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Add iterator+sentinel tests and docs for binary deserializers (#5265)
* Add iterator+sentinel tests and docs for binary deserializers This commit extends the C++20 ranges support (iterator+sentinel pairs) to the binary format deserializers from_cbor, from_msgpack, from_ubjson, from_bjdata, and from_bson, matching what was already done for parse(), accept(), and sax_parse(). Changes: - Add istreambuf_sentinel helper to test_utils.hpp for EOF detection in tests - Add 5 new test cases that read binary files directly via std::istreambuf_iterator<char> + sentinel, without pre-buffering - Update documentation for all 5 from_* functions to document overload (3) with SentinelType parameter - All tests pass; verified against existing test suite data - Fix potential buffer over-read warning in heterogeneous iterator test Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Merge iterator+sentinel overloads and fix ambiguity/CI issues Address PR review feedback and CI failures: - Merge the separate same-type and sentinel-type iterator overloads of parse(), accept(), sax_parse(), and the five from_* binary deserializers into a single overload with SentinelType defaulted to IteratorType, as suggested in review. Applied the same simplification to the detail::input_adapter() free functions. - Fix a latent ambiguity: some compilers (e.g. GCC 4.8) unreliably SFINAE the operator!= detection for std::nullptr_t against container/string types, making calls like parse(s, nullptr, ...) ambiguous with the compatible-input overload. can_compare_ne now explicitly excludes std::nullptr_t as a SentinelType. - Use a named enable_if_t template parameter instead of an unnamed function parameter for the SFINAE guard, fixing a clang-tidy hicpp-named-parameter/readability-named-parameter failure. - Update parse.md, accept.md, sax_parse.md, and the five from_*.md pages to document the merged overload instead of separate (2)/(3) overloads, also fixing an over-160-char line that broke the documentation style_check CI job. - Rework the BSON iterator+sentinel test to parse a BSON file already present in the test suite instead of writing/deleting a temp file. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix -Wunneeded-internal-declaration for CustomSentinel in test CustomSentinel lives in an anonymous namespace (internal linkage), and the library's parse loop only ever evaluates the iterator-first direction (it != last), so the reversed-order friend operator!= was never referenced. Clang's -Weverything flags such unused internal declarations as an error. Drop the unused overload; the used direction is enough to satisfy can_compare_ne's either-order detection. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy hicpp-named-parameter and misc-const-correctness - Drop the unused reversed-order operator!= overload from utils::istreambuf_sentinel (only iterator != sentinel is ever evaluated) and name the remaining friend's sentinel parameter, fixing hicpp-named-parameter/readability-named-parameter. - Mark the istreambuf_iterator first/last helper variable const in the five binary-format sentinel tests, fixing misc-const-correctness. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy misc-const-correctness in heterogeneous sentinel test json_str is only read via .data()/.size() and never reassigned, so clang-tidy correctly flags it as const-able. Verified against the exact CI job (silkeh/clang:dev, ci_clang_tidy target) by running clang-tidy directly on this file plus the five binary-format sentinel tests touched by prior commits; all are now clean. Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann
GitHub
@@ -155,7 +155,9 @@ class input_stream_adapter
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// General-purpose iterator-based adapter. It might not be as fast as
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// theoretically possible for some containers, but it is extremely versatile.
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template<typename IteratorType>
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// SentinelType defaults to IteratorType for backward compatibility, but may
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// be a different type (e.g., a C++20 sentinel or counted_iterator).
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template<typename IteratorType, typename SentinelType = IteratorType>
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class iterator_input_adapter
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{
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public:
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@@ -169,9 +171,10 @@ class iterator_input_adapter
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// in wide_string_input_adapter, which does not expose this).
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static constexpr bool supports_seek =
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std::is_same<typename std::iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value
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&& std::is_same<IteratorType, SentinelType>::value
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&& sizeof(char_type) == 1;
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iterator_input_adapter(IteratorType first, IteratorType last)
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iterator_input_adapter(IteratorType first, SentinelType last)
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: begin(first), current(std::move(first)), end(std::move(last))
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{}
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@@ -216,12 +219,14 @@ class iterator_input_adapter
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private:
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// whether IteratorType refers to a contiguous range and therefore supports
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// a std::memcpy fast path (pointers always do; in C++20 we can also detect
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// library iterators such as those of std::vector and std::string)
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// library iterators such as those of std::vector and std::string).
