Add json_document and json_view, a read-only, zero-copy index of a
JSON text, as the first public slice of the zero-copy view (#5295).
A parse produces a flat array of 16-byte nodes in document order,
one per value and one per object key. Strings stay in the source
text; escaped strings are decoded into an arena. Integers are
converted while their digits are in the cache; floats keep only
their digit layout and are converted on read. Containers store the
size of their subtree, so a reader can step over one in constant
time. A document makes a handful of allocations, however many
values it has.
The parser accepts exactly what json::parse accepts, with every
combination of ignore_comments and ignore_trailing_commas, with and
without a trailing NUL, and under JSON_STRICT_NUL_HANDLING. It is
portable C++11 and does not depend on byte order.
basic_json_document adds parse, parse_copy, accept, read (reuses a
document's memory), root, is_discarded, source, owns_source,
node_count, memory_usage, and shrink_to_fit. basic_json_view adds
type, the is_* queries, operator bool, size, empty, materialize,
and source_offset. A parse error throws the same exception
basic_json::parse would throw for the same input, message and
position included.
detail::abi_config keeps JSON_STRICT_NUL_HANDLING and
JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON readable after json.hpp
undefines them, in the ABI namespace so they always match the
basic_json in use.
A NUL byte that ends a // comment is the end of the input, as in
parse() since #5696.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Allow the same type for number_integer_t and number_unsigned_t
basic_json did not compile with NumberUnsignedType == NumberIntegerType
because overloads on both types collided. Such a basic_json now stores
every integer as number_integer: the colliding overloads take a
placeholder type, unsigned C++ integers are converted to number_integer_t,
and value_t::number_unsigned maps to number_integer.
Also fixes two problems this configuration would hit: the unsigned
integer parser accepted values that wrap around to negative numbers, and
dump() overflowed when computing the absolute value of the minimum.
A repeated NumberFloatType gets a static_assert.
Refs #2573
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Use json::with_integers_t in the test and the docs
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* ✅ skip patch test on GCC 5 to avoid internal compiler error
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix CI: name the unsigned overload type through template parameters
basic_json used number_unsigned_overload_t<basic_json> while the class was
still incomplete. MSVC rejected it as a recursive alias declaration and GCC
4.9, 5 and 7 crashed with an internal compiler error. basic_json now uses
number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>, which
also makes the GCC 5 workaround in the patch test unnecessary.
Infer reported a null dereference for the number_unsigned case in
from_json, which cannot happen for a basic_json whose number_unsigned_t is
number_integer_t; assert it.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Address review: conjunction/negation trait, astyle-friendly alias, docs table order
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Niels Lohmann