (RuntimeException)
    {
        if (!xExtension.is()) {
            throw RuntimeException();
        }
        ::osl::MutexGuard const g(m_Mutex);
        m_extensions.push_back( xExtension );
    }
}