Hey Samuel,
A long while ago I was one of the people who wrote Pathan (an XPath2
implementation on top of Xerces C). Its been replaced with XQilla now
(http://xqilla.sourceforge.net/HomePage). I expect its worth a look for
function implementations. We also had a thorough test suite which could still
be there / be of use.
Cheers,
G
On 30 Jul 2012, at 03:06, Steve Hathaway wrote:
> Samuel - GSOC 2012
>
> You're doing good.
>
> It looks like you understand the basics of the XPath function class that
> needs to be extended
> and customizing the appropriate execute() methods.
>
> Here are some comments:: Ref: file OspXpathConvertDate.cpp from zip example.
>
> YourXPathFunction::execute(
> XPathExecutionContext & executionContext,
> XalanNode * context, /*may not be needed*/
> const XObjectPtr arg1,
> const XObjectPtr arg2,
> const LocatorType * locator /*may not be needed*/
> ) const
> {
> CharVectorType theFirstArg;
> char * charFirstArg;
> CharVectorType theSecondArg;
> char * charSecondArg;
>
> MemoryManager * theManager = executionContext.getMemoryManager();
>
> theFirstArg = TranscodeToLocalCodePage(arg1->str());
> charFirstArg = theFirstArg.begin();
>
> theSecondArg = TranscodeToLocalCodePage(arg2->str());
> charSecondArg = theSecondArg.begin();
>
> /* NOTES
> *
> * TransCodeToLocalCodePage()
> * creates a new instance of CharVectorType containing
> * converted transformed Unicode to the host character set (ASCII/EBCDIC...)
> *
> * The CharVectorType.begin() method returns a pointer to the
> * null-terminated character string. This string is owned by the
> CharVectorType
> * class. This CharVectorType class is a local variable with local scope.
> * The allocation for CharVectorType will be properly destroyed when the
> * execute() method returns.
> *
> * You should not access the m_data storage variable directly, but instead
> * use the access method begin() to ensure a proper address.
> *
> * Note also that XalanDOMString may not be what you want. Its native
> * character storage is 16-bit characters (UTF-16) encoding.
> *
> * The above sample I have shown here will give you standard 'C' strings
> * extracted from the XPath function arguments in a safe way.
> *
> * The XalanDOMString class does know how to import data from (char *)
> * strings.
> */
>
> char * charResult;
> charResult = someFunction(...) // returning a pointer to type (char *);
>
> // The following creates a XalanDOMString and initializes it with charResult.
> // Declaring XalanDOMString as a local instance, it will be destroyed when
> // the execute method exits.
>
> XalanDOMString theResult(charResult);
>
> // You may need to free the memory associated with the charResult pointer
> // before you return. After charResult is saved in a XalanDOMString, you
> // should be able to release owhership of the (char *) pointer and free the
> // (char *) allocation.
>
> free(charResult); // or program specific equivalent.
>
> // The execution.GetXObjectFactory() creates a XObjectPtr to data owned
> // by the XObjectFactory. This content is returned to the XPath
> // interpreter execution context.
>
> return executionContext.getXObjectFactory().createString(theResult);
>
> }
>
> /*
> * Create an error reporter
> */
> const XalanDOMString &
> YourXPathFunction::getError(XalanDOMString & theResult) const
> {
> return XalanMessageLoader::getMessage(
> theResult,
> XalanMessages::FunctionTakesTwoArguments_1Param,
> "name of you XPath Function");
> }
>
> /* NOTE:
> * The example error reporter.
> * The XalanMessageLoader::getMessage(...) prepares a standard message
> * showing theResult, "The function '(0)' requires two arguments."
> * with '(0)' replaced with "name of your XPath Function");
> *
> * If you need messages that are not in the NLS library, we can create
> * new message templates and put them into the NLS library.
> *
> * FunctionTakesTwoArguments_1Param is an address to the NLS string:
> * "The function '(0)' requires two arguments."
> */
>
>
> Sincerely,
> Steven J. Hathaway
>
>
>
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