// Copyright 2017 The Abseil Authors.

//

// 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

//

//      https://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.

//

// This file declares INTERNAL parts of the Split API that are inline/templated

// or otherwise need to be available at compile time. The main abstractions

// defined in here are

//

//   - ConvertibleToStringView

//   - SplitIterator<>

//   - Splitter<>

//

// DO NOT INCLUDE THIS FILE DIRECTLY. Use this file by including

// absl/strings/str_split.h.

//

// IWYU pragma: private, include "absl/strings/str_split.h"

#ifndef ABSL_STRINGS_INTERNAL_STR_SPLIT_INTERNAL_H_

#define ABSL_STRINGS_INTERNAL_STR_SPLIT_INTERNAL_H_

#include <array>

#include <initializer_list>

#include <iterator>

#include <tuple>

#include <type_traits>

#include <utility>

#include <vector>

#include "absl/base/macros.h"

#include "absl/base/port.h"

#include "absl/meta/type_traits.h"

#include "absl/strings/string_view.h"

#ifdef _GLIBCXX_DEBUG

#include "absl/strings/internal/stl_type_traits.h"

#endif  // _GLIBCXX_DEBUG

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace strings_internal {

// This class is implicitly constructible from everything that absl::string_view

// is implicitly constructible from, except for rvalue strings.  This means it

// can be used as a function parameter in places where passing a temporary

// string might cause memory lifetime issues.

class ConvertibleToStringView {

 public:

  ConvertibleToStringView(const char* s)  // NOLINT(runtime/explicit)

      : value_(s) {}

  ConvertibleToStringView(char* s) : value_(s) {}  // NOLINT(runtime/explicit)

  ConvertibleToStringView(absl::string_view s)     // NOLINT(runtime/explicit)

      : value_(s) {}

  ConvertibleToStringView(const std::string& s)  // NOLINT(runtime/explicit)

      : value_(s) {}

  // Disable conversion from rvalue strings.

  ConvertibleToStringView(std::string&& s) = delete;

  ConvertibleToStringView(const std::string&& s) = delete;

  absl::string_view value() const { return value_; }

 private:

  absl::string_view value_;

};

// An iterator that enumerates the parts of a string from a Splitter. The text

// to be split, the Delimiter, and the Predicate are all taken from the given

// Splitter object. Iterators may only be compared if they refer to the same

// Splitter instance.

//

// This class is NOT part of the public splitting API.

template <typename Splitter>

class SplitIterator {

 public:

  using iterator_category = std::input_iterator_tag;

  using value_type = absl::string_view;

  using difference_type = ptrdiff_t;

  using pointer = const value_type*;

  using reference = const value_type&;

  enum State { kInitState, kLastState, kEndState };

  SplitIterator(State state, const Splitter* splitter)

      : pos_(0),

        state_(state),

        splitter_(splitter),

        delimiter_(splitter->delimiter()),

        predicate_(splitter->predicate()) {

    // Hack to maintain backward compatibility. This one block makes it so an

    // empty absl::string_view whose .data() happens to be nullptr behaves

    // *differently* from an otherwise empty absl::string_view whose .data() is

    // not nullptr. This is an undesirable difference in general, but this

    // behavior is maintained to avoid breaking existing code that happens to

    // depend on this old behavior/bug. Perhaps it will be fixed one day. The

    // difference in behavior is as follows:

    //   Split(absl::string_view(""), '-');  // {""}

    //   Split(absl::string_view(), '-');    // {}

    if (splitter_->text().data() == nullptr) {

      state_ = kEndState;

      pos_ = splitter_->text().size();

      return;

    }

    if (state_ == kEndState) {

      pos_ = splitter_->text().size();

    } else {

      ++(*this);

    }

  }

  bool at_end() const { return state_ == kEndState; }

  reference operator*() const { return curr_; }

  pointer operator->() const { return &curr_; }

  SplitIterator& operator++() {

    do {

      if (state_ == kLastState) {

        state_ = kEndState;

        return *this;

      }

      const absl::string_view text = splitter_->text();

      const absl::string_view d = delimiter_.Find(text, pos_);

      if (d.data() == text.data() + text.size()) state_ = kLastState;

      curr_ = text.substr(pos_,

                          static_cast<size_t>(d.data() - (text.data() + pos_)));

      pos_ += curr_.size() + d.size();

    } while (!predicate_(curr_));

    return *this;

