1 files changed, 120 insertions, 0 deletions
diff --git a/regsub.c b/regsub.c
new file mode 100644
index 0000000..4039b9b
--- /dev/null
+++ b/regsub.c
@@ -0,0 +1,120 @@
+/* $OpenBSD$ */
+
+/*
+ * Copyright (c) 2019 Nicholas Marriott <nicholas.marriott@gmail.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+
+#include <regex.h>
+#include <string.h>
+
+#include "tmux.h"
+
+static void
+regsub_copy(char **buf, size_t *len, const char *text, size_t start, size_t end)
+{
+	size_t	add = end - start;
+
+	*buf = xrealloc(*buf, (*len) + add + 1);
+	memcpy((*buf) + *len, text + start, add);
+	(*len) += add;
+}
+
+static void
+regsub_expand(char **buf, size_t *len, const char *with, const char *text,
+    regmatch_t *m, u_int n)
+{
+	const char	*cp;
+	u_int		 i;
+
+	for (cp = with; *cp != '\0'; cp++) {
+		if (*cp == '\\') {
+			cp++;
+			if (*cp >= '0' && *cp <= '9') {
+				i = *cp - '0';
+				if (i < n && m[i].rm_so != m[i].rm_eo) {
+					regsub_copy(buf, len, text, m[i].rm_so,
+					    m[i].rm_eo);
+					continue;
+				}
+			}
+		}
+		*buf = xrealloc(*buf, (*len) + 2);
+		(*buf)[(*len)++] = *cp;
+	}
+}
+
+char *
+regsub(const char *pattern, const char *with, const char *text, int flags)
+{
+	regex_t		 r;
+	regmatch_t	 m[10];
+	ssize_t		 start, end, last, len = 0;
+	int		 empty = 0;
+	char		*buf = NULL;
+
+	if (*text == '\0')
+		return (xstrdup(""));
+	if (regcomp(&r, pattern, flags) != 0)
+		return (NULL);
+
+	start = 0;
+	last = 0;
+	end = strlen(text);
+
+	while (start <= end) {
+		if (regexec(&r, text + start, nitems(m), m, 0) != 0) {
+			regsub_copy(&buf, &len, text, start, end);
+			break;
+		}
+
+		/*
+		 * Append any text not part of this match (from the end of the
+		 * last match).
+		 */
+		regsub_copy(&buf, &len, text, last, m[0].rm_so + start);
+
+		/*
+		 * If the last match was empty and this one isn't (it is either
+		 * later or has matched text), expand this match. If it is
+		 * empty, move on one character and try again from there.
+		 */
+		if (empty ||
+		    start + m[0].rm_so != last ||
+		    m[0].rm_so != m[0].rm_eo) {
+			regsub_expand(&buf, &len, with, text + start, m,
+			    nitems(m));
+
+			last = start + m[0].rm_eo;
+			start += m[0].rm_eo;
+			empty = 0;
+		} else {
+			last = start + m[0].rm_eo;
+			start += m[0].rm_eo + 1;
+			empty = 1;
+		}
+
+		/* Stop now if anchored to start. */
+		if (*pattern == '^') {
+			regsub_copy(&buf, &len, text, start, end);
+			break;
+		}
+	}
+	buf[len] = '\0';
+
+	regfree(&r);
+	return (buf);
+}