samples/ExternalFunction/ExternalFunction.cpp

/*
 * 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 <xalanc/Include/PlatformDefinitions.hpp>



#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>



#include <xercesc/util/PlatformUtils.hpp>



#include <xalanc/XalanTransformer/XalanTransformer.hpp>



#include <xalanc/XPath/Function.hpp>
#include <xalanc/XPath/XObjectFactory.hpp>



using xalanc::Function;
using xalanc::Locator;
using xalanc::XPathExecutionContext;
using xalanc::XalanDOMString;
using xalanc::XalanNode;
using xalanc::XObjectPtr;
using xalanc::MemoryManager;
using xalanc::XalanCopyConstruct;

// This class defines a function that will return the square root
// of its argument.
class FunctionSquareRoot : public Function
{
public:

    /**
     * Execute an XPath function object.  The function must return a valid
     * object.  Extension functions should override this version of execute(),
     * rather than one of the other calls designed for a specific number of
     * arguments.
     *
     * @param executionContext executing context
     * @param context          current context node
     * @param args             vector of pointers to XObject arguments
     * @param locator          Locator for the XPath expression that contains the function call
     * @return                 pointer to the result XObject
     */
    virtual XObjectPtr
    execute(
            XPathExecutionContext&          executionContext,
            XalanNode*                      context,
            const XObjectArgVectorType&     args,
            const Locator*                  locator) const
    {
        if (args.size() != 1)
        {
            XPathExecutionContext::GetAndReleaseCachedString    theGuard(executionContext);

            generalError(executionContext, context, locator);
        }

        assert(args[0].null() == false);    

        using std::sqrt;
#endif

        return executionContext.getXObjectFactory().createNumber(sqrt(args[0]->num(executionContext)));
    }

    using Function::execute;

    /**
     * Create a copy of the function object.
     *
     * @return pointer to the new object
     */
    virtual FunctionSquareRoot*
    clone(MemoryManager&    theManager) const
    {
        return XalanCopyConstruct(theManager, *this);
    }

protected:

    /**
     * Get the error message to report when
     * the function is called with the wrong
     * number of arguments.
     *
     * @return function error message
     */
    const XalanDOMString&
    getError(XalanDOMString&    theResult) const
    {
        theResult.assign("The square-root() function accepts one argument!");

        return theResult;
    }

private:

    // Not implemented...
    FunctionSquareRoot&
    operator=(const FunctionSquareRoot&);

    bool
    operator==(const FunctionSquareRoot&) const;
};



// This class defines a function that will return the cube
// of its argument.
class FunctionCube : public Function
{
public:

    /**
     * Execute an XPath function object.  The function must return a valid
     * object.  Extension functions should override this version of execute(),
     * rather than one of the other calls designed for a specific number of
     * arguments.
     *
     * @param executionContext executing context
     * @param context          current context node
     * @param args             vector of pointers to XObject arguments
     * @param locator          Locator for the XPath expression that contains the function call
     * @return                 pointer to the result XObject
     */
    virtual XObjectPtr
    execute(
            XPathExecutionContext&          executionContext,
            XalanNode*                      context,
            const XObjectArgVectorType&     args,
            const Locator*                  locator) const
    {
        if (args.size() != 1)
        {
            XPathExecutionContext::GetAndReleaseCachedString    theGuard(executionContext);

            generalError(executionContext, context, locator);
        }

        assert(args[0].null() == false);    

        using std::pow;

        return executionContext.getXObjectFactory().createNumber(pow(args[0]->num(executionContext), 3));
    }

    using Function::execute;

    /**
     * Create a copy of the function object.
     *
     * @return pointer to the new object
     */
    virtual FunctionCube*
    clone(MemoryManager&    theManager) const
    {
        return XalanCopyConstruct(theManager, *this);
    }

protected:

    /**
     * Get the error message to report when
     * the function is called with the wrong
     * number of arguments.
     *
     * @return function error message
     */
    const XalanDOMString&
    getError(XalanDOMString&    theResult) const
    {
        theResult.assign("The cube() function accepts one argument!");

        return theResult;
    }

private:

    // Not implemented...
    FunctionCube&
    operator=(const FunctionCube&);

    bool
    operator==(const FunctionCube&) const;
};



