The file set, which contains a list of file set entries, is implemented
by the file_set class. The list of files can be accessed
directly using the file_list method, but most users will not need
to do that because other methods are available to perform the common
operations. The add_file method adds a new file set entry to the
list. This method takes the names of the input file and output file and
returns the new file set entry. Either the input file or the output
file may be NULL. The file_set class also contains an
iterator, as most SUIF programmers will want to iterate through the list
of files. The reset_iter method resets the iterator to the first
file set entry. The next_file method returns the next file set
entry in the list.
Besides the list of files, the file set also contains the global symbol
table (see section The Global Symbol Table) which can be accessed using the
globals method. This symbol table contains the symbols and types
that are visible in all of the source files. Before a group of files
can be combined into a file set, their global symbol tables must be
merged together. A separate SUIF linker is provided for this purpose.
The library will complain if the files in the file set have not been
properly linked.
Currently, only one file set is allowed per SUIF program. This
restriction was made so that predefined types could be entered into the
global symbol table at initialization time. See section Predefined Types.
If multiple file sets were permitted, these predefined types would be
duplicated. A single global file set is created when the SUIF library
is initialized; the fileset global variable points to this file
set.
All of the low-level access to SUIF files is performed automatically by the library. The global and file symbol tables are read from the input files when they are added to the file set. Users can then read and write individual procedure bodies using methods on the procedure symbols (see section Procedure Symbols). The global symbol tables are not written out until the file set is destroyed. Throughout this process, the file set keeps track of the number of open files in order to avoid exceeding the OS limit. If there are too many files open at once, the file set will automatically find one to close. This is totally invisible to users. Files that are temporarily closed are automatically reopened as needed.
As an example of using the file set, the following code reads in the
files infile1 and infile2 and writes them out to
outfile1 and outfile2, respectively, after processing them
with the user-defined routine process_file.
fileset->add_file("infile1", "outfile1");
fileset->add_file("infile2", "outfile2");
file_set_entry *fse;
fileset->reset_iter();
while (fse = fileset->next_file()) {
process_file(fse);
}
delete fileset;