HP 3000 Manuals

Accessing Files Programmer's Guide

Parsing and Validating File Designators 

The FPARSE intrinsic parses and validates a file designator string to
determine if it is syntactically correct.  You can employ this intrinsic
to check a formal file designator representing a file before attempting
to open the file with HPFOPEN/FOPEN. 
MPE/iX file designators used for the file system and two user interface
commands include a remote environment ID (envid).  This allows the user
to indicate that a file is to be accessed from a remote environment
established by the user with the DSLINE or REMOTE HELLO command.  FPARSE
facilitates the changes required for the file designator extension.  It
provides the only location within MPE/iX where file designators are
parsed and syntax is checked.

The following are examples of the items and the vectors array pair.  The
order of entries in the vectors array corresponds to the order of items
in the items array.  Each 32-bit entry in the vectors array returns the
byte offset of the item in the first half-word, and the length in bytes
of the item in the second half-word.  However, the last entry of the
vectors array has a different meaning from that of the other entries:
the second half-word gives the total length of the file string, and the
first half-word gives a system file code when applicable.

In Figure 3-3  the file string is
"FILENAME/LOCKWORD.GROUP.ACCOUNT:ANIMAL.INDDCL.HPBCG":


          Figure 3-3.  Illustration of FPARSE Usage 

The items array, as illustrated above, can be listed in any order or can
be left unspecified if not required.

In Figure 3-4 , below, the file string is   "*FILENAME:ANIMAL":  


          Figure 3-4.  Illustration of FPARSE Usage 

In Figure 3-5 , below, the file string is  "$OLDPASS":


          Figure 3-5.  Illustration of FPARSE Usage 

Note that "$" is a special exception to the rules of file names and is
considered part of the file name, unlike "*", which is not.

MPE/iX 5.0 Documentation