mirror of
https://github.com/nlohmann/json.git
synced 2026-10-01 05:23:47 +07:00
Niels Lohmann
be837d5470
The public classes of the zero-copy view (#5295), in the new header <nlohmann/json_view.hpp>: - basic_json_document<BasicJsonType>: parse (borrowing contiguous byte inputs, owning rvalue strings, streams, and other inputs), parse_copy, accept, read, root, is_discarded, source, owns_source, node_count, memory_usage, shrink_to_fit - basic_json_view<BasicJsonType>: type and the is_* queries, size, empty, materialize (the value parse() would produce, built by the same SAX handler), source_offset - the aliases json_document, json_view, ordered_json_document, and ordered_json_view A parse error throws the exception basic_json::parse would throw for the same input: the library parser is run on the failing input, so messages, positions, and exception ids are the same. Inputs of 4 GiB or more are rejected with out_of_range.416. The single header single_include/nlohmann/json_view.hpp keeps including json.hpp; make amalgamate, check-amalgamation, include.zip, and release handle it. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
74 lines
2.1 KiB
C++
74 lines
2.1 KiB
C++
// __ _____ _____ _____
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// __| | __| | | | JSON for Modern C++
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// | | |__ | | | | | | version 3.12.0
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// |_____|_____|_____|_|___| https://github.com/nlohmann/json
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//
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// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
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// SPDX-License-Identifier: MIT
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#pragma once
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#include <cstddef> // size_t
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#include <string> // string
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#include <nlohmann/json.hpp>
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#include <nlohmann/detail/view/macro_scope.hpp>
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#include <nlohmann/detail/view/node.hpp>
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NLOHMANN_JSON_NAMESPACE_BEGIN
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namespace detail
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{
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namespace view
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{
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/*!
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@brief the value of the float token of a node, as parse() converts it
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Uses the lexer's conversion (detail::convert_float_fast, then the locale-aware
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strtod fallback), so that the values are bit-identical to parse(). The digit
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layout recorded while parsing locates the decimal point and the exponent
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without scanning the token.
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*/
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template<typename FloatType>
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NLOHMANN_VIEW_NOINLINE FloatType float_value(const char* first, const node& n)
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{
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const char* const last = first + n.len;
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const std::size_t neg = first[0] == '-' ? 1 : 0;
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const std::size_t int_digits = n.extra & 0xFFu;
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const std::size_t frac_digits = n.extra >> 8u;
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std::size_t dot = std::string::npos;
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std::size_t mantissa_end = n.len;
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if (int_digits != 255 && frac_digits != 255)
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{
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dot = frac_digits != 0 ? neg + int_digits : std::string::npos;
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mantissa_end = neg + int_digits + (frac_digits != 0 ? 1 + frac_digits : 0);
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}
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else
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{
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// more digits than the layout records: locate them
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for (std::size_t i = 0; i < n.len; ++i)
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{
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if (first[i] == '.')
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{
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dot = i;
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}
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else if (first[i] == 'e' || first[i] == 'E')
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{
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mantissa_end = i;
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break;
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}
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}
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}
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FloatType v{};
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if (!convert_float_fast(first, last, dot, mantissa_end, v))
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{
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std::string token(first, last);
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convert_float_locale_aware(token, dot, v);
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}
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return v;
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}
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} // namespace view
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} // namespace detail
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NLOHMANN_JSON_NAMESPACE_END
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