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// The fast path also requires SentinelType == IteratorType so std::distance works.
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static constexpr bool iterator_is_contiguous =
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std::is_same<IteratorType, SentinelType>::value && (
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#if defined(__cpp_lib_concepts) && defined(JSON_HAS_CPP_20)
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std::contiguous_iterator<IteratorType> ||
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std::contiguous_iterator<IteratorType> ||
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#endif
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std::is_pointer<IteratorType>::value;
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std::is_pointer<IteratorType>::value);
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// contiguous fast path: bulk copy the remaining range with std::memcpy
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template<class T>
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@@ -267,7 +272,7 @@ class iterator_input_adapter
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IteratorType begin;
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IteratorType current;
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IteratorType end;
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SentinelType end;
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template<typename BaseInputAdapter, size_t T>
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friend struct wide_string_input_helper;
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@@ -453,19 +458,54 @@ class wide_string_input_adapter
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std::size_t utf8_bytes_filled = 0;
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};
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template<typename IteratorType, typename Enable = void>
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template<typename IteratorType, typename SentinelType = IteratorType, typename Enable = void>
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struct iterator_input_adapter_factory
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{
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using iterator_type = IteratorType;
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using sentinel_type = SentinelType;
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using char_type = typename std::iterator_traits<iterator_type>::value_type;
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using adapter_type = iterator_input_adapter<iterator_type>;
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using adapter_type = iterator_input_adapter<iterator_type, sentinel_type>;
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static adapter_type create(IteratorType first, IteratorType last)
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static adapter_type create(IteratorType first, SentinelType last)
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{
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return adapter_type(std::move(first), std::move(last));
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}
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};
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// Detection: whether IteratorType and SentinelType can be compared with !=
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template<typename IteratorType, typename SentinelType, typename = void>
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struct can_compare_ne_impl : std::false_type {};
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template<typename IteratorType, typename SentinelType>
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struct can_compare_ne_impl < IteratorType, SentinelType,
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void_t < decltype(std::declval<IteratorType>() != std::declval<SentinelType>()) >>
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: std::true_type {};
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// Workaround for reversed operator order
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template<typename IteratorType, typename SentinelType, typename = void>
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struct can_compare_ne_reversed : std::false_type {};
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template<typename IteratorType, typename SentinelType>
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struct can_compare_ne_reversed < IteratorType, SentinelType,
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void_t < decltype(std::declval<SentinelType>() != std::declval<IteratorType>()) >>
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: std::true_type {};
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template<typename IteratorType, typename SentinelType>
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struct can_compare_ne_either_order : std::integral_constant < bool,
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can_compare_ne_impl<IteratorType, SentinelType>::value ||
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can_compare_ne_reversed<IteratorType, SentinelType>::value > {};
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// std::nullptr_t is excluded explicitly: a literal `nullptr` passed as a
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// trailing default argument (e.g. parse(s, nullptr, ...)) must never be
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// mistaken for a sentinel, and some compilers (e.g. GCC 4.8) unreliably
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// SFINAE the `operator!=` detection above for std::nullptr_t against
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// container/string types, which would otherwise make such calls ambiguous
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// with the compatible-input overload.
