cpp/src/gandiva/regex_util.cc

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// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
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//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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// under the License.

#include "gandiva/regex_util.h"

namespace gandiva {

const std::set<char> RegexUtil::pcre_regex_specials_ = {
    '[', ']', '(', ')', '|', '^', '-', '+', '*', '?', '{', '}', '$', '\\', '.'};

Status RegexUtil::SqlLikePatternToPcre(const std::string& sql_pattern, char escape_char,
                                       std::string& pcre_pattern) {
  /// Characters that are considered special by pcre regex. These needs to be
  /// escaped with '\\'.
  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 += "\\";
    }

    if (cur == escape_char) {
      // escape char must be followed by '_', '%' or the escape char itself.
      ++idx;
      ARROW_RETURN_IF(
          idx == sql_pattern.size(),
          Status::Invalid("Unexpected escape char at the end of pattern ", sql_pattern));

      cur = sql_pattern.at(idx);
      if (cur == '_' || cur == '%' || cur == escape_char) {
        pcre_pattern += cur;
      } else {
        return Status::Invalid("Invalid escape sequence in pattern ", sql_pattern,
                               " at offset ", idx);
      }
    } else if (cur == '_') {
      pcre_pattern += '.';
    } else if (cur == '%') {
      pcre_pattern += ".*";
    } else {
      pcre_pattern += cur;
    }
  }
  return Status::OK();
}

}  // namespace gandiva