// This class defines a function that runs the C function
// asctime() using the current system time.
class FunctionAsctime : public Function
{
public:

    /**
     * Execute an XPath function object.  The function must return a valid
     * object.  Extension functions should override this version of execute(),
     * rather than one of the other calls designed for a specific number of
     * arguments.
     *
     * @param executionContext executing context
     * @param context          current context node
     * @param args             vector of pointers to XObject arguments
     * @param locator          Locator for the XPath expression that contains the function call
     * @return                 pointer to the result XObject
     */
    virtual XObjectPtr
    execute(
            XPathExecutionContext&          executionContext,
            XalanNode*                      context,
            const XObjectArgVectorType&     args,
            const Locator*                  locator) const
    {
        if (args.empty() == false)
        {
            generalError(executionContext, context, locator);
        }

        using std::time;
        using std::time_t;
        using std::localtime;
        using std::asctime;
        using std::strlen;

        time_t  theTime;

        time(&theTime);

        char* const theTimeString = asctime(localtime(&theTime));
        assert(theTimeString != 0);

        // The resulting string has a newline character at the end,
        // so get rid of it.
        theTimeString[strlen(theTimeString) - 1] = '\0';

        return executionContext.getXObjectFactory().createString(XalanDOMString(theTimeString));
    }

    using Function::execute;

    /**
     * Create a copy of the function object.
     *
     * @return pointer to the new object
     */
    virtual FunctionAsctime*
    clone(MemoryManager&    theManager) const
    {
        return XalanCopyConstruct(theManager, *this);
    }

protected:

    /**
     * Get the error message to report when
     * the function is called with the wrong
     * number of arguments.
     *
     * @return function error message
     */
    const XalanDOMString&
    getError(XalanDOMString& theResult) const
    {
        theResult.assign("The asctime() function accepts one argument!");

        return theResult;
    }

private:

    // Not implemented...
    FunctionAsctime&
    operator=(const FunctionAsctime&);

    bool
    operator==(const FunctionAsctime&) const;
};



int
main(
            int     argc,
            char*   /* argv */[])
{
    using std::cerr;
    using std::endl;

    int theResult = 0;

    if (argc != 1)
    {
        cerr << "Usage: ExternalFunction"
             << endl
             << endl;
    }
    else
    {
        using xercesc::XMLPlatformUtils;
        using xercesc::XMLException;

        using xalanc::XalanTransformer;

        // Call the static initializer for Xerces.
        try
        {
             XMLPlatformUtils::Initialize();
        }
        catch (const XMLException& toCatch)
        {
             cerr << "Error during Xerces initialization.  Error code was "
                  << toCatch.getCode()
                  << "."
                  << endl;

             theResult = -1;
        }

        if (theResult == 0)
        {
            // Initialize Xalan.
            XalanTransformer::initialize();

            {
                // Create a XalanTransformer.
                XalanTransformer    theXalanTransformer;

                // The namespace for our functions...
                const XalanDOMString    theNamespace("http://ExternalFunction.xalan-c++.xml.apache.org");

                // Install the functions in the local space.  They will only
                // be installed in this instance, so no other instances
                // will know about them...
                theXalanTransformer.installExternalFunction(
                    theNamespace,
                    XalanDOMString("asctime"),
                    FunctionAsctime());

                theXalanTransformer.installExternalFunction(
                    theNamespace,
                    XalanDOMString("square-root"),
                    FunctionSquareRoot());

                theXalanTransformer.installExternalFunction(
                    theNamespace,
                    XalanDOMString("cube"),
                    FunctionCube());

                // Do the transform.
                theResult = theXalanTransformer.transform("foo.xml", "foo.xsl", "foo.out");
    
                if(theResult != 0)
                {
                    cerr << "ExternalFunction Error: \n" << theXalanTransformer.getLastError()
                         << endl
                         << endl;
                }
            }

            // Terminate Xalan...
            XalanTransformer::terminate();
        }

        // Terminate Xerces...
        XMLPlatformUtils::Terminate();

        // Clean up the ICU, if it's integrated...
        XalanTransformer::ICUCleanUp();
    }

    return theResult;
}