The default dump() (no indentation, no ensure_ascii) gets its own
writer that makes the same walk and produces the same output:
- the write position stays in a local variable instead of a
member, so the compiler keeps it in a register across stores
through aliasing char pointers;
- strings and number tokens are copied with fixed-size 32-byte
moves wherever enough source bytes remain, instead of one
memcpy call per token;
- the innermost open container lives in local variables; a stack
that starts as a local array of 32 entries holds the rest;
- unedited documents are walked through the node array in order,
and integer tokens are read from the source directly.
On top of that, float tokens of at most 15 significant digits are
written straight from their digits via zmij::to_shortest() and
write_shortest(), without converting to a double and back: such
decimals are farther apart than a double's rounding interval, so
the token's digits are the double's shortest digits. Tokens of
16+ digits, or edited values, still go through decimal_to_float().
The view's own NEON write_decimal() is removed in favor of the
shared writer, and the dump output now grows in 64 KiB steps
instead of being resized to its estimate at once.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Niels Lohmann
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