Installing a New Stream

A new stream is made accessible to Prolog using one of the functions:

     int SP_make_stream(
             void *handle,
             int (*sgetc)(),
             int (*sputc)(),
             int (*sflush)(),
             int (*seof)(),
             void (*sclrerr)(),
             int (*sclose)(),
             SP_stream **stream)
     
     int SP_make_stream_context(
             void *handle,
             int (*sgetc)(),
             int (*sputc)(),
             int (*sflush)(),
             int (*seof)(),
             void (*sclrerr)(),
             int (*sclose)(),
             SP_stream **stream,
             SP_atom option,
             int context)
     

The functions return SP_SUCCESS on success and SP_ERROR for invalid usage, and will:

• Allocate a SP_stream structure
• Install your low level I/O functions. For those not supplied default functions are installed.
• Determine if the stream is for input or output or both from the functions supplied.
• Fill in fields in the SP_stream structure with default values

The handle pointer will be supplied as the handle argument in the calls to the low level functions.

A stream without a close function will be treated as not closable i.e. close/1 will not have any effect on it.

The SP_make_stream_context() function has two additional arguments supplying information related to the handling of wide characters; see WCX Foreign Interface.