Version 5.0 The LEDA User Manual

9.24 Automatic Decoder ( AutoDecoder )
1. Definition
An instance C of AutoDecoder can be used for decoding any stream that has been encoded
with a LEDA coder or a pipe of LEDA coders. Thus this class is useful if you want to
decode a stream and have forgotten which combination of coders you have used to encode
it. This class is also helpful if the encoding method is not known at compile-time. Then
the decoding method cannot be fixed at compile-time either but it has to be determined
at run-time.
#include < LEDA/coding/auto decoder.h >
2. Types
In order to facilitate the usage of AutoDecoder with decoding istream we provide the
typedef autodecoding istream as a shorthand for decoding istream.
3. Creation
AutoDecoder C(streambuf ∗ src stream = 0, streambuf ∗ tgt stream = 0,
bool own streams = false);
creates an instance C which uses the given source and target
streams. If own streams is set, then C is responsible for the destruction
of the streams, otherwise the pointers src stream and tgt stream
must be valid during the life-time of C.
AutoDecoder
C(const char ∗ src file name, const char ∗ tgt file name);
creates an instance C which uses file-streams for input and output.
4. Operations
Standard Operations
void C.decode( ) decodes the source stream and writes the output to
the target stream.
streambuf ∗ C.get src stream( ) returns the current source stream.
uint32 C.decode memory chunk(const char ∗ in buf , uint32 in len, char ∗ out buf ,
uint32 out len)
decodes the memory chunk starting at in buf with
size in len into the buffer starting at out buf with size
out len. The function returns actual length of the
encoded chunk which may be smaller than out len. If
the output buffer is too small for the decoded data
the failure flag will be set (see below).