RWTTransformInputStreamImp

Module:  XML Streams   Package:  XML Streams

RWTTransformInputStreamImp  FilteredInputStreamImp

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• Description
• Public Typedef
• Static Public Member Functions
• Public Destructor
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• Protected Member Functions

Members

available() eback() ebuf() egptr() element_type

freeBuffer() gbump() gptr() isBad() isEof()

isFail() isGood() make() read() readUntil()

RWTTransformInputStreamImp() setBufferEnd() setg() underflow() ~RWTTransformInputStreamImp()

#include <rw/xmlstreams/RWTTransformInputStreamImp.h>

The class RWTTransformInputStreamImp implements a buffered char or byte input character stream that includes a transformation. The size of the buffer is specified as a parameter to the static make() function that is used to create it. If the buffer as initialized is not large enough to contain the entire XML document, it grows as needed to be able to do so. It is more efficient, though, to allocate a buffer of sufficient size initially.

RWTTransformInputStreamImp is a class template that is derived from one of its own template parameters.

The class is defined as

template <class InputStream, class FilteredInputStreamImp, 
          class Transform>
class RWTTransformInputStreamImp : 
   public FilteredInputStreamImp { ...}

When the read() or readUntil() is first called on this class, the transform() method of the transformation object passed into the constructor gets called. The transform() method reads from the source, applies the transformation defined by the method, and stores the result in the buffer. Once the buffer contains the entire transformed document, the call to read() or readUntil() is completed by reading from the buffer.

typedef typename InputStream::element_type
element_type;

In keeping with the pattern for all filtered input streams, the type of character contained by the stream is referred to as the"element_type." Characters in the stream are called "elements" (not to be confused with XML "elements").

---

NOTE -- Be aware that characters in the stream are called "elements," which have no connection to XML "elements."

---

static InputStream
make(const InputStream& sourceStream, Transform transform);

Constructs an RWTTransformInputStreamImp instance that uses sourceStream as its source of elements, and returns a handle to it. The internal buffer is initialized to be of size RW_STREAM_BUFFER_SIZE, which is defined as 512 bytes. The buffer grows as needed to contain the entire XML document.

The parameter sourceStream represents the input stream that serves as the source of elements.

The parameter transform represents the transformation object and must provide a public interface of:

transform(basic_istream<element_type,
          char_traits<element_type> >,
          basic_ostream<element_type>, 
          char_traits<element_type> >)

static InputStream
make(const InputStream& sourceStream, Transform transform,
     RWSize bufSize);

Constructs an RWTTransformInputStreamImp instance that uses sourceStream as its source of elements, and returns a handle to it. The internal buffer is initialized to be of size bufSize. The buffer grows as needed to contain the entire XML document.

The parameter sourceStream represents the input stream that serves as the source of elements.

The parameter transform represents the transformation object and must provide a public interface of:

transform(basic_istream<element_type,
          char_traits<element_type> >, 
          basic_ostream<element_type>, 
          char_traits<element_type> >)

The parameter bufSize represents the initial buffer capacity in number of elements.

static InputStream
make(const InputStream& sourceStream, Transform transform,
     element_type* buffer, RWSize bufSize);

Constructs an RWTTransformInputStreamImp instance that uses sourceStream as its source of elements, and returns a handle to it. The internal buffer is initialized using a pre-allocated element's array of size bufSize. The buffer grows as needed to contain the entire XML document.

The parameter sourceStream represents the input stream that serves as the source of elements.

The parameter transform represents the transformation object and must provide a public interface of:

transform(basic_istream<element_type,
          char_traits<element_type> >, 
          basic_ostream<element_type>, 
          char_traits<element_type> >)

The parameter buffer represents a pre-allocated buffer of size bufSize to be used internally by the constructed RWTTransformInputStreamImp object.

virtual
~RWTTransformInputStreamImp();

Virtual destructor. Throws no exceptions.

virtual RWSize
available() const;

Returns the number of elements that can be read from the stream without blocking. Throws no exceptions.

virtual bool
isEof() const;

Returns true if no character can be obtained from the input sequence, otherwise false. Throws no exceptions.

virtual bool
isBad() const;

Returns true if the stream is in a bad state, otherwise false. Throws no exceptions.

virtual bool
isFail() const;

Returns true if the stream is in fail state, otherwise false. Throws no exceptions.

virtual bool
isGood() const;

Returns false if the stream is in fail or bad state, otherwise true. Throws no exceptions.

virtual element_type
read();

Reads a single element from the input stream.

virtual RWSize
read(element_type* array, RWSize num);

Reads an array of elements from the input stream. Returns the actual number of elements read.

