Both were defined as explode | map(...) | implode, which took 4 seconds
on a 10 MB string, about 90 times as long as parsing it.
Change the case of A-Z or a-z a byte at a time in C, copying multibyte
UTF-8 sequences unchanged, so the output stays the same and the 10 MB
case now takes about 60 ms including parsing. On a non-string input the
error now names the function, "ascii_downcase input must be a string",
instead of "explode input must be a string".
jvp_utf8_next() had a fast path for ASCII, but it is not inlined into
its callers, so every byte of a string cost a function call.
Move the end check and the ASCII case into a static inline function in
jv_unicode.h and keep the rest out of line. This speeds up parsing of
string-heavy input by up to 1.17x and string functions such as length,
explode and @html, with the same output for every input.
Michiel van Slobbe