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template<typename IteratorType, typename SentinelType>
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struct can_compare_ne : std::integral_constant < bool,
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!std::is_same<SentinelType, std::nullptr_t>::value &&
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can_compare_ne_either_order<IteratorType, SentinelType>::value > {};
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template<typename T>
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struct is_iterator_of_multibyte
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{
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@@ -476,25 +516,31 @@ struct is_iterator_of_multibyte
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};
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};
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template<typename IteratorType>
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struct iterator_input_adapter_factory<IteratorType, enable_if_t<is_iterator_of_multibyte<IteratorType>::value>>
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template<typename IteratorType, typename SentinelType>
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struct iterator_input_adapter_factory<IteratorType, SentinelType, enable_if_t<is_iterator_of_multibyte<IteratorType>::value>>
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{
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using iterator_type = IteratorType;
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using sentinel_type = SentinelType;
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using char_type = typename std::iterator_traits<iterator_type>::value_type;
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using base_adapter_type = iterator_input_adapter<iterator_type>;
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using base_adapter_type = iterator_input_adapter<iterator_type, sentinel_type>;
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using adapter_type = wide_string_input_adapter<base_adapter_type, char_type>;
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static adapter_type create(IteratorType first, IteratorType last)
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static adapter_type create(IteratorType first, SentinelType last)
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{
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return adapter_type(base_adapter_type(std::move(first), std::move(last)));
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}
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};
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// General purpose iterator-based input
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template<typename IteratorType>
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typename iterator_input_adapter_factory<IteratorType>::adapter_type input_adapter(IteratorType first, IteratorType last)
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// General purpose iterator-based input (iterator+sentinel pair; SentinelType
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// defaults to IteratorType for the common same-type case, but may differ for
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// C++20 ranges-style iterator+sentinel pairs). Only enable for types that can
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// be compared with !=.
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template < typename IteratorType, typename SentinelType = IteratorType,
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typename = typename std::enable_if <
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can_compare_ne<IteratorType, SentinelType>::value >::type >
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typename iterator_input_adapter_factory<IteratorType, SentinelType>::adapter_type input_adapter(IteratorType first, SentinelType last)
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{
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using factory_type = iterator_input_adapter_factory<IteratorType>;
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using factory_type = iterator_input_adapter_factory<IteratorType, SentinelType>;
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return factory_type::create(first, last);
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}
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+32
-24
@@ -4083,12 +4083,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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return result;
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}
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/// @brief deserialize from a pair of character iterators
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/// @brief deserialize from a pair of character iterators (or an iterator+sentinel pair, C++20 ranges support)
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/// @sa https://json.nlohmann.me/api/basic_json/parse/
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template<typename IteratorType>
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template<typename IteratorType, typename SentinelType = IteratorType,
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detail::enable_if_t<detail::can_compare_ne<IteratorType, SentinelType>::value, int> = 0>
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JSON_HEDLEY_WARN_UNUSED_RESULT
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static basic_json parse(IteratorType first,
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IteratorType last,
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SentinelType last,
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parser_callback_t cb = nullptr,
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const bool allow_exceptions = true,
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const bool ignore_comments = false,
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@@ -4122,10 +4123,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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return parser(detail::input_adapter(std::forward<InputType>(i)), nullptr, false, ignore_comments, ignore_trailing_commas).accept(true);
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}
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/// @brief check if the input is valid JSON
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/// @brief check if the input is valid JSON (iterator pair, or iterator+sentinel pair for C++20 ranges support)
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/// @sa https://json.nlohmann.me/api/basic_json/accept/
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template<typename IteratorType>
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static bool accept(IteratorType first, IteratorType last,
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template<typename IteratorType, typename SentinelType = IteratorType,
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detail::enable_if_t<detail::can_compare_ne<IteratorType, SentinelType>::value, int> = 0>
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static bool accept(IteratorType first, SentinelType last,
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const bool ignore_comments = false,
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const bool ignore_trailing_commas = false)
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{
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@@ -4157,11 +4159,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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: detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(format, sax, strict);
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}
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/// @brief generate SAX events
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/// @brief generate SAX events (iterator pair, or iterator+sentinel pair for C++20 ranges support)
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/// @sa https://json.nlohmann.me/api/basic_json/sax_parse/
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template<class IteratorType, class SAX>
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template<class IteratorType, class SAX, class SentinelType = IteratorType,
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detail::enable_if_t<detail::can_compare_ne<IteratorType, SentinelType>::value, int> = 0>
