imported Henry Spencer's regex implementation from Tcl

Source: github.com/garyhouston/hsrex

* This version should be a Thompson NFA, using backtracking only
  for backreferences, so it should be much safer than PCRE (GRegex).
  Search times should be linear and there should be no way to cause
  stack overflows (unless we would generate backreferences).
* Importing the lib makes sure we don't add another compile-time
  dependency. Also, we could implement our own regcomp() which
  translates directly from TECO patterns.
* This is still WIP and currently only works with the ASCII version.
  The widechar version does not define re_comp() and re_exec().
* Apparently we can't have an ASCII and widechar version at the same time,
  so we must build two libtool libraries and somehow mangle the names.
* Ideally the widechar version will also work with UTF-8 strings.
* An alternative might be to import the Gnulib regex module.
  How does it choose the encoding anyway?
* Or we could just use Oniguruma - but this would have to be a new
  external library dependency.

1 files changed, 60 insertions, 0 deletions

diff --git a/contrib/hsrex/regfree.c b/contrib/hsrex/regfree.c
new file mode 100644
index 0000000..b0aaa70
--- /dev/null
+++ b/contrib/hsrex/regfree.c
@@ -0,0 +1,60 @@
+/*
+ * regfree - free an RE
+ *
+ * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
+ *
+ * Development of this software was funded, in part, by Cray Research Inc.,
+ * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
+ * Corporation, none of whom are responsible for the results.  The author
+ * thanks all of them.
+ *
+ * Redistribution and use in source and binary forms -- with or without
+ * modification -- are permitted for any purpose, provided that
+ * redistributions in source form retain this entire copyright notice and
+ * indicate the origin and nature of any modifications.
+ *
+ * I'd appreciate being given credit for this package in the documentation of
+ * software which uses it, but that is not a requirement.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
+ * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * You might think that this could be incorporated into regcomp.c, and that
+ * would be a reasonable idea... except that this is a generic function (with
+ * a generic name), applicable to all compiled REs regardless of the size of
+ * their characters, whereas the stuff in regcomp.c gets compiled once per
+ * character size.
+ */
+
+#include "regguts.h"
+
+/*
+ - regfree - free an RE (generic function, punts to RE-specific function)
+ *
+ * Ignoring invocation with NULL is a convenience.
+ */
+void
+regfree(
+    regex_t *re)
+{
+    if (re == NULL) {
+	return;
+    }
+    (*((struct fns *)re->re_fns)->free)(re);
+}
+
+/*
+ * Local Variables:
+ * mode: c
+ * c-basic-offset: 4
+ * fill-column: 78
+ * End:
+ */