[C++][Gandiva] Replace RegexUtil out references with pointer out args

Author: Reranko05

cpp/src/gandiva/regex_functions_holder.cc

@@ -129,7 +129,7 @@ Result<std::shared_ptr<LikeHolder>> LikeHolder::Make(const FunctionNode& node) {
 
 Result<std::shared_ptr<LikeHolder>> LikeHolder::Make(const std::string& sql_pattern) {
   std::string pcre_pattern;
-  ARROW_RETURN_NOT_OK(RegexUtil::SqlLikePatternToPcre(sql_pattern, pcre_pattern));
+  ARROW_RETURN_NOT_OK(RegexUtil::SqlLikePatternToPcre(sql_pattern, &pcre_pattern));
 
   RE2::Options regex_op;
   regex_op.set_dot_nl(true);  // set dotall mode for the regex.
@@ -150,9 +150,9 @@ Result<std::shared_ptr<LikeHolder>> LikeHolder::Make(const std::string& sql_patt
   std::string pcre_pattern;
   if (escape_char.length() == 1) {
     ARROW_RETURN_NOT_OK(
-        RegexUtil::SqlLikePatternToPcre(sql_pattern, escape_char.at(0), pcre_pattern));
+        RegexUtil::SqlLikePatternToPcre(sql_pattern, escape_char.at(0), &pcre_pattern));
   } else {
-    ARROW_RETURN_NOT_OK(RegexUtil::SqlLikePatternToPcre(sql_pattern, pcre_pattern));
+    ARROW_RETURN_NOT_OK(RegexUtil::SqlLikePatternToPcre(sql_pattern, &pcre_pattern));
   }
 
   auto lholder = std::shared_ptr<LikeHolder>(new LikeHolder(pcre_pattern, regex_op));
@@ -166,7 +166,7 @@ Result<std::shared_ptr<LikeHolder>> LikeHolder::Make(const std::string& sql_patt
 Result<std::shared_ptr<LikeHolder>> LikeHolder::Make(const std::string& sql_pattern,
                                                      RE2::Options regex_op) {
   std::string pcre_pattern;
-  ARROW_RETURN_NOT_OK(RegexUtil::SqlLikePatternToPcre(sql_pattern, pcre_pattern));
+  ARROW_RETURN_NOT_OK(RegexUtil::SqlLikePatternToPcre(sql_pattern, &pcre_pattern));
 
   auto lholder = std::shared_ptr<LikeHolder>(new LikeHolder(pcre_pattern, regex_op));
 

cpp/src/gandiva/regex_functions_holder_test.cc

@@ -89,7 +89,7 @@ TEST_F(TestLikeHolder, TestPcreSpecialWithNewLine) {
 
 TEST_F(TestLikeHolder, TestRegexEscape) {
   std::string res;
-  ARROW_EXPECT_OK(RegexUtil::SqlLikePatternToPcre("#%hello#_abc_def##", '#', res));
+  ARROW_EXPECT_OK(RegexUtil::SqlLikePatternToPcre("#%hello#_abc_def##", '#', &res));
 
   EXPECT_EQ(res, "%hello_abc.def#");
 }

cpp/src/gandiva/regex_util.cc

@@ -23,16 +23,19 @@ const std::set<char> RegexUtil::pcre_regex_specials_ = {
     '[', ']', '(', ')', '|', '^', '-', '+', '*', '?', '{', '}', '$', '\\', '.'};
 
 Status RegexUtil::SqlLikePatternToPcre(const std::string& sql_pattern, char escape_char,
-                                       std::string& pcre_pattern) {
+                                       std::string* const pcre_pattern) {
   /// Characters that are considered special by pcre regex. These needs to be
   /// escaped with '\\'.
-  pcre_pattern.clear();
+  if (pcre_pattern == nullptr) {
+    return Status::Invalid("pcre_pattern must not be null");
+  }
+  pcre_pattern->clear();
   for (size_t idx = 0; idx < sql_pattern.size(); ++idx) {
     auto cur = sql_pattern.at(idx);
 
     // Escape any char that is special for pcre regex
     if (pcre_regex_specials_.find(cur) != pcre_regex_specials_.end()) {
-      pcre_pattern += "\\";
+      (*pcre_pattern) += "\\";
     }
 
     if (cur == escape_char) {
@@ -44,17 +47,17 @@ Status RegexUtil::SqlLikePatternToPcre(const std::string& sql_pattern, char esca
 
       cur = sql_pattern.at(idx);
       if (cur == '_' || cur == '%' || cur == escape_char) {
-        pcre_pattern += cur;
+        (*pcre_pattern) += cur;
       } else {
         return Status::Invalid("Invalid escape sequence in pattern ", sql_pattern,
                                " at offset ", idx);
       }
     } else if (cur == '_') {
-      pcre_pattern += '.';
+      (*pcre_pattern) += '.';
     } else if (cur == '%') {
-      pcre_pattern += ".*";
+      (*pcre_pattern) += ".*";
     } else {
-      pcre_pattern += cur;
+      (*pcre_pattern) += cur;
     }
   }
   return Status::OK();

cpp/src/gandiva/regex_util.h

@@ -31,10 +31,10 @@ class GANDIVA_EXPORT RegexUtil {
  public:
   // Convert an sql pattern to a pcre pattern
   static Status SqlLikePatternToPcre(const std::string& like_pattern, char escape_char,
-                                     std::string& pcre_pattern);
+                                     std::string* const pcre_pattern);
 
   static Status SqlLikePatternToPcre(const std::string& like_pattern,
-                                     std::string& pcre_pattern) {
+                                     std::string* const pcre_pattern) {
     return SqlLikePatternToPcre(like_pattern, 0 /*escape_char*/, pcre_pattern);
   }