mirror of
https://github.com/arun11299/cpp-jwt.git
synced 2025-05-15 09:18:33 +00:00
353 lines
9.3 KiB
C++
353 lines
9.3 KiB
C++
#ifndef JWT_STRING_VIEW_HPP
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#define JWT_STRING_VIEW_HPP
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#include <limits>
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#include <string>
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#include <cassert>
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namespace jwt {
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/*
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* Implements c++17 string_view.
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* Could have used boost::string_ref, but wanted to
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* keep boost dependency off from this library.
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*/
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template <
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typename CharT,
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typename Traits = std::char_traits<CharT>
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>
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class basic_string_view
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{
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public: // Member Types
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using traits_type = std::char_traits<CharT>;
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using value_type = CharT;
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using pointer = const CharT*;
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using const_pointer = const CharT*;
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using reference = const CharT&;
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using const_reference = const CharT&;
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using iterator = const CharT*;
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using const_iterator = const CharT*;
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using reverse_iterator = std::reverse_iterator<iterator>;
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using const_reverse_iterator = std::reverse_iterator<const_iterator>;
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using size_type = size_t;
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using difference_type = std::ptrdiff_t;
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static constexpr size_type npos = size_type(-1);
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public: // 'tors
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/// The default constructor;
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basic_string_view() = default;
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/// Construct from string literal
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basic_string_view(const CharT* str) noexcept
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: data_(str)
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, len_(str ? traits_type::length(str) : 0)
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{
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}
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/// Construct from CharT pointer and provided length
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basic_string_view(const CharT* p, size_type len) noexcept
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: data_(p)
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, len_(len)
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{
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}
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/// Construct from std::string
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template <typename Allocator>
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basic_string_view(
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const std::basic_string<CharT, Traits, Allocator>& str) noexcept
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: data_(str.data())
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, len_(str.length())
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{
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}
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/// Copy constructor
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basic_string_view(const basic_string_view&) = default;
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/// Assignment operator
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basic_string_view& operator=(const basic_string_view&) = default;
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/// Destructor
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~basic_string_view()
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{
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data_ = nullptr;
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len_ = 0;
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}
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public: // Exposed APIs
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/// Iterator Member Functions
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iterator begin() const noexcept { return data_; }
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iterator end() const noexcept { return data_ + len_; }
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iterator rbegin() const noexcept { return reverse_iterator(end()); }
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iterator rend() const noexcept { return reverse_iterator(begin()); }
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const_iterator cbegin() const noexcept { return begin(); }
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const_iterator cend() const noexcept { return end(); }
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const_iterator crbegin() const noexcept { return rbegin(); }
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const_iterator crend() const noexcept { return rend(); }
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/// Capacity Member Functions
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size_type length() const noexcept { return len_; }
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size_type size() const noexcept { return len_; }
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size_type max_size() const noexcept
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{
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return (npos - sizeof(size_type) - sizeof(void*))
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/ sizeof(value_type) / 4;
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}
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bool empty() const noexcept { return len_ == 0; }
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/// Element Access Member Functions
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const_reference operator[](size_type idx) const noexcept
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{
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return data_[idx];
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}
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// NOTE: 'at' not supported
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//CharT at(size_type idx) const;
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const_reference front() const noexcept
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{
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return data_[0];
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}
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const_reference back() const noexcept
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{
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return data_[len_ - 1];
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}
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const_pointer data() const noexcept
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{
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return data_;
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}
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/// Modifier Member Functions
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void remove_prefix(size_type n) noexcept
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{
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assert (n < len_ && "Data would point out of bounds");
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data_ += n;
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len_ -= n;
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}
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void remove_suffix(size_type n) noexcept
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{
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assert (n < len_ && "Suffix length more than data length");
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len_ -= n;
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}
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void swap(basic_string_view& other)
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{
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std::swap(data_, other.data_);
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std::swap(len_, other.len_);
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}
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/// String Operation Member Functions
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template <typename Allocator>
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explicit operator std::basic_string<CharT, Traits, Allocator>() const
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{
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return {data_, len_};
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}
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template <typename Allocator = std::allocator<CharT>>
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std::basic_string<CharT, Traits, Allocator>
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to_string(const Allocator& alloc = Allocator()) const
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{
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return {data_, len_, alloc};
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}
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// NOTE: Does not throw
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size_type copy(CharT* dest, size_type n, size_type pos = 0) const noexcept
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{
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assert (pos < len_ && n < len_);
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size_type to_copy = std::min(n, len_ - pos);
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for (size_type i = 0; i < to_copy; i++) {
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dest[i] = data_[i + pos];
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}
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return to_copy;
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}
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// NOTE: Does not throw
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basic_string_view substr(size_type pos, size_type n = npos) const noexcept