The parameter array represents a pointer to the beginning of the element array used to store the input. The array must have been pre-allocated to contain at least num elements. The parameter num represents the number of elements to be read from the stream.

virtual RWSize
readUntil(element_type* array, RWSize maxSize,
          element_type delim);

Reads elements until the last element read is equivalent to delim, maxSize elements have been read, or the end of the input sequence is reached. The elements read are stored in array. The function returns the actual number of elements read from the stream.

The parameter array represents a pointer to the beginning of the element array holding the elements extracted from the stream.

The parameter maxSize represents the maximum number of elements to be read.

The parameter delim represents the element value used as the delimiter.

RWTTransformInputStreamImp(const InputStream& sourceStream,
  Transform transform);

Initializes the reference to the input stream used as the source of elements, and the internal buffer, whose capacity is set equal to RW_STREAM_BUFFER_SIZE, defined as 512 bytes.

The parameter sourceStream represents the input stream that serves as the source of elements.

The parameter transform represents the transformation object and must provide a public interface of:

transform(basic_istream<element_type,
          char_traits<element_type> >,
          basic_ostream<element_type>, 
          char_traits<element_type> >)

RWTTransformInputStreamImp(const InputStream& sourceStream,
  Transform transform, RWSize bufSize);

Initializes the reference to the input stream used as the source of elements, and the internal buffer, whose capacity is set to bufSize.

The parameter sourceStream represents the input stream that serves as the source of elements.

The parameter transform represents the transformation object and must provide a public interface of:

transform(basic_istream<element_type,
          char_traits<element_type> >,
          basic_ostream<element_type>,
          char_traits<element_type> >)

The parameter bufSize represents the buffer capacity in number of elements.

RWTTransformInputStreamImp(const InputStream& sourceStream, 
  Transform transform, element_type* buffer, RWSize bufSize);

Initializes the reference to the input stream used as the source of elements, and the internal buffer, which is initialized using a pre-allocated element's array of size bufSize.

The parameter sourceStream represents the input stream that serves as the source of elements.

The parameter transform represents the transformation object and must provide a public interface of:

transform(basic_istream<element_type,
          char_traits<element_type> >, 
          basic_ostream<element_type>, 
          char_traits<element_type> >)

The parameter buffer represents a pre-allocated buffer of size bufSize to be used internally by the constructed RWTTransformInputStreamImp object.

element_type*
eback() const;

Returns a pointer to the first element in the input buffer array. Throws no exceptions.

element_type*
ebuf() const;

Returns a pointer one position past the end of the input buffer array. Throws no exceptions.

element_type*
egptr() const;

Returns a pointer one position past the last element in the input sequence. Throws no exceptions.

void
freeBuffer();

Frees the memory allocated to the internal buffer, if necessary. Throws no exceptions.

void
gbump(RWSize n);

Moves the input buffer array pointer n positions forward. The array position now pointed to is the one returned by gptr(). Throws no exceptions.

element_type*
gptr() const;

Returns a pointer to the current position in the buffered input sequence. Throws no exceptions.

void
setBufferEnd(element_type* gend_arg);

Sets the buffer's end pointer. Assigns the parameter value bufEnd_. Throws no exceptions.

void
setg(element_type* gbeg_arg,element_type* gcur_arg, 
     element_type* gend_arg);

Assigns the parameter values to gbeg_, gnext_, and gend_ respectively. These data members represent the beginning of the buffer array, the current position in the array, and the end of the array.

bool
underflow();

Fills the input buffer. Returns true if there are elements available, otherwise false.

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