Using +Content Processor

This section explains how to implement the MContentProcessor interface +to parse, validate and autocorrect an XML document.

Introduction

The parsed document can also be validated +against a specification and auto-corrected for spelling errors in the validated +text. This can be done by writing three applications - a parser, a validator +and an autocorrector. These applications must implement the MContentProcessor interface.

Writing +a content processor is similar to writing a content handler as explained in Parsing an XML Document. MContentProcessor is +an extension of MContentHandler. Each application is writen +by implementing the callback functions of MContentHandler. +The only difference is that MContentProcessor has a mechanism +for directing output, so that the output of the parser is the input to the +validator, and the output of the validator is the input to the autocorrector.

Direct +output of a content processor by implementing the SetContentSink() function, +so that the parser outputs to the validator and the validator outputs to the +autocorrector. A sequence of several applications linked in this way is called +a Plug-in Chain.

Procedure

Implement the MContentProcessor interface.
Implement the MContentProcessor::SetContentSink() function.
Perform the actual parsing.

Use +a CParser object as explained in Choosing +a Parser Plug-in. To ensure that parsing is followed by validation +and autocorrection, associate the CParser object with the +plug-in chain. This can be done by calling SetProcessorChainL() function +of the CParser object with a list of the items in the plugin +chain as a parameter.

The following code illustrates how to validate +and autocorrect the parsed document:
RFs fs; +User::LeaveIfError( fs.Connect() ); +CleanupClosePushL( fs ); + +_LIT8( KXmlMimeType, "text/xml" ); +TSimpleContentHandler sax; // You’ll have to implement this class… + +CParser* parser = CParser::NewLC( KXmlMimeType, sax ); + +RContentProcessorUids uids; +uids.Append( KValidatorUid ); // The ECOM implementation UID of a validator plug-in +CleanupClosePushL( uids ); + +// Sets up the chain of call-back events from the parser through to the +// validating plug-in and then the client. +parser->SetProcessorChainL( uids ); + +parser->ParseFileL( fs, KMyFile ); + +CleanupStack::PopAndDestroy( 3 );