pattern_matcher.cc

/*
   Copyright (c) 2017, 2024, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is designed to work with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
*/

#include "pattern_matcher.h"

#include "my_dbug.h"
#include "my_sys.h"

struct CHARSET_INFO;

/**
  @brief Parses concatenated patterns and adds them to internal pattern list

  @param[in] patterns     concatenated patterns
  @param[in] delimiter    delimiter for pattern concatenation

  @return                 number of added patterns
*/
size_t Pattern_matcher::add_patterns(const std::string &patterns,
                                     char delimiter) {
  DBUG_TRACE;
  const size_t length = patterns.length();
  size_t pattern_count = 0;

  // we don't parse empty patterns
  if (length == 0) return pattern_count;

  size_t first = 0;
  size_t last = 0;
  do {
    // find end of the token
    if ((last = patterns.find(delimiter, first)) == std::string::npos)
      last = length;

    // we store only tokens that are not empty
    if (last - first > 0) {
      m_patterns.emplace(patterns, first, last - first);
      ++pattern_count;
    }

    first = last + 1;
  } while (last != length);

  return pattern_count;
}

/**
  @brief Verifies whether text matches any of the matcher internal patterns

  @param[in]  text      string to search for patterns
  @param[in]  info      charset information for comparison rules

  @return               result of matching the text to internal patterns
    @retval   true        at least one pattern matches provided string
    @retval   false       string does not match any of the patterns
*/
bool Pattern_matcher::is_matching(const std::string &text,
                                  const CHARSET_INFO *info) const {
  DBUG_TRACE;

  // traverse all patterns, return true on first match
  for (auto &pattern : m_patterns) {
    if (info->coll->wildcmp(info, text.c_str(), text.c_str() + text.length(),
                            pattern.c_str(), pattern.c_str() + pattern.length(),
                            WILD_ESCAPE, WILD_ONE, WILD_MANY) == 0) {
      return true;
    }
  }
  // none of the patterns matched
  return false;
}

/**
  @brief Removes all previously stored patterns from pattern matcher
*/
void Pattern_matcher::clear() { m_patterns.clear(); }