String.h

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/*
 * Copyright 2014-present Facebook, Inc.
 *
 * 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.
 */

#pragma once
#define FOLLY_GEN_STRING_H_

#include <folly/Range.h>
#include <folly/gen/Base.h>
#include <folly/io/IOBuf.h>

namespace folly {
namespace gen {

namespace detail {
class StringResplitter;

template <class Delimiter>
class SplitStringSource;

template <class Delimiter, class Output>
class Unsplit;

template <class Delimiter, class OutputBuffer>
class UnsplitBuffer;

template <class TargetContainer, class Delimiter, class... Targets>
class SplitTo;

} // namespace detail

// make this a template so we don't require StringResplitter to be complete
// until use
template <class S = detail::StringResplitter>
S resplit(char delimiter, bool keepDelimiter = false) {
  return S(delimiter, keepDelimiter);
}

template <class S = detail::SplitStringSource<char>>
S split(const StringPiece source, char delimiter) {
  return S(source, delimiter);
}

template <class S = detail::SplitStringSource<StringPiece>>
S split(StringPiece source, StringPiece delimiter) {
  return S(source, delimiter);
}

class MixedNewlines {};

template <class S = detail::SplitStringSource<MixedNewlines>>
S lines(StringPiece source) {
  return S(source, MixedNewlines{});
}

/*
 * Joins a sequence of tokens into a string, with the chosen delimiter.
 *
 * E.G.
 *   fbstring result = split("a,b,c", ",") | unsplit(",");
 *   assert(result == "a,b,c");
 *
 *   std::string result = split("a,b,c", ",") | unsplit<std::string>(" ");
 *   assert(result == "a b c");
 */

// NOTE: The template arguments are reversed to allow the user to cleanly
// specify the output type while still inferring the type of the delimiter.
template <
    class Output = folly::fbstring,
    class Delimiter,
    class Unsplit = detail::Unsplit<Delimiter, Output>>
Unsplit unsplit(const Delimiter& delimiter) {
  return Unsplit(delimiter);
}

template <
    class Output = folly::fbstring,
    class Unsplit = detail::Unsplit<fbstring, Output>>
Unsplit unsplit(const char* delimiter) {
  return Unsplit(delimiter);
}

/*
 * Joins a sequence of tokens into a string, appending them to the output
 * buffer.  If the output buffer is empty, an initial delimiter will not be
 * inserted at the start.
 *
 * E.G.
 *   std::string buffer;
 *   split("a,b,c", ",") | unsplit(",", &buffer);
 *   assert(buffer == "a,b,c");
 *
 *   std::string anotherBuffer("initial");
 *   split("a,b,c", ",") | unsplit(",", &anotherbuffer);
 *   assert(anotherBuffer == "initial,a,b,c");
 */
template <
    class Delimiter,
    class OutputBuffer,
    class UnsplitBuffer = detail::UnsplitBuffer<Delimiter, OutputBuffer>>
UnsplitBuffer unsplit(Delimiter delimiter, OutputBuffer* outputBuffer) {
  return UnsplitBuffer(delimiter, outputBuffer);
}

template <
    class OutputBuffer,
    class UnsplitBuffer = detail::UnsplitBuffer<fbstring, OutputBuffer>>
UnsplitBuffer unsplit(const char* delimiter, OutputBuffer* outputBuffer) {
  return UnsplitBuffer(delimiter, outputBuffer);
}

template <class... Targets>
detail::Map<detail::SplitTo<std::tuple<Targets...>, char, Targets...>>
eachToTuple(char delim) {
  return detail::Map<detail::SplitTo<std::tuple<Targets...>, char, Targets...>>(
      detail::SplitTo<std::tuple<Targets...>, char, Targets...>(delim));
}

template <class... Targets>
detail::Map<detail::SplitTo<std::tuple<Targets...>, fbstring, Targets...>>
eachToTuple(StringPiece delim) {
  return detail::Map<
      detail::SplitTo<std::tuple<Targets...>, fbstring, Targets...>>(
      detail::SplitTo<std::tuple<Targets...>, fbstring, Targets...>(delim));
}

template <class First, class Second>
detail::Map<detail::SplitTo<std::pair<First, Second>, char, First, Second>>
eachToPair(char delim) {
  return detail::Map<
      detail::SplitTo<std::pair<First, Second>, char, First, Second>>(
      detail::SplitTo<std::pair<First, Second>, char, First, Second>(delim));
}

template <class First, class Second>
detail::Map<detail::SplitTo<std::pair<First, Second>, fbstring, First, Second>>
eachToPair(StringPiece delim) {
  return detail::Map<
      detail::SplitTo<std::pair<First, Second>, fbstring, First, Second>>(
      detail::SplitTo<std::pair<First, Second>, fbstring, First, Second>(
          to<fbstring>(delim)));
}

template <class Callback>
class StreamSplitter {
 public:
  StreamSplitter(
      char delimiter,
      Callback&& pieceCb,
      uint64_t maxLength = 0,
      uint64_t initialCapacity = 0)
      : buffer_(IOBuf::CREATE, initialCapacity),
        delimiter_(delimiter),
        maxLength_(maxLength),
        pieceCb_(std::move(pieceCb)) {}

  bool flush();

  bool operator()(StringPiece in);

 private:
  // Holds the current "incomplete" chunk so that chunks can span calls to ()
  IOBuf buffer_;
  char delimiter_;
  uint64_t maxLength_; // The callback never gets more chars than this
  Callback pieceCb_;
};

template <class Callback> // Helper to enable template deduction
StreamSplitter<Callback>
streamSplitter(char delimiter, Callback&& pieceCb, uint64_t capacity = 0) {
  return StreamSplitter<Callback>(delimiter, std::move(pieceCb), capacity);
}

} // namespace gen
} // namespace folly

#include <folly/gen/String-inl.h>