* Move the scanned string into the value instead of copying it
The SAX interface documents that the string handed to json_sax::string() may
be moved from, and the DOM handlers already move the one handed to binary().
string() did not, so every string value was copy-constructed out of the
lexer's token buffer, which then kept the buffer alive at its high-water mark
until the next token overwrote it.
Moving hands that buffer to the new value instead. The allocation count is
unchanged - the value needed one either way - but the copy is gone.
jeopardy 247.3 ms -> 240.9 ms (-2.6%)
citm_catalog 4.61 ms -> 4.48 ms (-2.8%)
40k 30-char strings 7.80 ms -> 7.64 ms (-2.1%)
Note this deliberately does not extend to the object key. Moving the key
hands the lexer's buffer - sized for the largest token seen so far - to a key
that is usually short, so the next value has to grow a fresh buffer. Measured,
that costs 11.9% on a document of many small keys with longer values.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Spell out the move rationale at every handle_value(std::move) site
The comment explaining why the value is moved sat only on
json_sax_dom_parser::string(), and the callback parser's string() pointed
at it with "see json_sax_dom_parser::string()". That reference cannot be
searched for - the function is declared as `bool string(string_t& val)`
inside the class, so the qualified name appears nowhere - and the two
binary() overloads, which have always moved, carried no explanation at all.
Put the same comment on all four sites and name json_sax, which is
greppable, instead of a member that is not.
Comment-only; no generated code changes.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Niels Lohmann
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