Currently, `Integral#chr` in mruby changes behavior by `MRB_UTF8_STRING`
setting.
before this patch:
$ bin/mruby -e 'p 171.chr' #=> "\xab" (`MRB_UTF8_STRING` is disabled)
$ bin/mruby -e 'p 171.chr' #=> "«" (`MRB_UTF8_STRING` is enabled)
This behavior is incompatible with Ruby, and a little inconvenient because
it can't be interpreted as ASCII-8BIT with `MRB_UTF8_STRING`, I think.
So add encoding argument according to Ruby.
after this patch:
$ bin/mruby -e 'p 171.chr' #=> "\xab"
$ bin/mruby -e 'p 171.chr("ASCII-8BIT")' #=> "\xab"
$ bin/mruby -e 'p 171.chr("UTF-8")' #=> "«"
Allow only `String` for encoding because mruby doesn't have `Encoding`
class, and `"ASCII-8BIT"` (`"BINARY"`) and `"UTF-8"` (only with
`MRB_UTF8_STRING`) are valid value (default is `"ASCII-8BIT"`).
We have added internal convenience method `__to_str` which
does string type check.
The issue #3854 was fixed but fundamental flaw of lack of stack
depth check along with fibers still remains. Use `MRB_GC_FIXED_ARENA`
for workaround.
- String#ljust and String#rjust are now C functions to improve performance
- infinite loop because of an empty padding argument is now prevented (ArgumentError is raised)
- extra tests for ljust/rjust added
Here are some benchmarks:
each_char:
# /tmp/each_char.rb
a = "a" * 1000000
a.each_char do |x|
end
Without this change:
% time bin/mruby /tmp/each_char.rb
bin/mruby /tmp/each_char.rb 1.07s user 0.02s system 99% cpu 1.088 total
With this change:
% time bin/mruby /tmp/each_char.rb
bin/mruby /tmp/each_char.rb 0.52s user 0.01s system 99% cpu 0.530 total
2 times faster with this change.
codepoints:
# /tmp/codepoints.rb
a = "a" * 1000000
a.codepoints do |x|
end
Without this change:
% time bin/mruby /tmp/codepoints.rb
bin/mruby /tmp/codepoints.rb 1.16s user 0.05s system 99% cpu 1.216 total
With this change:
% time bin/mruby /tmp/codepoints.rb
bin/mruby /tmp/codepoints.rb 0.56s user 0.02s system 99% cpu 0.589 total
Yukihiro "Matz" Matsumoto