2
This is a version of Henry Spencer's famous regexp implementation. I've
3
modified it to meet my needs, this is what I've done:
5
2) added a new function regsublen(), this performs a dry run of the
6
regsub() function returning the length of the string needed to hold
7
the output from regsub().
8
3) changed regexec(prog,str) to regexec2(prog,str,eflags) with macro for
9
regexec(). This is so I can have the flag REG_NOTBOL which signifies
10
that the string passed to regexec[2]() is not actually the start of a
12
4) support for case-insignificant matching (with the flag REG_NOCASE)
13
5) split the definition of a compiled regexp from regexp.c into
15
6) created a new file regjade.c which uses the regexec() structure to
16
match regexp against editor buffers in place.
17
7) Altered the regexp structure to allow storing of subexpressions as
18
positions in a Jade buffer. Also altered calling conventions of
19
regsub() and regsublen() to support this.
20
8) support \w, \W, \s, \S, \d, \D, \b, \B, *?, +?, ?? syntax (as in Perl)
22
And probably some other things as well. Obviously all errors are my
23
responsibility. The original README follows,
29
This is a nearly-public-domain reimplementation of the V8 regexp(3) package.
30
It gives C programs the ability to use egrep-style regular expressions, and
31
does it in a much cleaner fashion than the analogous routines in SysV.
33
Copyright (c) 1986 by University of Toronto.
34
Written by Henry Spencer. Not derived from licensed software.
36
Permission is granted to anyone to use this software for any
37
purpose on any computer system, and to redistribute it freely,
38
subject to the following restrictions:
40
1. The author is not responsible for the consequences of use of
41
this software, no matter how awful, even if they arise
44
2. The origin of this software must not be misrepresented, either
45
by explicit claim or by omission.
47
3. Altered versions must be plainly marked as such, and must not
48
be misrepresented as being the original software.
50
Barring a couple of small items in the BUGS list, this implementation is
51
believed 100% compatible with V8. It should even be binary-compatible,
52
sort of, since the only fields in a "struct regexp" that other people have
53
any business touching are declared in exactly the same way at the same
54
location in the struct (the beginning).
56
This implementation is *NOT* AT&T/Bell code, and is not derived from licensed
57
software. Even though U of T is a V8 licensee. This software is based on
58
a V8 manual page sent to me by Dennis Ritchie (the manual page enclosed
59
here is a complete rewrite and hence is not covered by AT&T copyright).
60
The software was nearly complete at the time of arrival of our V8 tape.
61
I haven't even looked at V8 yet, although a friend elsewhere at U of T has
62
been kind enough to run a few test programs using the V8 regexp(3) to resolve
63
a few fine points. I admit to some familiarity with regular-expression
64
implementations of the past, but the only one that this code traces any
65
ancestry to is the one published in Kernighan & Plauger (from which this
66
one draws ideas but not code).
68
Simplistically: put this stuff into a source directory, copy regexp.h into
69
/usr/include, inspect Makefile for compilation options that need changing
70
to suit your local environment, and then do "make r". This compiles the
71
regexp(3) functions, compiles a test program, and runs a large set of
72
regression tests. If there are no complaints, then put regexp.o, regsub.o,
73
and regerror.o into your C library, and regexp.3 into your manual-pages
76
Note that if you don't put regexp.h into /usr/include *before* compiling,
77
you'll have to add "-I." to CFLAGS before compiling.
81
Makefile instructions to make everything
83
regexp.h header file, for /usr/include
84
regexp.c source for regcomp() and regexec()
85
regsub.c source for regsub()
86
regerror.c source for default regerror()
87
regmagic.h internal header file
88
try.c source for test program
89
timer.c source for timing program
90
tests test list for try and timer
92
This implementation uses nondeterministic automata rather than the
93
deterministic ones found in some other implementations, which makes it
94
simpler, smaller, and faster at compiling regular expressions, but slower
95
at executing them. In theory, anyway. This implementation does employ
96
some special-case optimizations to make the simpler cases (which do make
97
up the bulk of regular expressions actually used) run quickly. In general,
98
if you want blazing speed you're in the wrong place. Replacing the insides
99
of egrep with this stuff is probably a mistake; if you want your own egrep
100
you're going to have to do a lot more work. But if you want to use regular
101
expressions a little bit in something else, you're in luck. Note that many
102
existing text editors use nondeterministic regular-expression implementations,
103
so you're in good company.
105
This stuff should be pretty portable, given appropriate option settings.
106
If your chars have less than 8 bits, you're going to have to change the
107
internal representation of the automaton, although knowledge of the details
108
of this is fairly localized. There are no "reserved" char values except for
109
NUL, and no special significance is attached to the top bit of chars.
110
The string(3) functions are used a fair bit, on the grounds that they are
111
probably faster than coding the operations in line. Some attempts at code
112
tuning have been made, but this is invariably a bit machine-specific.