From 5edfa74e0f4b9830b4a3c8ac0662bde60c4ea8be Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Tue, 25 Nov 1997 11:19:39 +0000
Subject: [PATCH] Added regex library interface.

---
 lib/lib.h   |   9 ++++
 lib/regex.c | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 132 insertions(+)
 create mode 100644 lib/regex.c

diff --git a/lib/lib.h b/lib/lib.h
index 137c2472..24d7e352 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -140,3 +140,12 @@ uns nextprime(uns);
 
 void init_timer(void);
 uns get_timer(void);
+
+/* regex.c */
+
+typedef struct regex regex;
+
+regex *rx_compile(byte *r);
+void rx_free(regex *r);
+int rx_match(regex *r, byte *s);
+int rx_subst(regex *r, byte *by, byte *src, byte *dest, uns destlen);
diff --git a/lib/regex.c b/lib/regex.c
new file mode 100644
index 00000000..31a13845
--- /dev/null
+++ b/lib/regex.c
@@ -0,0 +1,123 @@
+/*
+ *	Sherlock Library -- Regular Expressions
+ *
+ *	(c) 1997 Martin Mares, <mj@atrey.karlin.mff.cuni.cz>
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <regex.h>
+
+#include "lib.h"
+
+#define INITIAL_MEM 1024		/* Initial space allocated for each pattern */
+
+struct regex {
+  struct re_pattern_buffer buf;
+  struct re_registers regs;		/* Must not change between re_match() calls */
+};
+
+regex *
+rx_compile(byte *p)
+{
+  regex *r = xmalloc(sizeof(regex));
+  const char *msg;
+
+  bzero(r, sizeof(*r));
+  r->buf.buffer = xmalloc(INITIAL_MEM);
+  r->buf.allocated = INITIAL_MEM;
+  msg = re_compile_pattern(p, strlen(p), &r->buf);
+  if (!msg)
+    return r;
+  die("Error parsing pattern `%s': %s", p, msg);
+}
+
+void
+rx_free(regex *r)
+{
+  free(r->buf.buffer);
+  free(r);
+}
+
+int
+rx_match(regex *r, byte *s)
+{
+  uns len = strlen(s);
+
+  if (re_match(&r->buf, s, len, 0, &r->regs) < 0)
+    return 0;
+  if (r->regs.start[0] || r->regs.end[0] != len) /* XXX: Why regex doesn't enforce implicit "^...$" ? */
+    return 0;
+  return 1;
+}
+
+int
+rx_subst(regex *r, byte *by, byte *src, byte *dest, uns destlen)
+{
+  byte *end = dest + destlen - 1;
+
+  if (!rx_match(r, src))
+    return 0;
+
+  while (*by)
+    {
+      if (*by == '\\')
+	{
+	  by++;
+	  if (*by >= '0' && *by <= '9')	/* \0 gets replaced by entire pattern */
+	    {
+	      int j = *by++ - '0';
+	      byte *s = src + r->regs.start[j];
+	      int i = r->regs.end[j] - r->regs.start[j];
+	      if (dest + i >= end)
+		return -1;
+	      memcpy(dest, s, i);
+	      dest += i;
+	      continue;
+	    }
+	}
+      if (dest < end)
+	*dest++ = *by++;
+      else
+	return -1;
+    }
+  *dest = 0;
+  return 1;
+}
+
+#ifdef TEST
+
+void main(int argc, char **argv)
+{
+  regex *r;
+  byte buf1[256], buf2[256];
+
+  r = rx_compile(argv[1]);
+  while (fgets(buf1, sizeof(buf1), stdin))
+    {
+      char *p = strchr(buf1, '\n');
+      if (p)
+	*p = 0;
+      if (argc == 2)
+	{
+	  if (rx_match(r, buf1))
+	    puts("MATCH");
+	  else
+	    puts("NO MATCH");
+	}
+      else
+	{
+	  int i = rx_subst(r, argv[2], buf1, buf2, sizeof(buf2));
+	  if (i < 0)
+	    puts("OVERFLOW");
+	  else if (!i)
+	    puts("NO MATCH");
+	  else
+	    puts(buf2);
+	}
+    }
+  rx_free(r);
+}
+
+#endif
-- 
2.39.5