xstr(1)xstr(1)NAMExstr - extract strings from C programs to implement shared strings
SYNOPSIS
[file]
DESCRIPTION
maintains a file into which strings in component parts of a large pro‐
gram are hashed. These strings are replaced with references to this
common area. This serves to implement shared constant strings, which
are most useful if they are also read-only.
The command:
extracts the strings from the C source in name, replacing string refer‐
ences with expressions of the form for some number. An appropriate
declaration of is placed at the beginning of the file. The resulting C
text is placed in the file for subsequent compiling. The strings from
this file are placed in the database if they are not there already.
Repeated strings and strings that are suffixes of existing strings do
not cause changes to the data base.
After all components of a large program have been compiled, a file
declaring the common space, can be created by the command:
This file should then be compiled and loaded with the rest of the pro‐
gram. If possible, the array can be made read-only (shared), saving
space and swap overhead.
can also be used on a single file. A command:
creates files and as before, without using or affecting any file in the
same directory.
It may be useful to run after the C preprocessor if any macro defini‐
tions yield strings or if there is conditional code containing strings
that are not, in fact, needed. reads from its standard input when the
argument is given. An appropriate command sequence for running after
the C preprocessor is:
does not touch the file unless new items are added, thus can avoid
remaking unless truly necessary (see make(1)).
WARNINGS
If a string is a suffix of another string in the data base, but the
shorter string is seen first by both strings are placed in the data
base, when placing only the longer one there would be sufficient.
AUTHOR
was developed by the University of California, Berkeley.
FILES
Data base of strings
Massaged C source
C source for definition of array
Temp file when `xstr name' does not touch
SEE ALSOmkstr(1).
xstr(1)
