Skip integer conversion in accept()/SAX validation when the value is unused

lexer::scan_number() always converted every numeric token with
strtoull()/strtoll() before returning, even though accept() (and any
consumer using json_sax_acceptor) immediately discards the converted
value. For value_unsigned/value_integer tokens whose digit count
already guarantees the value fits into 64 bits, the conversion cannot
change the accept/reject decision (such tokens are always finite and
unconditionally accepted), so scan_number() can skip strtoull()/
strtoll() entirely in that case when the caller signals it does not
need the value. Numbers with more digits keep using the exact,
unmodified conversion path, so overflow reclassification to
value_float (and the finiteness check on it) is unaffected.

parse() and value_float handling are completely unchanged.

Fixes #5411

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann
2026-09-05 20:59:51 +02:00
parent 09b6b6b5ba
commit 7b648c7dc4
5 changed files with 188 additions and 16 deletions
+6 -5
View File
@@ -164,11 +164,12 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
detail::parser_callback_t<basic_json>cb = nullptr,
const bool allow_exceptions = true,
const bool ignore_comments = false,
const bool ignore_trailing_commas = false
const bool ignore_trailing_commas = false,
const bool discard_number_values = false
)
{
return ::nlohmann::detail::parser<basic_json, InputAdapterType>(std::move(adapter),
std::move(cb), allow_exceptions, ignore_comments, ignore_trailing_commas);
std::move(cb), allow_exceptions, ignore_comments, ignore_trailing_commas, discard_number_values);
}
private:
@@ -4133,7 +4134,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
const bool ignore_comments = false,
const bool ignore_trailing_commas = false)
{
return parser(detail::input_adapter(std::forward<InputType>(i)), nullptr, false, ignore_comments, ignore_trailing_commas).accept(true);
return parser(detail::input_adapter(std::forward<InputType>(i)), nullptr, false, ignore_comments, ignore_trailing_commas, true).accept(true);
}
/// @brief check if the input is valid JSON (iterator pair, or iterator+sentinel pair for C++20 ranges support)
@@ -4144,7 +4145,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
const bool ignore_comments = false,
const bool ignore_trailing_commas = false)
{
return parser(detail::input_adapter(std::move(first), std::move(last)), nullptr, false, ignore_comments, ignore_trailing_commas).accept(true);
return parser(detail::input_adapter(std::move(first), std::move(last)), nullptr, false, ignore_comments, ignore_trailing_commas, true).accept(true);
}
JSON_HEDLEY_WARN_UNUSED_RESULT
@@ -4153,7 +4154,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
const bool ignore_comments = false,
const bool ignore_trailing_commas = false)
{
return parser(i.get(), nullptr, false, ignore_comments, ignore_trailing_commas).accept(true);
return parser(i.get(), nullptr, false, ignore_comments, ignore_trailing_commas, true).accept(true);
}
/// @brief generate SAX events