Added slre_replace() in the unit test

slre.c

@@ -368,6 +368,34 @@ static int static_failed_tests = 0;
   if (!(expr)) FAIL(#expr, __LINE__);   \
 } while (0)
 
+/* Regex must have exactly one bracket pair */
+static char *slre_replace(const char *regex, const char *buf,
+                          const char *sub) {
+  char *s = NULL;
+  int n, n1, n2, n3, s_len, len = strlen(buf);
+  struct slre_cap cap = { NULL, 0 };
+
+  do {
+    s_len = s == NULL ? 0 : strlen(s);
+    if ((n = slre_match(regex, buf, len, &cap, NULL)) > 0) {
+      n1 = cap.ptr - buf, n2 = strlen(sub),
+         n3 = &buf[n] - &cap.ptr[cap.len];
+    } else {
+      n1 = len, n2 = 0, n3 = 0;
+    }
+    s = realloc(s, s_len + n1 + n2 + n3 + 1);
+    memcpy(s + s_len, buf, n1);
+    memcpy(s + s_len + n1, sub, n2);
+    memcpy(s + s_len + n1 + n2, cap.ptr + cap.len, n3);
+    s[s_len + n1 + n2 + n3] = '\0';
+
+    buf += n > 0 ? n : len;
+    len -= n > 0 ? n : len;
+  } while (len > 0);
+
+  return s;
+}
+
 int main(void) {
   const char *msg = "";
   struct slre_cap caps[10];
@@ -457,6 +485,18 @@ int main(void) {
     } else {
       printf("Error parsing [%s]: [%s]\n", request, error_msg);
     }
+
+    ASSERT(caps[1].len == 11);
+    ASSERT(memcmp(caps[1].ptr, "/index.html", caps[1].len) == 0);
+  }
+
+  {
+    char *s = slre_replace("({{.+?}})",
+                           "Good morning, {{foo}}. How are you, {{bar}}?",
+                           "Bob");
+    printf("%s\n", s);
+    ASSERT(strcmp(s, "Good morning, Bob. How are you, Bob?") == 0);
+    free(s);
   }
 
   printf("Unit test %s (total test: %d, failed tests: %d)\n",