Skip to content

Parse a long input once instead of twice #411

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Algunenano wants to merge 1 commit into
base: main
Choose a base branch
from
Open

Parse a long input once instead of twice #411

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 8 additions & 0 deletions include/fast_float/parse_number.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -336,6 +336,14 @@ from_chars_float_advanced(UC const *first, UC const *last, T &value,
}
bool const bjf = uint64_t(fmt & detail::basic_json_fmt) != 0;

// A mantissa of more than 19 significant digits needs more than 19
// characters, so only a longer input can be too_many_digits. Predicting it
// from the length sends it straight to the span-materializing parse instead
// of parsing once without spans and then re-parsing with them.
if fastfloat_unlikely ((last - first) > 19) {
return parse_number_slow_path<T, UC>(first, last, value, options, bjf);
}

// Fast path: parse WITHOUT materializing the integer/fraction spans (read
// only by the rare slow paths). Skipping their stores keeps the fat
// parsed_number_string_t off the hot path. store_spans is a runtime argument,
Expand Down