  }

  SplitIterator operator++(int) {

    SplitIterator old(*this);

    ++(*this);

    return old;

  }

  friend bool operator==(const SplitIterator& a, const SplitIterator& b) {

    return a.state_ == b.state_ && a.pos_ == b.pos_;

  }

  friend bool operator!=(const SplitIterator& a, const SplitIterator& b) {

    return !(a == b);

  }

 private:

  size_t pos_;

  State state_;

  absl::string_view curr_;

  const Splitter* splitter_;

  typename Splitter::DelimiterType delimiter_;

  typename Splitter::PredicateType predicate_;

};

// HasMappedType<T>::value is true iff there exists a type T::mapped_type.

template <typename T, typename = void>

struct HasMappedType : std::false_type {};

template <typename T>

struct HasMappedType<T, absl::void_t<typename T::mapped_type>>

    : std::true_type {};

// HasValueType<T>::value is true iff there exists a type T::value_type.

template <typename T, typename = void>

struct HasValueType : std::false_type {};

template <typename T>

struct HasValueType<T, absl::void_t<typename T::value_type>> : std::true_type {

};

// HasConstIterator<T>::value is true iff there exists a type T::const_iterator.

template <typename T, typename = void>

struct HasConstIterator : std::false_type {};

template <typename T>

struct HasConstIterator<T, absl::void_t<typename T::const_iterator>>

    : std::true_type {};

// HasEmplace<T>::value is true iff there exists a method T::emplace().

template <typename T, typename = void>

struct HasEmplace : std::false_type {};

template <typename T>

struct HasEmplace<T, absl::void_t<decltype(std::declval<T>().emplace())>>

    : std::true_type {};

// IsInitializerList<T>::value is true iff T is an std::initializer_list. More

// details below in Splitter<> where this is used.

std::false_type IsInitializerListDispatch(...);  // default: No

template <typename T>

std::true_type IsInitializerListDispatch(std::initializer_list<T>*);

template <typename T>

struct IsInitializerList

    : decltype(IsInitializerListDispatch(static_cast<T*>(nullptr))) {};

// A SplitterIsConvertibleTo<C>::type alias exists iff the specified condition

// is true for type 'C'.

//

// Restricts conversion to container-like types (by testing for the presence of

// a const_iterator member type) and also to disable conversion to an

// std::initializer_list (which also has a const_iterator). Otherwise, code

// compiled in C++11 will get an error due to ambiguous conversion paths (in

// C++11 std::vector<T>::operator= is overloaded to take either a std::vector<T>

// or an std::initializer_list<T>).

template <typename C, bool has_value_type, bool has_mapped_type>

struct SplitterIsConvertibleToImpl : std::false_type {};

template <typename C>

struct SplitterIsConvertibleToImpl<C, true, false>

    : std::is_constructible<typename C::value_type, absl::string_view> {};

template <typename C>

struct SplitterIsConvertibleToImpl<C, true, true>

    : absl::conjunction<

          std::is_constructible<typename C::key_type, absl::string_view>,

          std::is_constructible<typename C::mapped_type, absl::string_view>> {};

template <typename C>

struct SplitterIsConvertibleTo

    : SplitterIsConvertibleToImpl<

          C,

#ifdef _GLIBCXX_DEBUG

          !IsStrictlyBaseOfAndConvertibleToSTLContainer<C>::value &&

#endif  // _GLIBCXX_DEBUG

              !IsInitializerList<

                  typename std::remove_reference<C>::type>::value &&

              HasValueType<C>::value && HasConstIterator<C>::value,

          HasMappedType<C>::value> {

};

template <typename StringType, typename Container, typename = void>

struct ShouldUseLifetimeBound : std::false_type {};

template <typename StringType, typename Container>

struct ShouldUseLifetimeBound<

    StringType, Container,

    std::enable_if_t<

        std::is_same<StringType, std::string>::value &&

        std::is_same<typename Container::value_type, absl::string_view>::value>>

    : std::true_type {};

template <typename StringType, typename First, typename Second>

using ShouldUseLifetimeBoundForPair = std::integral_constant<

    bool, std::is_same<StringType, std::string>::value &&

              (std::is_same<First, absl::string_view>::value ||

               std::is_same<Second, absl::string_view>::value)>;

// This class implements the range that is returned by absl::StrSplit(). This

// class has templated conversion operators that allow it to be implicitly

// converted to a variety of types that the caller may have specified on the

// left-hand side of an assignment.

