RWTTransformObjectInputStreamImp

Module:  XML Streams   Package:  XML Streams

RWTTransformObjectInputStreamImp  RWXmlObjectInputStreamImp

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Members

make()

RWTTransformObjectInputStreamImp()

#include <rw/xmlstreams/RWTTransformObjectInputStreamImp.h>

This class uses RWXmlObjectInputStreamImp and RWTTransformInputStreamImp to construct an XML input stream that applies a generic transformation to the XML document before reading it from the source.

// Open an fstream to serve as our source
ifstream s("foo.xml");

// Create a transformation object, which must have a
// transform(istream&,ostream&) interface
MyTransform t;

// Create an XML data stream using the fstream
RWObjectInputStream in =
  RWTTransformObjectInputStreamImp<MyTransform>::make(s,t);

// Read an integer from XML data stream.
int i;
in >> i;

static RWObjectInputStream
make(RW_SL_IO_STD(istream)& source, 
    Transform transformer, bool escape = true);

Constructs an RWTTransformObjectInputStreamImp instance that uses the data stream source as its source of bytes, and returns a handle to it. The XML input stream includes a transformation of the XML document based on the transformation object transformer.

The parameter escape sets whether the primitive element values will be unescaped. By default, this parameter is set to true.

static RWObjectInputStream
make(RW_SL_IO_STD(istream)& source, 
  Transform transformer,
  RW_SL_IO_STD(ios)*& formatter, bool escape = true);

This function is the same as the one above, except that it also takes a pointer reference to an std::ios formatting object. An empty formatting object pointer is created before the XML stream is created and is passed through this make() function to the constructor:

std::ios* formatter;            // uninitialized pointer
RWObjectOutputStream xostr = 
   RWTTransformObjectInputStreamImp<MyTransform>
   ::make(infile,script,formatter);

The constructor, in creating the underlying character stream for the XML stream, creates a formatting object for the stream and places the address of that object in the pointer reference. The calling application can then use this formatting object to manipulate data formats in the XML stream.

formatter->precision(15); // manipulate data format

RWTTransformObjectInputStreamImp(RW_SL_IO_STD(istream)& istr, Transform transformer, bool escape);

Used by the make() function and potentially by derived classes to initialize the source data stream and to insert into the stream a transformation of the XML document based on the transformation object transform.

The parameter istr is a handle to the initialized stream.

The parameter transformer is a transformation object that must supply a public interface function transform(istream&,ostream&).

The parameter escape sets whether the input stream contains escapes for XML reserved characters that need to be unescaped. Usually this would be because the objects serialized out with RWXmlObjectOutputStream contained embedded XML.

The reserved characters are:

<  >  &  "  '

You get slightly better performance if the escape parameter is set to false, but before doing so be certain that your data does not contain reserved characters.

RWTTransformObjectInputStreamImp(RW_SL_IO_STD(istream)& istr, 
  Transform transform, RW_SL_IO_STD(ios)*& formatter,
  bool escape);

This constructor is the same as the one above, except that it also takes a pointer reference to an std::ios formatting object. An empty formatting object pointer is created before the XML stream is created and is passed to this constructor through the make() function. This constructor, in creating the underlying character stream for the XML stream, creates a formatting object for the stream and places the address of that object in the pointer reference. The calling application can then use this formatting object to manipulate data formats in the XML stream. See the corresponding make() function description above for an example.

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