regex-matcher.cpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013-2021 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
 * ndn-cxx library is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * ndn-cxx library 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 Lesser General Public License for more details.
 *
 * You should have received copies of the GNU General Public License and GNU Lesser
 * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
 *
 * @author Yingdi Yu <http://irl.cs.ucla.edu/~yingdi/>
 */

#include "ndn-cxx/util/regex/regex-matcher.hpp"

namespace ndn {

RegexMatcher::RegexMatcher(const std::string& expr, RegexExprType type,
                           shared_ptr<RegexBackrefManager> backrefManager)
  : m_expr(expr)
  , m_type(type)
{
  if (backrefManager)
    m_backrefManager = std::move(backrefManager);
  else
    m_backrefManager = make_shared<RegexBackrefManager>();
}

RegexMatcher::~RegexMatcher() = default;

bool
RegexMatcher::match(const Name& name, size_t offset, size_t len)
{
  m_matchResult.clear();

  if (recursiveMatch(0, name, offset, len)) {
    for (size_t i = offset; i < offset + len; i++)
      m_matchResult.push_back(name.get(i));
    return true;
  }

  return false;
}

bool
RegexMatcher::recursiveMatch(size_t matcherNo, const Name& name, size_t offset, size_t len)
{
  if (matcherNo >= m_matchers.size())
    return len == 0;

  ssize_t tried = len;
  auto matcher = m_matchers[matcherNo];

  while (tried >= 0) {
    if (matcher->match(name, offset, tried) &&
        recursiveMatch(matcherNo + 1, name, offset + tried, len - tried))
      return true;
    tried--;
  }

  return false;
}

std::ostream&
operator<<(std::ostream& os, const RegexMatcher& rm)
{
  return os << rm.getExpr();
}

} // namespace ndn