//

// The main interface for interacting with this class is through its implicit

// conversion operators. However, this class may also be used like a container

// in that it has .begin() and .end() member functions. It may also be used

// within a range-for loop.

//

// Output containers can be collections of any type that is constructible from

// an absl::string_view.

//

// An Predicate functor may be supplied. This predicate will be used to filter

// the split strings: only strings for which the predicate returns true will be

// kept. A Predicate object is any unary functor that takes an absl::string_view

// and returns bool.

//

// The StringType parameter can be either string_view or string, depending on

// whether the Splitter refers to a string stored elsewhere, or if the string

// resides inside the Splitter itself.

template <typename Delimiter, typename Predicate, typename StringType>

class Splitter {

 public:

  using DelimiterType = Delimiter;

  using PredicateType = Predicate;

  using const_iterator = strings_internal::SplitIterator<Splitter>;

  using value_type = typename std::iterator_traits<const_iterator>::value_type;

  Splitter(StringType input_text, Delimiter d, Predicate p)

      : text_(std::move(input_text)),

        delimiter_(std::move(d)),

        predicate_(std::move(p)) {}

  absl::string_view text() const { return text_; }

  const Delimiter& delimiter() const { return delimiter_; }

  const Predicate& predicate() const { return predicate_; }

  // Range functions that iterate the split substrings as absl::string_view

  // objects. These methods enable a Splitter to be used in a range-based for

  // loop.

  const_iterator begin() const { return {const_iterator::kInitState, this}; }

  const_iterator end() const { return {const_iterator::kEndState, this}; }

  // An implicit conversion operator that is restricted to only those containers

  // that the splitter is convertible to.

  template <

      typename Container,

      std::enable_if_t<ShouldUseLifetimeBound<StringType, Container>::value &&

                           SplitterIsConvertibleTo<Container>::value,

                       std::nullptr_t> = nullptr>

  // NOLINTNEXTLINE(google-explicit-constructor)

  operator Container() const ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return ConvertToContainer<Container, typename Container::value_type,

                              HasMappedType<Container>::value>()(*this);

  }

  template <

      typename Container,

      std::enable_if_t<!ShouldUseLifetimeBound<StringType, Container>::value &&

                           SplitterIsConvertibleTo<Container>::value,

                       std::nullptr_t> = nullptr>

  // NOLINTNEXTLINE(google-explicit-constructor)

  operator Container() const {

    return ConvertToContainer<Container, typename Container::value_type,

                              HasMappedType<Container>::value>()(*this);

  }

Unexecuted instantiation: absl::strings_internal::Splitter<absl::ByChar, absl::AllowEmpty, absl::string_view>::operator std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > ><std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > >, (decltype(nullptr))0>() const

absl::strings_internal::Splitter<absl::ByChar, absl::AllowEmpty, absl::string_view>::operator std::__1::vector<absl::string_view, std::__1::allocator<absl::string_view> ><std::__1::vector<absl::string_view, std::__1::allocator<absl::string_view> >, (decltype(nullptr))0>() const

Line

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5.98M

  operator Container() const {

320

5.98M

    return ConvertToContainer<Container, typename Container::value_type,

321

5.98M

                              HasMappedType<Container>::value>()(*this);

322

5.98M

  }

  // Returns a pair with its .first and .second members set to the first two

  // strings returned by the begin() iterator. Either/both of .first and .second

  // will be constructed with empty strings if the iterator doesn't have a

  // corresponding value.

  template <typename First, typename Second,

            std::enable_if_t<

                ShouldUseLifetimeBoundForPair<StringType, First, Second>::value,

                std::nullptr_t> = nullptr>

  // NOLINTNEXTLINE(google-explicit-constructor)

  operator std::pair<First, Second>() const ABSL_ATTRIBUTE_LIFETIME_BOUND {

    return ConvertToPair<First, Second>();

  }

  template <typename First, typename Second,

            std::enable_if_t<!ShouldUseLifetimeBoundForPair<StringType, First,

                                                            Second>::value,

                             std::nullptr_t> = nullptr>

  // NOLINTNEXTLINE(google-explicit-constructor)

  operator std::pair<First, Second>() const {

    return ConvertToPair<First, Second>();

  }

 private:

  template <typename First, typename Second>

  std::pair<First, Second> ConvertToPair() const {

    absl::string_view first, second;

    auto it = begin();

    if (it != end()) {

      first = *it;

      if (++it != end()) {

        second = *it;

      }

    }

    return {First(first), Second(second)};

  }

  // ConvertToContainer is a functor converting a Splitter to the requested

  // Container of ValueType. It is specialized below to optimize splitting to

  // certain combinations of Container and ValueType.

