filterx: regexp_subst auto-disable 'groups' when no match groups are …

…present

The function now automatically checks the replacement pattern at config
parsing time. If no match group references are found in the pattern, it
will behave as if the 'groups' option is disabled, disabling match group
functionality for performance reasons.

By default, match groups are enabled in regexp_subst. However, this behavior
can now be explicitly disabled by setting the optional named argument
groups=false, as shown:
`regexp_subst(target, match_pattern, replace_pattern, groups=false);`

Signed-off-by: shifter <shifter@axoflow.com>

lib/filterx/expr-regexp-subst.c

@@ -160,7 +160,6 @@ _replace_matches(const FilterXFuncRegexpSubst *self, FilterXReMatchState *state)
       _build_replacement_stirng_with_match_groups(self, state, rep_str);
       replacement_string = rep_str->str;
     }
-
   do
     {
       ovector = pcre2_get_ovector_pointer(state->match_data);
@@ -296,6 +295,13 @@ _extract_optional_flags(FilterXFuncRegexpSubst *self, FilterXFunctionArgs *args,
   return TRUE;
 }
 
+static gboolean
+_contains_match_grp_ref(gchar *str)
+{
+  gchar *close = NULL;
+  return _next_matchgrp_ref(str, &close) != NULL;
+}
+
 static gboolean
 _extract_subst_args(FilterXFuncRegexpSubst *self, FilterXFunctionArgs *args, GError **error)
 {
@@ -320,7 +326,9 @@ _extract_subst_args(FilterXFuncRegexpSubst *self, FilterXFunctionArgs *args, GEr
   self->replacement = _extract_subst_replacement_arg(args, error);
   if (!self->replacement)
     return FALSE;
-
+  // turn off group mode if there is no match grp ref due to it's performance impact
+  if (!_contains_match_grp_ref(self->replacement))
+    set_flag(&self->flags, FILTERX_FUNC_REGEXP_SUBST_FLAG_GROUPS, FALSE);
 
   return TRUE;
 }
@@ -365,7 +373,8 @@ filterx_function_regexp_subst_new(FilterXFunctionArgs *args, GError **error)
   self->super.super.deinit = _subst_deinit;
   self->super.super.free_fn = _subst_free;
 
-  reset_flags(&self->flags, FLAG_VAL(FILTERX_FUNC_REGEXP_SUBST_FLAG_JIT));
+  reset_flags(&self->flags, FLAG_VAL(FILTERX_FUNC_REGEXP_SUBST_FLAG_JIT) | FLAG_VAL(
+                FILTERX_FUNC_REGEXP_SUBST_FLAG_GROUPS));
   if (!_extract_subst_args(self, args, error) ||
       !filterx_function_args_check(args, error))
     goto error;

lib/filterx/tests/test_expr_regexp_subst.c

@@ -69,9 +69,9 @@ _build_subst_func(const gchar *pattern, const gchar *repr, const gchar *str, Fil
   if (opts.utf8)
     args = g_list_append(args, filterx_function_arg_new(FILTERX_FUNC_REGEXP_SUBST_FLAG_UTF8_NAME,
                                                         filterx_literal_new(filterx_boolean_new(TRUE))));
-  if (opts.groups)
+  if (!opts.groups)
     args = g_list_append(args, filterx_function_arg_new(FILTERX_FUNC_REGEXP_SUBST_FLAG_GROUPS_NAME,
-                                                        filterx_literal_new(filterx_boolean_new(TRUE))));
+                                                        filterx_literal_new(filterx_boolean_new(FALSE))));
 
   GError *err = NULL;
   FilterXExpr *func = filterx_function_regexp_subst_new(filterx_function_args_new(args, NULL), &err);