| stpool_c |
|
Table of contents
Procedure
stpool_c ( String from pool )
void stpool_c ( ConstSpiceChar * item,
SpiceInt nth,
ConstSpiceChar * contin,
SpiceInt nthlen,
SpiceChar * nthstr,
SpiceInt * size,
SpiceBoolean * found )
AbstractRetrieve the nth string from a kernel pool variable, where the string may be continued across several components of the kernel pool variable. Required_ReadingNone. KeywordsPOOL Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- item I Name of the kernel pool variable. nth I Index of the full string to retrieve. contin I Character sequence used to indicate continuation. nthlen I Maximum length of output string `nth'. nthstr O A full string concatenated across continuations. size O The number of characters in the full string value. found O Flag indicating success or failure of request. Detailed_Input
item is the name of a kernel pool variable for which
the caller wants to retrieve a full (potentially
continued) string component.
nth is the number of the string to retrieve from the kernel
pool. The range of `nth' is 0 to one less than the
number of full strings that are present.
contin is a sequence of characters which (if they appear as the
last non-blank sequence of characters in a component of a
value of a kernel pool variable) act as a continuation
marker: the marker indicates that the string associated
with the component is continued into the next literal
component of the kernel pool variable.
If `contin' is blank or empty, all of the components of
`item' will be retrieved as a single string.
nthlen is the available space in the output `nthstr', counting
room for the terminating null. Up to nthlen-1 "data"
characters will be assigned to the output string.
Detailed_Output
nthstr is the `nth' full string associated with the kernel pool
variable specified by `item'.
Note that if `nthstr' is not sufficiently long to hold the fully
continued string, the value will be truncated. You can determine
if `nthstr' has been truncated by examining the variable `size'.
`nthstr' will always be null-terminated, even if truncation of
the data occurs.
size is the index of last non-blank character of the continued
string as it is represented in the kernel pool. This is
the actual number of characters needed to hold the
requested string. If `nthstr' contains a truncated portion
of the full string, strlen(nthstr) will be less than `size'.
If the value of `nthstr' should be a blank, then `size' will
be set to 1.
found is a logical variable indicating success of the request
to retrieve the `nth' string associated with `item'. If an
N'th string exists, `found' will be set to SPICETRUE;
otherwise SPICEFALSE will be set to SPICEFALSE
ParametersNone. Exceptions
1) If the variable specified by `item' is not present in the kernel
pool or is present but is not character valued, `nthstr' will be
returned as an empty string, `size' will be returned with the value 0
and `found' will be set to SPICEFALSE. In particular if `nth' is less
than 1, `nthstr' will be returned as an empty string, `size' will be
zero and `found' will be SPICEFALSE.
2) If the variable specified has a blank string associated
with its `nth' full string, `nthstr' will be blank, `size'
will be 1 and `found' will be set to SPICETRUE.
3) If `nthstr' is not long enough to hold all of the characters
associated with the `nth' string, it will be truncated on the
right. `nthstr' will still be null terminated.
4) If the continuation character is a blank, every component
of the variable specified by `item' will be inserted into
the output string.
5) If the continuation character is blank, then a blank component
of a variable is treated as a component with no letters. For
example:
STRINGS = ( 'This is a variable'
'with a blank'
' '
'component.' )
Is equivalent to
STRINGS = ( 'This is a variable'
'with a blank'
'component.' )
from the point of view of stpool_c if `contin' is set to the
blank character.
6) If any of the `item' or `contin' input string pointers is
null, the error SPICE(NULLPOINTER) is signaled.
7) If any of the `item' or `contin' input strings has zero
length, the error SPICE(EMPTYSTRING) is signaled.
8) If the `nthstr' output string pointer is null, the error
SPICE(NULLPOINTER) is signaled.
9) If the `nthstr' output string has length less than two
characters, the error SPICE(STRINGTOOSHORT) is signaled, since
the output string is too short to contain one character of
output data plus a null terminator.
FilesNone. Particulars
The SPICE Kernel Pool provides a very convenient interface for
supplying both numeric and textual data to user application
programs. However, any particular component of a character valued
component of a kernel pool variable is limited to 80 or fewer
characters in length.
This routine allows you to overcome this limitation by "continuing"
a character component of a kernel pool variable. To do this you need
to select a continuation sequence of characters and then insert this
sequence as the last non-blank set of characters that make up the
portion of the component that should be continued.
For example, you may decide to use the sequence "//" to indicate
that a string should be continued to the next component of a kernel
pool variable. Then set up the kernel pool variable as shown below:
LONG_STRINGS = ( 'This is part of the first component //'
'that needs more than one line when //'
'inserting it into the kernel pool.'