  //

  // This base template handles the generic case of storing the split results in

  // the requested non-map-like container and converting the split substrings to

  // the requested type.

  template <typename Container, typename ValueType, bool is_map = false>

  struct ConvertToContainer {

    Container operator()(const Splitter& splitter) const {

      Container c;

      auto it = std::inserter(c, c.end());

      for (const auto& sp : splitter) {

        *it++ = ValueType(sp);

      }

      return c;

    }

  };

  // Partial specialization for a std::vector<absl::string_view>.

  //

  // Optimized for the common case of splitting to a

  // std::vector<absl::string_view>. In this case we first split the results to

  // a small array of absl::string_view on the stack, to reduce reallocations.

  template <typename A>

  struct ConvertToContainer<std::vector<absl::string_view, A>,

                            absl::string_view, false> {

    std::vector<absl::string_view, A> operator()(

        const Splitter& splitter) const {

      struct raw_view {

        const char* data;

        size_t size;

        operator absl::string_view() const {  // NOLINT(runtime/explicit)

          return {data, size};

        }

      };

      std::vector<absl::string_view, A> v;

      std::array<raw_view, 16> ar;

      for (auto it = splitter.begin(); !it.at_end();) {

        size_t index = 0;

        do {

          ar[index].data = it->data();

          ar[index].size = it->size();

          ++it;

        } while (++index != ar.size() && !it.at_end());

        v.insert(v.end(), ar.begin(), ar.begin() + index);

      }

      return v;

    }

  };

  // Partial specialization for a std::vector<std::string>.

  //

  // Optimized for the common case of splitting to a std::vector<std::string>.

  // In this case we first split the results to a std::vector<absl::string_view>

  // so the returned std::vector<std::string> can have space reserved to avoid

  // std::string moves.

  template <typename A>

  struct ConvertToContainer<std::vector<std::string, A>, std::string, false> {

    std::vector<std::string, A> operator()(const Splitter& splitter) const {

      const std::vector<absl::string_view> v = splitter;

      return std::vector<std::string, A>(v.begin(), v.end());

    }

  };

  // Partial specialization for containers of pairs (e.g., maps).

  //

  // The algorithm is to insert a new pair into the map for each even-numbered

  // item, with the even-numbered item as the key with a default-constructed

  // value. Each odd-numbered item will then be assigned to the last pair's

  // value.

  template <typename Container, typename First, typename Second>

  struct ConvertToContainer<Container, std::pair<const First, Second>, true> {

    using iterator = typename Container::iterator;

    Container operator()(const Splitter& splitter) const {

      Container m;

      iterator it;

      bool insert = true;

      for (const absl::string_view sv : splitter) {

        if (insert) {

          it = InsertOrEmplace(&m, sv);

        } else {

          it->second = Second(sv);

        }

        insert = !insert;

      }

      return m;

    }

    // Inserts the key and an empty value into the map, returning an iterator to

    // the inserted item. We use emplace() if available, otherwise insert().

    template <typename M>

    static absl::enable_if_t<HasEmplace<M>::value, iterator> InsertOrEmplace(

        M* m, absl::string_view key) {

      // Use piecewise_construct to support old versions of gcc in which pair

      // constructor can't otherwise construct string from string_view.

      return ToIter(m->emplace(std::piecewise_construct, std::make_tuple(key),

                               std::tuple<>()));

    }

    template <typename M>

    static absl::enable_if_t<!HasEmplace<M>::value, iterator> InsertOrEmplace(

        M* m, absl::string_view key) {

      return ToIter(m->insert(std::make_pair(First(key), Second(""))));

    }

    static iterator ToIter(std::pair<iterator, bool> pair) {

      return pair.first;

    }

    static iterator ToIter(iterator iter) { return iter; }

  };

  StringType text_;

  Delimiter delimiter_;

  Predicate predicate_;

};

}  // namespace strings_internal

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_STRINGS_INTERNAL_STR_SPLIT_INTERNAL_H_