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{
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assert (pos < len_ && "Start position should be less than length of the view");
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assert (n == npos ? 1 : (n - pos) < len_ &&
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"Substring length asked for is more than the view length");
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if (n == npos) n = len_;
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return basic_string_view{data_ + pos, n};
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}
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/// Comparison Member Functions
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int compare(const basic_string_view& other) const noexcept
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{
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int ret = traits_type::compare(data_, other.data_, std::min(len_, other.len_));
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if (ret == 0) {
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ret = compare_length(len_, other.len_);
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}
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return ret;
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}
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int compare(size_type pos, size_type n, basic_string_view other) const noexcept
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{
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return substr(pos, n).compare(other);
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}
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int compare(const CharT* str) const noexcept
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{
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return compare(basic_string_view{str});
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}
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int compare(size_type pos, size_type n, const CharT* str) const noexcept
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{
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return compare(pos, n, basic_string_view{str});
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}
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int compare(size_type pos, size_type n1, const CharT* str, size_type n2) const noexcept
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{
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return compare(pos, n1, basic_string_view{str, n2});
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}
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/// Find operations
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size_type find(const CharT* str, size_type pos, size_type n) const noexcept;
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size_type find(const CharT ch, size_type pos) const noexcept;
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size_type find(basic_string_view sv, size_type pos = 0) const noexcept
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{
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return find(sv.data(), pos, sv.length());
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}
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size_type find(const CharT* str, size_type pos = 0) const noexcept
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{
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return find(str, pos, traits_type::length(str));
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}
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size_type rfind(const CharT* str, size_type pos, size_type n) const noexcept;
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size_type rfind(const CharT ch, size_type pos) const noexcept;
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size_type rfind(basic_string_view sv, size_type pos = 0) const noexcept
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{
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return rfind(sv.data(), pos, sv.length());
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}
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size_type rfind(const CharT* str, size_type pos = 0) const noexcept
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{
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return rfind(str, pos, traits_type::length(str));
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}
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size_type find_first_of(const CharT* str, size_type pos, size_type count) const noexcept;
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size_type find_first_of(basic_string_view str, size_type pos = 0) const noexcept
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{
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return find_first_of(str.data(), pos, str.length());
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}
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size_type find_first_of(CharT ch, size_type pos = 0) const noexcept
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{
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return find(ch, pos);
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}
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size_type find_first_of(const CharT* str, size_type pos = 0) const noexcept
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{
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return find_first_of(str, pos, traits_type::length(str));
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}
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size_type find_last_of(const CharT* str, size_type pos, size_type count) const noexcept;
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size_type find_last_of(basic_string_view str, size_type pos = npos) const noexcept
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{
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return find_last_of(str.data(), (pos == npos ? len_ - 1 : pos), str.length());
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}
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size_type find_last_of(CharT ch, size_type pos = npos) const noexcept
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{
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return rfind(ch, pos == npos ? len_ - 1 : pos);
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}
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size_type find_last_of(const CharT* str, size_type pos = npos) const noexcept
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{
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return find_last_of(str, (pos == npos ? len_ - 1 : pos), traits_type::length(str));
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}
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size_type find_first_not_of(const CharT* str, size_type pos, size_type n) const noexcept;
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size_type find_first_not_of(CharT ch, size_type pos) const noexcept;
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size_type find_first_not_of(basic_string_view str, size_type pos = 0) const noexcept
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{
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return find_first_not_of(str.data(), pos, str.length());
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}
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size_type find_first_not_of(const CharT* str, size_type pos = 0) const noexcept
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{
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return find_first_not_of(str, pos, traits_type::length(str));
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}
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size_type find_last_not_of(const CharT* str, size_type pos, size_type n) const noexcept;
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size_type find_last_not_of(CharT ch, size_type pos) const noexcept;
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size_type find_last_not_of(basic_string_view str, size_type pos = npos) const noexcept
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{
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return find_last_not_of(str.data(), (pos == npos ? len_ - 1 : pos), str.length());
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}
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size_type find_last_not_of(const CharT* str, size_type pos = npos) const noexcept
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{
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return find_last_not_of(str, (pos == npos ? len_ - 1 : pos), traits_type::length(str));
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}
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/// Comparison operators Member Functions
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/*
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friend bool operator== (basic_string_view a, basic_string_view b) noexcept;
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friend bool operator!= (basic_string_view a, basic_string_view b) noexcept;
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friend bool operator< (basic_string_view a, basic_string_view b) noexcept;
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friend bool operator> (basic_string_view a, basic_string_view b) noexcept;
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friend bool operator<= (basic_string_view a, basic_string_view b) noexcept;
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friend bool operator>= (basic_string_view a, basic_string_view b) noexcept;
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*/
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private: // private implementations
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static constexpr int compare_length(size_type n1, size_type n2) noexcept
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{
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return static_cast<difference_type>(n1 - n2) > std::numeric_limits<int>::max()
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? std::numeric_limits<int>::max()
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: static_cast<difference_type>(n1 - n2) < std::numeric_limits<int>::min()
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? std::numeric_limits<int>::min()
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: static_cast<int>(n1 - n2)
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;
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}
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private:
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// This is what view is basically...
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const char* data_ = nullptr;
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size_type len_ = 0;
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};
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/// Helper typedef
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using string_view = basic_string_view<char>;
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} // END namespace jwt
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#include "jwt/impl/string_view.ipp"
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#endif
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