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Niels Lohmann
5423dd8de3
After the digits are converted while scanning, copying the token text into token_buffer (an out-of-line std::string::append) was about 10% of parsing canada.json. The only reader is the string argument of json_sax::number_float(), and the library's own handlers (json_sax_dom_parser, json_sax_dom_callback_parser, json_sax_acceptor) ignore it. For contiguous input, the fast path now keeps a pointer to the token in the input, and get_string() copies it on first use. The parser passes an empty string to the handlers marked by the new internal trait sax_ignores_number_text instead of calling get_string(), so json::parse() and json::accept() never copy float text. User handlers, and JSON_DIAGNOSTIC_POSITIONS (which reads get_string().size()), still see the exact text. Keys and strings, which never have pending text, use the unchecked get_string_token(). Input read through a window into a stream (std::istream, FILE*) copies the text right away, because the next read may refill the window. Signed-off-by: Niels Lohmann <mail@nlohmann.me>