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hyung-hwan 2007-03-13 09:08:19 +00:00
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commit 10311f1433
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ase/doc/awk-en.man
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@ -136,63 +136,67 @@ struct ase_awk_srcios_t
};
}}}
The ##in## field of the ase_awk_srcios_t is mandatory and should be filled in. The ##out## field can be set to ASE_NULL or can point to a source output handling function. The ##custom_data## field is passed to the source handlers as the second argument. The first parameter ##cmd## of the source input handler is one of ##ASE_AWK_IO_OPEN##, ##ASE_AWK_IO_CLOSE##, ##ASE_AWK_IO_READ##. The first parameter ##cmd## of the source output handler is one of ##ASE_AWK_IO_OPEN##, ##ASE_AWK_IO_CLOSE##, ##ASE_AWK_IO_WRITE##. The third parameter ##data## and the fourth parameter ##count## are used if the first parameter ##cmd## is either ##ASE_AWK_IO_READ## or ##ASE_AWK_IO_WRITE##.
The ##in## field of the ase_awk_srcios_t is mandatory and should be filled in. The ##out## field can be set to ##ASE_NULL## or can point to a source output handling function. The ##custom_data## field is passed to the source handlers as the second argument. The first parameter ##cmd## of the source input handler is one of ##ASE_AWK_IO_OPEN##, ##ASE_AWK_IO_CLOSE##, ##ASE_AWK_IO_READ##. The first parameter ##cmd## of the source output handler is one of ##ASE_AWK_IO_OPEN##, ##ASE_AWK_IO_CLOSE##, ##ASE_AWK_IO_WRITE##. The third parameter ##data## and the fourth parameter ##count## are the pointer to the buffer to read data into and its size if the first parameter ##cmd## is ##ASE_AWK_IO_READ## while they are the pointer to the data and its size if ##cmd## is ##ASE_AWK_IO_WRITE##.
The source handler should return a negative value for an error and zero or a positive value otherwise. However, there is a subtle difference in the meaning of the return value depending on the value of the first parameter ##cmd##.
When ##cmd## is ##ASE_AWK_IO_OPEN##, the return value of -1 and 1 indicates the failure and the success respectively. In addition, the return value of 0 indicates that the operation is successful but has reached the end of the stream. The library calls the handler with ##ASE_AWK_IO_CLOSE## for deinitialization if the return value is 0 or 1. When ##cmd## is ##ASE_AWK_IO_CLOSE##, the return value of -1 and 0 indicate the failure and the success respectively. When ##cmd## is ##ASE_AWK_IO_READ## or ##ASE_AWK_IO_WRITE##, the return value of -1 indicates the failure, 0 the end of the stream, and other positive values the number of characters read or written.
The typical source handler will look as follows:
{{{
static ase_ssize_t awk_srcio_in (
int cmd, void* arg, ase_char_t* data, ase_size_t size)
ase_ssize_t awk_srcio_in (int cmd, void* arg, ase_char_t* data, ase_size_t size)
{
struct awk_src_io* src_io = (struct awk_src_io*)arg;
ase_cint_t c;
if (cmd == ASE_AWK_IO_OPEN)
{
if (src_io->input_file == ASE_NULL) return 0;
src_io->input_handle = ase_fopen (src_io->input_file, ASE_T("r"));
if (src_io->input_handle == NULL) return -1;
/* open the stream */
return 1;
}
else if (cmd == ASE_AWK_IO_CLOSE)
{
if (src_io->input_file == ASE_NULL) return 0;
fclose ((FILE*)src_io->input_handle);
/* close the stream */
return 0;
}
else if (cmd == ASE_AWK_IO_READ)
{
if (size <= 0) return -1;
c = ase_fgetc ((FILE*)src_io->input_handle);
if (c == ASE_CHAR_EOF) return 0;
*data = (ase_char_t)c;
/* read the stream */
return the number of characters read;
}
return -1;
}
ase_ssize_t awk_srcio_out (int cmd, void* arg, ase_char_t* data, ase_size_t size)
{
if (cmd == ASE_AWK_IO_OPEN)
{
/* open the stream */
return 1;
}
else if (cmd == ASE_AWK_IO_CLOSE)
{
/* close the stream after flushing it */
return 0;
}
else if (cmd == ASE_AWK_IO_WRITE)
{
/* write the stream */
return the number of characters written;
}
return -1;
}
}}}
Once you have the source handler ready, you can fill in the fields of a ##ase_awk_srcios_t## structure and pass it to the call of ##ase_awk_parse##.
{{{
static ase_ssize_t awk_srcio_out (
int cmd, void* arg, ase_char_t* data, ase_size_t size)
{
/*struct awk_src_io* src_io = (struct awk_src_io*)arg;*/
ase_awk_srcios_t srcios;
if (cmd == ASE_AWK_IO_OPEN) return 1;
else if (cmd == ASE_AWK_IO_CLOSE)
{
fflush (stdout);
return 0;
}
else if (cmd == ASE_AWK_IO_WRITE)
{
int n = ase_fprintf (stdout, ASE_T("%.*s"), size, data);
if (n < 0) return -1;
srcios.in = awk_srcio_in;
srcios.out = awk_srcio_out;
srcios.custom_data = point to the extra information necessary;
return size;
}
return -1;
}
ase_awk_parse (awk, &srcios);
}}}
=== External IO Handler ===