5f76edd296
- Extract the metric parsing routine from ranking. - Add a test. - Accept null for string view.
95 lines
3.4 KiB
C++
95 lines
3.4 KiB
C++
/**
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* Copyright 2021-2023 by XGBoost Contributors
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*/
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#ifndef XGBOOST_STRING_VIEW_H_
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#define XGBOOST_STRING_VIEW_H_
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#include <xgboost/logging.h> // CHECK_LT
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#include <xgboost/span.h> // Span
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#include <algorithm> // std::equal,std::min
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#include <iterator> // std::reverse_iterator
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#include <ostream> // std::ostream
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#include <string> // std::char_traits,std::string
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namespace xgboost {
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struct StringView {
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private:
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using CharT = char; // unsigned char
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using Traits = std::char_traits<CharT>;
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CharT const* str_{nullptr};
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size_t size_{0};
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public:
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using value_type = CharT; // NOLINT
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using iterator = const CharT*; // NOLINT
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using const_iterator = iterator; // NOLINT
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using reverse_iterator = std::reverse_iterator<const_iterator>; // NOLINT
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using const_reverse_iterator = reverse_iterator; // NOLINT
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public:
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constexpr StringView() = default;
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constexpr StringView(CharT const* str, std::size_t size) : str_{str}, size_{size} {}
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explicit StringView(std::string const& str) : str_{str.c_str()}, size_{str.size()} {}
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constexpr StringView(CharT const* str) // NOLINT
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: str_{str}, size_{str == nullptr ? 0ul : Traits::length(str)} {}
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CharT const& operator[](size_t p) const { return str_[p]; }
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CharT const& at(size_t p) const { // NOLINT
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CHECK_LT(p, size_);
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return str_[p];
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}
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constexpr std::size_t size() const { return size_; } // NOLINT
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constexpr bool empty() const { return size() == 0; } // NOLINT
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StringView substr(size_t beg, size_t n) const { // NOLINT
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CHECK_LE(beg, size_);
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size_t len = std::min(n, size_ - beg);
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return {str_ + beg, len};
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}
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CharT const* c_str() const { return str_; } // NOLINT
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constexpr CharT const* cbegin() const { return str_; } // NOLINT
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constexpr CharT const* cend() const { return str_ + size(); } // NOLINT
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constexpr CharT const* begin() const { return str_; } // NOLINT
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constexpr CharT const* end() const { return str_ + size(); } // NOLINT
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const_reverse_iterator rbegin() const noexcept { // NOLINT
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return const_reverse_iterator(this->end());
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}
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const_reverse_iterator crbegin() const noexcept { // NOLINT
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return const_reverse_iterator(this->end());
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}
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const_reverse_iterator rend() const noexcept { // NOLINT
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return const_reverse_iterator(this->begin());
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}
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const_reverse_iterator crend() const noexcept { // NOLINT
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return const_reverse_iterator(this->begin());
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}
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};
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inline std::ostream& operator<<(std::ostream& os, StringView const v) {
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for (auto c : v) {
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os.put(c);
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}
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return os;
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}
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inline bool operator==(StringView l, StringView r) {
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if (l.size() != r.size()) {
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return false;
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}
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return std::equal(l.cbegin(), l.cend(), r.cbegin());
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}
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inline bool operator!=(StringView l, StringView r) { return !(l == r); }
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inline bool operator<(StringView l, StringView r) {
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return common::Span<StringView::value_type const>{l.c_str(), l.size()} <
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common::Span<StringView::value_type const>{r.c_str(), r.size()};
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}
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inline bool operator<(std::string const& l, StringView r) { return StringView{l} < r; }
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inline bool operator<(StringView l, std::string const& r) { return l < StringView{r}; }
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} // namespace xgboost
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#endif // XGBOOST_STRING_VIEW_H_
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