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Contents
# frozen_string_literal: true
class ReeString::TruncateBytes
include Ree::FnDSL
fn :truncate_bytes
DEFAULT_OMISSION = "…"
doc(<<~DOC)
Truncates +text+ to at most <tt>bytesize</tt> bytes in length without
breaking string encoding by splitting multibyte characters or breaking
grapheme clusters ("perceptual characters") by truncating at combining
characters.
>> "🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪".size
=> 20
>> "🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪".bytesize
=> 80
>> truncate_bytes("🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪🔪", 20)
=> "🔪🔪🔪🔪…"
The truncated text ends with the <tt>:omission</tt> string, defaulting
to "…", for a total length not exceeding <tt>bytesize</tt>.
DOC
contract(
String,
Integer,
Ksplat[
omission?: String,
] => String
).throws(ArgumentError)
def call(str, truncate_at, **opts)
str = str.dup
omission = opts[:omission] || DEFAULT_OMISSION
case
when str.bytesize <= truncate_at
str
when omission.bytesize > truncate_at
raise ArgumentError, "Omission #{omission.inspect} is #{omission.bytesize}, larger than the truncation length of #{truncate_at} bytes"
when omission.bytesize == truncate_at
omission.dup
else
String.new.tap do |cut|
cut_at = truncate_at - omission.bytesize
str.each_grapheme_cluster do |grapheme|
if cut.bytesize + grapheme.bytesize <= cut_at
cut << grapheme
else
break
end
end
cut << omission
end
end
end
end
Version data entries
126 entries across 126 versions & 1 rubygems