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JSON_HEDLEY_NON_NULL(3)
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static bool sax_parse(IteratorType first, IteratorType last, SAX* sax,
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static bool sax_parse(IteratorType first, SentinelType last, SAX* sax,
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input_format_t format = input_format_t::json,
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const bool strict = true,
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const bool ignore_comments = false,
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@@ -4461,11 +4464,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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return res ? result : basic_json(value_t::discarded);
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}
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/// @brief create a JSON value from an input in CBOR format
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/// @brief create a JSON value from an input in CBOR format (iterator pair, or iterator+sentinel pair for C++20 ranges support)
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/// @sa https://json.nlohmann.me/api/basic_json/from_cbor/
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template<typename IteratorType>
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template<typename IteratorType, typename SentinelType = IteratorType,
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detail::enable_if_t<detail::can_compare_ne<IteratorType, SentinelType>::value, int> = 0>
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JSON_HEDLEY_WARN_UNUSED_RESULT
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static basic_json from_cbor(IteratorType first, IteratorType last,
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static basic_json from_cbor(IteratorType first, SentinelType last,
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const bool strict = true,
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const bool allow_exceptions = true,
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const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error)
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@@ -4518,11 +4522,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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return res ? result : basic_json(value_t::discarded);
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}
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/// @brief create a JSON value from an input in MessagePack format
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/// @brief create a JSON value from an input in MessagePack format (iterator pair, or iterator+sentinel pair for C++20 ranges support)
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/// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
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template<typename IteratorType>
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template<typename IteratorType, typename SentinelType = IteratorType,
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detail::enable_if_t<detail::can_compare_ne<IteratorType, SentinelType>::value, int> = 0>
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JSON_HEDLEY_WARN_UNUSED_RESULT
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static basic_json from_msgpack(IteratorType first, IteratorType last,
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static basic_json from_msgpack(IteratorType first, SentinelType last,
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const bool strict = true,
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const bool allow_exceptions = true)
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{
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@@ -4572,11 +4577,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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return res ? result : basic_json(value_t::discarded);
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}
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/// @brief create a JSON value from an input in UBJSON format
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/// @brief create a JSON value from an input in UBJSON format (iterator pair, or iterator+sentinel pair for C++20 ranges support)
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/// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
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template<typename IteratorType>
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template<typename IteratorType, typename SentinelType = IteratorType,
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detail::enable_if_t<detail::can_compare_ne<IteratorType, SentinelType>::value, int> = 0>
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JSON_HEDLEY_WARN_UNUSED_RESULT
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static basic_json from_ubjson(IteratorType first, IteratorType last,
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static basic_json from_ubjson(IteratorType first, SentinelType last,
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const bool strict = true,
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const bool allow_exceptions = true)
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{
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@@ -4626,11 +4632,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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return res ? result : basic_json(value_t::discarded);
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}
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/// @brief create a JSON value from an input in BJData format
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/// @brief create a JSON value from an input in BJData format (iterator pair, or iterator+sentinel pair for C++20 ranges support)
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/// @sa https://json.nlohmann.me/api/basic_json/from_bjdata/
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template<typename IteratorType>
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template<typename IteratorType, typename SentinelType = IteratorType,
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detail::enable_if_t<detail::can_compare_ne<IteratorType, SentinelType>::value, int> = 0>
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JSON_HEDLEY_WARN_UNUSED_RESULT
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static basic_json from_bjdata(IteratorType first, IteratorType last,
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static basic_json from_bjdata(IteratorType first, SentinelType last,
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const bool strict = true,
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const bool allow_exceptions = true)
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{
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@@ -4656,11 +4663,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
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return res ? result : basic_json(value_t::discarded);
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}
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/// @brief create a JSON value from an input in BSON format
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/// @brief create a JSON value from an input in BSON format (iterator pair, or iterator+sentinel pair for C++20 ranges support)
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/// @sa https://json.nlohmann.me/api/basic_json/from_bson/
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template<typename IteratorType>
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template<typename IteratorType, typename SentinelType = IteratorType,
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detail::enable_if_t<detail::can_compare_ne<IteratorType, SentinelType>::value, int> = 0>
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JSON_HEDLEY_WARN_UNUSED_RESULT
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static basic_json from_bson(IteratorType first, IteratorType last,
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static basic_json from_bson(IteratorType first, SentinelType last,
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const bool strict = true,
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const bool allow_exceptions = true)
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{
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