string_view.hpp

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/*
 * Copyright (c) 2019-2024, NVIDIA CORPORATION.
 *
 * 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://apache.ac.cn/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

#include <cudf/types.hpp>

#include <cuda_runtime.h>

#include <iterator>

namespace CUDF_EXPORT cudf {

using char_utf8 = uint32_t;

class string_view {
 public
 CUDF_HOST_DEVICE [[nodiscard]] inline size_type size_bytes() const { return _bytes; }
 [[nodiscard]] __device__ inline size_type length() const;
 CUDF_HOST_DEVICE [[nodiscard]] inline char const* data() const { return _data; }

 CUDF_HOST_DEVICE [[nodiscard]] inline bool empty() const { return size_bytes() == 0; }

 class const_iterator {
 public
 using difference_type = ptrdiff_t;
 using value_type = char_utf8;
 using reference = char_utf8&;
 using pointer = char_utf8*;
 using iterator_category = std::input_iterator_tag;
 __device__ inline const_iterator(string_view const& str, size_type pos);
 const_iterator(const_iterator const& mit) = default;
 const_iterator(const_iterator&& mit) = default;
 const_iterator& operator=(const_iterator const&) = default;
 const_iterator& operator=(const_iterator&&) = default;
 __device__ inline const_iterator& operator++();
 __device__ inline const_iterator operator++(int);
 __device__ inline const_iterator& operator+=(difference_type);
 __device__ inline const_iterator operator+(difference_type) const;
 __device__ inline const_iterator& operator--();
 __device__ inline const_iterator operator--(int);
 __device__ inline const_iterator& operator-=(difference_type);
 __device__ inline const_iterator operator-(difference_type) const;
 __device__ inline const_iterator& move_to(size_type);
 __device__ inline bool operator==(const_iterator const&) const;
 __device__ inline bool operator!=(const_iterator const&) const;
 __device__ inline bool operator<(const_iterator const&) const;
 __device__ inline bool operator<=(const_iterator const&) const;
 __device__ inline bool operator>(const_iterator const&) const;
 __device__ inline bool operator>=(const_iterator const&) const;
 __device__ inline char_utf8 operator*() const;
 [[nodiscard]] __device__ inline size_type position() const;
 [[nodiscard]] __device__ inline size_type byte_offset() const;

 private
 friend class string_view;
 char const* p{};
 size_type bytes{};
 size_type char_pos{};
 size_type byte_pos{};
 __device__ inline const_iterator(string_view const& str, size_type pos, size_type offset);
 };

 [[nodiscard]] __device__ inline const_iterator begin() const;
 [[nodiscard]] __device__ inline const_iterator end() const;

 __device__ inline char_utf8 operator[](size_type pos) const;
 [[nodiscard]] __device__ inline size_type byte_offset(size_type pos) const;

 [[nodiscard]] __device__ inline int compare(string_view const& str) const;
 __device__ inline int compare(char const* str, size_type bytes) const;

 __device__ inline bool operator==(string_view const& rhs) const;
 __device__ inline bool operator!=(string_view const& rhs) const;
 __device__ inline bool operator<(string_view const& rhs) const;
 __device__ inline bool operator>(string_view const& rhs) const;
 __device__ inline bool operator<=(string_view const& rhs) const;
 __device__ inline bool operator>=(string_view const& rhs) const;

 [[nodiscard]] __device__ inline size_type find(string_view const& str,
 size_type pos = 0,
 size_type count = -1) const;
 __device__ inline size_type find(char const* str,
 size_type bytes,
 size_type pos = 0,
 size_type count = -1) const;
 [[nodiscard]] __device__ inline size_type find(char_utf8 character,
 size_type pos = 0,
 size_type count = -1) const;
 [[nodiscard]] __device__ inline size_type rfind(string_view const& str,
 size_type pos = 0,
 size_type count = -1) const;
 __device__ inline size_type rfind(char const* str,
 size_type bytes,
 size_type pos = 0,
 size_type count = -1) const;
 [[nodiscard]] __device__ inline size_type rfind(char_utf8 character,
 size_type pos = 0,
 size_type count = -1) const;

 [[nodiscard]] __device__ inline string_view substr(size_type start, size_type length) const;

 CUDF_HOST_DEVICE inline static string_view min();

 CUDF_HOST_DEVICE inline static string_view max();

 CUDF_HOST_DEVICE inline string_view() : _data("") {}

 CUDF_HOST_DEVICE inline string_view(char const* data, size_type bytes)
 : _data(data), _bytes(bytes), _length(UNKNOWN_STRING_LENGTH)
 {
 }

 string_view(string_view const&) = default;
 string_view(string_view&&) = default;
 ~string_view() = default;
 string_view& operator=(string_view const&) = default;
 string_view& operator=(string_view&&) = default;

 static inline cudf::size_type const npos{-1};

 private
 char const* _data{};
 size_type _bytes{};
 mutable size_type _length{};

 static inline cudf::size_type const UNKNOWN_STRING_LENGTH{-1};

 [[nodiscard]] __device__ inline size_type character_offset(size_type bytepos) const;

 template <bool forward>
 __device__ inline size_type find_impl(char const* str,
 size_type bytes,
 size_type pos,
 size_type count) const;
};

} // namespace CUDF_EXPORT cudf