text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis vestibulum id augue id mattis. Praesent congue nisi quam, ac gravida enim viverra non. Vestibulum id interdum sapien, vitae volutpat nisi. Praesent id euismod ipsum. Vestibulum et pulvinar urna, id venenatis ante. Cras commodo eget ligula sit amet mattis. Maecenas congue turpis urna, a bibendum sem consequat nec."

def split_string(string, max_length)
  string.scan(/\b.{1,#{max_length}}\b/m).join("\n")
end

puts split_string(text, 50)

字符串

对以下最佳解决方案进行基准测试：

user     system      total        real
Smart Reg (by Cary Swoveland):     1.531920   0.000824   1.532744 (  1.534340)
Simple Reg (by Phil)         :     0.744567   0.000159   0.744726 (  0.745223)
split_string (by Rajagopalan):     0.587626   0.000095   0.587721 (  0.588453)
With index (by Phil)         :     0.696723   0.000051   0.696774 (  0.697468)

字符串
剧本：

require 'benchmark'
MAX_LEN = 70
str = "Exercitation incididunt tempor cupidatat aliquip eu sed ut dolore dolor incididunt amet deserunt culpa dolor cupidatat aliquip do adipisicing ut. Exercitation incididunt tempor cupidatat aliquip eu sed ut dolore dolor incididunt amet deserunt culpa dolor cupidatat aliquip do adipisicing ut. Exercitation incididunt tempor cupidatat aliquip eu sed ut dolore dolor incididunt amet deserunt culpa dolor cupidatat aliquip do adipisicing ut."

# split_string (by Rajagopalan)
def split_string(string, max_length)
  string
   .scan(/\b.{1,#{max_length}}\b/m)
   .join("\n")
end
# puts split_string(str, MAX_LEN)

# With index (by Phil)
def with_indexes(str, max_length)
  segs = []
  o = 0
  start_o = 0
  last_o  = nil
  while o = str.index(' ', o + 1)
    # puts "o = #{o}"
    if o - start_o > max_length
      segs << str[start_o...last_o]
      start_o = last_o + 1
    end
    last_o = o
  end
  segs << str[start_o..-1]
  segs.join("\n")
end
# puts with_indexes(str, MAX_LEN)

# Simple Reg (by Phil)
def with_simple_reg(str, max_length)
  str.scan(/(?:^| )(.{1,#{max_length}})(?:$| )/.freeze)
    .join("\n")
end
# puts with_simple_reg(str, MAX_LEN)

# Smart Reg (by Cary Swoveland)
def with_smart_reg(str, max_length)
  rgx = /
    \S         # match a non-whitespace char
    .{0,#{max_length}}    # match 49 chars
    (?<=\S)    # positive lookbehind asserts previous char is a non-whitespace
    \S         # match a non-whitepace char
    \K         # reset start of match and discard all consumed chars
    (?:\z|\s+) # match the end of the string or >= 1 whitespace chars
  /x           # invoke free-spacing regex definition mode
  s = str.gsub(rgx) { |s| s.empty? ? "" : "\n" }
end
# puts with_smart_reg(str, MAX_LEN)

n = 100000
Benchmark.bm(32) do |x|
  x.report("Smart Reg (by Cary Swoveland): ") { n.times do ; with_smart_reg(str, MAX_LEN)  end }
  x.report("Simple Reg (by Phil)         : ") { n.times do ; with_simple_reg(str, MAX_LEN) end }
  x.report("split_string (by Rajagopalan): ") { n.times do ; split_string(str, MAX_LEN)    end }
  x.report("With index (by Phil)         : ") { n.times do ; with_indexes(str, MAX_LEN)    end }
end

如果str保存字符串，

rgx = /
  \S         # match a non-whitespace char
  .{0,48}    # match up to 48 chars
  \S         # match a non-whitespace
  \K         # reset start of match and discard all consumed chars
  (?:\z|\s+) # match the end of the string or >= 1 whitespace chars
/x           # invoke free-spacing regex definition mode

s = str.gsub(rgx) { |s| s.empty? ? "" : "\n" }

puts s
Lorem ipsum dolor sit amet, consectetur adipiscing
elit. Duis vestibulum id augue id mattis. Praesent
congue nisi quam, ac gravida enim viverra non.
Vestibulum id interdum sapien, vitae volutpat
nisi. Praesent id euismod ipsum. Vestibulum et
pulvinar urna, id venenatis ante. Cras commodo
eget ligula sit amet mattis. Maecenas congue
turpis urna, a bibendum sem consequat nec.

Demo
假设最后一行包含至少两个非空白字符（例如，句点前面有一个字母）。如果最后一行可能包含一个空白字符，则将.{0,48}\S替换为.{0,49}(?<=\S)。

我的解决方案：

text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. […]"
text.scan(/(?:^| )(.{1,50})(?:$| )/)

字符串