RegexPipe.h

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// Copyright 2015, 2016 Thomas Trapp
//
// Licensed 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.
 
#ifndef HEXT_REGEX_PIPE_H_INCLUDED
#define HEXT_REGEX_PIPE_H_INCLUDED
 
/// @file
///   Declares hext::RegexPipe
 
#include "hext/Cloneable.h"
#include "hext/StringPipe.h"
#include "hext/Visibility.h"
 
#include <string>
 
#include <boost/regex.hpp>
 
 
namespace hext {
 
 
/// Filters a string according to a given regex.
///
/// @anchor RegexPipeBehavior
/// @par Regex behavior:
///   A regex containing a capture group will produce only the matched
///   content of that capture group, otherwise the whole regex match is
///   returned. All capture groups after the first one will be ignored.
///
/// @par Example regex:
///   Input                 | Regex             | Result
///   ----------------------|-------------------|-----------
///   Highway 61 revisited  |  `\d+`            | 61
///   Highway 61 revisited  |  `Highway \d+`    | Highway 61
///   Highway 61 revisited  |  `Highway (\d+)`  | 61
///   Highway 61 revisited  |  `\w+`            | Highway
///   Highway 61 revisited  |  `(\w+) (\d+)`    | Highway     (not an error)
class HEXT_PUBLIC RegexPipe final
  : public hext::Cloneable<RegexPipe, StringPipe>
{
public:
  /// Constructs a RegexPipe from a boost::regex.
  ///
  /// @param regex:  A regular expression that is applied to the string.
  ///                See @ref RegexPipeBehavior.
  explicit RegexPipe(boost::regex regex);
 
  /// Filters the string according to the regex given in the constructor.
  /// See @ref RegexPipeBehavior.
  std::string transform(std::string str) const override;
 
private:
  boost::regex regex_;
};
 
 
} // namespace hext
 
 
#endif // HEXT_REGEX_PIPE_H_INCLUDED