plugins/experimental/access_control/pattern.h

/*
  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/

/**
 * @file pattern.h
 * @brief PRCE related classes (header file).
 */

#pragma once

#include "common.h"

class Regex;

/**
 * @brief PCRE2 matching, capturing and replacing
 */
class Pattern
{
public:
  static const int TOKENCOUNT = 10; /**< @brief Capturing groups $0..$9 */

  Pattern();
  ~Pattern(); // Keep in pattern.cc for pimpl use of Regex.

  bool   init(const String &pattern, const String &replacement, bool replace);
  bool   init(const String &config);
  bool   empty() const;
  bool   match(const String &subject);
  bool   capture(const String &subject, StringVector &result);
  bool   replace(const String &subject, String &result);
  bool   process(const String &subject, StringVector &result);
  String getPattern();

private:
  bool compile();

  std::unique_ptr<Regex> _re; /**< @brief Regex compiled object, computed during initialization */

  String _pattern;     /**< @brief PCRE2 pattern string, containing PCRE2 patterns and capturing groups. */
  String _replacement; /**< @brief PCRE2 replacement string with $0..$9 placeholders for capturing groups */

  bool _replace = false; /**< @brief true if a replacement is needed, false if not, this is to distinguish between an empty
                    replacement string and no replacement needed case */

  int _tokenCount = 0;          /**< @brief number of replacements $0..$9 found in the replacement string if not empty */
  int _tokens[TOKENCOUNT];      /**< @brief replacement index 0..9, since they can be used in the replacement string in any order */
  int _tokenOffset[TOKENCOUNT]; /**< @brief replacement offset inside the replacement string */
};

/**
 * @brief Named list of regular expressions.
 */
class MultiPattern
{
public:
  MultiPattern(const String &name = "") : _name(name) {}
  virtual ~MultiPattern();

  bool          empty() const;
  void          add(std::unique_ptr<Pattern> pattern);
  virtual bool  match(const String &subject) const;
  virtual bool  match(const String &subject, String &pattern) const;
  const String &name() const;

protected:
  std::vector<std::unique_ptr<Pattern>> _list; /**< @brief vector which dictates the order of the pattern evaluation. */
  String                                _name; /**< @brief multi-pattern name */

  // noncopyable
  MultiPattern(const MultiPattern &)            = delete; // disallow
  MultiPattern &operator=(const MultiPattern &) = delete; // disallow
};

/**
 * @brief Named list of non-matching regular expressions.
 */
class NonMatchingMultiPattern : public MultiPattern
{
public:
  NonMatchingMultiPattern(const String &name) { _name = name; }
  /*
   * @brief Matches the subject string against all patterns.
   * @param subject subject string
   * @return return false if any of the patterns matches, true otherwise.
   */
  bool
  match(const String &subject) const override
  {
    return !MultiPattern::match(subject);
  }

  bool
  match(const String &subject, String &pattern) const override
  {
    return !MultiPattern::match(subject, pattern);
  }

  // noncopyable
  NonMatchingMultiPattern(const NonMatchingMultiPattern &)            = delete; // disallow
  NonMatchingMultiPattern &operator=(const NonMatchingMultiPattern &) = delete; // disallow
};

/**
 * @brief Simple classifier which classifies a subject string using a list of named multi-patterns.
 */
class Classifier
{
public:
  Classifier() {}
  ~Classifier();

  bool classify(const String &subject, String &name) const;
  bool classify(const String &subject, String &name, String &pattern) const;
  bool matchAll(const String &subject, String &name, String &pattern) const;

  void add(std::unique_ptr<MultiPattern> pattern);
  bool empty();

  // noncopyable
  Classifier(const Classifier &)            = delete; // disallow
  Classifier &operator=(const Classifier &) = delete; // disallow

private:
  std::vector<std::unique_ptr<MultiPattern>> _list; /**< @brief vector which dictates the multi-pattern evaluation order */
};