'This is the second string that is split //'
'up as several components of a kernel pool //'
'variable.' )
When loaded into the kernel pool, the variable LONG_STRINGS
will have six literal components:
component[0] == "This is part of the first component //"
component[1] == "that needs more than one line when //"
component[2] == "inserting it into the kernel pool."
component[3] == "This is the second string that is split //"
component[4] == "up as several components of a kernel pool //"
component[5] == "variable."
These are the components that would be retrieved by the call
gcpool_c ( "LONG_STRINGS", 1, 6, 81, &n, component, &found );
However, using the routine stpool_c you can view the variable
LONG_STRINGS as having two long components.
strgna == "This is part of the first component that "
"needs more than one line when inserting "
"it into the kernel pool. "
strgnb == "This is the second string that is split "
"up as several components of a kernel pool "
"variable. "
These string components would be retrieved by the following two
calls.
stpool_c( "LONG_STRINGS", 0, "//", 200, strgna, &size, &found );
stpool_c( "LONG_STRINGS", 1, "//", 200, strgnb, &size, &found );
Examples
Example 1. Retrieving file names.
Suppose a you have used the kernel pool as a mechanism for
specifying SPK files to load at startup but that the full names
of the files are too long to be contained in a single text line
of a kernel pool assignment.
By selecting an appropriate continuation character ("*" for
example) you can insert the full names of the SPK files into the
kernel pool and then retrieve them using this routine.
First set up the kernel pool specification of the strings
as shown here:
SPK_FILES = ( 'this_is_the_full_path_specification_*'
'of_a_file_with_a_long_name'
'this_is_the_full_path_specification_*'
'of_a_second_file_with_a_very_long_*'
'name' )
Now to retrieve and load the SPK_FILES one at a time,
exercise the following loop.
#include <stdio.h>
#include <string.h>
#include "SpiceUsr.h"
.
.
.
#define FILSIZ 255
SpiceBoolean found;
SpiceChar file [ FILSIZ ];
SpiceInt handle;
SpiceInt i;
SpiceInt size;
i = 0;
stpool_c ( "SPK_FILES", i, "*", FILSIZ, file, &size, &found );
while ( found && ( strlen(file) == size ) )
{
spklef_c ( file, &handle );
i++;
stpool_c ( "SPK_FILES", i, "*", FILSIZ,
file, &size, &found );
}
if ( found && ( strlen(file) != size ) )
{
printf ( "The %d th file name was too long\n", i );
}
Example 2. Retrieving all components as a string.
Occasionally, it may be useful to retrieve the entire
contents of a kernel pool variable as a single string. To
do this you can use the blank character as the
continuation character. For example if you place the
following assignment in a text kernel
COMMENT = ( 'This is a long note '
' about the intended '
' use of this text kernel that '
' can be retrieved at run time.' )
you can retrieve COMMENT as single string via the call below. Here
LENOUT is the declared length of commnt.
stpool_c ( "COMMENT", 1, " ", commnt, LENOUT, &size, &found );
The result will be that commnt will have the following value.
commnt == "This is a long note about the intended use of "
"this text kernel that can be retrieved at run "
"time. "
Note that the leading blanks of each component of COMMENT are
significant; trailing blanks are not significant.
If COMMENT had been set as
COMMENT = ( 'This is a long note '
'about the intended '
'use of this text kernel that '
'can be retrieved at run time.' )
Then the call to stpool_c above would have resulted in several
words being run together as shown below.
commnt == "This is a long noteabout the intendeduse of "
"this text kernel thatcan be retrieved at run "
"time. "
resulted in several words being run together as shown above.
RestrictionsNone. Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) W.L. Taber (JPL) Version
-CSPICE Version 1.3.0, 01-NOV-2021 (JDR)
Changed the arguments "lenout" and "string" to "nthlen" and "nthstr"
for consistency with other routines.
Edited the header to comply with NAIF standard.
-CSPICE Version 1.2.0, 06-SEP-2004 (NJB)
Bug fix: added CHKOSTR call to check output string pointer
and length. Made some minor header updates.
-CSPICE Version 1.1.0, 06-MAY-2003 (NJB)
Bug fix: removed extra #include statement referencing
SpiceZfc.h.
-CSPICE Version 1.0.1, 10-JUN-2001 (NJB)
Header was corrected: kernel variable assignments were shown
using double quotes; these have been changed to single quotes.
Various instances of the '=' operator were replaced with the
'==' operator in comments where the intent was to indicate
equality of two items.
-CSPICE Version 1.0.0, 10-JUN-1999 (NJB) (WLT)
Index_EntriesRetrieve a continued string value from the kernel pool |
Fri Dec 31 18:41:13 2021