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Feature #16006
closed
String count and alignment that consider multibyte characters
Status:
Rejected
Assignee:
-
Target version:
-
Description
In non-proportional font, multibyte characters have twice the width of ASCII characters. Since String#length, String#ljust, String#rjust, and String#center do not take this into consideration, applying these methods do not give the desired output.
array = ["aaあああ", "bいいいいいいいい", "cc"]
col_width = array.max(&:length)
array.each{|w| puts w.ljust(col_width, "*")}
# >> aaあああ****
# >> bいいいいいいいい
# >> cc*******
In order to do justification of strings that have multi-byte characters, we have to do something much more complicated such as the following:
col_widths =
array.to_h{|w| [
w,
w
.chars
.partition(&:ascii_only?)
.then{|ascii, non| ascii.length + (non.length * 2)}
]}
col_width = col_widths.values.max
array.each{|w| puts w + "*" * (col_width - col_widths[w])}
# Note that the following gives the desired alignment in non-proportional font, but may not appear so in this issue tracker.
# >> aaあああ*********
# >> bいいいいいいいい
# >> cc***************
This issue seems to be common, as several webpages can be found that attempt to do something similar.
I propose to give the relevant methods an option to take multibyte characters into consideration. Perhaps something like the proportional keyword in the following may work:
"aaあああ".length(proportional: true) # => 8
"aaあああ".ljust(17, "*", proportional: true) # => "aaあああ*********"
Then, the desired output would be given by this code:
col_width = array.max{|w| w.length(proportional: true)}
array.each{|w| puts w.ljust(col_width, "*", proportional: true)}
# >> aaあああ*********
# >> bいいいいいいいい
# >> cc***************
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