balber_berdecoder

Functions
	balber::BerDecoder::MemOutStream::MemOutStream (bslma::Allocator *basicAllocator=0)
void	balber::BerDecoder::MemOutStream::reset ()
	Reset the internal streambuf to the empty state.
const char *	balber::BerDecoder::MemOutStream::data () const
int	balber::BerDecoder::MemOutStream::length () const

Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Decoding an Employee Record

Purpose

Provide a BER decoder class.

Classes

• balber::BerDecoder: BER decoder

See also

balber_berencoder, bdem_bdemdecoder, balxml_decoder

Description

This component defines a single class, balber::BerDecoder, that contains a parameterized decode function. The decode function decodes data read from a specified stream and loads the corresponding object to an object of the parameterized type. The decode method is overloaded for two types of input streams:

• bsl::streambuf
• bsl::istream

This class decodes objects based on the X.690 BER specification and is restricted to types supported by the bdlat framework.

Usage

This section illustrates intended use of this component.

Example 1: Decoding an Employee Record

Suppose that an "employee record" consists of a sequence of attributes – name, age, and salary – that are of types bsl::string, int, and float, respectively. Furthermore, we have a need to BER encode employee records as a sequence of values (for out-of-process consumption).

Assume that we have defined a usage::EmployeeRecord class to represent employee record values, and assume that we have provided the bdlat specializations that allow the balber codec components to represent class values as a sequence of BER primitive values. See {bdlat_sequencefunctions |Usage} for details of creating specializations for a sequence type.

First, we create an employee record object having typical values:

usage::EmployeeRecord bob("Bob", 56, 1234.00);
assert("Bob"   == bob.name());
assert(  56    == bob.age());
assert(1234.00 == bob.salary());

Next, we create a balber::Encoder object and use it to encode our bob object. Here, to facilitate the examination of our results, the BER encoding data is delivered to a bslsb::MemOutStreamBuf object:

bdlsb::MemOutStreamBuf osb;
balber::BerEncoder     encoder;
int                    rc = encoder.encode(&osb, bob);
assert( 0 == rc);
assert(18 == osb.length());

Now, we create a bdlsb::FixedMemInStreamBuf object to manage our access to the data portion of the bdlsb::MemOutStreamBuf (where our BER encoding resides), decode the values found there, and use them to set the value of an usage::EmployeeRecord object.

balber::BerDecoderOptions  options;
balber::BerDecoder         decoder(&options);
bdlsb::FixedMemInStreamBuf isb(osb.data(), osb.length());
usage::EmployeeRecord      obj;
 
rc = decoder.decode(&isb, &obj);
assert(0 == rc);

Finally, we confirm that the object defined by the BER encoding has the same value as the original object.

assert(bob.name()   == obj.name());
assert(bob.age()    == obj.age());
assert(bob.salary() == obj.salary());

Function Documentation

data()

const char * balber::BerDecoder::MemOutStream::data ( ) const

inline

Return a pointer to the memory containing the formatted values formatted to this stream. The data is not null-terminated unless a null character was appended onto this stream.

length()

int balber::BerDecoder::MemOutStream::length ( ) const

inline

Return the length of the formatted data, including null characters appended to the stream, if any.

MemOutStream()

balber::BerDecoder::MemOutStream::MemOutStream ( bslma::Allocator *  basicAllocator = 0 )

inline

Create a stream object. Optionally specify a basicAllocator used to supply memory. If basicAllocator is 0, the currently installed default allocator is used.

reset()

void balber::BerDecoder::MemOutStream::reset ( )

inline