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76897a9b9b
basic_json_document<BasicJsonType, true> (json_editable_document,
ordered_json_editable_document) can be edited:
- set(view, value): replace a value
- set(object, key, value): assign a member, or add it (a null becomes an
object); with duplicate keys, the first is assigned and the others go
- set(array, index, value): assign an element
- set(json_pointer, value): the member, element, or ("-", or the size of
the array) the end of an array a pointer names
- push_back(array, value): append (a null becomes an array)
Values are views (of any document, copied), BasicJsonType values, and
everything BasicJsonType can be constructed from. The source text is never
written, and the parsed index never moves: new values and element
sequences go to storage owned by the document (edit_storage.hpp), so views
stay valid, and a view keeps referring to its value (after an assignment,
it sees the new one). Read-only documents are unchanged; editing one does
not compile.
Errors are those of basic_json where the operation corresponds
(type_error.305/308, out_of_range.401/403/405, parse_error.106/109); a view
of another document is invalid_iterator.202. Strings are checked for UTF-8
when they enter the document, with the type_error.316 that
basic_json::dump() throws for the same string, so that a document only
holds valid UTF-8. Binary values cannot be stored (the new
type_error.319), and edits of 4 GiB or more end with out_of_range.416.
Views of editable and read-only documents compare with each other.
Tests (unit-json_view_edit.cpp): random assignments, member and element
changes, copies within and between documents, and pushes, applied to an
ordered_json_editable_document and to the ordered_json value; after every
edit both must serialize (also indented and with ensure_ascii),
materialize, compare, and read back the same. Further: the errors, strings
that stay valid while the edit arena grows, numbers (NaN, infinities,
extremes; number_format::source), nulls that become containers, the root
replaced, duplicate keys, values of other documents, large objects, and
documents reused with read().
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
97 lines
3.3 KiB
C++
97 lines
3.3 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 <algorithm> // min
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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/builder.hpp>
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#include <nlohmann/detail/view/macro_scope.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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// Exceptions are thrown out of line, so that the accessors that may throw stay
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// small enough to be inlined.
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[[noreturn]] NLOHMANN_VIEW_NOINLINE inline void throw_type_error(int id, const char* prefix, const char* type)
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{
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NLOHMANN_VIEW_THROW(type_error::create(id, concat(prefix, type), nullptr));
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}
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[[noreturn]] NLOHMANN_VIEW_NOINLINE inline void throw_type_error(int id, const std::string& msg)
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{
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NLOHMANN_VIEW_THROW(type_error::create(id, msg, nullptr));
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}
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[[noreturn]] NLOHMANN_VIEW_NOINLINE inline void throw_out_of_range(int id, const std::string& msg)
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{
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NLOHMANN_VIEW_THROW(out_of_range::create(id, msg, nullptr));
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}
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[[noreturn]] NLOHMANN_VIEW_NOINLINE inline void throw_invalid_iterator(int id, const char* msg)
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{
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NLOHMANN_VIEW_THROW(invalid_iterator::create(id, msg, nullptr));
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}
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/// a parse error without a position (as those of json_pointer)
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[[noreturn]] NLOHMANN_VIEW_NOINLINE inline void throw_parse_error(int id, const std::string& msg)
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{
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NLOHMANN_VIEW_THROW(parse_error::create(id, 0, msg, nullptr));
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}
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/*!
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@brief throw the exception BasicJsonType::parse would throw for this input
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The view accepts exactly the inputs parse() accepts, so on a failure the
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library parser is run on the same bytes: it throws the exception parse() would
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throw, with the same message, position, and "last read" token. The error path
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is cold, so this costs nothing on valid input. Should parse() accept the input
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nevertheless (a bug), the view's own failure is reported.
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*/
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template<typename BasicJsonType>
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[[noreturn]] NLOHMANN_VIEW_NOINLINE void throw_parse_failure(const parse_failure& f, const char* src, std::size_t size,
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bool ignore_comments, bool ignore_trailing_commas)
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{
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if (f.code == error_code::input_too_large)
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{
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// LCOV_EXCL_START (4 GiB)
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NLOHMANN_VIEW_THROW(out_of_range::create(416, "input of 4 GiB or more is not supported by json_document", nullptr));
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// LCOV_EXCL_STOP
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}
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const BasicJsonType accepted = BasicJsonType::parse(src, src + size, nullptr, true, ignore_comments, ignore_trailing_commas);
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// LCOV_EXCL_START (only if parse() accepts what the view rejects: a bug)
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static_cast<void>(accepted);
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position_t pos;
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const std::size_t off = (std::min)(f.offset, size);
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pos.chars_read_total = off + 1;
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std::size_t line_start = 0;
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for (std::size_t i = 0; i < off; ++i)
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{
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if (src[i] == '\n')
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{
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++pos.lines_read;
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line_start = i + 1;
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}
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}
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pos.chars_read_current_line = off + 1 - line_start;
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NLOHMANN_VIEW_THROW(parse_error::create(101, pos, "syntax error while parsing value", nullptr));
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// LCOV_EXCL_STOP
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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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